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論文

Missing-mass measurement of the $$^{12}$$C$$(K^-,K^+)$$ reaction at 1.8 GeV/$$c$$ with the Superconducting Kaon spectrometer

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

Progress of Theoretical and Experimental Physics (Internet), 2024(9), p.091D01_1 - 091D01_13, 2024/09

https://doi.org/10.1093/ptep/ptae133
 被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)

We conducted a measurement of the inclusive missing-mass spectrum in the $$^{12}$$C$$(K^-, K^+)$$ reaction at an incident beam momentum of 1.8 GeV/$$c$$. This measurement was carried out utilizing the Superconducting Kaon Spectrometer (SKS) and the K1.8 beamline spectrometer at the Hadron Experimental Hall in J-PARC. Remarkably, our experimental setup yielded an exceptionaly good energy resolution of 8.2 MeV (FWHM), enabling us to observe significant enhancements in the vicinity of the $$^{12}_{Xi}$$Be threshold region. In order to estimate the spectrum information, we employed several fitting parameters assumptions. The best agreement with the spectrum shape was obtained with combining quasi-free (QF) component and two-Gaussian functions, with the experimental resolution $$sigma$$ being held constant. The peak positions were obtained to be $$B_{Xi} = 8.9 pm 1.4$$ (stat.) $$^{+3.8}_{-3.1}$$ (syst.) MeV and $$B_{Xi} = -2.4 pm 1.3$$ (stat.) $$^{+2.8}_{-1.2}$$ (syst.) MeV. Another model assumption, utilizing quasi-free (QF) and one Breit-Wigner function with $$B_{Xi} = -2.7 pm 2.2$$ (stat.) $$^{+0.5}_{-0.7}$$ (syst.) MeV and $$Gamma = 4.1 pm 2.1$$ (stat.) $$^{+1.2}_{-0.7}$$ (syst.) MeV, also yielded a similar $$chi^2$$ value.

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

https://doi.org/10.1016/j.physletb.2023.138128
 被引用回数：1 パーセンタイル：25.07(Astronomy & Astrophysics)

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

Observation of a threshold cusp at the $$Lambdaeta$$ threshold in the $$pK^-$$ mass spectrum with $$Lambda_c^+ to pK^-pi^+$$ decays

Yang, S.*; 谷田 聖; Belle Collaboration*; 他196名*

Physical Review D, 108(3), p.L031104_1 - L031104_6, 2023/08

https://doi.org/10.1103/PhysRevD.108.L031104
 被引用回数：5 パーセンタイル：57.15(Astronomy & Astrophysics)

We observe a narrow peaking structure in the $$pK^{-}$$ invariant-mass spectrum near the $$Lambdaeta$$ threshold. The peak is clearly seen in 1.5 million events of $$Lambda_{c}^{+} rightarrow p K^{-} pi^{+}$$ decay using the $$980~{rm fb^{-1}}$$ data sample collected by the Belle detector at the KEKB asymmetric-energy $$e^{+}e^{-}$$ collider. We try two approaches to explain this structure: as a new resonance and as a cusp at the $$Lambdaeta$$ threshold. The best fit is obtained with a coherent sum of a Flatt$$rm{acute{e}}$$ function and a constant background amplitude with the $$chi^2/{rm n.d.f}=257/243$$ ($$p = 0.25$$), while the fits to Breit-Wigner functions are unfavored by more than 7$$sigma$$. The best fit explains the structure as a cusp at the $$Lambdaeta$$ threshold, and the obtained parameters are consistent with the known properties of $$Lambda(1670)$$. The observation gives the first identification of a threshold cusp in hadrons from the spectrum shape.

