T. Aushev

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 present a measurement of the standard model CP violation parameter sin2φ1 based on a 29.1fb−1 data sample collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. One neutral B meson is fully reconstructed as a J/ψKS, ψ(2S)KS, χc1KS, ηcKS, J/ψKL, or J/ψK*0 decay and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we determine sin2φ1=0.99±0.14(stat)±0.06(syst). We conclude that we have observed CP violation in the neutral B meson system.Received 18 July 2001DOI:https://doi.org/10.1103/PhysRevLett.87.091802©2001 American Physical Society

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 present a search for lepton-flavor-violating tau decays into three leptons (electrons or muons) using 782 fb^-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. No evidence for these decays is observed and we set 90% confidence level upper limits on the branching fractions between 1.5 x 10^-8 and 2.7 x 10^-8.

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.

This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C. Please note that version 3 on the archive is the auxiliary version of the Physics of the B Factories book. This uses the notation alpha, beta, gamma for the angles of the Unitarity Triangle. The nominal version uses the notation phi_1, phi_2 and phi_3. Please cite this work as Eur. Phys. J. C74 (2014) 3026.

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.

The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2 /s luminosity. To exploit the increased luminosity, an upgrade of the Belle detector has been proposed. A new international collaboration Belle-II, is being formed. The Technical Design Report presents physics motivation, basic methods of the accelerator upgrade, as well as key improvements of the detector.

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.

With the full data sample of $772 \times 10^6$ $B{\bar B}$ pairs recorded by the Belle detector at the KEKB electron-positron collider, the decay $\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau$ is studied with the hadronic $\tau$ decays $\tau^- \rightarrow \pi^- \nu_\tau$ and $\tau^- \rightarrow \rho^- \nu_\tau$. The $\tau$ polarization $P_\tau(D^*)$ in two-body hadronic $\tau$ decays is measured, as well as 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. 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. The polarization values of $P_\tau(D^*) > +0.5$ are excluded at the 90\% confidence level.

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 a measurement of $R_{K^{\ast}}$, the branching fraction ratio ${{\cal B}(B\to K^\ast \mu^+ \mu^-)}$/ ${{\cal B}(B\to K^\ast e^+ e^-)}$, for both charged and neutral $B$ mesons. The ratio for the charged case, $R_{K{^{\ast +}}}$, is the first measurement ever performed. In addition, we report absolute branching fractions for the individual modes in bins of the squared dilepton invariant mass, $q^2$. The analysis is based on a data sample of $711~\mathrm{fb}^{-1}$, containing $772\times 10^{6}$ $B\bar B$ events, recorded at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The obtained results are consistent with Standard Model expectations.

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.

We report the first observation of the B-->Dmacr;D(sJ)(2317) and B-->Dmacr;D(sJ)(2457) decays based on 123.8x10(6) BBmacr; events collected with the Belle detector at KEKB. We observe the D(sJ)(2317) decay to D(s)pi(0) and the D(sJ)(2457) decay to the D(*)(s)pi(0) and D(s)gamma final states. We also set 90% C.L. upper limits for the decays D(sJ)(2317)-->D(*)(s)gamma, D(sJ)(2457)-->D(*)(s)gamma, D(sJ)(2457)-->D(s)pi(0), and D(sJ)(2457)-->D(s)pi(+)pi(-).

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 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 report the first observation of a charmoniumlike state recoiling from the J/psi in the inclusive process e+e- -->J/psi+anything at a mass of (3.943+/-0.006+/-0.006) GeV/c{2}. We also observe the decay of this state into D*D[over ] and determine its intrinsic width to be less than 52 MeV/c{2} at the 90% C.L. These results are obtained from a 357 fb{-1} data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric-energy e+e- collider.

