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論文

Precise lifetime measurement of $$^4_Lambda$$H hypernucleus using in-flight $$^4$$He$$(K^-, pi^0)^4_Lambda$$H reaction

赤石 貴也; 橋本 直; 谷田 聖; 他35名*

Physics Letters B, 845, p.138128_1 - 138128_4, 2023/10

We present a new measurement of the $$^4_Lambda$$H hypernuclear lifetime using in-flight $$K^-$$ + $$^4$$He $$rightarrow$$ $$^4_Lambda$$H + $$pi^0$$ reaction at the J-PARC hadron facility. We demonstrate, for the first time, the effective selection of the hypernuclear bound state using only the $$gamma$$-ray energy decayed from $$pi^0$$. This opens the possibility for a systematic study of isospin partner hypernuclei through comparison with data from ($$K^-$$, $$pi^-$$) reaction. As the first application of this method, our result for the $$^4_Lambda$$H lifetime, $$tau(^4_Lambda mathrm{H}) = 206 pm 8 (mathrm{stat.}) pm 12 (mathrm{syst.}) mathrm{ps}$$, is one of the most precise measurements to date. We are also preparing to measure the lifetime of the hypertriton ($$^3_Lambda$$H) using the same setup in the near future.

論文

Pole position of $$Lambda(1405)$$ measured in $$d(K^-,n)piSigma$$ reactions

相川 脩*; 橋本 直; 谷田 聖; 他73名*

Physics Letters B, 837, p.137637_1 - 137637_8, 2023/02

 被引用回数:0 パーセンタイル:0.02(Astronomy & Astrophysics)

We measured a set of $$pi^pmSigma^mp$$, $$pi^0Sigma^0$$, and $$pi^-Sigma^0$$ invariant mass spectra below and above the $$bar{K}N$$ mass threshold in $$K^-$$-induced reactions on deuteron. We deduced the $$S$$-wave$$bar{K}NrightarrowpiSigma$$ and $$bar{K}Nrightarrowbar{K}N$$ scattering amplitudes in the isospin 0 channel in the framework of a $$bar{K}N$$ and $$piSigma$$ coupled channel. We find that a resonance pole corresponding to $$Lambda(1405)$$ is located at 1417.7$$^{+6.0}_{-7.4}$$(fitting errors)$$^{+1.1}_{-1.0}$$(systematic errors) + $$[-26.1^{+6.0}_{-7.9}$$(fitting errors)$$^{+1.7}_{-2.0}$$(systematic errors)]$$i$$ MeV/$$c^2$$, closer to the $$bar{K}N$$ mass threshold than the value determined by the Particle Data Group.

論文

X ray spectroscopy on $$Xi$$$$^-$$ atoms (J-PARC E03, E07 and future)

山本 剛史; 藤田 真奈美; 後神 利志*; 原田 健志*; 早川 修平*; 細見 健二; 市川 裕大; 石川 勇二*; 鎌田 健人*; 叶内 萌香*; et al.

EPJ Web of Conferences, 271, p.03001_1 - 03001_5, 2022/11

X-ray spectroscopy of hadronic atoms give us various information on the strong interaction between hadrons and nuclei. At J-PARC, we are aiming for the world-first detection of the X rays from atoms with a doubly strange hyperon, $$Xi$$$$^-$$. Recently, two experiments, J-PARC E07 and J-PARC E03, have been performed for the detection of X rays from $$Xi$$$$^-$$ atoms. Overview and status of these measurements will be presented. We will also discuss future plan of X-ray spectroscopy on $$Xi$$$$^-$$-atoms, which can be performed together with high resolution $$Xi$$$$^-$$ hyper nuclear spectroscopy using newly constructed S-2S spectrometer. Preparation status will be shown in this contribution.