論文

Measurement of lepton mass squared moments in $$B to X_c ell bar nu_{ell}$$ decays with the Belle II experiment

Abudin$'e$n, F.*; 谷田 聖; Belle II Collaboration*; 他413名*

Physical Review D, 107(7), p.072002_1 - 072002_24, 2023/04

https://doi.org/10.1103/PhysRevD.107.072002
 被引用回数：9 パーセンタイル：76.22(Astronomy & Astrophysics)

We present measurements of the first to fourth moments of the lepton mass squared $$q^2$$ of $$B to X_c , ell, bar nu_{ell}$$ decays for $$ell = e, mu$$ and with $$X_c$$ a hadronic system containing a charm quark. These results use a sample of electron-positron collisions at the $$Upsilon(4S)$$ resonance corresponding to $$62.8 , mathrm{fb}^{-1}$$ of integrated luminosity and collected by the Belle II experiment in 2019 and 2020. To identify the $$X_c$$ system and reconstruct $$q^2$$, one of the $$B$$ mesons from an $$Upsilon(4S) to B kern 0.18emoverline{kern -0.18em B}$$ decay is fully reconstructed in a hadronic decay mode using a multivariate $$B$$ tagging algorithm. We report raw and central moments for $$ q^2 > 1.5 ; mathrm{GeV^2/c^4}$$ up to $$q^2 > 8.5 ; mathrm{GeV^2/c^4}$$, probing up to 77% of the accessible $$B to X_c , ell, bar nu_{ell}$$ phase space. This is the first measurement of moments in the experimentally challenging range of $$[ 1.5, 2.5 ] , mathrm{GeV^2/c^4}$$.

論文

Search for $$X(3872)topi^+pi^-pi^0$$ at Belle

Yin, J. H.*; 谷田 聖; Belle Collaboration*; 他193名*

Physical Review D, 107(5), p.052004_1 - 052004_8, 2023/03

https://doi.org/10.1103/PhysRevD.107.052004
 被引用回数：3 パーセンタイル：40.72(Astronomy & Astrophysics)

We present a search for the decay $$X(3872) to pi^+pi^-pi^0$$ in the $$(772pm11)times10^6$$ $$Upsilon(4S)to B bar B$$ data sample collected at the Belle detector, where the $$X(3872)$$ is produced in $$B^{pm}to K^{pm}X(3872)$$ and $$B^{0}to K_{S}^0 X(3872)$$ decays. We do not observe a signal, and set 90% credible upper limits for two different models of the decay processes: if the decay products are distributed uniformly in phase space, $$mathcal{B}(X(3872) to pi^+pi^-pi^0) < 1.3%$$; if $$M(pi^+pi^-)$$ is concentrated near the mass of the $$D^0 bar D^0$$ pair in the process $$X(3872)to D^0bar{D}^{*0}+c.c.to D^0 bar D^{0}pi^0topi^+ pi^- pi^0$$, $$mathcal{B}(X(3872) to pi^+pi^-pi^0) < 1.2times10^{-3}$$.

論文

Superconducting dipole magnet for Hyperon spectrometer

Ahn, J. K.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; 他10名*

Nuclear Instruments and Methods in Physics Research A, 1047, p.167775_1 - 167775_13, 2023/02

https://doi.org/10.1016/j.nima.2022.167775
 被引用回数：1 パーセンタイル：17.31(Instruments & Instrumentation)

We have constructed a conduction-cooled superconducting dipole magnet for the Hyperon spectrometer at Japan Proton Accelerator Research Complex (J-PARC). The magnet is a Helmholtz-type dipole magnet with two circular coils with a radius of 500 mm separated by 500 mm. It provides a uniform magnetic field of 1.0 T or higher in a volume of $$phi600$$ mm $$times$$ 600 mm, covering the drift region of a time projection chamber (TPC). Owing to the target location inside the TPC, the Hyperon spectrometer has a broad angular coverage with a nearly $$2pi$$ solid angle. We have successfully excited the magnet up to 1.3 T. At 1.0 T, we operated it stably for more than 1 week in single-magnet configuration and double-magnet configuration with a normal-conducting 0.7-T dipole magnet located 30 cm apart. The measured magnetic field distribution in the TPC volume is consistent with the calculated field map.

