S. Bahinipati

The cross section for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}J/\ensuremath{\psi}$ between 3.8 and $5.5\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ is measured using a $548\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected on or near the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at KEKB. A peak near $4.25\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, corresponding to the so called $Y(4260)$, is observed. In addition, there is another cluster of events at around $4.05\text{ }\text{ }\mathrm{GeV}/{c}^{2}$. A fit using two interfering Breit-Wigner shapes describes the data better than one that uses only the $Y(4260)$, especially for the lower-mass side of the 4.25 GeV enhancement.

We report the observation of a near-threshold enhancement in the omegaJ/psi invariant mass distribution for exclusive B-->KomegaJ/psi decays. The results are obtained from a 253 fb(-1) data sample that contains 275 x 10(6) BB pairs that were collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e(+)e(-) collider. The statistical significance of the omegaJ/psi mass enhancement is estimated to be greater than 8sigma.

The experimental results on the ratios of branching fractions $\mathcal{R}(D) = {\cal B}(\bar{B} \to D \tau^- \bar{\nu}_{\tau})/{\cal B}(\bar{B} \to D \ell^- \bar{\nu}_{\ell})$ and $\mathcal{R}(D^*) = {\cal B}(\bar{B} \to D^* \tau^- \bar{\nu}_{\tau})/{\cal B}(\bar{B} \to D^* \ell^- \bar{\nu}_{\ell})$, where $\ell$ denotes an electron or a muon, show a long-standing discrepancy with the Standard Model predictions, and might hint to a violation of lepton flavor universality. We report a new simultaneous measurement of $\mathcal{R}(D)$ and $\mathcal{R}(D^*)$, based on a data sample containing $772 \times 10^6$ $B\bar{B}$ events recorded at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ collider. In this analysis the tag-side $B$ meson is reconstructed in a semileptonic decay mode and the signal-side $\tau$ is reconstructed in a purely leptonic decay. The measured values are $\mathcal{R}(D)= 0.307 \pm 0.037 \pm 0.016$ and $\mathcal{R}(D^*) = 0.283 \pm 0.018 \pm 0.014$, where the first uncertainties are statistical and the second are systematic. These results are in agreement with the Standard Model predictions within $0.2$, $1.1$ and $0.8$ standard deviations for $\mathcal{R}(D)$, $\mathcal{R}(D^*)$ and their combination, respectively. This work constitutes the most precise measurements of $\mathcal{R}(D)$ and $\mathcal{R}(D^*)$ performed to date as well as the first result for $\mathcal{R}(D)$ based on a semileptonic tagging method.

We present measurements of the branching fractions for the decays $B\to K \mu^{+}\mu^{-}$ and $B\to K e^{+}e^{-}$, and their ratio ($R_{K}$), using a data sample of 711 $fb^{-1}$ that contains $772 \times 10^{6}$ $B\bar{B}$ events. The data were collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The ratio $R_{K}$ is measured in five bins of dilepton invariant-mass-squared ($q^{2}$): $q^{2} \in (0.1, 4.0), (4.0, 8.12), (1.0, 6.0)$, $(10.2, 12.8)$ and ($>14.18) GeV^{2}/c^{4}$, along with the whole $q^2$ region. The $R_{K}$ value for $q^{2} \in (1.0, 6.0) GeV^{2}/c^{4}$ is $1.03^{+0.28}_{-0.24} \pm 0.01$. The first and second uncertainties listed are statistical and systematic, respectively. All results for $R_{K}$ are consistent with Standard Model predictions. We also measure $C\!P$-averaged isospin asymmetries in the same $q^{2}$ bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the $q^{2}\in(1.0,6.0) GeV^{2}/c^{4}$ bin in the mode with muon final states. The measured differential branching fractions, ${d\cal B}/{dq^{2}}$, are consistent with theoretical predictions for charged $B$ decays, while the corresponding values are below the expectations for neutral $B$ decays. We have also searched for lepton-flavor-violating $B \rightarrow K\mu^{\pm}e^{\mp}$ decays and set $90\%$ confidence-level upper limits on the branching fraction in the range of $10^{-8}$ for $B^{+} \rightarrow K^{+}\mu^{\pm}e^{\mp}$, and $B^{0} \rightarrow K^{0}\mu^{\pm}e^{\mp}$ modes.

We observe evidence for D0−¯¯¯D0 mixing by measuring the difference in the apparent lifetime when a D0 meson decays to the CP eigenstates K+K− and π+π− and when it decays to the final state K−π+. We find the relative difference of the lifetimes yCP to be [1.31±0.32(stat)±0.25(syst)]%, 3.2 standard deviations from zero. We also search for a CP asymmetry between D0 and ¯¯¯D0 decays; no evidence for CP violation is found. These results are based on 540 fb−1 of data recorded by the Belle detector at the KEKB e+e− collider.Received 31 March 2007DOI:https://doi.org/10.1103/PhysRevLett.98.211803©2007 American Physical Society

The Collins effect connects transverse quark spin with a measurable azimuthal asymmetry in the yield of hadronic fragments around the quark's momentum vector. Using two different reconstruction methods we measure statistically significant azimuthal asymmetries for charged pion pairs in e+e− annihilation at center-of-mass energies of 10.52 GeV and 10.58 GeV, which can be attributed to the fragmentation of primordial quarks with transverse spin components. The measurement was performed using a data set of 547 fb−1 collected by the Belle detector at KEKB improving the statistics of the previously published results by nearly a factor of 20.17 MoreReceived 19 May 2008DOI:https://doi.org/10.1103/PhysRevD.78.032011©2008 American Physical Society

We present the results of a search for the rare decays $B\to h\nu\overline{\nu}$, where $h$ stands for $K^+,\:K^0_{\mathrm{S}},\:K^{\ast +},\:K^{\ast 0},\:\pi^+,\:\pi^0,\:\rho^+$ and $\rho^{0}$. The results are obtained with $772\times10^{6}$ $B\overline{B}$ pairs collected with the Belle detector at the KEKB $e^+ e^-$ collider. We reconstruct one $B$ meson in a semileptonic decay and require a single $h$ meson but nothing else on the signal side. We observe no significant signal and set upper limits on the branching fractions. The limits set on the $B\to K^0_{\mathrm{S}}\nu\overline{\nu}$, $B^0\to K^{*0}\nu\overline{\nu}$, $B\to \pi^+\nu\overline{\nu}$, $B^0\to\pi^0\nu\overline{\nu}$, $B^+\to\rho^+\nu\overline{\nu}$, and $B^0\to\rho^0\nu\overline{\nu}$ channels are the world's most stringent.

We present a measurement of the differential shapes of exclusive $B\ensuremath{\rightarrow}{D}^{*}\ensuremath{\ell}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}}$ ($B={B}^{\ensuremath{-}},{\overline{B}}^{0}$ and $\ensuremath{\ell}=e$, $\ensuremath{\mu}$) decays with hadronic tag-side reconstruction for the full $711\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ Belle dataset. We extract the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) form factor parameters and use an external input for the absolute branching fractions to determine the Cabibbo-Kobayashi-Maskawa matrix element and find $|{V}_{cb}{|}_{\mathrm{CLN}}=(40.2\ifmmode\pm\else\textpm\fi{}0.9)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ and $|{V}_{cb}{|}_{\mathrm{BGL}}=(40.7\ifmmode\pm\else\textpm\fi{}1.0)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ with the zero-recoil lattice QCD point $\mathcal{F}(1)=0.906\ifmmode\pm\else\textpm\fi{}0.013$. We also perform a study of the impact of beyond zero-recoil lattice QCD calculations on the $|{V}_{cb}|$ determinations. Additionally, we present the lepton-flavor universality ratio ${R}_{e\ensuremath{\mu}}=\mathcal{B}(B\ensuremath{\rightarrow}{D}^{*}e{\overline{\ensuremath{\nu}}}_{e})/\mathcal{B}(B\ensuremath{\rightarrow}{D}^{*}\ensuremath{\mu}{\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}})=0.993\ifmmode\pm\else\textpm\fi{}0.023\ifmmode\pm\else\textpm\fi{}0.023$, the electron and muon forward-backward asymmetry and their difference $\mathrm{\ensuremath{\Delta}}{A}_{FB}=0.028\ifmmode\pm\else\textpm\fi{}0.028\ifmmode\pm\else\textpm\fi{}0.008$, and the electron and muon ${D}^{*}$ longitudinal polarization fraction and their difference $\mathrm{\ensuremath{\Delta}}{F}_{L}^{{D}^{*}}=0.030\ifmmode\pm\else\textpm\fi{}0.025\ifmmode\pm\else\textpm\fi{}0.007$. The uncertainties quoted correspond to the statistical and systematic uncertainties, respectively.

We report results on the Dalitz analysis of three-body charmless B + → K + π + π -and B + → K + K + K -decays based on a 140 fb -1 data sample collected with the Belle detector.Measurements of branching fractions for quasi-two-body decays to scalar-pseudoscalar states: B + → f 0 (980)K + , B + → K * 0 (1430) 0 π + , and to vector-pseudoscalar states:Upper limits on decays to some pseudoscalar-tensor final states are reported.We also report the measurement of the B + → χ c0 K + branching fraction in two χ c0 decays channels: χ c0 → π + π -and χ c0 → K + K -.

We present an improved measurement of the branching fraction for the electroweak penguin process B->Xsll, where l is an electron or a muon and Xs is a hadronic system containing an s-quark. The measurement is based on a sample of 152*10^6 Upsilon(4S) -> BB events collected with the Belle detector at the KEKB energy asymmetric e+e- collider. The Xs hadronic system is reconstructed from one K^{+-} or K^{0}_{S} and up to four pions, where at most one pion can be neutral. Averaging over both lepton flavors, the inclusive branching fraction is measured to be Br(B->Xsll)=(4.11+-0.83(stat)+0.85-0.81(syst))*10^{-6} for M_ll > 0.2GeV/c2.

We present a new analysis of double charmonium production in e + e -annihilation.The observation of the processes e + e -→ J/ψ ηc, J/ψ χc0, and J/ψ ηc(2S) is confirmed using a dataset more than three times larger than that of Belle's previous report, and no evidence for the process e + e -→ J/ψ J/ψ is found.We perform an angular analysis for J/ψ ηc production and set an upper limit on the production of J/ψ J/ψ.Processes of the type e + e -→ ψ(2S)(cc)res have been observed for the first time; their rates are found to be comparable to those of e + e -→ J/ψ(cc)res processes.

We report measurements of the properties of the D(+)(sJ)(2317) and D(+)(sJ)(2457) resonances produced in continuum e(+)e(-) annihilation near sqrt[s]=10.6 GeV. The analysis is based on an 86.9 fb(-1) data sample collected with the Belle detector at KEKB. We determine the masses to be M(D(+)(sJ)(2317))=2317.2+/-0.5(stat)+/-0.9(syst) MeV/c(2) and M(D(+)(sJ)(2457))=2456.5+/-1.3(stat)+/-1.3(syst) MeV/c(2). We observe the radiative decay mode D(+)(sJ)(2457)-->D(+)(s)gamma and the dipion decay mode D(+)(sJ)(2457)-->D(+)(s)pi(+)pi(-) and determine their branching fractions. No corresponding decays are observed for the D(sJ)(2317) state. These results are consistent with the spin-parity assignments of 0(+) for the D(sJ)(2317) and 1(+) for the D(sJ)(2457).

We report an observation of the decay B{0}-->D{*-}tau{+}nu{tau} in a data sample containing 535x10{6} BB pairs collected with the Belle detector at the KEKB asymmetric-energy e{+}e{-} collider. We find a signal with a significance of 5.2sigma and measure the branching fraction B(B{0}-->D{*-}tau{+}nu{tau})=(2.02{-0.37}{+0.40}(stat)+/-0.37(syst))%. This is the first observation of an exclusive B decay with a b-->ctaunu{tau} transition.