論文

Development of a Ge detector array and an in-beam calibration system for highly precise measurement of $$Xi^-$$ atomic X-rays

藤田 真奈美; 細見 健二; 石川 勇二*; 叶内 萌香*; 小池 武志*; 小椋 裕*; 田村 裕和; 谷田 聖; 鵜養 美冬*; 山本 剛史

Nuclear Instruments and Methods in Physics Research A, 1042, p.167439_1 - 167439_9, 2022/11

 被引用回数:1 パーセンタイル:35.78(Instruments & Instrumentation)

$$Xi^-$$ atomic X-ray spectroscopy is a powerful method of studying the $$Xi$$N interaction, for which very limited experimental data are currently available. For this reason, we constructed a germanium (Ge) detector array referred to as Hyperball-X and conducted the first-ever $$Xi^-$$ atomic X-ray measurements in 2016 and 2017 at J-PARC. We developed a novel method for in-beam energy calibration of Ge detectors. Three $$gamma$$ rays (202 keV, 307 keV, and 511 keV) from $$^{176}$$Lu in LSO scintillation counters and $$^{22}$$Na source were used as reference. The $$beta-gamma$$ and $$gamma-gamma$$ coincidence detection using the Ge detectors and LSO counters allows for continuous in-beam calibration with this new calibration method, and the calibration uncertainty is reduced to less than $$pm$$100 eV for energies ranging from 202 to 511 keV.

論文

Measurement of differential cross sections for $$Sigma^+ p$$ elastic scattering in the momentum range 0.44-0.80 GeV/c

七村 拓野; 藤田 真奈美; 長谷川 勝一; 市川 真也; 市川 裕大; 今井 憲一*; 成木 恵; 佐藤 進; 佐甲 博之; 田村 裕和; et al.

Progress of Theoretical and Experimental Physics (Internet), 2022(9), p.093D01_1 - 093D01_35, 2022/09

 被引用回数:1 パーセンタイル:51.04(Physics, Multidisciplinary)

We performed a novel $$Sigma^+p$$ scattering experiment at the J-PARC Hadron Experimental Facility. Approximately 2400 $$Sigma^+p$$ elastic scattering events were identified from $$4.9 times 10^7$$ tagged $$Sigma^+$$ particles in the $$Sigma^+$$ momentum range 0.44 - 0.80 GeV/c. The differential cross sections of the $$Sigma^+p$$ elastic scattering were derived with much better precision than in previous experiments. The obtained differential cross sections were approximately 2 mb/sr or less, which were not as large as those predicted by the fss2 and FSS models based on the quark cluster model in the short-range region. By performing phase-shift analyses for the obtained differential cross sections, we experimentally derived the phase shifts of the $$^3S_1$$ and $$^1P_1$$ channels for the first time. The phase shift of the 3S1 channel, where a large repulsive core was predicted owing to the Pauli effect between quarks, was evaluated to be $$20^circ<|delta_{^3S_1}|<35^circ$$. If the sign of $$delta_{^3S_1}$$ is assumed to be negative, the interaction in this channel is moderately repulsive, as the Nijmegen extended-sort-core models predicted.

論文

Measurements of strong-interaction effects in kaonic-helium isotopes at sub-eV precision with X-ray microcalorimeters

橋本 直; 谷田 聖; 他68名*

Physical Review Letters, 128(11), p.112503_1 - 112503_6, 2022/03

 被引用回数:4 パーセンタイル:77.67(Physics, Multidisciplinary)

We have measured the $$3d to 2p$$ transition X-rays of kaonic $$^3$$He and $$^4$$He atoms using superconducting transition-edge-sensor microcalorimeters with an energy resolution better than 6 eV (FWHM). We determined the energies to be $$6224.5 pm 0.4$$ (stat) $$pm 0.2$$ (syst) eV and $$6463.7pm 0.3$$ (stat) $$pm 0.1$$ (syst) eV, and widths to be $$2.5pm 1.0$$ (stat) $$pm 0.4$$ (syst) eV and $$1.0 pm 0.6$$ (stat) $$pm 0.3$$ (stat) eV, for kaonic $$^3$$He and $$^4$$He, respectively. These values are nearly 10 times more precise than in previous measurements. Our results exclude the large strong-interaction shifts and widths that are suggested by a coupled-channel approach, and agree with calculations based on optical-potential models.

