P. Chang

We report the first observation of a narrow charmmonium state produced in the exclusive decay process B+->K+ pi+pi- J/psi. This state, which decays into pi+pi-J/psi, has a mass of 3871.8+-0.7(stat)+-0.4(syst) MeV, which is very near the M_D + M_D* mass threshold. The results are based on an analysis of 152M BBbar events collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider.

The cross section for ee+ e- → π+ π- J/ψ between 3.8 and 5.5 GeV is measured with a 967 fb(-1) data sample collected by the Belle detector at or near the Υ(nS) (n = 1,2,…,5) resonances. The Y(4260) state is observed, and its resonance parameters are determined. In addition, an excess of π+ π- J/ψ production around 4 GeV is observed. This feature can be described by a Breit-Wigner parametrization with properties that are consistent with the Y(4008) state that was previously reported by Belle. In a study of Y(4260) → π+ π- J/ψ decays, a structure is observed in the M(π(±)J/ψ) mass spectrum with 5.2σ significance, with mass M = (3894.5 ± 6.6 ± 4.5) MeV/c2 and width Γ = (63 ± 24 ± 26) MeV/c2, where the errors are statistical and systematic, respectively. This structure can be interpreted as a new charged charmoniumlike state.

We report a measurement of the branching fraction ratios R(D(*)) of Bbar -> D(*) tau- nubar_tau relative to Bbar -> D()* l- nubar_l (where l = e or mu) using the full Belle data sample of 772 x 10^6 BBbar pairs collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. The measured values are R(D)= 0.375 +- 0.064(stat.) +- 0.026(syst.) and R(D*) = 0.293 +- 0.038(stat.) +- 0.015(syst.). The analysis uses hadronic reconstruction of the tag-side B meson and purely leptonic tau decays. The results are consistent with earlier measurements and do not show a significant deviation from the standard model prediction.

We report the observation of two narrow structures in the mass spectra of the π(±)Υ(nS) (n=1, 2, 3) and π(±)h(b)(mP) (m=1, 2) pairs that are produced in association with a single charged pion in Υ(5S) decays. The measured masses and widths of the two structures averaged over the five final states are M(1)=(10,607.2±2.0) MeV/c2, Γ(1)=(18.4±2.4) MeV, and M(2)=(10,652.2±1.5) MeV/c2, Γ(2)=(11.5±2.2) MeV. The results are obtained with a 121.4 fb(-1) data sample collected with the Belle detector in the vicinity of the Υ(5S) resonance at the KEKB asymmetric-energy e+ e- collider.

A distinct peak is observed in the ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\psi}}^{\ensuremath{'}}$ invariant mass distribution near 4.43 GeV in $B\ensuremath{\rightarrow}K{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\psi}}^{\ensuremath{'}}$ decays. A fit using a Breit-Wigner resonance shape yields a peak mass and width of $M=4433\ifmmode\pm\else\textpm\fi{}4(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}2(\mathrm{syst})\text{ }\text{ }\mathrm{MeV}$ and $\ensuremath{\Gamma}={45}_{\ensuremath{-}13}^{+18}(\mathrm{stat}{)}_{\ensuremath{-}13}^{+30}(\mathrm{syst})\text{ }\text{ }\mathrm{MeV}$. The product branching fraction is determined to be $\mathcal{B}\mathbf{(}{B}^{0}\ensuremath{\rightarrow}{K}^{\ensuremath{\mp}}{Z}^{\ifmmode\pm\else\textpm\fi{}}(4430)\mathbf{)}\ifmmode\times\else\texttimes\fi{}\mathcal{B}\mathbf{(}{Z}^{\ifmmode\pm\else\textpm\fi{}}(4430)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\psi}}^{\ensuremath{'}}\mathbf{)}=(4.1\ifmmode\pm\else\textpm\fi{}1.0(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.4(\mathrm{syst}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, where ${Z}^{\ifmmode\pm\else\textpm\fi{}}(4430)$ is used to denote the observed structure. The statistical significance of the observed peak is $6.5\ensuremath{\sigma}$. These results are obtained from a $605\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample that contains $657\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected near the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric energy ${e}^{+}{e}^{\ensuremath{-}}$ collider.

We report the first measurement of the $\tau$ lepton polarization $P_\tau(D^*)$ in the decay $\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau$ as well as a new measurement of the ratio of the branching fractions $R(D^{*}) = \mathcal{B}(\bar {B} \rightarrow D^* \tau^- \bar{\nu}_\tau) / \mathcal{B}(\bar{B} \rightarrow D^* \ell^- \bar{\nu}_\ell)$, where $\ell^-$ denotes an electron or a muon, and the $\tau$ is reconstructed in the modes $\tau^- \rightarrow \pi^- \nu_\tau$ and $\tau^- \rightarrow \rho^- \nu_\tau$. We use the full data sample of $772 \times 10^6$ $B{\bar B}$ pairs recorded with the Belle detector at the KEKB electron-positron collider. Our results, $P_\tau(D^*) = -0.38 \pm 0.51 {\rm (stat.)} ^{+0.21}_{-0.16} {\rm (syst.)}$ and $R(D^*) = 0.270 \pm 0.035{\rm (stat.)} ^{+0.028}_{-0.025}{\rm (syst.)}$, are consistent with the theoretical predictions of the Standard Model.

We study B→K(*)ℓ+ℓ− decays (ℓ=e, μ) based on a data sample of 657×106 BB¯ pairs collected with the Belle detector at the KEKB e+e− collider. We report the differential branching fraction, isospin asymmetry, K* polarization, and the forward-backward asymmetry (AFB) as functions of q2=Mℓℓ2c2. The fitted AFB spectrum exceeds the standard model expectation by 2.7 standard deviations. The measured branching fractions are B(B→K*ℓ+ℓ−)=(10.7−1.0+1.1±0.9)×10−7 and B(B→Kℓ+ℓ−)=(4.8−0.4+0.5±0.3)×10−7, where the first errors are statistical and the second are systematic, with the muon to electron ratios RK*=0.83±0.17±0.08 and RK=1.03±0.19±0.06.Received 5 April 2009DOI:https://doi.org/10.1103/PhysRevLett.103.171801©2009 American Physical Society

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.

The cross section for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\psi}(2S)$ between threshold and $\sqrt{s}=5.5\text{ }\text{ }\mathrm{GeV}$ is measured using $673\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data on and off the $\ensuremath{\Upsilon}(4S)$ resonance collected with the Belle detector at KEKB. Two resonant structures are observed in the ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\psi}(2S)$ invariant-mass distribution, one at $4361\ifmmode\pm\else\textpm\fi{}9\ifmmode\pm\else\textpm\fi{}9\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ with a width of $74\ifmmode\pm\else\textpm\fi{}15\ifmmode\pm\else\textpm\fi{}10\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, and another at $4664\ifmmode\pm\else\textpm\fi{}11\ifmmode\pm\else\textpm\fi{}5\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ with a width of $48\ifmmode\pm\else\textpm\fi{}15\ifmmode\pm\else\textpm\fi{}3\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, if the mass spectrum is parametrized with the coherent sum of two Breit-Wigner functions. These values do not match those of any of the known charmonium states.

The Belle experiment, running at the KEKB e+e− asymmetric energy collider during the first decade of the century, achieved its original objective of precisely measuring differences between particles and antiparticles in the B system. After collecting 1000 fb−1 of data at various Υ resonances, Belle also obtained the many other physics results described in this article.