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 charmed strange baryons that decay into Lambda(c)(+)Kappa(-)pi(+). The broader of the two states is measured to have a mass of 2978.5+/-2.1+/-2.0 MeV/c2 and a width of 43.5+/-7.5+/-7.0 MeV/c2. The mass and width of the narrow state are measured to be 3076.7+/-0.9+/-0.5 MeV/c;{2} and 6.2+/-1.2+/-0.8 MeV/c2, respectively. We also perform a search for the isospin partner states that decay into Lambda(c)(+)Kappa(0)/(s)pi(-) and observe a significant signal at the mass of 3082.8+/-1.8+/-1.5 MeV/c2. The data used for this analysis were accumulated at or near the Upsilon(4S) resonance, using the Belle detector at the e+ e- asymmetric-energy collider KEKB. The integrated luminosity of the data sample used is 461.5 fb(-1).

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 on a search for new resonant states in the process γγ→D¯¯¯D. A candidate C-even charmonium state is observed in the vicinity of 3.93 GeV/c2. The production rate and the angular distribution in the γγ center-of-mass frame suggest that this state is the previously unobserved χ′c2, the 23P2 charmonium state.Received 15 December 2005DOI:https://doi.org/10.1103/PhysRevLett.96.082003©2006 American Physical Society

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 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 $\mathrm{sin}2{\ensuremath{\varphi}}_{1}=0.719\ifmmode\pm\else\textpm\fi{}0.074(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.035(\mathrm{syst}).$

We report a measurement of the process gamma gamma* --> pi0 with a 759 fb^{-1} data sample recorded with the Belle detector at the KEKB asymmetric-energy e+e- collider. The pion transition form factor, F(Q^2), is measured for the kinematical region 4 GeV^2 <~ Q^2 <~ 40 GeV^2, where -Q^2 is the invariant mass squared of a virtual photon. The measured values of Q^2|F(Q^2)| agree well with the previous measurements below Q^2 ~= 9 GeV^2 but do not exhibit the rapid growth in the higher Q^2 region seen in another recent measurement, which exceeds the asymptotic QCD expectation by as much as 50%.

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 present results from a study of X(3872) --> pi+pi- J/psi decays produced via exclusive B--> K X(3872) decays. We determine the mass to be M_X(3872)= (3871.84\pm 0.27 (stat)\pm 0.19 (syst)) MeV, a 90% CL upper limit on the natural width of Gamma_X(3872)<1.2 MeV, the product branching fraction Bf(B+-> K+X(3872))xBf(X(3872)-->pi+pi-J/psi)=(8.61 \pm 0.82(stat) \pm 0.52 (syst)) x10^{-6}, and a ratio of branching fractions Bf(B0--> K0 X(3872))/BF(B+--> K+ X(3872))=0.50\pm 0.14(stat)\pm0.04(syst). The difference in mass between the X(3872)-->pi+pi-J/psi signals in B+ and B0 decays is Delta M_{X(3872)= (-0.69 \pm 0.97 (stat)} \pm 0.19 (syst)) MeV. A search for a charged partner of the X(3872) in the decays Bbar0-->K- X+ or B+-->K0X+, X+-->pi+pi0 J/psi resulted in upper limits on the product branching fractions for these processes that are well below expectations for the case that the X(3872) is the neutral member of an isospin triplet. In addition, we examine possible J^{PC} quantum number assignments for the X(3872) based on comparisons of angular correlations between final state particles in X(3872)-->pi+pi-J/psi decays with simulated data for J^{PC} values of 1^{++} and 2^{-+}. We examine the influence of rho-omega interference in the M(pi+pi-) spectrum. The analysis is based on a 711fb^{-1} data sample that contains 772 million BBbar meson pairs collected at the Upsilon(4S) resonance in the Belle detector at the KEKB e+e- collider.