論文

Study of $$e^+e^-to Upsilon(rm1S,2S)eta$$ and $$e^+e^-to Upsilon(rm 1S)eta^{prime}$$ at $$sqrt{s}=10.866$$ GeV with the Belle detector

Kovalenko, E.*; 谷田 聖; Belle Collaboration*; 他181名*

Physical Review D, 104(11), p.112006_1 - 112006_12, 2021/12

 被引用回数:0 パーセンタイル:0.01(Astronomy & Astrophysics)

We report the first observation of the processes $$e^+e^-toUpsilon(rm 1S,2S)eta$$ at $$sqrt{s}$$=10.866 GeV with a $$10.2sigma$$ and $$16.5sigma$$ significance respectively. The measured Born cross sections are $$sigma(e^+e^- to Upsilon(2S)eta)=2.07 pm 0.21 pm 0.19$$ pb, and $$sigma(e^+e^- to Upsilon(rm 1S)eta)=0.42 pm 0.08 pm 0.04$$ pb. We also set the upper limit on the cross section of the process $$e^+e^- to Upsilon(rm 1S)eta^{prime}$$ to be $$sigma(e^+e^- to Upsilon(rm 1S)eta^{prime}) < 0.035$$~pb at $$90%$$ CL. The results are obtained with the data sample collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider in the energy range from 10.63 GeV to 11.02 GeV.

論文

Measurements of $$q^2$$ moments of inclusive $$B rightarrow X_c ell^+ nu_{ell}$$ decays with hadronic tagging

van Tonder, R.*; 谷田 聖; Belle Collaboration*; 他202名*

Physical Review D, 104(11), p.112011_1 - 112011_32, 2021/12

 被引用回数:5 パーセンタイル:64.26(Astronomy & Astrophysics)

We present the measurement of the first to fourth order moments of the four-momentum transfer squared, $$q^2$$, of inclusive $$B rightarrow X_c ell^+ nu_{ell}$$ decays using the full Belle data set of 711 $$mathrm{fb}^{-1}$$ of integrated luminosity at the $$Upsilon(4S)$$ resonance where $$ell = e, mu$$. The determination of these moments and their systematic uncertainties open new pathways to determine the absolute value of the CKM matrix element $$V_{cb}$$ using a reduced set of matrix elements of the heavy quark expansion. In order to identify and reconstruct the $$X_c$$ system, we reconstruct one of the two $$B$$-mesons using machine learning techniques in fully hadronic decay modes. The moments are measured with progressively increasing threshold selections on $$q^2$$ starting with a lower value of 3.0 $$mathrm{GeV}^2$$ in steps of 0.5 $$mathrm{GeV}^2$$ up to a value of 10.0 $$mathrm{GeV}^2$$. The measured moments are further unfolded, correcting for reconstruction and selection effects as well as QED final state radiation. We report the moments separately for electron and muon final states and observe no lepton flavor universality violating effects.

論文

Measurement of differential branching fractions of inclusive $${B to X_u , ell^+, nu_{ell}}$$ decays

Cao, L.*; 谷田 聖; Belle Collaboration*; 他199名*

Physical Review Letters, 127(26), p.261801_1 - 261801_8, 2021/12

 被引用回数:1 パーセンタイル:32.46(Physics, Multidisciplinary)

The first measurements of differential branching fractions of inclusive semileptonic $${B to X_u , ell^+, nu_{ell}}$$ decays are performed using the full Belle data set of 711 fb$$^{-1}$$ of integrated luminosity at the $$Upsilon(4S)$$ resonance and for $$ell = e, mu$$. Differential branching fractions are reported as a function of the lepton momentum, the four-momentum-transfer squared, light-cone momenta, the hadronic mass, and the hadronic mass squared. They are obtained by subtracting the backgrounds from semileptonic $${B to X_c , ell^+, nu_{ell}}$$ decays and other processes, and corrected for resolution and acceptance effects. The measured distributions are compared to predictions from inclusive and hybrid $${B to X_u , ell^+, nu_{ell}}$$ calculations.