We report evidence for direct CP violation in the decay B0-->K+pi(-) with 253 fb(-1) of data collected with the Belle detector at the KEKB e(+)e(-) collider. Using 275x10(6) BB pairs we observe a B-->K+/-pi(-/+) signal with 2140+/-53 events. The measured CP violating asymmetry is A(CP)(K+pi(-))=-0.101+/-0.025(stat)+/-0.005(syst), corresponding to a significance of 3.9sigma including systematics. We also search for CP violation in the decays B+-->K+pi(0) and B+-->pi(+)pi(0). The measured CP violating asymmetries are A(CP)(K+pi(0))=0.04+/-0.05(stat)+/-0.02(syst) and A(CP)(pi(+)pi(0))=-0.02+/-0.10(stat)+/-0.01(syst), corresponding to the intervals -0.05<A(CP)(K+pi(0))<0.13 and -0.18<A(CP)(pi(+)pi(0))<0.14 at 90% confidence level.

We report results on a Dalitz analysis of three-body charmless B+/- --> K+/-pi+/-pi+/- decay including searches for direct CP violation. We report the first observation of the decay B+/- --> f2(1270)K+/- with a statistical significance above 6sigma. We also observe first evidence for large direct CP violation in the B+/- --> rho(770)0K+/- channel. The results are obtained with a data sample that contains 386 10(6) BB pairs collected at the Y(4s) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

Received 25 April 2018DOI:https://doi.org/10.1103/PhysRevD.97.099902© 2018 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFlavor changing neutral currentsParticle decaysParticle interactionsParticles & Fields

We present a search for the direct production of a light pseudoscalar a decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process e^{+}e^{-}→γa, a→γγ in the mass range 0.2<m_{a}<9.7 GeV/c^{2} using data corresponding to an integrated luminosity of (445±3) pb^{-1}. Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axionlike particles or ALPs) are frequently postulated in extensions of the standard model. We find no evidence for ALPs and set 95% confidence level upper limits on the coupling strength g_{aγγ} of ALPs to photons at the level of 10^{-3} GeV^{-1}. The limits are the most restrictive to date for 0.2<m_{a}<1 GeV/c^{2}.

We present the study of $\bar{B}^{0} \to \Sigma_{c}(2455)^{0,++} \pi^{\pm} \bar{p}$ decays based on $772\times 10^{6}$ $B\bar{B}$ events collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The $\Sigma_{c}(2455)^{0,++} $ candidates are reconstructed via their decay to $\Lambda_{c}^{+} \pi^{\mp}$ and $\Lambda_{c}^{+}$ decays to $pK^{-}\pi^{+},~pK_{S}^{0},$ and $\Lambda\pi^{+}$ final states. The corresponding branching fractions are measured to be ${\cal B}(\bar{B}^{0} \to \Sigma_{c}(2455)^{0} \pi^{+} \bar{p}) = (1.09 \pm 0.06 \pm 0.07)\times10^{-4}$ and ${\cal B}(\bar{B}^{0} \to \Sigma_{c}(2455)^{++} \pi^{-} \bar{p}) = (1.84\pm 0.11 \pm 0.12)\times 10^{-4}$, which are consistent with the world average values with improved precision. A new structure is found in the $M_{\Sigma_{c}(2455)^{0,++}\pi^{\pm}}$ spectrum with a significance of $4.2\sigma$ including systematic uncertainty. The structure is possibly an excited $\Lambda_{c}^{+}$ and is tentatively named $\Lambda_{c}(2910)^{+}$. Its mass and width are measured to be $(2913.8 \pm 5.6 \pm 3.8)$ MeV/$c^{2}$ and $(51.8\pm20.0 \pm 18.8)$ MeV, respectively. The products of branching fractions for the $\Lambda_{c}(2910)^{+}$ are measured to be ${\cal B}(\bar{B}^{0} \to \Lambda_{c}(2910)^{+}\bar{p})\times{\cal B}(\Lambda_{c}(2910)^{+} \to \Sigma_{c}(2455)^{0}\pi^{+}) = (9.5 \pm 3.6 \pm 1.6)\times 10^{-6}$ and ${\cal B}(\bar{B}^{0} \to \Lambda_{c} (2910)^{+}\bar{p})\times {\cal B}(\Lambda_{c}(2910)^{+} \to \Sigma_{c}(2455)^{++}\pi^{-}) = (1.24 \pm 0.35 \pm 0.10)\times 10^{-5}$. Here, the first and second uncertainties are statistical and systematic, respectively.

We present the first measurement of the ratio of branching fractions of inclusive semileptonic B-meson decays, R(X_{e/μ})=B(B→Xeν)/B(B→Xμν), a precision test of electron-muon universality, using data corresponding to 189 fb^{-1} from electron-positron collisions collected with the Belle II detector. In events where the partner B meson is fully reconstructed, we use fits to the lepton momentum spectra above 1.3 GeV/c to obtain R(X_{e/μ})=1.007±0.009(stat)±0.019(syst), which is the most precise lepton-universality test of its kind and agrees with the standard-model expectation.

We present measurements of decay amplitudes and triple-product correlations in B→ϕK∗ decays based on 253 fb−1 of data recorded at the Υ(4S) resonance with the Belle detector at the KEKB e+e− storage ring. The decay amplitudes for the three different helicity states are determined from the angular distributions of final-state particles. The longitudinal polarization amplitudes are found to be 0.45±0.05±0.02 for B0→ϕK*0 and 0.52±0.08±0.03 for B+→ϕK*+ decays. CP- and T-odd CP-violating triple-product asymmetries are measured to be consistent with zero.Received 6 March 2005DOI:https://doi.org/10.1103/PhysRevLett.94.221804©2005 American Physical Society

We report the first observation of the charmless vector-vector decay process B∓→ρ∓ρ0. The measurement uses a 78 fb−1 data sample collected with the Belle detector at the KEKB asymmetric e+e− collider operating at the Υ(4S) resonance. We obtain a branching fraction of B(B∓→ρ∓ρ0)=[31.7±7.1(stat)−6.7+3.8(syst)]×10−6. An analysis of the ρ helicity-angle distributions gives a longitudinal polarization fraction of ΓL/Γ=0.95±0.11(stat)±0.02(syst). We also measure the direct-CP-violating asymmetry ACP(B∓→ρ∓ρ0)=0.00±0.22(stat)±0.03(syst).Received 3 June 2003DOI:https://doi.org/10.1103/PhysRevLett.91.221801©2003 American Physical Society

We report measurements of the radiative decay B → K * γ.The analysis is based on a data sample containing 85.0 × 10 6 B meson pairs collected by the Belle detector at the KEKB storage ring.We measure branching fractions of B(B 0 → K * 0 γ) = (4.01 ± 0.21 ± 0.17) × 10 -5 and B(B + → K * + γ) = (4.25 ± 0.31 ± 0.24) × 10 -5 , where the first and second errors are statistical and systematic, respectively.The isospin asymmetry between B 0 and B + decay widths is measured to be ∆0+ = +0.012± 0.044 ± 0.026.We search for a partial rate asymmetry between CP conjugate modes, and find ACP (B → K * γ) = -0.015± 0.044 ± 0.012.

We present an improved measurement of CP-violation parameters in B0-->phiK(0)(S), K(+)K(-)K(0)(S), and eta(')K(0)(S) decays based on a 140 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. One neutral B meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters for each of the three modes are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays. We find that the observed CP asymmetry in the B-->phiK(0)(S) decay differs from the standard model (SM) expectation by 3.5 standard deviations, while the other cases are consistent with the SM.

We present a precise measurement of the standard model $CP$-violation parameter $\mathrm{sin}2{\ensuremath{\phi}}_{1}$, the direct $CP$ violation parameter $|\ensuremath{\lambda}|$, the lifetimes of charged and neutral $B$ mesons and their ratio, and the ${B}^{0}$-${\overline{B}}^{0}$ mixing parameter $\ensuremath{\Delta}{m}_{d}$ based on a sample of $152\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. One of two $B$ mesons is fully reconstructed in a $CP$-eigenstate or a flavor-eigenstate decay channel. The flavor of the accompanying $B$ meson is identified from its decay products. From the distributions of the time interval between the two $B$ meson decay points, we obtain $\mathrm{sin}2{\ensuremath{\phi}}_{1}=0.728\ifmmode\pm\else\textpm\fi{}0.056(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.023(\mathrm{syst})$, $|\ensuremath{\lambda}|=1.007\ifmmode\pm\else\textpm\fi{}0.041(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.033(\mathrm{syst})$, ${\ensuremath{\tau}}_{{B}^{0}}=[1.534\ifmmode\pm\else\textpm\fi{}0.008(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.010(\mathrm{syst})]\text{ }\text{ }\mathrm{ps}$, ${\ensuremath{\tau}}_{{B}^{+}}=[1.635\ifmmode\pm\else\textpm\fi{}0.011(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.011(\mathrm{syst})]\text{ }\text{ }\mathrm{ps}$, ${\ensuremath{\tau}}_{{B}^{+}}/{\ensuremath{\tau}}_{{B}^{0}}=1.066\ifmmode\pm\else\textpm\fi{}0.008(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.008(\mathrm{syst})$ and $\ensuremath{\Delta}{m}_{d}=[0.511\ifmmode\pm\else\textpm\fi{}0.005(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.006{(\mathrm{syst})]\text{ }\text{ }\mathrm{ps}}^{\ensuremath{-}1}$. The results for $\mathrm{sin}2{\ensuremath{\phi}}_{1}$ and $|\ensuremath{\lambda}|$ are consistent with the standard model expectations. The significance of the observed deviation from unity in the lifetime ratio exceeds 5 standard deviations.

In the original article, it was found in Monte Carlo simulations that the reconstructed A₀ results are roughly consistent with the generated asymmetries, while the A₁₂ results systematically underestimate the generated asymmetries. This underestimation can be attributed to the difference between the reconstructed thrust axis and the original quark-antiquark axis. The corresponding correction factors are 1.6 ± 0.04 for the A₁₂ results and 1.11 ± 0.05 for the A₀ results. Because of a flaw in the original analysis program, these correction factors were not applied to the AUC-type asymmetries in Table V as well as in some figures. In addition, a small mistake in the error propagation in the charm correction resulted in slightly underestimated statistical uncertainties. These omissions affect all but the charm asymmetry results. The correct central values are therefore given in Tables IV and V of this Erratum. The systematic uncertainties of the original publication remain unchanged.

Using a data sample of $980\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider, we report the results of a study of excited ${\mathrm{\ensuremath{\Xi}}}_{c}$ states that decay, via the emission of photons and/or charged pions, into ${\mathrm{\ensuremath{\Xi}}}_{c}^{0}$ or ${\mathrm{\ensuremath{\Xi}}}_{c}^{+}$ ground state charmed-strange baryons. We present new measurements of the masses of all members of the ${\mathrm{\ensuremath{\Xi}}}_{c}^{\ensuremath{'}}$, ${\mathrm{\ensuremath{\Xi}}}_{c}(2645)$, ${\mathrm{\ensuremath{\Xi}}}_{c}(2790)$, ${\mathrm{\ensuremath{\Xi}}}_{c}(2815)$, and ${\mathrm{\ensuremath{\Xi}}}_{c}(2980)$ isodoublets, measurements of the intrinsic widths of those that decay strongly, and evidence of previously unknown transitions.

We report a study of Λc+→Λh+ and Λc+→Σ0h+ (h=K,π) decays based on a data sample of 980fb-1 collected with the Belle detector at the KEKB energy-asymmetric e+e- collider. The first results of direct CP asymmetry in two-body singly Cabibbo-suppressed (SCS) decays of charmed baryons are measured, ACPdir(Λc+→ΛK+)=+0.021±0.026±0.001 and ACPdir(Λc+→Σ0K+)=+0.025±0.054±0.004. We also make the most precise measurement of the decay asymmetry parameters (α) for the four modes of interest and search for CP violation via the α-induced CP asymmetry (ACPα). We measure ACPα(Λc+→ΛK+)=-0.023±0.086±0.071 and ACPα(Λc+→Σ0K+)=+0.08±0.35±0.14, which are the first ACPα results for SCS decays of charmed baryons. We search for Λ-hyperon CP violation in Λc+→(Λ,Σ0)π+ and find ACPα(Λ→pπ-)=+0.013±0.007±0.011. This is the first time that hyperon CP violation has been measured via Cabibbo-favored charm decays. No evidence of baryon CP violation is found. We also obtain the most precise branching fractions for two SCS Λc+ decays, B(Λc+→ΛK+)=(6.57±0.17±0.11±0.35)×10-4 and B(Λc+→Σ0K+)=(3.58±0.19±0.06±0.19)×10-4. The first uncertainties are statistical and the second systematic, while the third uncertainties come from the uncertainties on the world average branching fractions of Λc+→(Λ,Σ0)π+.