We report a measurement of the ratio ${\cal R}(D^*) = {\cal B}(\bar{B}^0 \rightarrow D^{*+} \tau^- \bar{\nu}_{\tau})/{\cal B}(\bar{B}^0 \rightarrow D^{*+} \ell^- \bar{\nu}_{\ell})$, where $\ell$ denotes an electron or a muon. The results are based on a data sample containing $772\times10^6$ $B\bar{B}$ pairs recorded at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ collider. We select a sample of $B^0 \bar{B}^0$ pairs by reconstructing both $B$ mesons in semileptonic decays to $D^{*\mp} \ell^{\pm}$. We measure ${\cal R}(D^*)= 0.302 \pm 0.030({\rm stat)} \pm 0.011({\rm syst)}$, which is within $1.6 \sigma$ of the Standard Model theoretical expectation, where the standard deviation $\sigma$ includes systematic uncertainties. We use this measurement to constrain several scenarios of new physics in a model-independent approach.

We present a measurement of angular observables and a test of lepton flavor universality in the B→K^{*}ℓ^{+}ℓ^{-} decay, where ℓ is either e or μ. The analysis is performed on a data sample corresponding to an integrated luminosity of 711 fb^{-1} containing 772×10^{6} BB[over ¯] pairs, collected at the ϒ(4S) resonance with the Belle detector at the asymmetric-energy e^{+}e^{-} collider KEKB. The result is consistent with standard model (SM) expectations, where the largest discrepancy from a SM prediction is observed in the muon modes with a local significance of 2.6σ.

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 report the observation of prompt J/psi via double cc; production from the e+e- continuum. In this process one cc; pair fragments into a J/psi meson while the remaining pair either produces a charmonium state or fragments into open charm. Both cases have been experimentally observed. We find cross sections of sigma[e+e- -->J/psieta(c)(gamma)]xB(eta(c)-->>or=4 charged)=(0.033(+0.007)(-0.006)+/-0.009) pb and sigma(e+e- -->J/psiD(*+)X)=(0.53(+0.19)(-0.15)+/-0.14) pb and infer sigma(e+e- -->J/psicc;)/sigma(e+e- -->J/psiX)=0.59(+0.15)(-0.13)+/-0.12. These results are obtained from a 46.2 fb(-1) data sample collected near the Upsilon(4S) resonance, with the Belle detector at the KEKB collider.

We have measured the branching fraction of the inclusive radiative B meson decay B --> X(s) gamma to be Br(B->X(s)gamma)=(3.36 +/- 0.53(stat) +/- 0.42(sys) +0.50-0.54(th)) x 10^{-4}. The result is based on a sample of 6.07 x 10^6 BBbar events collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e^+e^- storage ring.

A strong signal for double parton (DP) scattering is observed in a $16{\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ sample of $\overline{p}p\ensuremath{\rightarrow}\ensuremath{\gamma}/{\ensuremath{\pi}}^{0}+3\mathrm{jets}+X$ data from the CDF experiment at the Fermilab Tevatron. In DP events, two separate hard scatterings take place in a single $\overline{p}p$ collision. We isolate a large sample of data $(\ensuremath{\sim}14000\mathrm{events})$ of which 53% are found to be DP. The process-independent parameter of double parton scattering, ${\ensuremath{\sigma}}_{\mathrm{eff}},$ is obtained without reference to theoretical calculations by comparing observed DP events to events with hard scatterings in separate $\overline{p}p$ collisions. The result ${\ensuremath{\sigma}}_{\mathrm{eff}}=(14.5\ifmmode\pm\else\textpm\fi{}{1.7}_{\ensuremath{-}2.3}^{+1.7})\mathrm{mb}$ represents a significant improvement over previous measurements, and is used to constrain simple models of parton spatial density. The Feynman $x$ dependence of ${\ensuremath{\sigma}}_{\mathrm{eff}}$ is investigated and none is apparent. Further, no evidence is found for kinematic correlations between the two scatterings in DP events.

We report a measurement of the exclusive e+ e- -->Lambda+_(c)Lambda-_(c) cross section as a function of center-of-mass energy near the Lambda+_(c)Lambda-_(c) threshold. A clear peak with a significance of 8.2sigma is observed in the Lambda+_(c)Lambda-_(c) invariant mass distribution just above threshold. With an assumption of a resonance origin for the observed peak, a mass and width of M=[4634 (+8)_(-7)(stat)(+5)_(-8)(syst)] MeV/c(2) and Gamma_(tot)=[92 (+40)_(-24)(stat)(+10)_(-21)(syst)] MeV are determined. The analysis is based on a study of events with initial-state-radiation photons in a data sample collected with the Belle detector at the Upsilon(4S) resonance and nearby continuum with an integrated luminosity of 695 fb(-1) at the KEKB asymmetric-energy e+ e- collider.

We have measured the fraction of $J/\ensuremath{\psi}$ mesons originating from ${\ensuremath{\chi}}_{c}$ meson decays in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$. The fraction, for ${P}_{T}^{J/\ensuremath{\psi}}>4.0\mathrm{GeV}/c$ and $|{\ensuremath{\eta}}^{J/\ensuremath{\psi}}|<0.6$, not including contributions from $b$ flavored hadrons, is $29.7%\ifmmode\pm\else\textpm\fi{}1.7%(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}5.7%(\mathrm{syst})$. We have determined the cross sections for $J/\ensuremath{\psi}$ mesons originating from ${\ensuremath{\chi}}_{c}$ decays and for directly produced $J/\ensuremath{\psi}$ mesons. We have found that direct $J/\ensuremath{\psi}$ production is in excess of the prediction of the color singlet model by the same factor found for direct $\ensuremath{\psi}(2S)$ production.

We report the results of a study of charged B decays to the D+- pi-+ pi-+ and D*+- pi-+ pi-+ final states using complete D(*) reconstruction. The contributions of two-body B => D** pi decays with narrow (j=3/2) and broad (j=1/2) D** states have been determined and the masses and widths of four D** states have been measured. This is the first observation of the broad D*0_0 and D'0_1 mesons. The analysis is based on a data sample of 65 million B barB pairs collected in the Belle experiment.

We present the first evidence of the decay B- --> tau- nu_tau-bar using 414 fb^-1 of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. We detect the signal with a significance of 3.5 standard deviations including systematics, and measure the branching fraction to be Br(B- --> tau- nu_tau-bar) = (1.79 +0.56-0.49(stat) +0.46-0.51(syst))*10^-4. This implies that f_B = 0.229 +0.036-0.031(stat) +0.034-0.037(syst) GeV and is the first direct measurement of this quantity.

We report the first observation of two resonance-like structures in the pi+ chi_c1 invariant mass distribution near 4.1 GeV/c^2 in exclusive B0-bar --> K- pi+ chi_c1 decays. From a Dalitz plot analysis in which the pi+ chi_c1 mass structures are represented by Breit-Wigner resonance amplitudes, we determine masses and widths of: M_1 = (4051 +-14 +20-41) MeV/c^2, Gamma_1 = (82 +21-17 +47-22) MeV, M_2 = (4248 +44-29 +180-35}) MeV/c^2, and Gamma_2 =(177 +54-39 +316-61) MeV; and product branching fractions of BF(B0-bar --> K- Z+_1,2) x BF(Z+_1,2 --> pi+ chi_c1) = (3.0 +1.5-0.8 +3.7-1.6) x 10^-5 and (4.0 +2.3-0.9 +19.7-0.5) x 10^-5 respectively. Here the first uncertainty is statistical, the second is systematic. The significance of each of the pi+ chi_c1 structures exceeds 5 sigma, including the systematic uncertainty from various fit models. This analysis is based on 657 x 10^6 BB-bar events collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

We report a fully inclusive measurement of the flavor changing neutral current decay b --> sgamma in the energy range 1.8 GeV < or = E*gamma < or = 2.8 GeV, covering 95% of the total spectrum. Using 140 fb(-1), we obtain B(b --> sgamma) = (3.55+/-0.32(+0.30+0.11)(-0.31-0.07)) x 10(-4), where the errors are statistical, systematic, and from theory corrections. We also measure the first and second moments of the photon energy spectrum above 1.8 GeV and obtain (Egamma) = 2.292+/-0.026+/-0.034 GeV and (E2gamma) - (Egamma)2 = 0.0305+/-0.0074+/-0.0063 GeV2, where the errors are statistical and systematic.

