Yakhshiev, U.*; Kim, H.-C.; 岡 眞
Physical Review D, 99(5), p.054027_1 - 054027_11, 2019/03
Kim, H.*; Kim, K. S.*; Cheoun, M.-K.*; 慈道 大介*; 岡 眞
Physical Review D, 99(1), p.014005_1 - 014005_15, 2019/01
Bartiyar, H.*; Can, K. U.*; Erkol, G.*; 岡 眞; 高橋 徹*
Physical Review D, 98(11), p.114505_1 - 114505_14, 2018/12
Pal, B.*; 谷田 聖; Belle Collaboration*; 他158名*
Physical Review D, 98(11), p.112008_1 - 112008_8, 2018/12
We measure the branching fraction and time-dependent -violating asymmetry for decays using a data sample of 711 collected on the resonance by the Belle experiment running at the KEKB collider. The branching fraction is measured to be , which is the most precise measurement to date. The measured asymmetry parameters are and . The mixing-induced asymmetry () differs from the case of no violation by 3.0 standard deviations, and the direct asymmetry () is consistent with zero.
Berger, M.*; 谷田 聖; Belle Collaboration*; 他197名*
Physical Review D, 98(11), p.112006_1 - 112006_10, 2018/12
We report measurements of the branching fractions of the decays , and relative to the reference channel . The analysis is based on the full data sample collected at and close to resonance by the Belle detector at the KEKB asymmetric-energy collider corresponding to the integrated luminosity of 711 fb. We measure , and . The listed uncertainties are statistical and systematic, respectively.
Gelb, M.*; 谷田 聖; Belle Collaboration*; 他185名*
Physical Review D, 98(11), p.112016_1 - 112016_13, 2018/12
We present the result of the search for the rare meson decay of with . For the search the full data set recorded by the Belle experiment of integrated luminosity near the resonance is used. Signal candidates are reconstructed for photon energies larger than using a novel multivariate tagging algorithm. The novel algorithm fully reconstructs the second meson produced in the collision using hadronic modes and was specifically trained to recognize the signal signature in combination with hadronic tag-side meson decays. This approach greatly enhances the performance. Background processes that can mimic this signature, mainly charmless semileptonic decays and continuum processes, are suppressed using multivariate methods. The number of signal candidates is determined by analyzing the missing mass squared distribution as inferred from the signal side particles and the kinematic properties of the tag-side meson. No significant excess over the background-only hypothesis is observed and upper limits on the partial branching fraction with individually for electron and muon final states as well as for the average branching fraction of both lepton final states are reported. We find a Bayesian upper limit of at 90% CL and also report an upper limit on the first inverse moment of the light-cone distribution amplitude of the meson of at 90% CL.
Adare, A.*; 長谷川 勝一; 今井 憲一; 永宮 正治*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他351名*
Physical Review D, 98(9), p.092006_1 - 092006_13, 2018/11
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section of (1020) meson production at forward rapidity in collisions at 510 GeV via the dimuon decay channel. The integrated cross section in the rapidity and ranges and GeV/ is ~mb. The energy dependence of (; GeV/) is studied using the PHENIX measurements at 200 and 510 GeV and the Large-Hadron-Collider measurements at 2.76 and 7 TeV. The experimental results are compared to various event generator predictions (pythia6, pythia8, phojet, ampt, epos3, and epos-lhc).
足立 一郎*; 谷田 聖; Belle Collaboration*; 他406名*
Physical Review D, 98(11), p.112012_1 - 112012_29, 2018/11
We report measurements of and from a time-dependent Dalitz plot analysis of with decays, where the light unflavored and neutral hadron is a , , or meson. The analysis is performed with a combination of the final data sets of the BABAR and Belle experiments containing and pairs collected at the resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. We measure and . The result for the direct measurement of the angle is . The last quoted uncertainties are due to the composition of the decay amplitude model, which is newly established by a Dalitz plot amplitude analysis of a high-statistics data sample as part of this analysis. We find the first evidence for at the level of standard deviations. The measurement excludes the trigonometric multifold solution at the level of standard deviations and therefore resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle. The hypothesis of is ruled out at the level of standard deviations, and thus violation is observed in decays.