We report a study of the processes e+e−→J/ψD(*)¯¯¯D(*). In J/ψD∗¯¯¯D∗ we observe a significant enhancement in the D∗¯¯¯D∗ invariant mass spectrum, which we interpret as a new charmoniumlike state and denote X(4160). The X(4160) parameters are M=(4156+25−20±15) MeV/c2 and Γ=(139+111−61±21) MeV. We also report a new measurement of the X(3940) mass and width: M=(3942+7−6±6) MeV/c2 and Γ=(37+26−15±8) MeV. The analysis is based on a 693 fb−1 data sample recorded near the Υ(4S) resonance by the Belle detector at the KEKB asymmetric-energy collider.Received 5 October 2007DOI:https://doi.org/10.1103/PhysRevLett.100.202001©2008 American Physical Society

We present the results of an amplitude analysis of ${\overline{B}}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ decays. A new charged charmoniumlike state ${Z}_{c}(4200{)}^{+}$ decaying to $J/\ensuremath{\psi}{\ensuremath{\pi}}^{+}$ is observed with a significance of $6.2\ensuremath{\sigma}$. The mass and width of the ${Z}_{c}(4200{)}^{+}$ are $419{6}_{\ensuremath{-}29\ensuremath{-}13}^{+31+17}\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ and $37{0}_{\ensuremath{-}70\ensuremath{-}132}^{+70+70}\text{ }\text{ }\mathrm{MeV}$, respectively; the preferred assignment of the quantum numbers is ${J}^{P}={1}^{+}$. In addition, we find evidence for ${Z}_{c}(4430{)}^{+}\ensuremath{\rightarrow}\phantom{\rule{0ex}{0ex}}J/\ensuremath{\psi}{\ensuremath{\pi}}^{+}$. The analysis is based on a $711\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected by the Belle detector at the asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider KEKB.

We measure the branching fraction of B- -> tau- nu_tau-bar using the full Upsilon(4S) data sample containing 772*10^6 BBbar pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. Events with BBbar pairs are tagged by reconstructing one of the B mesons decaying into hadronic final states, and B- -> tau- nu_tau-bar candidates are detected in the recoil. We find evidence for B- -> tau- nu_tau-bar with a significance of 3.0 standard deviations including systematic errors and measure a branching fraction B(B- -> tau- nu_tau-bar) = [0.72^{+0.27}_{-0.25}(stat) +/- 0.11(syst)] * 10^-4.

From a Dalitz plot analysis of $B\ensuremath{\rightarrow}K{\ensuremath{\pi}}^{+}{\ensuremath{\psi}}^{\ensuremath{'}}$ decays, we find a signal for $Z(4430{)}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\psi}}^{\ensuremath{'}}$ with a mass $M=({4443}_{\ensuremath{-}12\ensuremath{-}13}^{+15+19})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, width $\ensuremath{\Gamma}=({107}_{\ensuremath{-}43\ensuremath{-}56}^{+86+74})\text{ }\text{ }\mathrm{MeV}$, product branching fraction $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}Z(4430{)}^{+})\ifmmode\times\else\texttimes\fi{}\mathcal{B}(Z(4430{)}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\psi}}^{\ensuremath{'}})=({3.2}_{\ensuremath{-}0.9\ensuremath{-}1.6}^{+1.8+5.3})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, and significance of $6.4\ensuremath{\sigma}$ that agrees with previous Belle measurements based on the same data sample. In addition, we determine the branching fraction $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{K}^{*}(892{)}^{0}{\ensuremath{\psi}}^{\ensuremath{'}})=({5.52}_{\ensuremath{-}0.32\ensuremath{-}0.58}^{+0.35+0.53})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and the fraction of ${K}^{*}(892{)}^{0}$ mesons that are longitudinally polarized ${f}_{L}=({44.8}_{\ensuremath{-}2.7\ensuremath{-}5.3}^{+4.0+4.0})%$. 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 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 the results of a study of the exclusive semileptonic decays B -→ π 0 ℓ -νℓ , B0 → π + ℓ -νℓ , B -→ ρ 0 ℓ -νℓ , B0 → ρ + ℓ -νℓ and B -→ ωℓ -νℓ , where ℓ represents an electron or a muon.The events are tagged by fully reconstructing a second B meson in the event in a hadronic decay mode.The measured branching fractions arewhere the first error is statistical and the second one is systematic.The obtained branching fractions are inclusive of soft photon emission.We also determine the branching fractions as a function of the 4-momentum transfer squared to the leptonic system q 2 = (p ℓ + p ν ) 2 , where p ℓ and p ν are the lepton and neutrino 4-momenta, respectively.Using the pion modes, a recent LCSR calculation, lattice QCD results and a model-independent description of the hadronic form factor, a value of the CKM matrix element |V ub | = (3.52 ± 0.29) × 10 -3 is extracted.For the first time, a charmless state with invariant mass greater than 1 GeV/c 2 , which might be dominated by the decay B -→ f 2 ℓ -νℓ , is observed.These results are obtained from a 711 fb -1 data sample that contains 772 × 10 6 BB pairs, collected near the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e -collider.