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

We have measured the polarization of J/psi and psi(2S) mesons produced in pp collisions at sqrt[s] = 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992-1995. The polarization of promptly produced J/psi [psi(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4 [5.5]<P(T)<20 GeV/c and |y|<0.6. For P(T) greater than or approximately equal 12 GeV/c we do not observe significant polarization in the prompt component.

We present an improved measurement of the standard model CP violation parameter $\mathrm{sin}2{\ensuremath{\varphi}}_{1}$ (also known as $\mathrm{sin}2\ensuremath{\beta})$ based on a sample of $85\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. One neutral B meson is reconstructed in a $J/\ensuremath{\psi}{K}_{S}^{0},$ $\ensuremath{\psi}{(2S)K}_{S}^{0},$ ${\ensuremath{\chi}}_{c1}{K}_{S}^{0},$ ${\ensuremath{\eta}}_{c}{K}_{S}^{0},$ $J/\ensuremath{\psi}{K}^{*0},$ or $J/\ensuremath{\psi}{K}_{L}^{0}$ CP-eigenstate decay channel and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time interval between the two B meson decay points, we obtain $\mathrm{sin}2{\ensuremath{\varphi}}_{1}=0.719\ifmmode\pm\else\textpm\fi{}0.074(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.035(\mathrm{syst}).$

The Collins effect connects transverse quark spin with a measurable azimuthal dependence in the yield of hadronic fragments around the quark's momentum vector. Using two different reconstruction methods, we find evidence of statistically significant azimuthal asymmetries for charged pion pairs in e(+)e(-) annihilation at a center-of-mass energy of 10.52 GeV, which can be attributed to a transverse polarization of the primordial quarks. The measurement was performed using a sample of 79 x 10(6) hadronic events collected with the Belle detector.

We report the first observation of a near-threshold enhancement in the D(0)D[over](0)pi(0) system from B-->D(0)D[over](0)pi(0)Kappa decays using a 414 fb(-1) data sample collected at the Upsilon(4S) resonance. The enhancement peaks at a mass M=3875.2+/-0.7(+0.3)/(-1.6) +/-0.8 MeV/c2 and the branching fraction for events in the peak is B(B-->D(0)D[over](0)pi(0)Kappa)=(1.22+/-0.31(+0.23)/(-0.30))x10(-4). The data were collected with the Belle detector at the KEKB energy-asymmetric e+ e- collider.

We report a high-statistics measurement of the branching fraction for τ -→ π -π 0 ν τ and the invariant mass spectrum of the produced π -π 0 system using 72.2 fb -1 of data recorded with the Belle detector at the KEKB asymmetric-energy e + e -collider.The branching fraction obtained is (25.24 ± 0.01 ± 0.39)%, where the first error is statistical and the second is systematic.The unfolded π -π 0 mass spectrum is used to determine resonance parameters for the ρ(770), ρ ′ (1450), and ρ ′′ (1700) mesons.We also use this spectrum to estimate the hadronic (2π) contribution to the anomalous magnetic moment of the muon (a ππ µ ).Our result for a ππ µ integrated over the mass range √ s = 2m π -1.8 GeV/c 2 is a ππ µ = (523.5 ± 1.5 (exp) ± 2.6 (Br) ± 2.5 (isospin)) × 10 -10 , where the first error is due to the experimental uncertainties, the second is due to the uncertainties in the branching fractions and the third is due to the uncertainties in the isospin-violating corrections.

We report the first observation of e;{+}e;{-}-->Upsilon(1S)pi;{+}pi;{-}, Upsilon(2S)pi;{+}pi;{-}, and first evidence for e;{+}e;{-}-->Upsilon(3S)pi;{+}pi;{-}, Upsilon(1S)K+K-, near the peak of the Upsilon(5S) resonance at sqrt[s] approximately 10.87 GeV. The results are based on a data sample of 21.7 fb;{-1} collected with the Belle detector at the KEKB e;{+}e;{-} collider. Attributing the signals to the Upsilon(5S) resonance, the partial widths Gamma(Upsilon(5S)-->Upsilon(1S)pi;{+}pi;{-})=0.59+/-0.04(stat)+/-0.09(syst) MeV and Gamma(Upsilon(5S)-->Upsilon(2S)pi;{+}pi;{-})=0.85+/-0.07(stat)+/-0.16(syst) MeV are obtained from the observed cross sections. These values exceed by more than 2 orders of magnitude the previously measured partial widths for dipion transitions between lower Upsilon resonances.

We report on a search for the lepton flavor violating τ−→μ−γ and τ−→e−γ decays based on 535 fb−1 of data accumulated at the Belle experiment. No signal is found and we set 90% confidence level upper limits on the branching ratios B(τ−→μ−γ)<4.5×10−8 and B(τ−→e−γ)<1.2×10−7.

We report the observation of a new $D_{sJ}$ meson produced in $B^{+} \to \bar{D}^{0} D_{sJ} \to \bar{D}^{0} D^{0} K^{+}$. This state has a mass of $M=2708 \pm 9 ^{+11}_{-10} \rm{MeV}/{\it c}^{2}$, a width $\Gamma = 108 \pm 23 ^{+36}_{-31} ~\rm{MeV}/ {\it c}^{2}$ and a $1^{-}$ spin-parity. The results are based on an analysis of 449 million $B\bar{B}$ events collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+} e^{-}$ collider.

We report the first observations of the spin-singlet bottomonium states h(b)(1P) and h(b)(2P). The states are produced in the reaction e(+)e(-)→h(b)(nP)π(+)π(-) using a 121.4 fb(-1) data sample collected at energies near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We determine M[h(b)(1P)]=(9898.2(-1.0-1.1)(+1.1+1.0)) MeV/c(2) and M[h(b)(2P)]=(10,259.8±0.6(-1.0)(+1.4)) MeV/c(2), which correspond to P-wave hyperfine splittings ΔM(HF)=(+1.7±1.5) and (+0.5(-1.2)(+1.6)) MeV/c(2), respectively. The significances of the h(b)(1P) and h(b)(2P) are 5.5σ and 11.2σ, respectively. We find that the production of the h(b)(1P) and h(b)(2P) is not suppressed relative to the production of the Υ(1S), Υ(2S), and Υ(3S).

We report the results of a search for a charmonium-like state produced in the process gamma gamma --> omega J/psi in the 3.9-4.2 GeV/c^2 mass region. We observe a significant enhancement, which is well-described by a resonant shape with mass M = (3915 +/- 3 +/- 2) MeV/c^2 and total width Gamma = (17 +/- 10 +/- 3) MeV. This enhancement may be related to one or more of the three charmonium-like states so far reported in the 3.90-3.95 GeV/c^2 mass region.