We present measurements of the first to fourth moments of the lepton mass squared q2 of B→Xcℓ¯νℓ decays for ℓ=e, μ and with Xc a hadronic system containing a charm quark. These results use a sample of electron-positron collisions at the Υ(4S) resonance corresponding to 62.8 fb−1 of integrated luminosity and collected by the Belle II 2 experiment in 2019 and 2020. To identify the Xc system and reconstruct q2, one of the B mesons from an Υ(4S)→B¯B decay is fully reconstructed in a hadronic decay mode using a multivariate B tagging algorithm. We report raw and central moments for q2>1.5 GeV2/c4 up to q2>8.5 GeV2/c4, probing up to 77% of the accessible B→Xcℓ¯νℓ phase space. This is the first measurement of moments in the experimentally challenging range of [1.5,2.5] GeV2/c4. The results can be used for a new determination of |Vcb| using inclusive B→Xcℓ¯νℓ decays.9 MoreReceived 16 May 2022Accepted 20 October 2022DOI:https://doi.org/10.1103/PhysRevD.107.072002Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasHeavy quark effective theoryLeptonic, semileptonic & radiative decaysPhysical SystemsBottom mesonsTechniquesParticle data analysisPrecision measurementsParticles & Fields

This paper presents a search for the rare flavor-changing neutral current process ${B}^{0}\ensuremath{\rightarrow}{K}^{*0}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ using data taken with the Belle detector at the KEKB asymmetric energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. The analysis is based on the entire $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance data sample of $711\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, corresponding to $772\ifmmode\times\else\texttimes\fi{}{10}^{6}B\overline{B}$ pairs. In our search we fully reconstruct the companion $B$ meson produced in the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Upsilon}}(4S)\ensuremath{\rightarrow}B\overline{B}$ from its hadronic decay modes, and look for the decay ${B}^{0}\ensuremath{\rightarrow}{K}^{*0}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ in the rest of the event. No evidence for a signal is found. We report an upper limit on the branching fraction $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{K}^{*0}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}})&lt;3.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ at 90% confidence level. This is the first direct limit on $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{K}^{*0}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}})$.

We measure the ratio of branching fractions for the $\mathrm{\ensuremath{\Upsilon}}(4S)$ decays to ${B}^{+}{B}^{\ensuremath{-}}$ and ${B}^{0}{\overline{B}}^{0}$ using ${B}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}(\ensuremath{\ell}\ensuremath{\ell}){K}^{+}$ and ${B}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}(\ensuremath{\ell}\ensuremath{\ell}){K}^{0}$ samples, where $J/\ensuremath{\psi}(\ensuremath{\ell}\ensuremath{\ell})$ stands for $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ ($\ensuremath{\ell}=e$ or $\ensuremath{\mu}$), with $711\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected at the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance with the Belle detector. We find the decay rate ratio of $\mathrm{\ensuremath{\Upsilon}}(4S)\ensuremath{\rightarrow}{B}^{+}{B}^{\ensuremath{-}}$ over $\mathrm{\ensuremath{\Upsilon}}(4S)\ensuremath{\rightarrow}{B}^{0}{\overline{B}}^{0}$ to be $1.065\ifmmode\pm\else\textpm\fi{}0.012\ifmmode\pm\else\textpm\fi{}0.019\ifmmode\pm\else\textpm\fi{}0.047$, which is the most precise measurement to date. The first and second uncertainties are statistical and systematic, respectively, and the third uncertainty is due to the assumption of isospin symmetry in $B\ensuremath{\rightarrow}J/\ensuremath{\psi}(\ensuremath{\ell}\ensuremath{\ell})K$.

We search for lepton-flavor-violating τ^{-}→e^{-}α and τ^{-}→μ^{-}α decays, where α is an invisible spin-0 boson. The search uses electron-positron collisions at 10.58 GeV center-of-mass energy with an integrated luminosity of 62.8 fb^{-1}, produced by the SuperKEKB collider and collected with the Belle II detector. We search for an excess in the lepton-energy spectrum of the known τ^{-}→e^{-}ν[over ¯]_{e}ν_{τ} and τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} decays. We report 95% confidence-level upper limits on the branching-fraction ratio B(τ^{-}→e^{-}α)/B(τ^{-}→e^{-}ν[over ¯]_{e}ν_{τ}) in the range (1.1-9.7)×10^{-3} and on B(τ^{-}→μ^{-}α)/B(τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ}) in the range (0.7-12.2)×10^{-3} for α masses between 0 and 1.6 GeV/c^{2}. These results provide the most stringent bounds on invisible boson production from τ decays.

The L_{μ}-L_{τ} extension of the standard model predicts the existence of a lepton-flavor-universality-violating Z^{'} boson that couples only to the heavier lepton families. We search for such a Z^{'} through its invisible decay in the process e^{+}e^{-}→μ^{+}μ^{-}Z^{'}. We use a sample of electron-positron collisions at a center-of-mass energy of 10.58 GeV collected by the Belle II experiment in 2019-2020, corresponding to an integrated luminosity of 79.7 fb^{-1}. We find no excess over the expected standard-model background. We set 90%-confidence-level upper limits on the cross section for this process as well as on the coupling of the model, which ranges from 3×10^{-3} at low Z^{'} masses to 1 at Z^{'} masses of 8 GeV/c^{2}.

We present a measurement of the τ-lepton mass using a sample of about 175 million e+e−→τ+τ− events collected with the Belle II detector at the SuperKEKB e+e− collider at a center-of-mass energy of 10.579 GeV. This sample corresponds to an integrated luminosity of 190 fb−1. We use the kinematic edge of the τ pseudomass distribution in the decay τ−→π−π+π−ντ and measure the τ mass to be 1777.09±0.08±0.11 MeV/c2, where the first uncertainty is statistical and the second systematic. This result is the most precise to date.Received 31 May 2023Accepted 13 July 2023DOI:https://doi.org/10.1103/PhysRevD.108.032006Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Physical SystemsTau leptonsPropertiesMassTechniquesPrecision measurementsParticles & Fields

We present a measurement of the unitarity triangle angle ${\ensuremath{\phi}}_{3}$ using a Dalitz plot analysis of the three-body decay of the neutral $D$ meson from the ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{D}^{(*)}{K}^{\ifmmode\pm\else\textpm\fi{}}$ process. The method employs the interference between ${D}^{0}$ and $\overline{{D}^{0}}$ to extract both the weak and strong phases. We apply this method to a $140\text{ }\text{ }{\mathrm{f}\mathrm{b}}^{\ensuremath{-}1}$ data sample collected by the Belle experiment. The analysis uses the modes ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}D{K}^{\ifmmode\pm\else\textpm\fi{}}$ and ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{D}^{*}{K}^{\ifmmode\pm\else\textpm\fi{}}$, ${D}^{*}\ensuremath{\rightarrow}D{\ensuremath{\pi}}^{0}$, where the neutral $D$ meson decays into ${K}_{S}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$. We obtain 146 signal candidates for ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}D{K}^{\ifmmode\pm\else\textpm\fi{}}$ and 39 candidates for ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{D}^{*}{K}^{\ifmmode\pm\else\textpm\fi{}}$. From a combined maximum likelihood fit to the ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}D{K}^{\ifmmode\pm\else\textpm\fi{}}$ and ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{D}^{*}{K}^{\ifmmode\pm\else\textpm\fi{}}$ modes, we obtain ${\ensuremath{\phi}}_{3}=77\ifmmode^\circ\else\textdegree\fi{}\genfrac{}{}{0}{}{+17\ifmmode^\circ\else\textdegree\fi{}}{\ensuremath{-}19\ifmmode^\circ\else\textdegree\fi{}}(\mathrm{\text{stat}})\ifmmode\pm\else\textpm\fi{}13\ifmmode^\circ\else\textdegree\fi{}(\mathrm{\text{syst}})\ifmmode\pm\else\textpm\fi{}11\ifmmode^\circ\else\textdegree\fi{}(\mathrm{\text{model}})$. The corresponding 2 standard deviation interval is $26\ifmmode^\circ\else\textdegree\fi{}&lt;{\ensuremath{\phi}}_{3}&lt;126\ifmmode^\circ\else\textdegree\fi{}$.

We report the results of a search for D0-D0 mixing in D0 --> K+ pi- decays based on 400 fb(-1) of data accumulated by the Belle detector at KEKB. Both assuming CP conservation and allowing for CP violation, we fit the decay-time distribution for the mixing parameters x and y, as well as for the parameter R(D), the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays. The 95% confidence level region in the (x'2,y') plane is obtained using a frequentist method. Assuming CP conservation, we find x'2 < 0.72 x 10(-3) and -9.9 x 10(-3) < y' < 6.8 x 10(-3) at the 95% confidence level; these are the most stringent constraints on the mixing parameters to date. The no-mixing point (0,0) has a confidence level of 3.9%. Assuming no mixing, we measure R(D) = (0.377 +/- 0.008 +/- 0.005)%.

We present a measurement of the unitarity triangle angle ${\ensuremath{\phi}}_{3}$ using a Dalitz plot analysis of the ${K}_{S}^{0}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ decay of the neutral $D$ meson from the ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{D}^{(*)}{K}^{(*)\ifmmode\pm\else\textpm\fi{}}$ process. The method exploits the interference between ${D}^{0}$ and ${\overline{D}}^{0}$ to extract the angle ${\ensuremath{\phi}}_{3}$, strong phase $\ensuremath{\delta}$ and the ratio $r$ of suppressed and allowed amplitudes. We apply this method to a $357\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected by the Belle experiment. The analysis uses three modes: ${B}^{+}\ensuremath{\rightarrow}D{K}^{+}$, ${B}^{+}\ensuremath{\rightarrow}{D}^{*}{K}^{+}$ with ${D}^{*}\ensuremath{\rightarrow}D{\ensuremath{\pi}}^{0}$, and ${B}^{+}\ensuremath{\rightarrow}D{K}^{*+}$ with ${K}^{*+}\ensuremath{\rightarrow}{K}_{S}^{0}{\ensuremath{\pi}}^{+}$, as well as the corresponding charge-conjugate modes. From a combined maximum likelihood fit to the three modes, we obtain ${\ensuremath{\phi}}_{3}=53\ifmmode^\circ\else\textdegree\fi{}\genfrac{}{}{0}{}{+15\ifmmode^\circ\else\textdegree\fi{}}{\ensuremath{-}18\ifmmode^\circ\else\textdegree\fi{}}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}3\ifmmode^\circ\else\textdegree\fi{}(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}9\ifmmode^\circ\else\textdegree\fi{}(\mathrm{\text{model}})$. The corresponding 2 standard deviation interval is $8\ifmmode^\circ\else\textdegree\fi{}&lt;{\ensuremath{\phi}}_{3}&lt;111\ifmmode^\circ\else\textdegree\fi{}$.

We present new measurements of CP-violation parameters in B0 -&gt; phiK0, K+K-Ks, f0(980)Ks, eta'Ks, omegaKs and Kspi0 decays based on a sample of 275 x 10^6 BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e- collider. One neutral B meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters for each of the decay modes are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays. The combined result for the B0-&gt;phiK0, K+K-Ks, f0(980)Ks, eta'Ks, omegaKs, Kspi0, and previously reported KsKsKs decays differs from the SM expectation by 2.4 standard deviations.