論文

Search for $$B^{0} to tau^pm ell^mp$$ ($$ell=e,mu$$) with a hadronic tagging method at Belle

Atmacan, H.*; 谷田 聖; Belle Collaboration*; 他219名*

Physical Review D, 104(9), p.L091105_1 - L091105_9, 2021/11

 被引用回数:2 パーセンタイル:22.23(Astronomy & Astrophysics)

We present a search for the lepton-flavor-violating decays $$B^{0} to tau^pm ell^mp$$, where $$ell=(e,,mu)$$, using the full data sample of $$772 times 10^6$$ $$B overline{B}$$ pairs recorded by the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider. We use events in which one $$B$$ meson is fully reconstructed in a hadronic decay mode. The $$tau^pm$$ lepton is reconstructed indirectly using the momentum of the reconstructed $$B$$ and that of the $$ell^mp$$ from the signal decay. We find no evidence for $$B^{0} to tau^pm ell^mp$$ decays and set upper limits on their branching fractions at 90% confidence level of $$cal B$$($$B^{0} to tau^pm mu^{mp}$$)$$ < 1.5 times 10^{-5}$$ and $$cal B$$($$B^{0} to tau^pm e^{mp}$$)$$ < 1.6 times 10^{-5}$$.

論文

Precise measurement of the $$D^0$$ and $$D^+$$ lifetimes at Belle II

Abudin$'e$n, F.*; 谷田 聖; Belle II Collaboration*; 他385名*

Physical Review Letters, 127(21), p.211801_1 - 211801_9, 2021/11

 被引用回数:3 パーセンタイル:51.94(Physics, Multidisciplinary)

We report a measurement of the $$D^0$$ and $$D^+$$ lifetimes using $$D^0to K^-pi^+$$ and $$D^+to K^-pi^+pi^+$$ decays reconstructed in $$e^+e^-to cbar{c}$$ data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $$e^+e^-$$ collider. The data, collected at center-of-mass energies at or near the $$Upsilon(4S)$$ resonance, correspond to an integrated luminosity of $$72,{rm fb}^{-1}$$. The results, $$tau(D^0) = 410.5pm1.1,{rm(stat)}pm0.8,{rm(syst.)},{rm fs}$$ and $$tau(D^+) = 1030.4pm4.7,{rm(stat)}pm3.1,{rm(syst.)},{rm fs}$$, are the most precise to date and are consistent with previous determinations.

論文

Search for lepton-flavor-violating tau-lepton decays to $$ellgamma$$ at Belle

宇野 健太*; 谷田 聖; Belle Collaboration*; 他181名*

Journal of High Energy Physics (Internet), 2021(10), p.19_1 - 19_12, 2021/10

 被引用回数:7 パーセンタイル:68.32(Physics, Particles & Fields)

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

論文

Performance of RHICf detector during operation in 2017

Adriani, O.*; 谷田 聖; RHICf Collaboration*; 他17名*

Journal of Instrumentation (Internet), 16(10), p.P10027_1 - P10027_16, 2021/10

 被引用回数:0 パーセンタイル:0(Instruments & Instrumentation)

In the RHIC forward (RHICf) experiment, an operation with $$pp$$ collisions was performed at $$sqrt{s},=,$$510 GeV from 24-27 June 2017. The performances, energy and position resolutions, trigger efficiency, stability, and background during the operation, have been studied using data and simulations, which revealed that the requirements for production cross-section and transverse single-spin asymmetry measurements of very forward photons, $$pi^0$$s, and neutrons were satisfied. In this paper, we describe the details of these studies.

論文

Measurement of the differential cross sections of the $$Sigma^- p$$ elastic scattering in momentum range 470 to 850 MeV/$$c$$

三輪 浩司*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; 佐藤 進; et al.