We report measurement of the cross section of $e^+e^-\to \pi^+\pi^-\psi(2S)$ between 4.0 and $5.5 {\rm GeV}$, based on an analysis of initial state radiation events in a $980 \rm fb^{-1}$ data sample recorded with the Belle detector. The properties of the $Y(4360)$ and $Y(4660)$ states are determined. Fitting the mass spectrum of $\pi^+\pi^-\psi(2S)$ with two coherent Breit-Wigner functions, we find two solutions with identical mass and width but different couplings to electron-positron pairs: $M_{Y(4360)} = (4347\pm 6\pm 3) {\rm MeV}/c^2$, $\Gamma_{Y(4360)} = (103\pm 9\pm 5) {\rm MeV}$, $M_{Y(4660)} = (4652\pm10\pm 8) {\rm MeV}/c^2$, $\Gamma_{Y(4660)} = (68\pm 11\pm 1) \rm MeV$; and ${\cal{B}}[Y(4360)\to \pi^+\pi^-\psi(2S)]\cdot \Gamma_{Y(4360)}^{e^+e^-} = (10.9\pm 0.6\pm 0.7) \rm eV$ and ${\cal{B}}[Y(4660)\to \pi^+\pi^-\psi(2S)]\cdot \Gamma_{Y(4660)}^{e^+e^-} = (8.1\pm 1.1\pm 0.5) \rm eV$ for one solution; or ${\cal{B}}[Y(4360)\to \pi^+\pi^-\psi(2S)]\cdot \Gamma_{Y(4360)}^{e^+e^-} = (9.2\pm 0.6\pm 0.6) \rm eV$ and ${\cal{B}}[Y(4660)\to \pi^+\pi^-\psi(2S)]\cdot \Gamma_{Y(4660)}^{e^+e^-} = (2.0\pm 0.3\pm 0.2) \rm eV$ for the other. Here, the first errors are statistical and the second systematic. Evidence for a charged charmoniumlike structure at $4.05 {\rm GeV}/c^2$ is observed in the $\pi^{\pm}\psi(2S)$ intermediate state in the $Y(4360)$ decays.

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 report on a search for heavy neutrinos in B-meson decays. The results are obtained using a data sample that contains 772x10^6 BB-bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. No signal is observed and upper limits are set on mixing of heavy neutrinos with left-handed neutrinos of the Standard Model in the mass range 0.5 - 5.0 GeV/c^2.

We report a search for the rare decays B→h(*)ν¯ν, where h(*) stands for K+, K0S, K*+, K*0, π+, π0, ρ+, ρ0 and ϕ. The results are obtained from a 711 fb−1 data sample that contains 772×106B¯¯¯B pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB e+e− collider. We search for signal candidates by fully reconstructing a hadronic decay of the accompanying B meson and requiring a single h(*) meson left on the signal side. No significant signal is observed and we set upper limits on the branching fractions at 90% confidence level. The measurements of B+→K*+ν¯ν, B+→π+ν¯ν, B0→π0ν¯ν and B0→ρ0ν¯ν provide the world’s currently most restrictive limits.Received 15 March 2013DOI:https://doi.org/10.1103/PhysRevD.87.111103© 2013 American Physical Society

Abstract A multi-TeV muon collider offers a spectacular opportunity in the direct exploration of the energy frontier. Offering a combination of unprecedented energy collisions in a comparatively clean leptonic environment, a high energy muon collider has the unique potential to provide both precision measurements and the highest energy reach in one machine that cannot be paralleled by any currently available technology. The topic generated a lot of excitement in Snowmass meetings and continues to attract a large number of supporters, including many from the early career community. In light of this very strong interest within the US particle physics community, Snowmass Energy, Theory and Accelerator Frontiers created a cross-frontier Muon Collider Forum in November of 2020. The Forum has been meeting on a monthly basis and organized several topical workshops dedicated to physics, accelerator technology, and detector R&amp;D. Findings of the Forum are summarized in this report.

We have searched for heavy neutral gauge bosons (Z′) in dielectron and dimuon decay modes using 110pb−1 of ¯pp collisions at √s=1.8TeV collected with the Collider Detector at Fermilab. We present a limit on the production cross section times branching ratio of a Z′ boson decaying into dileptons as a function of Z′ mass. For mass MZ′>600GeV/c2, the upper limit is 40 fb at 95% confidence level. We set the lower mass limits of 690, 590, 620, 595, 565, 630, and 600GeV/c2 for Z′SM, Zψ, Zη, Zχ, ZI, ZLR, and ZALRM, respectively.Received 6 May 1997DOI:https://doi.org/10.1103/PhysRevLett.79.2192©1997 American Physical Society

We report the observation of a narrow peak in the K(S)K-pi(+) invariant mass distribution in a sample of exclusive B-->KK(S)K-pi(+) decays collected with the Belle detector at the KEKB asymmetric e(+)e(-) collider. The measured mass of the peak is M=3654+/-6(stat)+/-8(syst) MeV/c(2), and we place a 90% confidence level upper limit on the width of Gamma<55 MeV/c(2). The properties agree with heavy-quark potential model expectations for the eta(c)(2S) meson, the n=2 singlet S charmonium state.

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 have searched for a CP violation signature arising from an electric dipole moment (dτ) of the τ lepton in the e+e−→τ+τ− reaction. Using an optimal observable method and 29.5 fb−1 of data collected with the Belle detector at the KEKB collider at s=10.58 GeV, we find Re(dτ)=(1.15±1.70)×10−17 ecm and Im(dτ)=(−0.83±0.86)×10−17 ecm and set the 95% confidence level limits −2.2×10−17<Re(dτ)<4.5×10−17 ecm and −2.5×10−17<Im(dτ)<0.8×10−17 ecm.

We present an improved measurement of the branching fraction for the electroweak penguin process B-&gt;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) -&gt; 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-&gt;Xsll)=(4.11+-0.83(stat)+0.85-0.81(syst))*10^{-6} for M_ll &gt; 0.2GeV/c2.

We report evidence for the decay ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$. The analysis is based on a data sample of ${\mathrm{152}\mathrm{\ifmmode\times\else\texttimes\fi{}}\mathrm{10}}^{6}$ $B\overline{B}$ pairs collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB ${e}^{+}{e}^{\ensuremath{-}}$ storage ring. We detect a signal for ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ with a significance of 3.4 standard deviations, and measure the branching fraction to be $\mathrm{[}\mathrm{1.7}\ifmmode\pm\else\textpm\fi{}\mathrm{0.6}\mathrm{(}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{)}\ifmmode\pm\else\textpm\fi{}\mathrm{0.2}\mathrm{(}\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{)}\mathrm{]}\ifmmode\times\else\texttimes\fi{}{\mathrm{10}}^{\ensuremath{-}\mathrm{6}}$.

We report on measurements of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) differential cross sections (d(2)sigma/dp(T)dy)(/y/<0.4), as well as on the Upsilon(1S) polarization in p p macro collisions at square root of s = 1.8 TeV using a sample of 77+/-3 pb(-1) collected by the collider detector at Fermilab. The three resonances were reconstructed through the decay Upsilon-->mu(+)mu(-). The measured angular distribution of the muons in the Upsilon(1S) rest frame is consistent with unpolarized meson production.

The transverse momentum and total cross section of e^+e^- pairs in the Z-boson region of 66<M_{ee}<116 GeV$/c^2$ from $p\bar{p}$ collisions at $\sqrt{s}=1.8$ TeV are measured using 110 pb^{-1} of collisions taken by the Collider Detector at Fermilab during 1992-1995. The total cross section is measured to be $248 \pm 11$ pb. The differential transverse momentum cross section is compared with calculations that match quantum chromodynamics perturbation theory at high transverse momentum with the gluon resummation formalism at low transverse momentum.

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.