The angular distributions of the baryon-antibaryon low-mass enhancements seen in the charmless three-body baryonic B decays B+ -> p pbar K+, B0 -> p pbar Ks, and B0 -> p Lambdabar pi- are reported. A quark fragmentation interpretation is supported, while the gluonic resonance picture is disfavored. Searches for the Theta+ and Theta++ pentaquarks in the relevant decay modes and possible glueball states G with 2.2 GeV/c2 < M-ppbar < 2.4 GeV/c2 in the ppbar systems give null results. We set upper limits on the products of branching fractions, B(B0 -> Theta+ p)\times B(Theta+ -> p Ks) < 2.3 \times 10^{-7}, B(B+ -> Theta++ pbar) \times B(Theta++ -> p K+) < 9.1 \times 10^{-8}, and B(B+ -> G K+) \times B(G -> p pbar) < 4.1 \times 10^{-7} at the 90% confidence level. The analysis is based on a 140 fb^{-1} data sample recorded on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

The e þ e -→ π þ π -π 0 χ bJ (J ¼ 0; 1; 2) processes are studied using a 118 fb -1 data sample acquired with the Belle detector at a center-of-mass energy of 10.867 GeV.Unambiguous π þ π -π 0 χ bJ (J ¼ 1; 2), ωχ b1 signals are observed, and indication for ωχ b2 is seen, both for the first time, and the corresponding cross section measurements are presented.No significant π þ π -π 0 χ b0 or ωχ b0 signals are observed, and 90% confidence level upper limits on the cross sections for these two processes are obtained.In the π þ π -π 0 invariant mass spectrum, significant non-ω signals are also observed.We search for the Xð3872Þ-like state (named X b ) decaying into ωϒð1SÞ; no significant signal is observed with a mass between 10.55 and 10.65 GeV=c 2 .

Using data recorded with the Belle detector, we observe a new excited hyperon, an $\Omega^{*-}$ candidate decaying into $\Xi^0K^-$ and $\Xi^-K^0_S$ with a mass of $2012.4\pm0.7\ {\rm (stat)\pm\ 0.6\ (\rm syst)}\ {\rm MeV}/c^2$ and a width of $\Gamma=6.4^{+2.5}_{-2.0}\ {\rm(stat)}\pm1.6\ {\rm(syst)}\ {\rm MeV}$. The $\Omega^{*-}$ is seen primarily in $\Upsilon(1S), \Upsilon(2S)$, and $\Upsilon(3S)$ decays.

We report a study of the decay D^{0}→K_{S}^{0}K_{S}^{0} using 921 fb^{-1} of data collected at or near the ϒ(4S) and ϒ(5S) resonances with the Belle detector at the KEKB asymmetric energy e^{+}e^{-} collider. The measured time-integrated CP asymmetry is A_{CP}(D^{0}→K_{S}^{0}K_{S}^{0})=(-0.02±1.53±0.02±0.17)%, and the branching fraction is B(D^{0}→K_{S}^{0}K_{S}^{0})=(1.321±0.023±0.036±0.044)×10^{-4}, where the first uncertainty is statistical, the second is systematic, and the third is due to the normalization mode (D^{0}→K_{S}^{0}π^{0}). These results are significantly more precise than previous measurements available for this mode. The A_{CP} measurement is consistent with the standard model expectation.

Abstract From April to July 2018, a data sample at the peak energy of the <?CDATA $ \varUpsilon \left( {4{\rm{S}}} \right)$?> resonance was collected with the Belle II detector at the SuperKEKB electron-positron collider. This is the first data sample of the Belle II experiment. Using Bhabha and digamma events, we measure the integrated luminosity of the data sample to be ( <?CDATA $ 496.3 \pm 0.3 \pm 3.0)\;{\rm pb}^{-1}$?> , where the first uncertainty is statistical and the second is systematic. This work provides a basis for future luminosity measurements at Belle II.

Charged lepton flavor violation is forbidden in the Standard Model but possible in several new physics scenarios. In many of these models, the radiative decays $\tau^{\pm}\rightarrow\ell^{\pm}\gamma$ ($\ell=e,\mu$) are predicted to have a sizeable probability, making them particularly interesting channels to search at various experiments. An updated search via $\tau^{\pm}\rightarrow\ell^{\pm}\gamma$ using full data of the Belle experiment, corresponding to an integrated luminosity of 988 fb$^{-1}$, is reported for charged lepton flavor violation. No significant excess over background predictions from the Standard Model is observed, and the upper limits on the branching fractions, $\mathcal{B}(\tau^{\pm}\rightarrow \mu^{\pm}\gamma)$ $\leq$ $4.2\times10^{-8}$ and $\mathcal{B}(\tau^{\pm}\rightarrow e^{\pm}\gamma)$ $\leq$ $5.6\times10^{-8}$, are set at 90\% confidence level.

Abstract The Silicon Vertex Detector of Belle II is a state-of-the-art tracking and vertexing system based on double-sided silicon strip sensors, designed and fabricated by a large international collaboration in the period 2012–2018. Since 2019 it has been in operation providing high quality data with a small number of defective channels (&lt;1%), a large hit-finding efficiency (&gt;99%), a good signal-to-noise ratio (well in excess of 10 for all sensor configurations and tracks). Together with the good control over the alignment, these are all essential factors to achieve good tracking reconstruction and physics performance. In this extended paper we try to document all the aspects of the SVD challenges and achievements, in the spirit of providing information to the broader community and help the development of high quality detector systems, which are essential tools to carry out physics research.

We report a study of Λ+c→Σ+π0, Λ+c→Σ+η, and Λ+c→Σ+η′ using the data sample corresponding to an integrated luminosity of 980 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. The branching fractions relative to Λ+c→Σ+π0 are measured as BΛ+c→Σ+η/BΛ+c→Σ+π0=0.25±0.03±0.01 and BΛ+c→Σ+η′/BΛ+c→Σ+π0=0.33±0.06±0.02. Using BΛ+c→Σ+π0=(1.25±0.10)%, we obtain BΛ+c→Σ+η=(3.14±0.35±0.17±0.25)×10−3 and BΛ+c→Σ+η′=(4.16±0.75±0.25±0.33)×10−3. Here the uncertainties are statistical, systematic, and from BΛ+c→Σ+π0, respectively. The ratio of the branching fraction of Λ+c→Σ+η′ with respect to that of Λ+c→Σ+η is measured to be BΛ+c→Σ+η′/BΛ+c→Σ+η=1.34±0.28±0.08. We update the asymmetry parameter of Λ+c→Σ+π0, αΣ+π0=−0.48±0.02±0.02, with a considerably improved precision. The asymmetry parameters of Λ+c→Σ+η and Λ+c→Σ+η′ are measured to be αΣ+η=−0.99±0.03±0.05 and αΣ+η′=−0.46±0.06±0.03 for the first time.1 MoreReceived 23 August 2022Accepted 8 December 2022DOI:https://doi.org/10.1103/PhysRevD.107.032003Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBranching fractionPhysical SystemsCharmed baryonsTechniquesLepton collidersParticles & Fields

We measure the ${B}^{0}$ lifetime and flavor-oscillation frequency using ${B}^{0}\ensuremath{\rightarrow}{D}^{(*)\ensuremath{-}}{\ensuremath{\pi}}^{+}$ decays collected by the Belle II experiment in asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collisions produced by the SuperKEKB collider operating at the $\mathrm{\ensuremath{\Upsilon}}(4\mathrm{S})$ resonance. We fit the decay-time distribution of signal decays, where the initial flavor is determined by identifying the flavor of the other $B$ meson in the event. The results, based on 33000 signal decays reconstructed in a data sample corresponding to $190\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, are ${\ensuremath{\tau}}_{{B}^{0}}=(1.499\ifmmode\pm\else\textpm\fi{}0.013\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0ex}{0ex}}0.008)\text{ }\text{ }\mathrm{ps}$, $\mathrm{\ensuremath{\Delta}}{m}_{d}=(0.516\ifmmode\pm\else\textpm\fi{}0.008\ifmmode\pm\else\textpm\fi{}0.005)\text{ }\text{ }{\mathrm{ps}}^{\ensuremath{-}1}$, where the first uncertainties are statistical and the second are systematic. These results are consistent with the world-average values.

We report the observation of the radiative decay B+ --> K1(1270)+ gamma using a data sample of 140 fb-1 taken at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. We find the branching fraction to be Br(B+ --> K1(1270)+ gamma) = (4.3 +- 0.9(stat.) +- 0.9(syst.)) x 10-5 with a statistical significance of 7.3sigma. We find no significant signal for B+ --> K1(1400)+ gamma and set an upper limit Br(B+ --> K1(1400)+ gamma) < 1.5 x 10-5 at the 90% confidence level. We also measure inclusive branching fractions for B+ --> K+ pi+ pi- gamma and B0 --> K0 pi+ pi- gamma in the mass range 1 GeV/c^2 < M(K+(0)pi+pi-) < 2 GeV/c^2.

We have measured π+π− and K+K− production in two-photon collisions using 87.7fb−1 of data collected with the Belle detector at the asymmetric energy e+e− collider KEKB. The cross sections are measured to high precision in the two-photon center-of-mass energy (W) range between 2.4GeV<W<4.1GeV and angular region |cosθ∗|<0.6. The cross section ratio σ(γγ→K+K−)/σ(γγ→π+π−) is measured to be 0.89±0.04(stat.)±0.15(syst.) in the range of 3.0GeV<W<4.1GeV, where the ratio is energy-independent. We observe a sin−4θ∗ behavior of the cross section in the same W range. Production of χc0 and χc2 mesons is observed in both γγ→π+π− and γγ→K+K− modes.

We present a search for the rare decays B → h ( * ) νν, where h ( * ) stands for a light meson.A data sample of 535 million BB pairs collected with the Belle detector at the KEKB e + e -collider is used.Signal candidates are required to have an accompanying B meson fully reconstructed in a hadronic mode and signal-side particles consistent with a single h ( * ) meson.No significant signal is observed and we set upper limits on the branching fractions at 90% confidence level.The limits on B 0 → K * 0 νν and B + → K + νν decays are more stringent than the previous constraints, while the first searches for B 0 → K 0 νν, π 0 νν, ρ 0 νν, φνν and B + → K * + νν, ρ + νν are reported.

We report results of a Dalitz plot analysis of the three-body charmless B 0 → K 0 π + π -decay.The analysis is performed with a data sample that contains 388 million B B pairs collected near the Υ(4S) resonance with the Belle detector at the KEKB asymmetric energy e + e -collider.Measurements of branching fractions for the quasi-two-body decays B 0 → ρ(770) 0 K 0 , B 0 → f0(980)K 0 , B 0 → K * (892) + π -, B 0 → K * (1430) + π -, and upper limits on several other quasi-two-body decay modes are reported.

We report the first observation of the double strange baryon Ξ(1620)^{0} in its decay to Ξ^{-}π^{+} via Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+} decays based on a 980 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The mass and width are measured to be 1610.4±6.0(stat)_{-4.2}^{+6.1} (syst) MeV/c^{2} and 59.9±4.8(stat)_{-7.1}^{+2.8}(syst) MeV, respectively. We obtain 4.0σ evidence of the Ξ(1690)^{0} with the same data sample. These results shed light on the structure of hyperon resonances with strangeness S=-2.

We report a new measurement of the $e^+e^-\to\Upsilon(nS)\pi^+\pi^-$ ($n=1,2,3$) cross sections at energies from 10.52 to 11.02 GeV using data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We observe a new structure in the energy dependence of the cross sections; if described by a Breit-Wigner function its mass and width are found to be $M=(10752.7\pm5.9\,^{+0.7}_{-1.1})\,$MeV/$c^2$ and $\Gamma=(35.5^{+17.6}_{-11.3}\,^{+3.9}_{-3.3})\,$MeV, where the first error is statistical and the second is systematic. The global significance of the new structure including systematic uncertainty is 5.2 standard deviations. We also find evidence for the $e^+e^-\to\Upsilon(1S)\pi^+\pi^-$ process at the energy 10.52 GeV, which is below the $B\bar{B}$ threshold.