Physical Review C, 104(4), p.045204_1 - 045204_20, 2021/10

 被引用回数:9 パーセンタイル:86.94(Physics, Nuclear)

A high statistics $$Sigma p$$ scattering experiment is performed at the J-PARC Hadron Experimental Facility. Momentum-tagged $$Sigma^-$$s running in a liquid hydrogen target are accumulated by detecting the reaction with a high intensity $$pi^-$$ beam of 20 M/spill. The differential cross sections of the $$Sigma^- p$$ elastic scattering were derived with a drastically improved accuracy by identifying approximately 4,500 events from 1.72 $$times$$ 10$$^7$$ $$Sigma^-$$. The derived differential cross section shows a clear forward-peaking angular distribution for a $$Sigma^-$$ momentum range from 470 to 850 MeV/$$c$$. The accurate data will impose a strong constraint on the theoretical models of the baryon-baryon interactions.

論文

Measurement of the branching fraction of $$Lambda_c^+ to p omega$$ decay at Belle

Li, S. X.*; 谷田 聖; Belle Collaboration*; 他193名*

Physical Review D, 104(7), p.072008_1 - 072008_8, 2021/10

 被引用回数:3 パーセンタイル:31.84(Astronomy & Astrophysics)

Using 980.6 $$rm fb^{-1}$$ of data collected with the Belle detector operating at the KEKB asymmetric-energy $$e^+e^-$$ collider, we present a measurement of the branching fraction of the singly Cabibbo-suppressed decay $$Lambda_c^+ to p omega$$. A clear $$Lambda_c^+$$ signal is observed for $$Lambda_c^+ to p omega$$ with a statistical significance of 9.1 standard deviations, and we measure the ratio of branching fractions $${cal B}(Lambda_c^+ to p omega)/{cal B}(Lambda_c^+ to p K^- pi^+) = (1.32 pm 0.12 (rm stat) pm 0.10 (rm syst))times 10^{-2}$$, from which we infer the branching fraction $${cal B}(Lambda_c^+ to p omega) = (8.27 pm 0.75 (rm stat) pm 0.62 (rm syst) pm 0.42 (rm ref))times 10^{-4}$$. The first quoted uncertainty is statistical, the second systematic, and the third from the reference mode $$Lambda_c^+ to p K^- pi^+$$.

論文

Probing gluon spin-momentum correlations in transversely polarized protons through midrapidity isolated direct photons in $$p^uparrow+p$$ collisions at $$sqrt{s}$$=200 GeV

Acharya, U. A.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他306名*

Physical Review Letters, 127(16), p.162001_1 - 162001_8, 2021/10

 被引用回数:5 パーセンタイル:71.69(Physics, Multidisciplinary)

Studying spin-momentum correlations in hadronic collisions offers a glimpse into a three-dimensional picture of proton structure. The transverse single-spin asymmetry for midrapidity isolated direct photons in $$p^uparrow+p$$ collisions at $$sqrt{s}$$=200 GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular are produced from the hard scattering and do not interact via the strong force, this measurement is a clean probe of initial-state spin-momentum correlations inside the proton and is in particular sensitive to gluon interference effects within the proton. This is the first time direct photons have been used as a probe of spin-momentum correlations at RHIC. The uncertainties on the results are a fifty-fold improvement with respect to those of the one prior measurement for the same observable, from the Fermilab E704 experiment. These results constrain gluon spin-momentum correlations in transversely polarized protons.

論文

Measurement of branching fractions and search for $$CP$$ violation in $$D^{0}topi^{+}pi^{-}eta$$, $$D^{0}to K^{+}K^{-}eta$$, and $$D^{0}tophieta$$ at Belle

Li, L. K.*; 谷田 聖; Belle Collaboration*; 他187名*

Journal of High Energy Physics (Internet), 2021(9), p.75_1 - 75_21, 2021/09

 被引用回数:1 パーセンタイル:11.5(Physics, Particles & Fields)