We report measurements of the exclusive cross section for e+e−→D¯¯¯D, where D=D0 or D+, in the center-of-mass energy range from the D¯¯¯D threshold to 5 GeV with initial-state radiation. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 673 fb−1.Received 18 October 2007DOI:https://doi.org/10.1103/PhysRevD.77.011103©2008 American Physical Society

We present the first measurement of decay amplitudes in B→φK* and measurements of branching fractions in B→φK(*) decays based on 78.1 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 different φK*0 helicity states are measured from the angular distributions of final state particles in the transversity basis. The longitudinal and transverse complex amplitudes are |A0|2=0.43±0.09±0.04, |A⊥|2=0.41±0.10±0.04, arg(A∥)=−2.57±0.39±0.09, and arg(A⊥)=0.48±0.32±0.06. The direct CP-violating asymmetries are found to be consistent with zero.Received 8 July 2003DOI:https://doi.org/10.1103/PhysRevLett.91.201801©2003 American Physical Society

We present improved measurements of CP-violation parameters in B0→ϕK0, η′K0, K0SK0SK0S decays based on a sample of 535×106 B¯¯¯B pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e− collider. We obtain sin2ϕeff1=+0.64±0.10(stat)±0.04(syst) for B0→η′K0, +0.50±0.21(stat)±0.06(syst) for B0→ϕK0, and +0.30±0.32(stat)±0.08(syst) for B0→K0SK0SK0S decays. We have observed CP violation in the B0→η′K0 decay with a significance of 5.6 standard deviations. We also perform an improved measurement of CP asymmetries in B0→J/ψK0 decays and obtain sin2ϕ1=+0.642±0.031(stat)±0.017(syst).Received 2 October 2006DOI:https://doi.org/10.1103/PhysRevLett.98.031802©2007 American Physical Society

We report a measurement of ${D}^{0}\ensuremath{-}{\overline{D}}^{0}$ mixing parameters in ${D}^{0}\ensuremath{\rightarrow}{K}_{S}^{0}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ decays using a time-dependent Dalitz-plot analysis. We first assume $CP$ conservation and subsequently allow for $CP$ violation. The results are based on $540\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data accumulated with the Belle detector at the KEKB ${e}^{+}{e}^{\ensuremath{-}}$ collider. Assuming negligible $CP$ violation, we measure the mixing parameters $x=(0.80\ifmmode\pm\else\textpm\fi{}{0.29}_{\ensuremath{-}0.07\ensuremath{-}0.14}^{+0.09+0.10})%$ and $y=(0.33\ifmmode\pm\else\textpm\fi{}{0.24}_{\ensuremath{-}0.12\ensuremath{-}0.08}^{+0.08+0.06})%$, where the errors are statistical, experimental systematic, and systematic due to the Dalitz decay model, respectively. Allowing for $CP$ violation, we obtain the $CP$-violating parameters $|q/p|={0.86}_{\ensuremath{-}0.29\ensuremath{-}0.03}^{+0.30+0.06}\ifmmode\pm\else\textpm\fi{}0.08$ and $\mathrm{arg}(q/p)=(\ensuremath{-}{14}_{\ensuremath{-}18\ensuremath{-}3\ensuremath{-}4}^{+16+5+2})\ifmmode^\circ\else\textdegree\fi{}$.

We report a measurement of the exclusive e+e−→D(*)±D*∓ cross section as a function of center-of-mass energy near the D(*)±D*∓ threshold with initial-state radiation. A partial reconstruction technique is used to increase the efficiency and to suppress background. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 547.8 fb−1.Received 12 January 2007DOI:https://doi.org/10.1103/PhysRevLett.98.092001©2007 American Physical Society

We present a new measurement of the unitarity triangle angle phi3 using a Dalitz plot analysis of the KsPi+Pi- decay of the neutral D meson produced in B->D(*)K decays. The method exploits the interference between D0 and D0bar to extract the angle phi3, strong phase delta and the ratio r of suppressed and allowed amplitudes. We apply this method to a 605 fb-1 data sample collected by the Belle experiment. The analysis uses three decays: B->DK, and B->D*K with D*->DPi0 and D*->Dgamma, as well as the corresponding charge-conjugate modes. From a combined maximum likelihood fit to the three modes, we obtain phi3 = 78.4^+10.8_-11.6 +- 3.6 (syst) +- 8.9 (model) degrees. CP conservation in this process is ruled out at the confidence level (1-CL)=5x10^-4, or 3.5 standard deviations.

Using 605 fb(-1) of data collected at the Upsilon(4S) resonance we present a measurement of the inclusive radiative B-meson decay channel, B-->X(s)gamma. For the lower photon energy thresholds of 1.7, 1.8, 1.9, and 2.0 GeV, as defined in the rest frame of the B meson, we measure the partial branching fraction and the mean and variance of the photon energy spectrum. At the 1.7 GeV threshold we obtain the partial branching fraction BF(B-->X(s)}gamma)=(3.45+/-0.15+/-0.40)x10(-4), where the errors are statistical and systematic.

The cross sections for e+e−→ϕπ+π− and e+e−→ϕf0(980) are measured from threshold to √s=3.0 GeV using initial-state radiation. The analysis is based on a data sample of 673 fb−1 collected on and below the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. First measurements are reported for the resonance parameters of the ϕ(1680) in the ϕπ+π− mode: m=(1689±7±10) MeV/c2 and Γ=(211±14±19) MeV/c2. A structure at √s=2.1 GeV/c2, corresponding to the so called Y(2175), is observed; its mass and width are determined to be (2079±13+79−28) MeV/c2 and (192±23+25−61) MeV/c2, respectively.Received 24 May 2009DOI:https://doi.org/10.1103/PhysRevD.80.031101©2009 American Physical Society

Using the entire Belle data sample of $980\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ collisions, we present the results of a study of excited ${\mathrm{\ensuremath{\Omega}}}_{c}$ charmed baryons in the decay mode ${\mathrm{\ensuremath{\Xi}}}_{c}^{+}{K}^{\ensuremath{-}}$. We show confirmation of four of the five narrow states reported by the LHCb Collaboration: the ${\mathrm{\ensuremath{\Omega}}}_{c}(3000)$, ${\mathrm{\ensuremath{\Omega}}}_{c}(3050)$, ${\mathrm{\ensuremath{\Omega}}}_{c}(3066)$, and ${\mathrm{\ensuremath{\Omega}}}_{c}(3090)$.

Measurements of two-particle angular correlations of charged particles emitted in hadronic Z decays are presented. The archived e^{+}e^{-} annihilation data at a center-of-mass energy of 91 GeV were collected with the ALEPH detector at LEP between 1992 and 1995. The correlation functions are measured over a broad range of pseudorapidity and full azimuth as a function of charged particle multiplicity. No significant long-range correlation is observed in either the lab coordinate analysis or the thrust coordinate analysis, where the latter is sensitive to a medium expanding transverse to the color string between the outgoing qq[over ¯] pair from Z boson decays. The associated yield distributions in both analyses are in better agreement with the prediction from the pythia v6.1 event generator than from herwig v7.1.5. They provide new insights to showering and hadronization modeling. These results serve as an important reference to the observed long-range correlation in proton-proton, proton-nucleus, and nucleus-nucleus collisions.

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 a measurement of the standard model CP violation parameter sin2 phi(1) (also known as sin2beta) based on a 10.5 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) collider. One neutral B meson is reconstructed in the J/psiK(S), psi(2S)K(S), chi(c1)K(S), eta(c)K(S), J/psiK(L), or J/psipi(0) CP-eigenstate decay channel and the flavor of the accompanying B meson is identified from its charged particle decay products. From the asymmetry in the distribution of the time interval between the two B-meson decay points, we determine sin2 phi(1) = 0.58(+0.32)(-0.34)(stat)+0.09-0.10(syst).

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 a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations.

This Letter describes a direct search for charged Higgs boson production in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ recorded by the Collider Detector at Fermilab. Two-Higgs-double extensions to the standard model predict the existence of charged Higgs bosons $({H}^{\ifmmode\pm\else\textpm\fi{}})$. In such models, the branching fraction for top quarks $B(t\ensuremath{\rightarrow}{H}^{+}b\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}\ensuremath{\nu}b)$ can be large. This search uses the hadronic decays of the tau lepton in this channel to significantly extend previous limits on ${H}^{\ifmmode\pm\else\textpm\fi{}}$ production.