We report a study of $B\to (J/\psi \gamma) K$ and $B\to (\psi' \gamma)K$ decay modes using $772\times 10^{6}$ $B\bar{B}$ events collected at the \Upsilon(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric $e^+ e^-$ collider. We observe $X(3872) \to J/\psi \gamma$ and report the first evidence for $\chi_{c2} \to J/\psi \gamma$ in $B\to (X_{c\bar{c}}\gamma) K$ decays, while in a search for $X(3872) \to \psi' \gamma$ no significant signal is found. We measure the branching fractions, $\mathcal{B}(B^{\pm} \to X(3872) K^{\pm}) \mathcal{B}(X(3872) \to J/\psi\gamma)$ $=$ $(1.78^{+0.48}_{-0.44}\pm 0.12)\times 10^{-6}$, $\mathcal{B} (B^{\pm} \to\chi_{c2} K^{\pm})$$=$ $(1.11^{+0.36}_{-0.34} \pm 0.09) \times 10^{-5}$, $\mathcal{B}(B^{\pm} \to X(3872) K^{\pm}) \mathcal{B}(X(3872) \to \psi'\gamma)$ $<$ $3.45\times 10^{-6}$ (upper limit at 90% C.L.) and also provide upper limits for other searches.

The process gammagamma-->phiJ/psi is measured using a data sample of 825 fb{-1} collected with the Belle detector. A narrow peak of 8.8{-3.2}{+4.2} events, with a significance of 3.2 standard deviations including systematic uncertainty, is observed. The mass and natural width of the structure [named X(4350)] are measured to be [4350.6{-5.1}{+4.6}(stat)+/-0.7(syst)] MeV/c{2} and [13{-9}{+18}(stat)+/-4(syst)] MeV, respectively. The product of its two-photon decay width and branching fraction to phiJ/psi is [6.7{-2.4}{+3.2}(stat)+/-1.1(syst)] eV for J{P}=0{+}, or [1.5{-0.6}{+0.7}(stat)+/-0.3(syst)] eV for J{P}=2{+}. No signal for the Y(4140)-->phiJ/psi structure reported by the CDF Collaboration in B-->K{+}phiJ/psi decays is observed, and limits of Gamma_{gammagamma}(Y(4140))B(Y(4140)-->phiJ/psi)<41 eV for J{P}=0;{+} or <6.0 eV for J{P}=2{+} are determined at the 90% C.L. This disfavors the scenario in which the Y(4140) is a D{s}{*+}D{s}{*-} molecule.

We present measurements of B+→¯¯¯D*0τ+ντ and B+→¯¯¯D0τ+ντ decays in a data sample of 657×106 B¯¯¯B pairs collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. We find 446+58−56 B+→¯¯¯D*0τ+ντ events with a significance of 8.1 standard deviations, and 146+42−41 B+→¯¯¯D0τ+ντ events with a significance of 3.5 standard deviations. The latter signal provides the first evidence for this decay mode. The measured branching fractions are B(B+→¯¯¯D*0τ+ντ)=(2.12+0.28−0.27(stat)±0.29(syst))% and B(B+→¯¯¯D0τ+ντ)=(0.77±0.22(stat)±0.12(syst))%.Received 13 May 2010DOI:https://doi.org/10.1103/PhysRevD.82.072005© 2010 The American Physical Society