We measure the branching fractions and $$CP$$ asymmetries for the singly Cabibbo-suppressed decays $$D^{0}topi^{+}pi^{-}eta$$, $$D^{0}to K^{+}K^{-}eta$$, and $$D^{0}tophieta$$, using 980 fb$$^{-1}$$ of data from the Belle experiment at the KEKB $$e^+e^-$$ collider. We obtain $$mathcal{B}(D^{0}topi^{+}pi^{-}eta) = [1.22pm 0.02,({rm stat})pm 0.02,({rm syst})pm 0.03,(mathcal{B}_{rm ref})]times 10^{-3},, mathcal{B}(D^{0}to K^{+}K^{-}eta) = [1.80,^{+0.07}_{-0.06},({rm stat})pm 0.04,({rm syst})pm 0.05,(mathcal{B}_{rm ref})]times 10^{-4},, mathcal{B}(D^{0}tophieta) = [1.84pm 0.09,({rm stat})pm 0.06,({rm syst})pm 0.05,(mathcal{B}_{rm ref})]times 10^{-4},, $$ where the third uncertainty ($$mathcal{B}_{rm ref}$$) is from the uncertainty in the branching fraction of the reference mode $$D^{0} to K^{-}pi^{+}eta$$. The color-suppressed decay $$D^{0}tophieta$$ is observed for the first time, with very high significance. The results for the $$CP$$ asymmetries are $$A_{CP}(D^{0}topi^{+}pi^{-}eta) = [0.9pm 1.2,({rm stat})pm 0.5,({rm syst})]%,, A_{CP}(D^{0}to K^{+}K^{-}eta) = [-1.4pm 3.3,({rm stat})pm 1.1,({rm syst})]%,, A_{CP}(D^{0}tophieta) = [-1.9pm 4.4,({rm stat})pm 0.6,({rm syst})]%,. $$ The results for $$D^{0}topi^{+}pi^{-}eta$$ are a significant improvement over previous results. The branching fraction and $$A_{CP}$$ results for $$D^{0}to K^{+}K^{-}eta$$, and the $$A_{CP}$$ result for $$D^{0}tophieta$$, are the first such measurements. No evidence for $$CP$$ violation is found in any of these decays.

論文

Evidence for the decay $$Omega_{c}^{0} to pi^+Omega(2012)^- to pi^+ (bar{K}Xi)^{-}$$

Li, Y.*; 谷田 聖; Belle Collaboration*; 他190名*

Physical Review D, 104(5), p.052005_1 - 052005_9, 2021/09

 被引用回数:7 パーセンタイル:64.26(Astronomy & Astrophysics)

Using a data sample of 980~fb$$^{-1}$$ collected with the Belle detector operating at the KEKB asymmetric-energy $$e^+e^-$$ collider, we present evidence for the $$Omega(2012)^-$$ in the resonant substructure of $$Omega_{c}^{0} to pi^+ (bar{K}Xi)^{-}$$ ($$(bar{K}Xi)^{-}$$ = $$K^-Xi^0$$ + $$bar{K}^0 Xi^-$$) decays. The significance of the $$Omega(2012)^-$$ signal is 4.2$$sigma$$ after considering the systematic uncertainties. The ratio of the branching fraction of $$Omega_{c}^{0} to pi^{+} Omega(2012)^- to pi^+ (bar{K}Xi)^{-}$$ relative to that of $$Omega_{c}^{0} to pi^{+} Omega^-$$ is calculated to be 0.220 $$pm$$ 0.059(stat.) $$pm$$ 0.035(syst.). The individual ratios of the branching fractions of the two isospin modes are also determined, and found to be $${cal B}(Omega_{c}^0 to pi^+ Omega(2012)^-) times {cal B}(Omega(2012)^- to K^-Xi^0)/{cal B}(Omega_{c}^0 to pi^+ K^- Xi^0)$$ =(9.6 $$pm$$ 3.2(stat.) $$pm$$ 1.8(syst.))% and $${cal B}(Omega_{c}^0 to pi^+ Omega(2012)^-) times {cal B}(Omega(2012)^- to bar{K}^0 Xi^-)/{cal B}(Omega_{c}^0 to pi^+ bar{K}^0 Xi^-)$$ = (5.5 $$pm$$ 2.8(stat.) $$pm$$ 0.7(syst.))%.