The B meson decay modes B --> D p pbar and B --> D* p pbar have been studied using 29.4 fb^{-1} of data collected with the Belle detector at KEKB. The B0bar --> D0 p pbar and B0bar --> D*0 p pbar decays have been observed for the first time with branching fractions Br(B0bar --> D0 p pbar) =(1.18\pm 0.15\pm 0.16) 10^{-4} and Br(B0bar --> D*0 p pbar) =(1.20^{+0.33}_{-0.29}\pm 0.21) 10^{-4}. No signal has been found for the B+ --> D+ p pbar and B+ --> D*+ p pbar decay modes, and the corresponding upper limits at 90% C.L. are presented.

Inclusive ${\ensuremath{\pi}}^{0}$ and direct-photon cross sections in the kinematic range $3.5&lt;{p}_{T}&lt;12\mathrm{GeV}/c$ with central rapidities ( ${y}_{\mathrm{cm}}$) are presented for $530\mathrm{and}800\mathrm{GeV}/c$ proton beams and a $515\mathrm{GeV}/c$ ${\ensuremath{\pi}}^{\ensuremath{-}}$ beam incident on Be targets. Current next-to-leading-order perturbative QCD calculations fail to adequately describe the data for conventional choices of scales. Kinematic distributions from these hard scattering events provide evidence that the interacting partons carry significant initial-state parton transverse momentum ( ${k}_{T}$). Incorporating these ${k}_{T}$ effects phenomenologically greatly improves the agreement between calculations and the measured cross sections.

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.

Using a 282 1/fb data sample collected by the Belle experiment at the KEKB e+e- collider, we study D0 decays to K-l+nu and pi-l+nu final states. The D0 flavor and momentum are tagged through a full reconstruction of the recoiling charm meson and additional mesons from fragmentation. The reconstruction method provides very good resolution in neutrino momentum and in q^2 = (p_l+p_nu)^2. Normalizing to the total number of D0 tags, we measure the absolute branching fractions to be B(D0 -> Klnu) =(3.45 +- 0.07stat +- 0.20syst)% and B(D0 -> pilnu) = (0.255 +- 0.019stat +- 0.016syst)% and the semi-leptonic form factors (within the modified pole model) f+^K(0) = 0.695 +- 0.007stat +- 0.022syst and f+^pi(0) = 0.624 +- 0.020stat +- 0.030syst.

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.

We report the first measurement of the forward-backward asymmetry and the ratios of Wilson coefficients A 9 /A 7 and A 10 /A 7 in B → K * ℓ + ℓ -, where ℓ represents an electron or a muon.We observe a large integrated forward-backward asymmetry with a significance of 3.4σ.The results are obtained from a data sample containing 386 ×10 6 B B pairs that were collected on the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e -collider.

We report measurements of the exclusive cross section for e + e -→ D 0 D * -π + as a function of center-of-mass energy from the D 0 D * -π + threshold to 5.2 GeV with initial-state radiation.No evidence is found for Y (4260) → D 0 D * -π + decays.The analysis is based on a data sample collected with the Belle detector at or near a center-of-mass energy of 10.58 GeV with an integrated luminosity of 695 fb -1 at the KEKB asymmetric-energy e + e -collider.

We measure the CP-violating asymmetries in decays to the D0 -> K+K- and D0 -> pi+pi- CP eigenstates using 540 fb^{-1} of data collected with the Belle detector at or near the Upsilon(4S) resonance. Cabibbo-favored D0 -> K-pi+ decays are used to correct for systematic detector effects. The results, A_{CP}^{KK} = (-0.43 +- 0.30 +- 0.11)% and A_{CP}^{pipi} = (+0.43 +- 0.52 +- 0.12)%, are consistent with no CP violation.

We measure the production cross sections for e+e- -> Upsilon(1S)pi+pi-, Upsilon(2S)pi+pi-, and Upsilon(3S)pi+pi- as a function of sqrt{s} between 10.83 GeV and 11.02 GeV. The data consists of 8.1 fb^-1 collected with the Belle detector at the KEKB e+e- collider. We observe enhanced production in all three final states that does not agree well with the conventional Upsilon(10860) lineshape. A fit using a Breit-Wigner resonance shape yields a peak mass of [10888.4 +2.7/-2.6 (stat) +- 1.2 (syst)] MeV/c^2 and a width of [30.7 +8.3/-7.0 (stat) +- 3.1 (syst)] MeV/c^2.

We present a measurement of the decay B−→τ−ν¯τ using a data sample containing 657×106 BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. A sample of B+B− pairs are tagged by reconstructing one B+ meson decaying semileptonically. We detect the B−→τ−ν¯τ candidate in the recoil. We obtain a signal with a significance of 3.6 standard deviations including systematic uncertainties, and measure the branching fraction to be B(B−→τ−ν¯τ)=[1.54−0.37+0.38(stat)−0.31+0.29(syst)]×10−4. This result confirms the evidence for B−→τ−ν¯τ obtained in a previous Belle measurement that used a hadronic B tagging method.Received 21 June 2010DOI:https://doi.org/10.1103/PhysRevD.82.071101© 2010 The American Physical Society

The differential cross section for the process γγ→ηπ0 has been measured in the kinematic range 0.84 GeV<W<4.0 GeV, |cosθ∗|<0.8, where W and θ∗ are the energy and π0 (or η) scattering angle, respectively, in the γγ center-of-mass system. The results are based on a 223 fb−1 data sample collected with the Belle detector at the KEKB e+e− collider. Clear peaks due to the a0(980) and a2(1320) are visible. The differential cross sections are fitted in the energy region 0.9 GeV<W<1.46 GeV to obtain the parameters of the a0(980). Its mass, width and ΓγγB(ηπ0) are measured to be 982.3+0.6+3.1−0.7−4.7 MeV/c2, 75.6±1.6+17.4−10.0 MeV and 128+3+502−2−43 eV, respectively. The energy and angular dependences above 3.1 GeV are compared with those measured in the π0π0 channel. The integrated cross section over |cosθ∗|<0.8 has a W−n dependence with n=10.5±1.2±0.5, which is slightly larger than that for π0π0. The differential cross sections show a sin−4θ∗ dependence similar to γγ→π0π0. The measured cross section ratio, σ(ηπ0)/σ(π0π0)=0.48±0.05±0.04, is consistent with a QCD-based prediction.9 MoreReceived 8 June 2009DOI:https://doi.org/10.1103/PhysRevD.80.032001©2009 American Physical Society

This article describes a determination of the Cabibbo-Kobayashi-Maskawa matrix element $|{V}_{cb}|$ from the decay ${B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ using $711\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of Belle data collected near the $\ensuremath{\Upsilon}(4S)$ resonance. We simultaneously measure the product of the form factor normalization $\mathcal{F}(1)$ and the matrix element $|{V}_{cb}|$ as well as the three parameters ${\ensuremath{\rho}}^{2}$, ${R}_{1}(1)$ and ${R}_{2}(1)$, which determine the form factors of this decay in the framework of the heavy quark effective theory. The results, based on about 120 000 reconstructed ${B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ decays, are ${\ensuremath{\rho}}^{2}=1.214\ifmmode\pm\else\textpm\fi{}0.034\ifmmode\pm\else\textpm\fi{}0.009$, ${R}_{1}(1)=1.401\ifmmode\pm\else\textpm\fi{}0.034\ifmmode\pm\else\textpm\fi{}0.018$, ${R}_{2}(1)=0.864\ifmmode\pm\else\textpm\fi{}0.024\ifmmode\pm\else\textpm\fi{}0.008$ and $\mathcal{F}(1)|{V}_{cb}|=(34.6\ifmmode\pm\else\textpm\fi{}0.2\ifmmode\pm\else\textpm\fi{}1.0)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. The branching fraction of ${B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ is measured at the same time; we obtain a value of $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}})=(4.58\ifmmode\pm\else\textpm\fi{}0.03\ifmmode\pm\else\textpm\fi{}0.26)%$. The errors correspond to the statistical and systematic uncertainties. These results give the most precise determination of the form factor parameters and $\mathcal{F}(1)|{V}_{cb}|$ to date. In addition, a direct, model-independent determination of the form factor shapes has been carried out.