We report results from a study of the spin and parity of ${\mathrm{\ensuremath{\Xi}}}_{c}(2970{)}^{+}$ using a $980\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected by the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. The decay angle distributions in the chain ${\mathrm{\ensuremath{\Xi}}}_{c}(2970{)}^{+}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}_{c}(2645{)}^{0}{\ensuremath{\pi}}^{+}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}_{c}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ are analyzed to determine the spin of this charmed-strange baryon. The angular distributions strongly favor the ${\mathrm{\ensuremath{\Xi}}}_{c}(2970{)}^{+}$ spin $J=1/2$ over $3/2$ or $5/2$, under an assumption that the lowest partial wave dominates in the decay. We also measure the ratio of ${\mathrm{\ensuremath{\Xi}}}_{c}(2970{)}^{+}$ decay branching fractions $R=\mathcal{B}[{\mathrm{\ensuremath{\Xi}}}_{c}(2970{)}^{+}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}_{c}(2645{)}^{0}{\ensuremath{\pi}}^{+}]/\mathcal{B}[{\mathrm{\ensuremath{\Xi}}}_{c}(2970{)}^{+}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}_{c}^{\ensuremath{'}0}{\ensuremath{\pi}}^{+}]=\phantom{\rule{0ex}{0ex}}1.67\ifmmode\pm\else\textpm\fi{}0.29{(\mathrm{stat})}_{\ensuremath{-}0.09}^{+0.15}(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.25(\mathrm{IS})$, where the last uncertainty is due to possible isospin-symmetry-breaking effects. This $R$ value favors the spin-parity ${J}^{P}=1/{2}^{+}$ with the spin of the light-quark degrees of freedom ${s}_{l}=0$. This is the first determination of the spin and parity of a charmed-strange baryon.

We present the first observation of the Ω0c→Ω−μ+νμ decay and present measurements of the branching fraction ratios of the Ω0c→Ω−ℓ+νℓ decays compared to the reference mode Ω0c→Ω−π+, (ℓ=e or μ). This analysis is based on 89.5 fb−1, 711 fb−1, and 121.1 fb−1 data samples collected with the Belle detector at the KEKB asymmetric-energy e+e− collider at the center-of-mass energies of 10.52 GeV, 10.58 GeV, and 10.86 GeV, respectively. The Ω0c signal yields are extracted by fitting MΩℓ and MΩπ spectra. The branching fraction ratios B(Ω0c→Ω−e+νe)/B(Ω0c→Ω−π+) and B(Ω0c→Ω−μ+νμ)/B(Ω0c→Ω−π+) are measured to be 1.98±0.13(stat)±0.08(syst) and 1.94±0.18(stat)±0.10(syst), respectively. The ratio of B(Ω0c→Ω−e+νe)/B(Ω0c→Ω−μ+νμ) is measured to be 1.02±0.10(stat)±0.02(syst), which is consistent with the expectation of lepton flavor universality.Received 20 December 2021Accepted 26 April 2022Corrected 23 May 2022DOI:https://doi.org/10.1103/PhysRevD.105.L091101Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBranching fractionLeptonic, semileptonic & radiative decaysPhysical SystemsCharmed baryonsTechniquesLepton collidersParticles & Fields

We report the first observation of the charmless hyperonic $B$ decay, ${B}^{+}\ensuremath{\rightarrow}\ensuremath{\Lambda}\overline{\ensuremath{\Lambda}}{K}^{+}$, using a $140\text{ }{\mathrm{f}\mathrm{b}}^{\ensuremath{-}1}$ data sample recorded at the $\ensuremath{\Upsilon}(4\mathrm{S})$ resonance with the Belle detector at the KEKB ${e}^{+}{e}^{\ensuremath{-}}$ collider. The measured branching fraction is $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}\ensuremath{\Lambda}\overline{\ensuremath{\Lambda}}{K}^{+})=({2.91}_{\ensuremath{-}0.70}^{+0.90}\ifmmode\pm\else\textpm\fi{}0.38)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. We also perform a search for the related decay mode ${B}^{+}\ensuremath{\rightarrow}\ensuremath{\Lambda}\overline{\ensuremath{\Lambda}}{\ensuremath{\pi}}^{+}$, but do not find a significant signal. We set a 90% confidence-level upper limit of $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}\ensuremath{\Lambda}\overline{\ensuremath{\Lambda}}{\ensuremath{\pi}}^{+})&lt;2.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$.

We have measured the branching fraction B, longitudinal polarization fraction f L , and CP asymmetry coefficients A and S for B 0 → ρ + ρ -decays with the Belle detector at the KEKB e + e -collider using 253 fb -1 of data.We obtain B = 22.8 ± 3.8 (stat) +2.3 -2.6 (syst) × 10 -6 , f L = 0.941 +0.034 -0.040 (stat) ± 0.030 (syst), A = 0.00 ± 0.30 (stat) ± 0.09 (syst), and S = 0.08 ± 0.41 (stat) ± 0.09 (syst).These values are used to constrain the Cabibbo-Kobayashi-Maskawa phase φ 2 ; the solution consistent with the Standard Model is φ 2 = (88 ± 17) • or 59 • < φ 2 < 115 • at 90% C.L.

We report the observation of the flavor-changing neutral current process b --&gt; d gamma using a sample of 386*10^6 B meson pairs accumulated by the Belle detector at the KEKB e+ e- collider. We measure branching fractions for the exclusive modes B- --&gt; rho- gamma, B0bar --&gt; rho0 gammaand B0bar --&gt; omega gamma. Assuming that these three modes are related by isospin, we find Br(B --&gt; (rho,omega) gamma) = (1.32 +0.34-0.31(stat.) +0.10-0.09(syst.)) * 10^-6 with a significance of 5.1 sigma. This result is used to determine the ratio of CKM matrix elements |V_td/V_ts| to be 0.199 +0.026-0.025(exp.) +0.018-0.015(theo.).

We report the results of a study of neutral $B$ meson decays to the ${D}^{0}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ final state, where the ${D}^{0}$ is fully reconstructed. The results are obtained from an event sample containing $388\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$-meson pairs collected in the Belle experiment at the KEKB ${e}^{+}{e}^{\ensuremath{-}}$ collider. The total branching fraction of the three-body decay $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})=(8.4\ifmmode\pm\else\textpm\fi{}0.4(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.8(\mathrm{syst}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ has been measured. The intermediate resonant structure of these three-body decays has been studied. From a Dalitz plot analysis we have obtained the product of the branching fractions for ${D}_{2}^{*+}$ and ${D}_{0}^{*+}$ production: $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{D}_{2}^{*+}{\ensuremath{\pi}}^{\ensuremath{-}})\ifmmode\times\else\texttimes\fi{}\mathcal{B}({D}_{2}^{*+}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{+})=(2.15\ifmmode\pm\else\textpm\fi{}0.17(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.29(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.12(\mathrm{mod}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, and $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{D}_{0}^{*+}{\ensuremath{\pi}}^{\ensuremath{-}})\ifmmode\times\else\texttimes\fi{}\mathcal{B}({D}_{0}^{*+}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{+})=(0.60\ifmmode\pm\else\textpm\fi{}0.13(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.15(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.22(\mathrm{mod}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. This is the first observation of the ${\overline{B}}^{0}\ensuremath{\rightarrow}{D}_{0}^{*+}{\ensuremath{\pi}}^{\ensuremath{-}}$ decay. The ${\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\rho}}^{0}$ and ${D}^{0}{f}_{2}$ branching fractions are measured to be: $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\rho}}^{0})=(3.19\ifmmode\pm\else\textpm\fi{}0.20(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.24(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.38(\mathrm{mod}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, and $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{0}{f}_{2})=(1.20\ifmmode\pm\else\textpm\fi{}0.18(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.21(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.32(\mathrm{mod}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$.

The ATLAS detector has been designed for operation at the Large Hadron Collider at CERN. ATLAS includes electromagnetic and hadronic liquid argon calorimeters, with almost 200,000 channels of data that must be sampled at the LHC bunch crossing frequency of 40 MHz. The calorimeter electronics calibration and readout are performed by custom electronics developed specifically for these purposes. This paper describes the system performance of the ATLAS liquid argon calibration and readout electronics, including noise, energy and time resolution, and long term stability, with data taken mainly from full-system calibration runs performed after installation of the system in the ATLAS detector hall at CERN.

We present a measurement of angular observables, $P_4'$, $P_5'$, $P_6'$, $P_8'$, in the decay $B^0 \to K^\ast(892)^0 \ell^+ \ell^-$, where $\ell^+\ell^-$ is either $e^+e^-$ or $\mu^+\mu^-$. The analysis is performed on a data sample corresponding to an integrated luminosity of $711~\mathrm{fb}^{-1}$ containing $772\times 10^{6}$ $B\bar B$ pairs, collected at the $\Upsilon(4S)$ resonance with the Belle detector at the asymmetric-energy $e^+e^-$ collider KEKB. Four angular observables, $P_{4,5,6,8}'$ are extracted in five bins of the invariant mass squared of the lepton system, $q^2$. We compare our results for $P_{4,5,6,8}'$ with Standard Model predictions including the $q^2$ region in which the LHCb collaboration reported the so-called $P_5'$ anomaly.

We report inclusive and exclusive measurements for χc1 and χc2 production in B decays.We measure B(B → χc1X)= (3.03 ± 0.05(stat) ± 0.24(syst)) × 10 -3 and B(B → χc2X)= (0.70 ± 0.06(stat) ± 0.10(syst)) × 10 -3 .For the first time, χc2 production in exclusive B decays in the modes B 0 → χc2π -K + and B + → χc2π + π -K + has been observed, along with first evidence for the B + → χc2π + K 0 S decay mode.For χc1 production, we report the first observation in theS and B 0 → χc1π 0 π -K + decay modes.Using these decay modes, we observe a difference in the production mechanism of χc2 in comparison to χc1 in B decays.In addition, we report searches for X(3872) and χc1(2P ) in the B + → (χc1π + π -)K + decay mode.The reported results use 772 × 10 6 BB events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e -collider.

We report an improved measurement of D0–D‾0 mixing and a search for CP violation in D0 decays to CP-even final states K+K− and π+π−. The measurement is based on the final Belle data sample of 976 fb−1. The results are yCP=(1.11±0.22±0.09)% and AΓ=(−0.03±0.20±0.07)%, where the first uncertainty is statistical and the second is systematic.

We report evidence for the charged charmed-strange baryon $\Xi_{c}(2930)^+$ with a signal significance of 3.9$\sigma$ with systematic errors included. The charged $\Xi_{c}(2930)^+$ is found in its decay to $K_{S}^{0} \Lambda_{c}^+$ in the substructure of $\bar{B}^{0} \to K^{0}_{S} \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-}$ decays. The measured mass and width are $[2942.3 \pm 4.4 (\rm stat.) \pm 1.5(\rm syst.)]$~MeV/$c^{2}$ and $[14.8 \pm 8.8(\rm stat.) \pm 2.5(\rm syst.)]$~MeV, respectively, and the product branching fraction is $\cal{B}(\bar{B}^{0} \to \Xi_c(2930)^{+} \bar{\Lambda}_{c}^{-}) \cal{B}(\Xi_c(2930)^{+}\to \bar{K}^{0} \Lambda_{c}^{+})=[2.37 \pm 0.51 (\rm stat.)\pm 0.31(\rm syst.)]\times 10^{-4}$. We also measure $\cal{B}(\bar{B}^{0} \to \bar{K}^{0} \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-}) = [3.99 \pm 0.76(\rm stat.) \pm 0.51(\rm syst.)] \times 10^{-4}$ with greater precision than previous experiments, and present the results of a search for the charmonium-like state $Y(4660)$ and its spin partner, $Y_{\eta}$, in the $\Lambda_{c}^{+}\bar{\Lambda}_{c}^{-}$ invariant mass spectrum. No clear signals of the $Y(4660)$ or $Y_{\eta}$ are observed and the 90\% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of $(772\pm11)\times 10^{6} B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.

Using data samples of $e^+e^-$ collisions collected at the $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ resonances with the Belle detector, we search for the three-body decay of the $\Omega(2012)$ baryon to $K\pi\Xi$. This decay is predicted to dominate for models describing the $\Omega(2012)$ as a $K\Xi(1530)$ molecule. No significant $\Omega(2012)$ signals are observed in the studied channels, and 90\% credibility level upper limits on the ratios of the branching fractions relative to $K \Xi$ decay modes are obtained.