Yin, J. H.*; 谷田 聖; Belle Collaboration*; 他189名*
Physical Review D, 98(9), p.091102_1 - 091102_9, 2018/11
We report searches for the processes and (J=1,2) in the vicinity of the resonance using energy scan data collected by the Belle experiment at the KEKB collider. We observe and find evidence for processes for data with center-of-mass energies from 10.96 to 11.05~GeV for the first time. The statistical significance for and are and , respectively. We investigate energy dependence of the cross section and find that it is consistent with production of and resonances without significant non-resonant contribution. Assuming proceeds via and , the branching fraction is measured for the first time, where the first error is statistical, the second is systematic, and the third from the branching fraction of . The signals for are not significant, and the upper limits of the Born cross sections at the 90% confidence level are and ~pb for and , respectively, for center-of-mass energies from 10.96 to 11.05 GeV.
Jia, S.*; 谷田 聖; Belle Collaboration*; 他191名*
Physical Review D, 98(9), p.092015_1 - 092015_8, 2018/11
Using data samples of 89.5~fb, 711.0~fb, and 121.4~fb collected with the Belle detector at the KEKB asymmetric-energy collider at center-of-mass energies 10.52 GeV, 10.58 GeV, and 10.867 GeV, respectively, we study the exclusive reactions () and . A significant signal is observed for the first time at GeV with a significance of including systematic uncertainties. No significant excesses for , , and final states are found, and we set 90% credibility level upper limits on the Born cross sections () at 10.52 GeV, 10.58 GeV, and 10.867~GeV. Together with cross sections measured by BESIII at lower center-of-mass energies, the energy dependency of is obtained.
Sandilya, S.*; 谷田 聖; Belle Collaboration*; 他211名*
Physical Review D, 98(7), p.071101_1 - 071101_8, 2018/10
We have searched for the lepton-flavor-violating decay using a data sample of 711 fb that contains pairs. The data were collected near the resonance with the Belle detector at the KEKB asymmetric-energy collider. No signals were observed, and we set 90% confidence level upper limits on the branching fractions of , , and, for both decays combined, . These are the most stringent limits on these decays to date.
Xu, Q. N.*; 谷田 聖; Belle Collaboration*; 他176名*
Physical Review D, 98(7), p.072001_1 - 072001_17, 2018/10
We report the measurement of , with decays to and using 941 fb of data collected with the Belle detector at the KEKB asymmetric-energy collider. The mass and width are measured to be MeV/ and MeV, respectively. First observation of with a significance of including systematic error is obtained, and the mass is measured to be MeV/. The products of the two-photon decay width and branching fraction of decays to are determined to be eV for and eV for . A new decay mode for the to with is observed with a statistical significance of . The mass and width are determined to be MeV/ and MeV. The cross sections for and are measured for the first time.
Aidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他287名*
Physical Review D, 98(7), p.072004_1 - 072004_13, 2018/10
Dihadron and isolated direct photon-hadron angular correlations are measured in collisions at GeV. The correlations are sensitive to nonperturbative initial-state and final-state transverse momentum and in the azimuthal nearly back-to-back region . In this region, transverse-momentum-dependent evolution can be studied when several different hard scales are measured. To have sensitivity to small transverse momentum scales, nonperturbative momentum widths of , the out-of-plane transverse momentum component perpendicular to the trigger particle, are measured. These widths are used to investigate possible effects from transverse-momentum-dependent factorization breaking. When accounting for the longitudinal momentum fraction of the away-side hadron with respect to the near-side trigger particle, the widths are found to increase with the hard scale; this is qualitatively similar to the observed behavior in Drell-Yan and semi-inclusive deep-inelastic scattering interactions. The momentum widths are also studied as a function of center-of-mass energy by comparing to previous measurements at GeV. The nonperturbative jet widths also appear to increase with at a similar , which is qualitatively consistent to similar measurements in Drell-Yan interactions.