We report measurements of the branching fractions and direct CP asymmetries (A_{CP}) for B->K pi, pi pi and KK decays (but not pi^0 pi^0) based on the final data sample of 772x10^6 B B-bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider. We set a 90% confidence-level upper limit for K^+- K^-+ at 2.0x10^{-7}; all other decays are observed with branching fractions ranging from 10^{-6} to 10^{-5}. In the $B^0/B^0-bar -> K^+-\pi^-+ mode, we confirm Belle's previously reported large A_{CP} with a value of -0.069 +- 0.014 +- 0.007 and a significance of 4.4 sigma. For all other flavor-specific modes, we find A_{CP} values consistent with zero, including A_{CP}(K^+- \pi^0) = +0.043 +- 0.024 +- 0.007 with 1.8 sigma significance. The difference of CP asymmetry between B^+- -> K^+- pi^0 and B^0/B^0-bar -> K^+-\pi^-+ is found to be Delta A_{K pi} equiv A_{CP} (K^+ pi^0) - A_{CP}(K^+ pi^-) = +0.112 +- 0.027 +- 0.007 with 4.0 sigma significance. We also calculate the ratios of partial widths for the B-> K pi decays. Using our results, we test the validity of the sum rule A_{CP}(K^+ pi^-) + A_{CP}(K^0\pi^+) x Gamma(K^0\pi^+)/Gamma(K^+ pi^-)} - A_{CP}(K^+ pi^0)x 2Gamma(K^+ pi^0)/Gamma(K^+ pi^-) - A_{CP}(K^0 pi^0)x 2Gamma(K^0 pi^0)/Gamma(K^+ pi^-) = 0 and obtain a sum of -0.270 +- 0.132 +- 0.060 with 1.9 sigma significance.

We report the observation of B(s)⁰→J/ψf₀(980) and evidence for B(s)⁰→J/ψf₀(1370), which are CP eigenstate decay modes. These results are obtained from 121.4 fb⁻¹ of data collected at the Υ(5S) resonance with the Belle detector at the KEKB e(+)e⁻ collider. We measure the branching fractions B(B(s)⁰→J/ψf₀(980); f₀(980)→π(+)π⁻)=(1.16(-0.19)(+0.31)(stat)(-0.17)(+0.15)(syst)(-0.18)(+0.26)(N(B(s)((*))B(s)((*)))))×10⁻⁴ with a significance of 8.4σ, and B(B(s)⁰→J/ψf₀(1370); f₀(1370)→π(+)π⁻)=(0.34(-0.14)(+0.11)(stat)(-0.02)(+0.03)(syst)(-0.05)(+0.08)(N(B(s)((*))B(s)((*)))))×10⁻⁴ with a significance of 4.2σ. The last error listed is due to uncertainty in the number of produced B(s)((*))B(s)((*)) pairs.

A bstract We present measurements of absolute branching fractions of hadronic and lep-tonic $ D_s^{+} $ decays to K − K + π + , $ {{\overline{K}}^0} $ K + , ηπ + , μ + ν μ and τ + ν τ and report a search for the leptonic $ D_s^{+} $ → e + ν e decays. The results are obtained from a data sample of 913 fb −1 collected at or near the $ \varUpsilon $ (4 S ) and $ \varUpsilon $ (5 S ) resonances with the Belle detector at the KEKB asymmetric-energy e + e − collider. The branching fractions of hadronic decays are measured to be $ \begin{array}{*{20}{c}} {\mathcal{B}\left( {D_s^{+}\ \to\ {K^{-}}{K^{+}}{\pi^{+}}} \right) = \left( {5.06\pm 0.15\pm 0.21} \right)\%,} \\ {\mathcal{B}\left( {D_s^{+}\ \to\ {{\overline{K}}^0}{K^{+}}} \right) = \left( {2.95\pm 0.11\pm 0.09} \right)\%,} \\ {\mathcal{B}\left( {D_s^{+}\ \to\ \eta {\pi^{+}}} \right) = \left( {1.82\pm 0.14\pm 0.07} \right)\%,} \\ \end{array} $ where the first and second uncertainties are statistical and systematic, respectively. The branching fractions of leptonic decays are measured to be $ \begin{array}{*{20}{c}} {\mathcal{B}\left( {D_s^{+}\ \to\ {\mu^{+}}{\nu_{\mu }}} \right)=\left( {0.531\pm 0.028\pm 0.020} \right)\%,} \\ {\mathcal{B}\left( {D_s^{+}\to {\tau^{+}}{\nu_{\tau }}} \right)=\left( {5.70\pm 0.21_{-0.30}^{-0.31 }} \right)\%,} \\ \end{array} $ which are combined to determine the $ D_s^{+} $ meson decay constant $ {f_{{{D_s}}}}=\left( {255.5\pm 4.2\pm 5.1} \right)\ \mathrm{MeV}. $ We find no significant signal for $ D_s^{+} $ → e + ν e decays and set an upper limit of $ \mathcal{B}\left( {D_s^{+}\ \to\ {e^{+}}{\nu_e}} \right) $ &lt; 1 . 0(0 . 83) × 10 −4 at 95% (90%) confidence level.

We report the first observation of Y(5S) -> Y(nS) pi0 pi0 decays. The neutral partner of the Zb+-(10610), the Zb0(10610) decaying to Y(2,3S) pi0, is observed for the first time with a 6.5 sigma significance using a Dalitz analysis of Y(5S) -> Y(2,3S) pi0 pi0 decays. The results are obtained with a 121.4 fb^-1 data sample collected with the Belle detector at the Y(5S) resonance at the KEKB asymmetric-energy e+e- collider.

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

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 observation of the flavor-changing neutral current decay B-->K(*)l(+)l(-) and an im-proved measurement of the decay B-->Kl(+)l(-), where l represents an electron or a muon, with a data sample of 140 fb(-1) accumulated at the Upsilon(4S) resonance with the Belle detector at KEKB. The results for the branching fractions are B(B-->K(*)l(+)l(-))=(11.5(+2.6)(-2.4)+/-0.8+/-0.2)x10(-7) and B(B-->Kl(+)l(-))=(4.8(+1.0)(-0.9)+/-0.3+/-0.1)x10(-7), where the first error is statistical, the second is systematic and the third is from model dependence.