We present a determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ using the decay $B\to D\ell\nu_\ell$ ($\ell=e,\mu$) based on 711 fb$^{-1}$ of $e^+e^-\to \Upsilon(4S)$ data recorded by the Belle detector and containing $772 \times 10^6$ $B\bar{B}$ pairs. One $B$ meson in the event is fully reconstructed in a hadronic decay mode while the other, on the signal side, is partially reconstructed from a charged lepton and either a $D^+$ or $D^0$ meson in a total of 23 hadronic decay modes. The isospin-averaged branching fraction of the decay $B\to D\ell\nu_\ell$ is found to be $\mathcal{B}(B^0 \to D^- \ell^+ \nu_{\ell})=(2.31\pm 0.03(\mathrm{stat})\pm 0.11(\mathrm{syst}))\%$. Analyzing the differential decay rate as a function of the hadronic recoil with the parameterization of Caprini, Lelouch and Neubert and using the form-factor prediction $\mathcal{G}(1)=1.0541\pm 0.0083$ calculated by FNAL/MILC, we obtain $\eta_\mathrm{EW}|V_{cb}|=(40.12\pm 1.34)\times 10^{-3}$, where $\eta_\mathrm{EW}$ is the electroweak correction factor. Alternatively, assuming the model-independent form-factor parameterization of Boyd, Grinstein and Lebed and using lattice QCD data from the FNAL/MILC and HPQCD collaborations, we find $\eta_\mathrm{EW}|V_{cb}|=(41.10 \pm 1.14)\times 10^{-3}$.

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

We report the analysis of the three-body e^{+}e^{-}→BB[over ¯]π^{±}, BB[over ¯]^{*}π^{±}, and B^{*}B[over ¯]^{*}π^{±} processes, including the first observations of the Z_{b}^{±}(10610)→[BB[over ¯]^{*}+c.c.]^{±} and Z_{b}^{±}(10650)→[B^{*}B[over ¯]^{*}]^{±} transitions that are found to dominate the corresponding final states. We measure Born cross sections for the three-body production of σ(e^{+}e^{-}→[BB[over ¯]^{*}+c.c.]^{±}π^{∓})=[17.4±1.6(stat)±1.9(syst)] pb and σ(e^{+}e^{-}→[B^{*}B[over ¯]^{*}]^{±}π^{∓})=[8.75±1.15(stat)±1.04(syst)] pb and set a 90% C.L. upper limit of σ(e^{+}e^{-}→[BB[over ¯]]^{±}π^{∓})<2.9 pb. The results are based on a 121.4 fb^{-1} data sample collected with the Belle detector at a center-of-mass energy near the ϒ(10860) peak.

We present a new measurement of the Cabibbo-Kobayashi-Maskawa matrix element jV cb j from B 0 → D Ã-l þ ν l decays, reconstructed with the full Belle data set of 711 fb -1 integrated luminosity.Two form factor parametrizations, originally conceived by the Caprini-Lellouch-Neubert (CLN) and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product F ð1Þη EW jV cb j and the decay form factors, where F ð1Þ is the normalization factor and η EW is a small electroweak correction.In the CLN parametrization we find F ð1Þη EW jV cb j ¼ ð35.06 AE 0.15 AE 0.56Þ × 10 -3 , ρ 2 ¼ 1.106 AE 0.031 AE 0.007, R 1 ð1Þ ¼ 1.229 AE 0.028 AE 0.009, R 2 ð1Þ ¼ 0.852 AE 0.021 AE 0.006.For the BGL parametrization we obtain F ð1Þη EW jV cb j ¼ ð34.93 AE 0.23 AE 0.59Þ × 10 -3 , which is consistent with the world average when correcting for F ð1Þη EW .The branching fraction ofWe also present a new test of lepton flavor universality violation in semileptonic B decays, BðB 0 →D Ã-e þ νÞ BðB 0 →D Ãμ þ νÞ ¼ 1.01 AE 0.01 AE 0.03.The errors quoted correspond to the statistical and systematic uncertainties, respectively.This is the most precise measurement of F ð1Þη EW jV cb j and form factors to date and the first experimental study of the BGL form factor parametrization in an experimental measurement.