Using $980~fb^{-1}$ of data collected on and around the $\Upsilon(nS)(n=1,2,3,4,5)$ resonances with the Belle detector at the KEKB collider, we measure the cross section of $e^{+}e^{-}\to \eta\phi$ from threshold to $3.95~{\rm GeV}/c^{2}$ via initial-state radiation. From a multi-parameter fit assuming $\phi(2170)$ exists in the $\eta\phi$ final state according to previous measurement by BESIII, the resonant parameters of $\phi(1680)$ are determined to be $m_{\phi(1680)} = (1683 \pm 7 \pm 9)~{\rm MeV}/c^{2}$ (statistical and systematic errors, respectively), $\Gamma_{\phi(1680)} = (149 \pm 12 \pm 13)~{\rm MeV}$ and, depending on the possible presence of interfering resonances, $\Gamma^{e^{+}e^{-}}_{\phi(1680)}\cdot {\cal B}[\phi(1680)\to\eta\phi] = (122 \pm 6 \pm 13)~{\rm eV}$, $(219 \pm 15 \pm 18)~{\rm eV}$, $(163 \pm 11 \pm 13)~{\rm eV}$ or $(203 \pm 12 \pm 18)~{\rm eV}$. The branching fraction of $\phi(1680)\to\eta\phi$ decay is determined to be approximately 20%. Additionally, the branching fraction for $J/\psi\to\eta\phi$ is measured to be $(7.1\pm 1.0 \pm 0.5)\times 10^{-4}$. However, there is no significant observed $\phi(2170)$ signal in the $\eta\phi$ final states in this analysis, and correspondingly the upper limit for $\Gamma^{e^{+}e^{-}}_{\phi(2170)}\cdot {\cal B}(\phi(2170)\to\eta\phi)$ is determined to be either $0.17~{\rm eV}$ (for two fits), or $18.6~{\rm eV}$ (remaining two fits), at 90% confidence level.

The dark photon A^{'} and the dark Higgs boson h^{'} are hypothetical particles predicted in many dark sector models. We search for the simultaneous production of A^{'} and h^{'} in the dark Higgsstrahlung process e^{+}e^{-}→A^{'}h^{'} with A^{'}→μ^{+}μ^{-} and h^{'} invisible in electron-positron collisions at a center-of-mass energy of 10.58 GeV in data collected by the Belle II experiment in 2019. With an integrated luminosity of 8.34 fb^{-1}, we observe no evidence for signal. We obtain exclusion limits at 90% Bayesian credibility in the range of 1.7-5.0 fb on the cross section and in the range of 1.7×10^{-8}-200×10^{-8} on the effective coupling ϵ^{2}×α_{D} for the A^{'} mass in the range of 4.0 GeV/c^{2}<M_{A^{'}}<9.7 GeV/c^{2} and for the h^{'} mass M_{h^{'}}<M_{A^{'}}, where ϵ is the mixing strength between the standard model and the dark photon and α_{D} is the coupling of the dark photon to the dark Higgs boson. Our limits are the first in this mass range.

We determine the Cabibbo-Kobayashi-Maskawa matrix-element magnitude |Vcb| using B¯0→D*+ℓ−ν¯ℓ decays reconstructed in 189 fb−1 of collision data collected by the Belle II experiment, located at the SuperKEKB e+e− collider. Partial decay rates are reported as functions of the recoil parameter w and three decay angles separately for electron and muon final states. We obtain |Vcb| using the Boyd-Grinstein-Lebed and Caprini-Lellouch-Neubert parametrizations, and find |Vcb|BGL=(40.57±0.31±0.95±0.58)×10−3 and |Vcb|CLN=(40.13±0.27±0.93±0.58)×10−3 with the uncertainties denoting statistical components, systematic components, and components from the lattice QCD input, respectively. The branching fraction is measured to be B(B¯0→D*+ℓ−ν¯ℓ)=(4.922±0.023±0.220)%. The ratio of branching fractions for electron and muon final states is found to be 0.998±0.009±0.020. In addition, we determine the forward-backward angular asymmetry and the D*+ longitudinal polarization fractions. All results are compatible with lepton-flavor universality in the Standard Model.4 MoreReceived 3 October 2023Accepted 20 October 2023DOI:https://doi.org/10.1103/PhysRevD.108.092013Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCabibbo–Kobayashi–Maskawa matrixElectroweak interactionForm factorsParticles & Fields

Direct CP violation in the b→sγ process is a sensitive probe of physics beyond the standard model. We report a measurement of the CP asymmetry in B→Xsγ, where the hadronic recoil system Xs is reconstructed using a pseudoreconstruction technique. In this approach there is negligible contamination from b→dγ decays, which are expected to have a much larger CP asymmetry. We find ACP=0.002±0.050(stat)±0.030(syst) for B→Xsγ events having recoil mass smaller than 2.1 GeV/c2. The analysis is based on a data sample of 140 fb−1 recorded at the Υ(4S) resonance with the Belle detector at the KEKB e+e− storage ring.Received 4 April 2004DOI:https://doi.org/10.1103/PhysRevLett.93.031803©2004 American Physical Society

We have searched for neutrinoless τ lepton decays into three charged leptons using an 87.1fb−1 data sample collected with the Belle detector at the KEKB e+e− collider. Since the number of signal candidate events is compatible with that expected from the background, we set 90% confidence level upper limits on the branching fractions in the range (1.9–3.5)×10−7 for various decay modes τ−→ℓ−ℓ+ℓ− where ℓ represents e or μ.

We present results of a study of the charmless vector-vector decays B 0 → K * 0 ρ 0 and B + → K * 0 ρ + .The results are based on a 140 fb -1 data sample collected by the Belle detector at the KEKB asymmetric e + e -collider.We obtain the branching fraction B(B + → K * 0 ρ + ) = (6.6 ± 2.2(stat.)± 0.8(syst.))× 10 -6 , and set upper limits on the branching fractions B(B 0 → K * 0 ρ 0 ) < 2.6 × 10 -6 and B(B 0 → f 0 (980)K * 0 ) < 5.2 × 10 -6 .We also perform a helicity analysis of the ρ and K * vector mesons in the decay B + → K * 0 ρ + , and obtain the longitudinal polarization fraction R 0 (B + → K * 0 ρ + ) = 0.50 ± 0.19(stat.)+0.05 -0.07 (syst.).

We report the observation of the decay B0-->pi(0)pi(0), using a 253 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) collider. The measured branching fraction is B(B0-->pi(0)pi(0))=(2.3(+0.4+0.2)(-0.5-0.3))x10(-6), with a significance of 5.8 standard deviations including systematic uncertainties. We also make a measurement of the direct CP violating asymmetry in this mode.

We report a study of the modes D_CP K+- and D^*_CP K+- where D^(*) decays to CP eigenstates. The data sample used contains 275 x 10^6 BB events at the Upsilon(4S) resonance collected by the Belle detector at the KEKB energy-asymmetric e^+ e^- collider. The CP asymmetries obtained for D_CP K are: A_1 = 0.06 +- 0.14 (stat) +- 0.05 (sys), A_2 = -0.12 +- 0.14 (stat) +- 0.05 (sys) and for D^*_CP K : A_1^* = -0.20 +- 0.22 (stat) +- 0.04 (sys), A_2^* = 0.13 +- 0.30 (stat) +- 0.08 (sys).

We report measurements of partial branching fractions of inclusive charmless semileptonic B-meson decays at the endpoint of the electron momentum spectrum. The measurements are made in six overlapping momentum intervals that have lower bounds ranging from 1.9 to 2.4 GeV/c and a common upper bound of 2.6 GeV/c, as measured in the centre of mass frame. The results are based on a sample of 29 million BB¯ pairs, accumulated by the Belle detector at the KEKB asymmetric e+e− collider operating on the ϒ(4S) resonance. In the momentum interval ranging from 1.9 to 2.6 GeV/c we measure the partial branching fraction ΔB(B→Xueνe)=(8.47±0.37±1.53)×10−4, where the first error is statistical and the second is systematic. A prediction of the partial rate R=(21.69±3.62−1.98+2.18)|Vub|2ps−1 in this momentum interval based on theory is calculated with input HQET parameters that have been derived from Belle's measurement of the B→Xsγ photon energy spectrum, where the first error is due to the uncertainty on HQET parameters and the second error is from theory. Using both ΔB(B→Xueνe) and R we find |Vub|=(5.08±0.47±0.42−0.23+0.26)×10−3, where the first error is from the partial branching fraction, and the second and third errors are from uncertainties in R.

We study the following charmless baryonic three-body decays of $B$ mesons: ${B}^{+}\ensuremath{\rightarrow}p\overline{\ensuremath{\Lambda}}\ensuremath{\gamma}$, ${B}^{+}\ensuremath{\rightarrow}p\overline{\ensuremath{\Lambda}}{\ensuremath{\pi}}^{0}$, and ${B}^{0}\ensuremath{\rightarrow}p\overline{\ensuremath{\Lambda}}{\ensuremath{\pi}}^{\ensuremath{-}}$. The partial branching fractions as a function of the baryon-antibaryon mass and the polar angle distributions of the proton in the baryon-antibaryon system are presented. This study includes the first observation of ${B}^{+}\ensuremath{\rightarrow}p\overline{\ensuremath{\Lambda}}{\ensuremath{\pi}}^{0}$, which is measured to have a branching fraction of $({3.00}_{\ensuremath{-}0.53}^{+0.61}\ifmmode\pm\else\textpm\fi{}0.33)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. We also set upper limits on branching fractions of the two-body decays ${B}^{0}\ensuremath{\rightarrow}p{\overline{\ensuremath{\Sigma}}}^{*\ensuremath{-}}$, ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\Delta}}^{0}\overline{\ensuremath{\Lambda}}$, ${B}^{+}\ensuremath{\rightarrow}p{\overline{\ensuremath{\Sigma}}}^{*0}$, and ${B}^{+}\ensuremath{\rightarrow}{\ensuremath{\Delta}}^{+}\overline{\ensuremath{\Lambda}}$ at the 90% confidence level. These results are obtained from a $414\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected near the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider.

We search for the decay B 0 s → γγ and measure the branching fraction for B 0 s → ϕγ using 121.4 fb -1 of data collected at the ϒð5SÞ resonance with the Belle detector at the KEKB asymmetric-energy e þ e - collider.The B 0 s → ϕγ branching fraction is measured to be ð3.6 AE 0.5ðstatÞ AE 0.3ðsystÞ AE 0.6ðf s ÞÞ × 10 -5 , where f s is the fraction of B ðÃÞ s BðÃÞs in b b events.Our result is in good agreement with the theoretical predictions as well as with a recent measurement from LHCb.We observe no statistically significant signal for the decay B 0 s → γγ and set a 90% confidence-level upper limit on its branching fraction at 3.1 × 10 -6 .This constitutes a significant improvement over the previous result.