We report on a study of three-body charmless decays B+→K+h+h− based on a 29.1fb−1 data sample collected with the Belle detector. With no assumptions on the intermediate mechanisms, the following three-body branching fractions have been measured for the first time: B(B+→K+π−π+)=(55.6±5.8±7.7)×10−6 and B(B+→K+K−K+)=(35.3±3.7±4.5)×10−6. We present the first observation of the decay B+→f0(980)K+ with a branching fraction product of B(B+→f0(980)K+)×B(f0(980)→π+π−)=(9.6+2.5+1.5+3.4−2.3−1.5−0.8)×10−6. This is the first reported example of a B meson decay to a scalar pseudoscalar final state. We also report the first observation of B+→K*(892)0π+ decay with a branching fraction of B(B+→K*(892)0π+)=(19.4+4.2+2.1+3.5−3.9−2.1−6.8)×10−6. Received 27 December 2001DOI:https://doi.org/10.1103/PhysRevD.65.092005©2002 American Physical Society

We have used $106{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ by the Collider Detector at Fermilab to measure jet angular distributions in events with two jets in the final state. The angular distributions agree with next to leading order predictions of QCD in all dijet invariant mass regions. The data exclude at 95% CL a model of quark substructure in which only up and down quarks are composite and the contact interaction scale is ${\ensuremath{\Lambda}}_{\mathrm{ud}}^{+}\ensuremath{\le}1.6\mathrm{TeV}$ or ${\ensuremath{\Lambda}}_{\mathrm{ud}}^{\ensuremath{-}}\ensuremath{\le}1.4\mathrm{TeV}$. For a model in which all quarks are composite the excluded regions are ${\ensuremath{\Lambda}}^{+}\ensuremath{\le}1.8\mathrm{TeV}$ and ${\ensuremath{\Lambda}}^{\ensuremath{-}}\ensuremath{\le}1.6\mathrm{TeV}$.

We report a search for the flavor-changing neutral current decay B-->K(*)l+l- using a 29.1 fb(-1) data sample accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- storage ring. We observe the decay process B-->Kl+l-(l = e, mu), for the first time, with a branching fraction of B(B-->Kl+l-) = (0.75(+0.25)(-0.21)+/-0.09)x10(-6).

We report the first observation of a b -> u type charmless baryonic B decay, B+ -> p pbar pi+, as well as b -> s type B0 -> p pbar K0 and B+ -> p pbar K*+ decays. The analysis is based on a 78fb^{-1} data sample recorded on the Upsilon(4S) resonance with the Belle detector at KEKB. We find BF(B+ -> p pbar pi+) = (3.06^{+0.73}_{-0.62} \pm 0.37)*10^{-6}, BF(B0 -> p pbar K0) =(1.88^{+0.77}_{-0.60} \pm 0.23)*10^{-6}, and BF(B+ -> p pbar K*+) = (10.3^{+3.6 + 1.3}_{-2.8 -1.7})*10^{-6}. We also update BF(B+ -> p pbar K+) = (5.66^{+0.67}_{-0.57} \pm 0.62)* 10^{-6}, and present an upper limit on BF(B0 -> p pbar K*0) at the 90% confidence level. A common feature of the observed decay modes is threshold peaking in baryon pair invariant mass.

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 $8\ifmmode^\circ\else\textdegree\fi{}&lt;{\ensuremath{\phi}}_{3}&lt;111\ifmmode^\circ\else\textdegree\fi{}$.

The production of prompt $J/\ensuremath{\psi}$, $\ensuremath{\psi}(2S)$, ${\ensuremath{\chi}}_{c1}$, and ${\ensuremath{\chi}}_{c2}$ is studied using a $32.4{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected with the Belle detector at $\ensuremath{\Upsilon}(4S)$ and at $60\mathrm{MeV}$ below the resonance. The yield of prompt $J/\ensuremath{\psi}$ mesons in the $\ensuremath{\Upsilon}(4S)$ sample is compatible with that of continuum production; we set an upper limit $B(\ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}J/\ensuremath{\psi}X)&lt;1.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ at the $95%$ confidence level, and find $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}X)\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.47\ifmmode\pm\else\textpm\fi{}0.10\ifmmode\pm\else\textpm\fi{}0.13\mathrm{pb}$. The cross sections for prompt $\ensuremath{\psi}(2S)$ and direct $J/\ensuremath{\psi}$ are measured. The $J/\ensuremath{\psi}$ momentum spectrum, production angle distribution, and polarization are studied.

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 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 .

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 present a study of the $X(3872)$ lineshape in the decay $B \to X(3872)K\to D^0\overline{D}{}^{*0}K$ using a data sample of $772\times 10^6$ $B\overline{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The peak near the threshold in the $D^0\overline{D}{}^{*0}$ invariant mass spectrum is fitted using a relativistic Breit-Wigner lineshape. We determine the mass and width parameters to be $m = 3873.71 ^{+0.56}_{-0.50} ({\rm stat}) \pm0.13 ({\rm syst}) ~{\rm MeV}/c^2$ and $\Gamma_0 = 5.2 ^{+2.2}_{-1.5} ({\rm stat}) \pm 0.4 ({\rm syst})~{\rm MeV}$, respectively. The branching fraction is found to be ${\cal B} (B^+\to X(3872)K^+) \times {\cal{B}}(X(3872) \to D^0\overline{D}{}^{*0}) = (0.97 ^{+0.21}_{-0.18} ({\rm stat}) \pm 0.10 ({\rm syst})) \times 10^{-4}$. The signal from $B^0$ decays is observed for the first time with $5.2\sigma$ significance, and the ratio of branching fractions between charged and neutral $B$ decays is measured to be ${\cal B}(B^0\to X(3872)K^0)/{\cal B}(B^+ \to X(3872)K^+) = 1.34^{+0.47}_{-0.40} ({\rm stat}) ^{+0.10}_{-0.12} ({\rm syst})$. The peak is also studied using a Flatt\'{e} lineshape. We determine the lower limit on the $D\overline{D}{}^{*}$ coupling constant $g$ to be $0.075$ at 95% credibility in the parameter region where the ratio of $g$ to the mass difference from the $D^0\overline{D}{}^{*0}$ threshold is equal to $-15.11~{\rm GeV}^{-1}$, as measured by LHCb.

We report results of a study of charmless B meson decays to three-body Kππ,KKπ and KKK final states. Measurements of branching fractions for B decays to K+(0)π+π−,K+K+K−,K0K+K−,K+K0SK0S and K0SK0SK0S final states are presented. The decays B0→K0K+K−,B+→K+K0SK0S and B0→K0SK0SK0S are observed for the first time. We also report evidence for B+→K+K−π+ decay. For the three-body final states K0K+π−,K0SK0Sπ+,K+K+π− and K−π+π+, 90% confidence level upper limits are reported. Finally, we discuss the possibility of using the three-body B0→K0SK+K− decay for CP violation studies. The results are obtained with a 78 fb−1 data sample collected at the Υ(4S) resonance by the Belle detector operating at the KEKB asymmetric energy e+e− collider.Received 1 August 2003DOI:https://doi.org/10.1103/PhysRevD.69.012001©2004 American Physical Society

We report the first measurement of the branching fraction for the inclusive decay B-->X(s)l(+)l(-), where l is either an electron or a muon, and X(s) is a hadronic recoil system that contains an s quark. We analyzed a data sample of 65.4 x 10(6) B meson pairs collected with the Belle detector at the KEKB e(+)e(-) asymmetric-energy collider. We find B(B-->X(s)l(+)l(-))=[6.1 +/-1.4(stat) +1.4-1.1(syst)] x 10(-6) for dilepton masses greater than 0.2 GeV/c(2).

We report measurements of CP violation parameters in B0→K0Sπ0γ transitions based on a data sample of 535×106B¯¯¯B pairs collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. One neutral B meson is fully reconstructed in the B0→K0Sπ0γ mode. The flavor of the accompanying B meson is identified from its decay products. We obtain time-dependent and direct CP violation parameters S and A for a K0Sπ0 invariant mass up to 1.8 GeV/c2 as SK0Sπ0γ=−0.10±0.31±0.07 and AK0Sπ0γ=−0.20±0.20±0.06. For a K0Sπ0 invariant mass near the K*0(892) resonance, we obtain SK*0γ=−0.32+0.36−0.33±0.05 and AK*0γ=−0.20±0.24±0.05.Received 10 November 2006DOI:https://doi.org/10.1103/PhysRevD.74.111104©2006 American Physical Society