The Nuclotron-based Ion Collider fAcility (NICA) is under construction at the Joint Institute for Nuclear Research (JINR), with commissioning of the facility expected in late 2022. The Multi-Purpose Detector (MPD) has been designed to operate at NICA and its components are currently in production. The detector is expected to be ready for data taking with the first beams from NICA. This document provides an overview of the landscape of the investigation of the QCD phase diagram in the region of maximum baryonic density, where NICA and MPD will be able to provide significant and unique input. It also provides a detailed description of the MPD set-up, including its various subsystems as well as its support and computing infrastructures. Selected performance studies for particular physics measurements at MPD are presented and discussed in the context of existing data and theoretical expectations.

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 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 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 present a study of the decay τ−→KSπ−ντ using a 351 fb−1 data sample collected with the Belle detector. The analysis is based on 53,110 lepton-tagged signal events. The measured branching fraction B(τ−→KSπ−ντ)=(0.404±0.002(stat.)±0.013(syst.))% is consistent with the world average value and has better accuracy. An analysis of the KSπ− invariant mass spectrum reveals contributions from the K∗(892)− as well as other states. For the first time the K∗(892)− mass and width have been measured in τ decay: M(K∗(892)−)=(895.47±0.20(stat.)±0.44(syst.)±0.59(mod.))MeV/c2, Γ(K∗(892)−)=(46.2±0.6(stat.)±1.0(syst.)±0.7(mod.))MeV. The K∗(892)− mass is significantly different from the current world average value.

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 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 study of B → X(3872)K with X(3872) decaying to D * 0 D0 using a sample of 657 million B B pairs recorded at the Υ(4S) resonance with the Belle detector at the KEKB asymmetricenergy e + e -collider.Both D * 0 → D 0 γ and D * 0 → D 0 π 0 decay modes are used.We find a peak of 50.1 +14.8 -11.1 events with a mass of (3872.9+0.6 +0.4 -0.4 -0.5 ) MeV/c 2 , a width of (3.9 +2.8 +0.2 -1.4 -1.1 ) MeV/c 2 and a product branching fraction B(B → X(3872)K)×B(X(3872) → D * 0 D0 ) = (0.80±0.20±0.10)×10 - , where the first errors are statistical and the second ones are systematic.The significance of the signal is 6.4σ.The difference between the fitted mass and the D * 0 D0 threshold is calculated to be (1.1 +0.6 +0.1 -0.4 -0.3 ) MeV/c 2 .We also obtain an upper limit on the product of branching fractions B(B → Y (3940)K) × B(Y (3940) → D * 0 D0 ) of 0.67 × 10 -4 at 90% CL.

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 interference fragmentation function translates the fragmentation of a quark with a transverse projection of the spin into an azimuthal asymmetry of two final-state hadrons. In e+e- annihilation the product of two interference fragmentation functions is measured. We report nonzero asymmetries for pairs of charge-ordered pi+pi- pairs, which indicate a significant interference fragmentation function in this channel. The results are obtained from a 672 fb-1 data sample that contains 711 \times 106 pi+pi- pairs and was collected at and near the ?(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider.

We present a precise measurement of the CP violation parameter sin2phi_1 and the direct CP violation parameter A_f using the final data sample of 772x10^6 B\bar B pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is reconstructed in a J/psi K0S, psi(2S) K0S, chi_c1 K0S or J/psi K0L CP-eigenstate and its flavor is identified from the decay products of the accompanying B meson. From the distribution of proper time intervals between the two B decays, we obtain the following CP violation parameters: sin2phi_1=0.667+-0.023(stat)+-0.012(syst) and A_f=0.006+-0.016(stat)+-0.012(syst).

We report measurements of B→χ(c1)γK and χ(c2)γK decays using 772×10(6) BB[over ¯] events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. Evidence of a new resonance in the χ(c1)γ final state is found with a statistical significance of 3.8σ. This state has a mass of 3823.1±1.8(stat)±0.7(syst) MeV/c(2), a value that is consistent with theoretical expectations for the previously unseen 1(3)D(2) cc[over ¯] meson. We find no other narrow resonance and set upper limits on the branching fractions of the X(3872)→χ(c1)γ and χ(c2)γ decays.

