江川 弘行; 足利 沙希子; 長谷川 勝一; 橋本 直; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 金原 慎二*; 七村 拓野; et al.
Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D02_1 - 021D02_11, 2019/02
A double- hypernucleus, , was observed by the J-PARC E07 collaborationin nuclear emulsions tagged by the reaction. This event was interpreted as a production and decay of ,, or via capture in .By assuming the capture in the atomic 3D state, the binding energy of two hyperons()of these double- hypernuclei are obtained to be, , and , respectively. Based on the kinematic fitting, is the most likely explanation for the observed event.
Theint, A. M. M.*; 江川 弘行; 吉田 純也; 他7名*
Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D01_1 - 021D01_10, 2019/02
In the E373 experiment at KEK-PS, we have located nearly stopping events of hyperon candidates in nuclear emulsion. Among them, the identification of hyperon was performed with Constant Sagitta (CS) method by measuring multiple Coulomb scattering for 695 clearly stopping events. With use of Geant4 simulation, the parameters for the CS method were optimised and we obtained the number of real stopping events to be with 3.2% systematic error. The trapping probabilities of two hyperons for light and heavy nuclei were found to be % and %, respectively. For at least one trapping, the probabilities were % and % for light and heavy nuclei. These results are the first time to present the trapping probabilities of hyperons via hyperon capture at rest in the emulsion.
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.
足立 一郎*; 谷田 聖; Belle Collaboration*; 他421名*
Physical Review Letters, 121(26), p.261801_1 - 261801_11, 2018/12
We present first evidence that the cosine of the -violating weak phase is positive, and hence exclude trigonometric multifold solutions of the CKM Unitarity Triangle using a time-dependent Dalitz plot analysis of with decays, where denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BaBar and Belle experiments collected at the resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain pairs recorded by the BaBar detector and pairs recorded by the Belle detector. The results of the measurement are and . The result for the direct measurement of the angle of the CKM Unitarity Triangle is . The quoted model uncertainties are due to the composition of the decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics data sample. CP violation is observed in decays at the level of standard deviations. The significance for is standard deviations. The trigonometric multifold solution is excluded at the level of standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle.
Fulsom, B. G.*; 谷田 聖; Belle Collaboration*; 他197名*
Physical Review Letters, 121(23), p.232001_1 - 232001_8, 2018/12
We report the observation of decay based on analysis of the inclusive photon spectrum of fb of collisions at the center-of-mass energy collected with the Belle detector at the KEKB asymmetric-energy collider. We measure a branching fraction of , and derive an mass of MeV/, where the uncertainties are statistical and systematic, respectively. The significance of our measurement is greater than 7 standard deviations, constituting the first observation of this decay mode.
Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他175名*
European Physical Journal C, 78(11), p.928_1 - 928_8, 2018/11
We report evidence for the charged charmed-strange baryon with a signal significance of 3.9 with systematic errors included. The charged is found in its decay to in the substructure of decays. The measured mass and width are ~MeV/ and ~MeV, respectively, and the product branching fraction is . We also measure with greater precision than previous experiments, and present the results of a search for the charmonium-like state and its spin partner, , in the invariant mass spectrum. No clear signals of the or are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of pairs collected at the resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.
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.
Tamponi, U.*; 谷田 聖; Belle Collaboration*; 他174名*
European Physical Journal C, 78, p.633_1 - 633_10, 2018/08
We study bottomonium production in association with an meson in annihilations near the , at a center of mass energy of GeV. The results are based on the fb data sample collected by the Belle experiment at the asymmetric energy KEKB collider. Only the meson is reconstructed and the missing-mass spectrum of candidates is investigated. We observe the process and find evidence for the process, while no significant signals of , , nor are found. Cross sections for the studied processes are reported.
Yelton, J.*; 谷田 聖; Belle Collaboration*; 他190名*
Physical Review Letters, 121(5), p.052003_1 - 052003_7, 2018/08
Using data recorded with the Belle detector, we observe a new excited hyperon, an candidate decaying into and with a mass of and a width of . The is seen primarily in , and decays.
Guido, E.*; 谷田 聖; Belle Collaboration*; 他168名*
Physical Review Letters, 121(6), p.062001_1 - 062001_7, 2018/08
We report the first observation of the hadronic transition , using 496 fb data collected at the resonance with the Belle detector at the KEKB asymmetric-energy collider. We reconstruct the meson through its decays to and to , with . We measure: , with a significance of 5.7.
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.
Sibidanov, A.*; 谷田 聖; Belle Collaboration*; 他187名*
Physical Review Letters, 121(3), p.031801_1 - 031801_8, 2018/07
We report the result of a search for the decay . The signal events are selected based on the presence of a high momentum muon and the topology of the rest of the event showing properties of a generic -meson decay, as well as the missing energy and momentum being consistent with the hypothesis of a neutrino from the signal decay. We find a 2.4 standard deviation excess above background including systematic uncertainties, which corresponds to a branching fraction of or a frequentist 90% confidence level interval on the branching fraction of . This result is obtained from a 711 fb data sample that contains pairs, collected near the resonance with the Belle detector at the KEKB asymmetric-energy collider.
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.