We present the results of the first Dalitz plot analysis of the decay ${D}^{0}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}\ensuremath{\eta}$. The analysis is performed on a data set corresponding to an integrated luminosity of $953\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected by the Belle detector at the asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ KEKB collider. The Dalitz plot is well described by a combination of the six resonant decay channels ${\overline{K}}^{*}(892{)}^{0}\ensuremath{\eta}$, ${K}^{\ensuremath{-}}{a}_{0}(980{)}^{+}$, ${K}^{\ensuremath{-}}{a}_{2}(1320{)}^{+}$, ${\overline{K}}^{*}(1410{)}^{0}\ensuremath{\eta}$, ${K}^{*}(1680{)}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ and ${K}_{2}^{*}(1980{)}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$, together with $K\ensuremath{\pi}$ and $K\ensuremath{\eta}$ S-wave components. The decays ${K}^{*}(1680{)}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}\ensuremath{\eta}$ and ${K}_{2}^{*}(1980{)}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}\ensuremath{\eta}$ are observed for the first time. We measure ratio of the branching fractions, $\frac{\mathcal{B}({D}^{0}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}\ensuremath{\eta})}{\mathcal{B}({D}^{0}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+})}=0.500\ifmmode\pm\else\textpm\fi{}0.002(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.020(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.003({\mathcal{B}}_{\mathrm{PDG}})$. Using the Dalitz fit result, the ratio $\frac{\mathcal{B}({K}^{*}(1680)\ensuremath{\rightarrow}K\ensuremath{\eta})}{\mathcal{B}({K}^{*}(1680)\ensuremath{\rightarrow}K\ensuremath{\pi})}$ is measured to be $0.11\ifmmode\pm\else\textpm\fi{}0.02{(\mathrm{stat})}_{\ensuremath{-}0.04}^{+0.06}(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.04({\mathcal{B}}_{\mathrm{PDG}})$; this is much lower than the theoretical expectations ($\ensuremath{\approx}1$) made under the assumption that ${K}^{*}(1680)$ is a pure ${1}^{3}{D}_{1}$ state. The product branching fraction $\mathcal{B}({D}^{0}\ensuremath{\rightarrow}[{K}_{2}^{*}(1980{)}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}\ensuremath{\eta}]{\ensuremath{\pi}}^{+})=(2.{2}_{\ensuremath{-}1.9}^{+1.7})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ is determined. In addition, the $\ensuremath{\pi}{\ensuremath{\eta}}^{\ensuremath{'}}$ contribution to the ${a}_{0}(980{)}^{\ifmmode\pm\else\textpm\fi{}}$ resonance shape is confirmed with $10.1\ensuremath{\sigma}$ statistical significance using the three-channel Flatt\'e model. We also measure $\mathcal{B}({D}^{0}\ensuremath{\rightarrow}{\overline{K}}^{*}(892{)}^{0}\ensuremath{\eta})=(1.4{1}_{\ensuremath{-}0.12}^{+0.13})%$. This is consistent with, and more precise than, the current world average $(1.02\ifmmode\pm\else\textpm\fi{}0.30)%$, deviates with a significance of more than $3\ensuremath{\sigma}$ from the theoretical predictions of (0.51--0.92)%.

Using 980 fb−1 of data at and around the ϒ(nS) (n=1, 2, 3, 4, 5) resonances collected with the Belle detector at the KEKB asymmetric-energy e+e− collider, the two-photon process γγ→γψ(2S) is studied from the threshold to 4.2 GeV for the first time. Two structures are seen in the invariant mass distribution of γψ(2S): one at MR1=3922.4±6.5±2.0 MeV/c2 with a width of ΓR1=22±17±4 MeV, and another at MR2=4014.3±4.0±1.5 MeV/c2 with a width of ΓR2=4±11±6 MeV; the signals are parametrized with the incoherent sum of two Breit-Wigner functions. The first structure is consistent with the X(3915) or the χc2(3930), and the local statistical significance is determined to be 3.1σ with the systematic uncertainties included. The second matches none of the known charmonium or charmoniumlike states, and its global significance is determined to be 2.8σ including the look-elsewhere effect. The production rates are ΓγγB(R1→γψ(2S))=9.8±3.6±1.3 eV assuming (JPC,|λ|)=(0++,0) or 2.0±0.7±0.2 eV with (2++,2) for the first structure and ΓγγB(R2→γψ(2S))=6.2±2.2±0.8 eV with (0++,0) or 1.2±0.4±0.2 eV with (2++,2) for the second. Here, the first errors are statistical and the second systematic, and λ is the helicity.Received 6 January 2022Accepted 15 June 2022DOI:https://doi.org/10.1103/PhysRevD.105.112011© 2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle interactionsParticles & Fields

A high precision study of the process γγ→pp¯ has been performed using a data sample of 89 fb−1 collected with the Belle detector at the KEKB e+e− collider. The cross section of pp¯ production has been measured at two-photon center-of-mass (c.m.) energies between 2.025 and 4.0 GeV and in the c.m. angular range of |cosθ∗|<0.6. Production of γγ→ηc→pp¯ is observed and the product of the two-photon width of the ηc and its branching ratio to pp¯ is determined.

We present a measurement of the angle ${\ensuremath{\phi}}_{1}$ of the Cabibbo-Kobayashi-Maskawa unitarity triangle using a time-dependent Dalitz analysis of $D\ensuremath{\rightarrow}{K}_{S}^{0}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ decays produced in neutral $B$ meson decay to a neutral $D$ meson and a light meson (${\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{(*)}{h}^{0}$). The method allows a direct extraction of $2{\ensuremath{\phi}}_{1}$ and, therefore, helps to resolve the ambiguity between $2{\ensuremath{\phi}}_{1}$ and $\ensuremath{\pi}\ensuremath{-}2{\ensuremath{\phi}}_{1}$ in the measurement of $\mathrm{sin}2{\ensuremath{\phi}}_{1}$. We obtain $\mathrm{sin}2{\ensuremath{\phi}}_{1}=0.78\ifmmode\pm\else\textpm\fi{}0.44\ifmmode\pm\else\textpm\fi{}0.22$ and $\mathrm{cos}2{\ensuremath{\phi}}_{1}={1.87}_{\ensuremath{-}0.53\ensuremath{-}0.32}^{+0.40+0.22}$. The sign of $\mathrm{cos}2{\ensuremath{\phi}}_{1}$ is determined to be positive at 98.3% C.L.

We search for CP violation in neutral charm meson decays using a data sample with an integrated luminosity of 966 fb^-1 collected with the Belle detector at the KEKB e+e- asymmetric-energy collider. The asymmetry obtained in the rate of D^0 and D^0-bar decays to the pi^0 pi^0 final state, [-0.03+-0.64(stat)+-0.10(syst)]%, is consistent with no CP violation. This constitutes an order of magnitude improvement over the existing result. We also present an updated measurement of the CP asymmetry in the D^0 -> K_S pi^0 decay: A_{CP}(D^0 -> K_S pi^0) = [-0.21+-0.16(stat)+-0.07(syst)]%.

We report the first observation ofWe measure the product of branching fractions for the former to be BðB.6 AE 3.0ðstatÞ AE 0.9ðsystÞÞ × 10 -6 .This study is based on the full data sample of 711 fb -1 (772 × 10 6 B B pairs) collected at the Υð4SÞ resonance with the Belle detector at the KEKB collider.

We report the results of a search for the rare, purely leptonic decay B^{-}→μ^{-}ν[over ¯]_{μ} performed with a 711 fb^{-1} data sample that contains 772×10^{6} BB[over ¯] pairs, collected near the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The signal events are selected based on the presence of a high momentum muon and the topology of the rest of the event showing properties of a generic B-meson decay, as well as the missing energy and momentum being consistent with the hypothesis of a neutrino from the signal decay. We find a 2.4 standard deviation excess above background including systematic uncertainties, which corresponds to a branching fraction of B(B^{-}→μ^{-}ν[over ¯]_{μ})=(6.46±2.22±1.60)×10^{-7} or a frequentist 90% confidence level interval on the B^{-}→μ^{-}ν[over ¯]_{μ} branching fraction of [2.9,10.7]×10^{-7}.

We measure the decay $B_s^0\rightarrow K^0\overline{K}^0$ using data collected at the $\Upsilon(5S)$ resonance with the Belle detector at the KEKB $e^+e^-$ collider. The data sample used corresponds to an integrated luminosity of 121.4 ${\rm fb^{-1}}$. We measure a branching fraction $\mathcal{B}(B_s^0\rightarrow K^0\overline{K}^0) = [19.6\,^{+5.8}_{-5.1}({\rm stat.})\,\pm1.0({\rm sys.})\,\pm 2.0(N^{}_{B_s^0\overline{B}_s^0})]\times 10^{-6}$ with a significance of 5.1 standard deviations. This measurement constitutes the first observation of this decay.

We report measurements of the branching fractions of singly Cabibbo-suppressed decays $Λ_c^+ \to p η$ and $Λ_c^+ \to p π^0$ using the full Belle data sample corresponding to an integrated luminosity of 980.6 $\rm fb^{-1}$. The data were collected by the Belle detector at the KEKB $e^{+}$$e^{-}$ asymmetric-energy collider. A clear $Λ_c^+$ signal is seen in the invariant mass distribution of $p η$. The signal yield of the $Λ_c^+ \to p η$ process is $7734 \pm 263$; from this, we measure the ratio of branching fractions ${\cal B}(Λ_c^+ \to p η)/{\cal B}(Λ_c^+ \to p K^- π^+) = (2.258 \pm 0. 077(\rm stat. ) \pm 0.136(\rm syst. ))\times 10^{-2}$, from which we infer the branching fraction ${\cal B}(Λ_c^+ \to p η) = (1.42 \pm 0.05(\rm stat.) \pm 0.11(\rm syst.)) \times 10^{-3}$. In addition, no significant signal for $Λ_c^+ \to p π^0$ is found so an upper limit on the branching fraction of ${\cal B}(Λ_c^+ \to p π^0)&lt;8.0 \times 10^{-5}$ at 90\% credibility level is set, more than three times better than the best current upper limit.

We report a measurement of the $CP$-violating parameters $C$ and $S$ in ${B}^{0}\ensuremath{\rightarrow}{K}_{S}^{0}{\ensuremath{\pi}}^{0}$ decays at Belle II using a sample of $387\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }B\overline{B}$ events recorded in ${e}^{+}{e}^{\ensuremath{-}}$ collisions at a center-of-mass energy corresponding to the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance. These parameters are determined by fitting the proper decay-time distribution of a sample of 415 signal events. We obtain $C=\ensuremath{-}0.0{4}_{\ensuremath{-}0.15}^{+0.14}\ifmmode\pm\else\textpm\fi{}0.05$ and $S=0.7{5}_{\ensuremath{-}0.23}^{+0.20}\ifmmode\pm\else\textpm\fi{}0.04$, where the first uncertainties are statistical and the second are systematic.

A bstract We measure CP asymmetries and branching-fraction ratios for B ± → DK ± and Dπ ± decays with D → $$ {K}_{\textrm{S}}^0 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>K</mml:mi> <mml:mi>S</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> K ± π ∓ , where D is a superposition of D 0 and $$ \overline{D} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>D</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> 0 . We use the full data set of the Belle experiment, containing 772 × 10 6 $$ B\overline{B} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>B</mml:mi> <mml:mover> <mml:mi>B</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> pairs, and data from the Belle II experiment, containing 387 × 10 6 $$ B\overline{B} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>B</mml:mi> <mml:mover> <mml:mi>B</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> pairs, both collected in electron-positron collisions at the Υ(4 S ) resonance. Our results provide model-independent information on the unitarity triangle angle ϕ 3 .

We report measurements of the branching fractions and direct CP asymmetries of the decays B0→K+π−, B+→K+π0, B+→K0π+, and B0→K0π0, and use these for testing the standard model through an isospin-based sum rule. In addition, we measure the branching fraction and direct CP asymmetry of the decay B+→π+π0 and the branching fraction of the decay B0→π+π−. The data are collected with the belle II detector from e+e− collisions at the ϒ(4S) resonance produced by the SuperKEKB asymmetric-energy collider and contain 387×106 bottom-antibottom meson pairs. Signal yields are determined in two-dimensional fits to background-discriminating variables, and range from 500 to 3900 decays, depending on the channel. We obtain −0.03±0.13±0.04 for the sum rule in agreement with the standard model expectation of zero and with a precision comparable to the best existing determinations.Received 11 October 2023Accepted 21 November 2023DOI:https://doi.org/10.1103/PhysRevD.109.012001Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasHadronic decaysRare decaysSum rulesPhysical SystemsBottom mesonsPropertiesCP violationTechniquesParticle data analysisParticles & Fields

The ratio of branching fractions $R(D^{*}) = \mathcal{B}(\overline{B} \rightarrow D^{*} \tau^{-} \overline{\nu}_{\tau})$/$\mathcal{B} (\overline{B} \rightarrow D^{*} \ell^{-} \overline{\nu}_{\ell})$, where $\ell$ is an electron or muon, is measured using a Belle~II data sample with an integrated luminosity of $189~\mathrm{fb}^{-1}$ at the SuperKEKB asymmetric-energy $e^{+} e^{-}$ collider. Data is collected at the $\Upsilon(\mathrm{4S})$ resonance, and one $B$ meson in the $\Upsilon(\mathrm{4S})\rightarrow B\overline{B}$ decay is fully reconstructed in hadronic decay modes. The accompanying signal $B$ meson is reconstructed as $\overline{B}\rightarrow D^{*} \tau^{-}\overline{\nu}_{\tau}$ using leptonic $\tau$ decays. The normalization decay, $\overline{B}\rightarrow D^{*} \ell^{-} \overline{\nu}_{\ell}$, where $\ell$ is an electron or muon, produces the same observable final state particles. The ratio of branching fractions is extracted in a simultaneous fit to two signal-discriminating variables in both channels and yields $R(D^{*}) = 0.262~_{-0.039}^{+0.041}(\mathrm{stat})~_{-0.032}^{+0.035}(\mathrm{syst})$. This result is consistent with the current world average and with standard model predictions.