We present the first model-independent measurement of the absolute branching fraction of the Λ(c)(+) → pK(-)π(+) decay using a data sample of 978 fb(-1) collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The number of Λ(c)(+) baryons is determined by reconstructing the recoiling D((*)-) pπ(+) system in events of the type e(+)e(-) → D((*)-) pπ(+)Λ(c)(+). The branching fraction is measured to be B(Λ(c)(+) → pK(-)π(+)) = (6.84 ± 0.24(-0.27)(+0.21))%, where the first and second uncertainties are statistical and systematic, respectively.

We report results of a study of doubly charmed baryons and charmed strange baryons.The analysis is performed using a 980 fb -1 data sample collected with the Belle detector at the KEKB asymmetric-energy e þ e -collider.We search for doubly charmed baryons ΞNo significant signal is observed.We also search for two excited charmed strange baryons, Ξ c ð3055Þ þ and Ξ c ð3123Þ þ with the Σ þþ c ð2455ÞK -and Σ þþ c ð2520ÞK -final states.The Ξ c ð3055Þ þ signal is observed with a significance of 6.6 standard deviations including systematic uncertainty, while no signature of the Ξ c ð3123Þ þ is seen.We also study properties of the Ξ c ð2645Þ þ and measure a width of 2.6 AE 0.2ðstatÞ AE 0.4ðsystÞ MeV=c 2 , which is the first significant determination.

We report the first evidence for the η(b)(2S) using the h(b)(2P)→η(b)(2S)γ transition and the first observation of the h(b)(1P)→η(b)(1S)γ and h(b)(2P)→η(b)(1S)γ transitions. The mass and width of the η(b)(1S) and η(b)(2S) are measured to be m(η(b)(1S))=(9402.4±1.5±1.8) MeV/c(2), m(η(b)(2S))=(9999.0±3.5(-1.9)(+2.8)) MeV/c(2), and Γ(η(b)(1S))=(10.8(-3.7-2.0)(+4.0+4.5)) MeV. We also update the h(b)(1P) and h(b)(2P) mass measurements. We use a 133.4 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 report results on studies of the e+e- annihilation into three-body Y(nS)pi+pi- (n=1,2,3) final states including measurements of cross sections and the full amplitude analysis. The cross sections measured at sqrt(s)=10.865 GeV and corrected for the initial state radiation are sigma(e+e-=>Y(1S)pi+pi-)=(2.27+-0.12+-0.14) pb, sigma(e+e-=>Y(2S)pi+pi-)=(4.07+-0.16+-0.45) pb, and sigma(e+e-=>Y(3S)pi+pi-)=(1.46+-0.09+-0.16) pb. Amplitude analysis of the three-body Y(nS)pi+pi- final states strongly favors I^G(J^P)=1^+(1^+) quantum-number assignments for the two bottomonium-like Zb+- states, recently observed in the Y(nS)pi+- and hb(mP)pi+- (m=1,2) decay channels. The results are obtained with a $121.4 1/fb data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider.

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 ${\mathrm{\ensuremath{\Omega}}}_{c}(3090)$.

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}.

A search for the flavor-changing neutral-current decay B^{+}→K^{+}νν[over ¯] is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The data sample corresponds to an integrated luminosity of 63 fb^{-1} collected at the ϒ(4S) resonance and a sample of 9 fb^{-1} collected at an energy 60 MeV below the resonance. Because the measurable decay signature involves only a single charged kaon, a novel measurement approach is used that exploits not only the properties of the B^{+}→K^{+}νν[over ¯] decay, but also the inclusive properties of the other B meson in the ϒ(4S)→BB[over ¯] event, to suppress the background from other B meson decays and light-quark pair production. This inclusive tagging approach offers a higher signal efficiency compared to previous searches. No significant signal is observed. An upper limit on the branching fraction of B^{+}→K^{+}νν[over ¯] of 4.1×10^{-5} is set at the 90% confidence level.