Adare, A.*; 長谷川 勝一; 今井 憲一; 永宮 正治; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他423名*
Physical Review D, 98(3), p.032007_1 - 032007_14, 2018/08
We have measured the cross section and single spin asymmetries from forward production in longitudinally polarized collisions at GeV using the PHENIX detector at the Relativistic Heavy Ion Collider. The cross sections are consistent with previous measurements at this collision energy, while the most forward and backward longitudinal single spin asymmetries provide new insights into the sea quark helicities in the proton. The charge of the bosons provides a natural flavor separation of the participating partons.
Aidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他286名*
Physical Review D, 98(1), p.012006_1 - 012006_11, 2018/07
We report the transverse single-spin asymmetries of production at forward and backward rapidity, , as a function of transverse momentum () and Feynman- (). The data analyzed were recorded by the PHENIX experiment at the Relativistic Heavy Ion Collider in 2015 from , Al, and Au collisions with transversely polarized proton beams at GeV. At this collision energy, single-spin asymmetries for heavy-flavor particle production of collisions provide access to the spin-dependent gluon distribution and higher-twist correlation functions inside the nucleon, such as the gluon Qiu-Sterman and trigluon correlation functions. Proton + nucleus collisions offer an excellent opportunity to study nuclear effects on the correlation functions. The data indicate negative asymmetries at the two-standard-deviation level in the Au data for GeV/ at both forward and backward rapidity, while in and Al collisions the asymmetries are consistent with zero within the range of experimental uncertainties.
Vossen, A.*; 谷田 聖; Belle Collaboration*; 他164名*
Physical Review D, 98(1), p.012005_1 - 012005_9, 2018/07
We report a measurement of the branching fraction of the decay . The analysis uses 772 pairs produced in data recorded by the Belle experiment at the KEKB asymmetric-energy collider. The tagging meson in the decay is fully reconstructed in a hadronic decay mode. On the signal side, we reconstruct the decay . The measured branching fractions are = [4.55 0.27 (stat.) 0.39 (syst.)], = [4.05 0.36 (stat.) 0.41 (syst.)], = [6.03 0.43 (stat.) 0.38 (syst.)], and = [6.46 0.53 (stat.) 0.52 (syst.)]. These are in good agreement with the current world average values.
Jimmenez, S.*; 岡 眞; 佐々木 潔*
Physical Review D, 97(11), p.114506_1 - 114506_28, 2018/06
Jia, S.*; 谷田 聖; Belle Collaboration*; 他181名*
Physical Review D, 97(11), p.112004_1 - 112004_16, 2018/06
The first search for pair production in and decays and in annihilation at = 10.52, 10.58, and 10.867 GeV is conducted using data collected with the Belle detector at the KEKB asymmetric energy electron-positron collider. No significant signals are observed in any of the studied modes, and the 90% credibility level upper limits on their product branching fractions in and decays ( (, , )) and the product of Born cross section and branching fraction for () at = 10.52, 10.58, and 10.867 GeV are determined. Here, refers to the and observed in the final state, the and in the state, and the and in the state.
Kim, H.*; Kim, K. S.*; Cheoun, M.-K.*; 岡 眞
Physical Review D, 97(9), p.094005_1 - 094005_17, 2018/05
中野 浩至*; 谷田 聖; Belle Collaboration*; 他188名*
Physical Review D, 97(9), p.092003_1 - 092003_10, 2018/05
We report a measurement of time-dependent violation parameters in decays. The study is based on a data sample, containing pairs, that was collected at the resonance with the Belle detector at the KEKB asymmetric-energy collider. We obtain the violation parameters of and for the invariant mass of the system up to 2.1 GeV/.