We present a measurement of $B^{0} \rightarrow \omega \omega$, a charmless decay into two vector mesons, using 772 $\times 10^6$ $B\overline{B}$ pairs collected with the Belle detector at the KEKB $e^+e^-$ collider. The decay is observed with a significance of 7.9 standard deviations. We measure a branching fraction $\mathcal{B} = (1.53 \pm 0.29 \pm 0.17) \times 10^{-6}$, a fraction of longitudinal polarization $f_L = 0.87 \pm 0.13 \pm 0.13$, and a time-integrated $CP$ asymmetry $A_{CP}$ = $-0.44 \pm 0.43 \pm 0.11$, where the first uncertainties listed are statistical and the second are systematic. This is the first observation of $B^{0} \rightarrow \omega \omega$, and the first measurements of $f_L$ and $A_{CP}$ for this decay.

The Belle II experiment located at KEK, Japan takes data from asymmetric e+e− collision provided by the SuperKEKB accelerator. The Silicon Vertex Detector (SVD), which is part of the Belle II Vertex Detector (VXD), has been operating smoothly and reliably since the start of data taking in March 2019. In this article, we report on the performance of the SVD in terms of the large signal-to-noise ratio, the good hit position resolution as well as the good hit-time resolution. New algorithms based on hit-time information are under development to improve robustness of tracking performance within the anticipated high background environment. The Background situation of the SVD has been constantly monitored and no degradation in performance is observed so far. To investigate the SVD performance at high luminosity runs in the future, simulation as well as an irradiation campaign are launched and their results are summarized. During the first long shutdown of the Belle II experiment, which starts from June 2022, the VXD has been refurbished with a new two-layer DEPFET pixel detector located inside the SVD. All the delicate phases of the disassembly, re-assembly and installation of the new VXD have been successfully completed. The new VXD commissioning phase began in Sept 2023 to get ready for beam operation starting in early 2024.

We search for the baryon and lepton number violating charm decays, D→pℓ, where D is either a D0 or a D¯0 and ℓ is a muon or an electron, using a data sample of 921 fb−1 collected by the Belle detector at the KEKB asymmetric energy e+e− collider. In the absence of significant signals, we set upper limits on the branching fractions in the range (5–8)×10−7 at a 90% confidence level, depending on the decay mode.Received 19 October 2023Accepted 18 December 2023DOI:https://doi.org/10.1103/PhysRevD.109.L031101Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasGrand unified modelsParticle decaysParticle interactionsSupersymmetric modelsPhysical SystemsCharm quarkElectronsLeptoquarksMuonsTechniquesLepton collidersParticles & Fields

Abstract The silicon vertex detector (SVD) is installed at the heart of the Belle II experiment, taking data at the high-luminosity B-Factory SuperKEKB since 2019. The SVD is a four-layer double-sided strip detector with tracking and particle-identification capabilities. In this paper, we report on the performance of the reconstruction of SVD hits. The detector has shown a stable and above-99% hit efficiency, with a large signal-to-noise in all sensors since the beginning of data taking. Cluster position and time resolution have been measured with 2020 and 2022 data and show excellent performance and stability. In particular, the cluster-position resolution is between 7 and 12 μm for the small-pitch sensors, in reasonable agreement with the expectations, while the cluster time resolution is measured to be below 3 ns. The effect of radiation damage is visible, but not affecting the performance. As the luminosity increases, higher machine backgrounds are expected and the excellent hit-time information in SVD can be exploited for background rejection. In particular, we have recently developed a novel procedure to select hits by grouping them event-by-event based on their time. This new procedure allows a significant reduction of the fake rate, while preserving the tracking efficiency, and it has therefore replaced the previous cut-based procedure. We have developed a method that uses the SVD hits to estimate the track time (previously unavailable) and the collision time. It has a similar precision to the estimate based on the drift chamber readout but its execution time is three orders of magnitude smaller, allowing a faster online reconstruction that is crucial in a high luminosity regime. The track time is a powerful information that allows, together with the aforementioned grouping selection, to raise the occupancy limit above that expected at nominal luminosity, leaving room for a safety factor. Finally, in June 2022 the data taking of the Belle II experiment was stopped to install a new two-layer DEPFET detector (PXD) and upgrade components of the accelerator. The whole silicon tracker (PXD+SVD) has been extracted from Belle II, the new PXD installed, the detector closed and commissioned. We briefly describe the SVD results of this upgrade.

We report on a search for a resonance $X$ decaying to a pair of muons in $e^{+}e^{-}\rightarrow \mu^+ \mu^- X$ events in the 0.212-9.000 GeV/$c^{2}$ mass range, using 178 fb$^{-1}$ of data collected by the BelleII experiment at the SuperKEKB collider at a center of mass energy of 10.58 GeV. The analysis probes two different models of $X$ beyond the standard model: a $Z^{\prime}$ vector boson in the $L_{\mu}-L_{\tau}$ model and a muonphilic scalar. We observe no evidence for a signal and set exclusion limits at the 90\% confidence level on the products of cross section and branching fraction for these processes, ranging from 0.046 fb to 0.97 fb for the $L_{\mu}-L_{\tau}$ model and from 0.055 fb to 1.3 fb for the muonphilic scalar model. For masses below 6 GeV/$c^{2}$, the corresponding constraints on the couplings of these processes to the standard model range from 0.0008 to 0.039 for the $L_{\mu}-L_{\tau}$ model and from 0.0018 to 0.040 for the muonphilic scalar model. These are the first constraints on the muonphilic scalar from a dedicated search.

Using the data samples of 102 million $\Upsilon(1S)$ and 158 million $\Upsilon(2S)$ events collected by the Belle detector, we search for a pentaquark state in the $pJ/\psi$ final state from $\Upsilon(1,2S)$ inclusive decays. Here, the charge-conjugate $\bar{p}J/\psi$ is included. We observe clear $pJ/\psi$ production in $\Upsilon(1,2S)$ decays and measure the branching fractions to be $\mathcal{B}[\Upsilon(1S) \to pJ/\psi + anything] = [4.27 \pm 0.16(stat.) \pm 0.20(syst.)] \times 10^{-5}$ and $\mathcal{B}[\Upsilon(2S) \to pJ/\psi + anything] = [3.59 \pm 0.14(stat.) \pm 0.16(syst.)] \times 10^{-5}$. We also measure the cross section of inclusive $pJ/\psi$ production in $e^+e^-$ annihilation to be $\sigma(e^+e^- \to pJ/\psi + anything) = [57.5 \pm 2.1 (stat.) \pm 2.5(syst.)]$~fb at $\sqrt{s} = 10.52~\hbox{GeV}$ using an 89.5~fb$^{-1}$ continuum data sample. There is no significant $P_c(4312)^+$, $P_c(4440)^+$ or $P_c(4457)^+$ signal found in the $pJ/\psi$ final states in $\Upsilon(1,2S)$ inclusive decays. We determine the upper limits of $\mathcal{B}[\Upsilon(1,2S)\to P_c^{+} + anything] \cdot \mathcal{B}(P_c^{+}\to pJ/\psi)$ to be at the $10^{-6}$ level.

Using the full data sample of 980 fb−1 collected with the Belle detector at the KEKB asymmetric energy electron-positron collider, we report the results of the first search for the rare semileptonic decays Ξc0→Ξ0ℓ+ℓ− (ℓ=e or μ). No significant signals are observed in the Ξ0ℓ+ℓ− invariant-mass distributions. Taking the decay Ξc0→Ξ−π+ as the normalization mode, we report 90% credibility upper limits on the branching fraction ratios B(Ξc0→Ξ0e+e−)/B(Ξc0→Ξ−π+)<6.7×10−3 and B(Ξc0→Ξ0μ+μ−)/B(Ξc0→Ξ−π+)<4.3×10−3 based on the phase-space assumption for signal decays. The 90% credibility upper limits on the absolute branching fractions of B(Ξc0→Ξ0e+e−) and B(Ξc0→Ξ0μ+μ−) are found to be 9.9×10−5 and 6.5×10−5, respectively.Received 7 December 2023Accepted 21 February 2024DOI:https://doi.org/10.1103/PhysRevD.109.052003Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Physical SystemsBaryonsCharm quarkTechniquesParticle decaysParticles & Fields

We report a measurement of the $e^+e^- \to \pi^+\pi^-\pi^0$ cross section in the energy range from 0.62 to 3.50 GeV using an initial-state radiation technique. We use an $e^+e^-$ data sample corresponding to 191 $\text{fb}^{-1}$ of integrated luminosity, collected at a center-of-mass energy at or near the $\Upsilon{(4S)}$ resonance with the Belle II detector at the SuperKEKB collider. Signal yields are extracted by fitting the two-photon mass distribution in $e^+e^- \to \pi^+\pi^-\pi^0\gamma$ events, which involve a $\pi^0 \to \gamma\gamma$ decay and an energetic photon radiated from the initial state. Signal efficiency corrections with an accuracy of 1.6% are obtained from several control data samples. The uncertainty on the cross section at the $\omega$ and $\phi$ resonances is dominated by the systematic uncertainty of 2.2%. The resulting cross sections in the 0.62-1.80 GeV energy range yield $ a_\mu^{3\pi} = [48.91 \pm 0.23~(\mathrm{stat}) \pm 1.07~(\mathrm{syst})] \times 10^{-10} $ for the leading-order hadronic vacuum polarization contribution to the muon anomalous magnetic moment. This result differs by $2.5$ standard deviations from the most precise current determination.

We search for the e+e−→ηb(1S)ω and e+e−→χb0(1P)ω processes at a center-of-mass energy of 10.745 GeV, which is close to the peak of the ϒ(10753) state. We use data collected by the Belle II experiment during a special run, corresponding to an integrated luminosity of 9.8 fb−1. We reconstruct ω→π+π−π0 decays and use the ω meson's recoil mass to search for the signals. We do not find evidence for either process, and set upper limits on the corresponding Born-level cross sections of 2.5 pb and 7.8 pb, respectively, at the 90% confidence level. The χb0(1P)ω limit is the result of a combination of this analysis and a previous search using full reconstruction.Received 21 December 2023Accepted 7 March 2024DOI:https://doi.org/10.1103/PhysRevD.109.072013Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasMultiquark bound statesQuark modelParticles & Fields

We report the observation of B0 decays to the K+π−π0 final state using a data sample of 78 fb−1 collected by the Belle detector at the KEKB e+e− collider. With no assumptions about intermediate states in the decay, the branching fraction is measured to be (36.6−4.3+4.2±3.0)×10−6. We also search for B decays to intermediate two-body states with the same K+π−π0 final state. Significant B signals are observed in the ρ(770)−K+ and K*(892)+π− channels, with branching fractions of (15.1−3.3−1.5−2.1+3.4+1.4+2.0)×10−6 and (14.8−4.4−1.0−0.9+4.6+1.5+2.4)×10−6, respectively. The first error is statistical, the second is systematic and the third is due to the largest possible interference. Contributions from other possible two-body states will be discussed. No CP asymmetry is found in the inclusive K+π−π0 or ρ−K+ modes, and we set 90% confidence level bounds on the asymmetry of −0.12<ACP<0.26 and −0.18<ACP<0.64, respectively.