論文

Measurement of the masses and widths of the $$Sigma_c(2455)^+$$ and $$Sigma_c(2520)^+$$ baryons

Yelton, J.*; 谷田 聖; Belle Collaboration*; 他205名*

Physical Review D, 104(5), p.052003_1 - 052003_8, 2021/09

 被引用回数:3 パーセンタイル:31.84(Astronomy & Astrophysics)

Using 980 $${rm fb}^{-1}$$ of data ${collected}$ with the Belle detector operating at the KEKB asymmetric-energy $$e^+e^-$$ collider, we report the measurements of the masses, and the first measurements of the instrinsic widths, of the $$Sigma_c(2455)^+$$ and $$Sigma_c(2520)^+$$ charmed baryons. We find $$M(Sigma_c(2455)^+)-M(Lambda_c^+) = 166.17pm 0.05^{+0.16}_{-0.07} {rm MeV}/c^2$$, $$Gamma(Sigma_c(2455)^+) = 2.3 pm 0.3 pm 0.3 {rm MeV/c^2}$$, $$M(Sigma_c(2520)^+)-M(Lambda_c^+) = 230.9 pm 0.5 ^{+0.5}_{-0.1} {rm MeV}/c^2$$, and $$Gamma(Sigma_c(2520)^+) = 17.2^{+2.3 +3.1}_{-2.1 -0.7} {rm MeV}/c^2$$, where the uncertainties are statistical and systematic, respectively. These measurements can be used to test models of the underlying quark structure of the $$Sigma_c$$ states.

論文

Measurements of the branching fractions of the semileptonic decays $$Xi_{c}^{0} to Xi^{-} ell^{+} nu_{ell}$$ and the asymmetry parameter of $$Xi_{c}^{0} to Xi^{-} pi^{+}$$

Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他182名*

Physical Review Letters, 127(12), p.121803_1 - 121803_8, 2021/09

 被引用回数:19 パーセンタイル:91.73(Physics, Multidisciplinary)

Using data samples of 89.5 and 711 fb$$^{-1}$$ recorded at energies of $$sqrt{s}=10.52$$ and $$10.58$$ GeV, respectively, with the Belle detector at the KEKB $$e^+e^-$$ collider, we report measurements of branching fractions of semileptonic decays $$Xi_{c}^{0} to Xi^{-} ell^{+} nu_{ell}$$ ($$ell=e$$ or $$mu$$) and the $$CP$$-asymmetry parameter of $$Xi_{c}^{0} to Xi^{-} pi^{+}$$ decay. The branching fractions are measured to be $${cal B}(Xi_{c}^{0} to Xi^{-} e^{+} nu_{e}$$)=($$1.31 pm 0.04 pm 0.07 pm 0.38$$)% and $${cal B}(Xi_{c}^{0} to Xi^{-} mu^{+} nu_{mu}$$)=($$1.27 pm 0.06 pm 0.10 pm 0.37$$)%, and the decay parameter $$alpha_{Xipi}$$ is measured to be $$0.63 pm 0.03 pm 0.01$$ with much improved precision compared to the current world average. The corresponding ratio $${cal B}(Xi_{c}^{0} to Xi^{-} e^{+} nu_{e})$$/$${cal B}(Xi_{c}^{0} to Xi^{-} mu^{+} nu_{mu})$$ is 1.03 $$pm$$ 0.05 $$pm$$ 0.07, which is consistent with the expectation of lepton flavor universality. The first measured asymmetry parameter $${cal A}_{CP} = (alpha_{Xi^{-}pi^{+}} + alpha_{bar{Xi}^{+}pi^{-}})/(alpha_{Xi^{-}pi^{+}} - alpha_{bar{Xi}^{+}pi^{-}}) = 0.024 pm 0.052 pm 0.014$$ is found to be consistent with zero. The first and the second uncertainties above are statistical and systematic, respectively, while the third ones arise due to the uncertainty of the $$Xi_{c}^{0} to Xi^{-} pi^+$$ branching fraction.

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