From superconductors to atomic nuclei, strongly-interacting many-body systems are ubiquitous in nature. Measuring the microscopic structure of such systems is a formidable challenge, often met by particle knockout scattering experiments. While such measurements are fundamental for mapping the structure of atomic nuclei, their interpretation is often challenged by quantum mechanical initial- and final-state interactions (ISI/FSI) of the incoming and scattered particles. Here we overcome this fundamental limitation by measuring the quasi-free scattering of 48 GeV/c 12C ions from hydrogen. The distribution of single protons is studied by detecting two protons at large angles in coincidence with an intact 11B nucleus. The 11B detection is shown to select the transparent part of the reaction and exclude the otherwise large ISI/FSI that would break the 11B apart. By further detecting residual 10B and 10Be nuclei, we also identified short-range correlated (SRC) nucleon-nucleon pairs, and provide direct experimental evidence for the separation of the pair wave-function from that of the residual many-body nuclear system. All measured reactions are well described by theoretical calculations that do not contain ISI/FSI distortions. Our results thus showcase a new ability to study the short-distance structure of short-lived radioactive atomic nuclei at the forthcoming FAIR and FRIB facilities. These studies will be pivotal for developing a ground-breaking microscopic understanding of the structure and properties of nuclei far from stability and the formation of visible matter in the universe.

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 study the processes e+e−→ωχbJ(1P) (J=0, 1, or 2) using samples at center-of-mass energies √s=10.701, 10.745, and 10.805 GeV, corresponding to 1.6, 9.8, and 4.7 fb−1 of integrated luminosity, respectively. These data were collected with the Belle II detector during special operations of the SuperKEKB collider above the Υ(4S) resonance. We report the first observation of ωχbJ(1P) signals at √s=10.745 GeV. By combining Belle II data with Belle results at √s=10.867 GeV, we find energy dependencies of the Born cross sections for e+e−→ωχb1,b2(1P) to be consistent with the shape of the Υ(10753) state. These data indicate that the internal structures of the Υ(10753) and Υ(10860) states may differ. Including data at √s=10.653 GeV, we also search for the bottomonium equivalent of the X(3872) state decaying into ωΥ(1S). No significant signal is observed for masses between 10.45 and 10.65 GeV/c2.Received 29 August 2022Accepted 25 January 2023DOI:https://doi.org/10.1103/PhysRevLett.130.091902Published 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 SystemsExotic mesonsQuarkoniaTechniquesLepton collidersParticles & Fields

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.

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.

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 have performed a search for the lepton-flavor-violating decay tau -> mu gamma using a data sample of 86.3fb^{-1} accumulated by the Belle detector at KEK. No evidence for a signal is seen, and we set an upper limit for the branching fraction of B(tau -> mu gamma) < 3.1 x 10^{-7} at the 90% confidence level.

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 report the results of several studies of the Lambda(c)(+)pi(+)pi(-)X final state in continuum e(+)e(-) annihilation data collected by the Belle detector. An analysis of angular distributions in Lambda(c)(2880)(+)-->Sigma(c)(2455)(0,++)pi(+,-) decays strongly favors a Lambda(c)(2880)(+) spin assignment of 5/2 over 3/2 or 1/2. We find evidence for Lambda(c)(2880)(+)-->Sigma(c)(2520)(0,++)pi(+,-) decay and measure the ratio of Lambda(c)(2880)(+) partial widths Gamma(Sigma(c)(2520)pi)/Gamma(Sigma(c)(2455)pi)=0.225+/-0.062+/-0.025. This value favors the Lambda(c)(2880)(+) spin-parity assignment of 5/2(+) over 5/2(-). We also report the first observation of Lambda(c)(2940)(+)-->Sigma(c)(2455)(0,++)pi(+,-) decay and measure Lambda(c)(2880)(+) and Lambda(c)(2940)(+) mass and width parameters. These studies are based on a 553 fb(-1) data sample collected at or near the Upsilon(4S) resonance at the KEKB collider.

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.