論文

Measurement of branching fractions of $$Lambda_c^+to{}pK_S^0K_S^0$$ and $$Lambda_c^+to{}pK_S^0eta$$ at Belle

Li, L. K.*; 谷田 聖; Belle Collaboration*; 他204名*

Physical Review D, 107(3), p.032004_1 - 032004_9, 2023/02

https://doi.org/10.1103/PhysRevD.107.032004
 被引用回数：5 パーセンタイル：57.15(Astronomy & Astrophysics)

We present a study of a singly Cabibbo-suppressed decay $$Lambda_c^+to{}pK_S^0K_S^0$$ and a Cabibbo-favored decay $$Lambda_c^+to{}pK_S^0eta$$ based on 980 $$rm fb^{-1}$$ of data collected by the Belle detector, operating at the KEKB energy-asymmetric $$e^+e^-$$ collider. We measure their branching fractions relative to $$Lambda_c^+to{}pK_S^0$$: $$mathcal{B}(Lambda_c^+to{}pK_S^0K_S^0)/mathcal{B}(Lambda_c^+to{}pK_S^0)={(1.48 pm 0.08 pm 0.04)times 10^{-2}}$$ and $$mathcal{B}(Lambda_c^+to{}pK_S^0eta)/mathcal{B}(Lambda_c^+to{}pK_S^0)={(2.73pm 0.06pm 0.13)times 10^{-1}}$$. Combining with the world average $$mathcal{B}(Lambda_c^+to{}pK_S^0)$$, we have the absolute branching fractions: $$mathcal{B}(Lambda_c^+to{}pK_S^0K_S^0) = {(2.35pm 0.12pm 0.07 pm 0.12 )times 10^{-4}}$$ and $$mathcal{B}(Lambda_c^+to{}pK_S^0eta) = {(4.35pm 0.10pm 0.20 pm 0.22 )times 10^{-3}}$$. The first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the uncertainty on $$mathcal{B}(Lambda_c^+to{}pK_S^0)$$. The mode $$Lambda_c^+to{}pK_S^0K_S^0$$ is observed for the first time and has a statistical significance of $$>10sigma$$. The branching fraction of $$Lambda_c^+to{}pK_S^0eta$$ has been measured with a threefold improvement in precision over previous results and is found to be consistent with the world average.

論文

Measurement of the $$B^+/B^0$$ production ratio in $$e^+e^-$$ collisions at the $$Upsilon(4S)$$ resonance using $$B rightarrow J/psi(ellell) K$$ decays at Belle

Choudhury, S.*; 谷田 聖; Belle Collaboration*; 他198名*

Physical Review D, 107(3), p.L031102_1 - L031102_6, 2023/02

https://doi.org/10.1103/PhysRevD.107.L031102
 被引用回数：12 パーセンタイル：72.68(Astronomy & Astrophysics)

We measure the ratio of branching fractions for the $$Upsilon (4S)$$ decays to $$B^+B^-$$ and $$B^0bar{B}{}^0$$ using $$B^+ rightarrow J/psi(ellell) K^+$$ and $$B^0 rightarrow J/psi(ellell) K^0$$ samples, where $$J/psi(ellell)$$ stands for $$J/psi to ell^+ell^-$$ ($$ell = e$$ or $$mu$$), with $$711$$ fb$$^{-1}$$ of data collected at the $$Upsilon(4S)$$ resonance with the Belle detector. We find the decay rate ratio of $$Upsilon(4S) rightarrow B^+B^-$$ over $$Upsilon(4S) rightarrow B^0bar{B}{}^0$$ to be $$1.065pm0.012pm 0.019 pm 0.047$$, which is the most precise measurement to date. The first and second uncertainties are statistical and systematic, respectively, and the third uncertainty is systematic due to the assumption of isospin symmetry in $$B to J/psi(ellell) K$$.

論文

Measurement of the branching fraction of $$Xi_{c}^{0}to Lambda_{c}^{+}pi^{-}$$ at Belle

Tang, S. S.*; 谷田 聖; Belle Collaboration*; 他173名*

Physical Review D, 107(3), p.032005_1 - 032005_6, 2023/02

https://doi.org/10.1103/PhysRevD.107.032005
 被引用回数：4 パーセンタイル：49.66(Astronomy & Astrophysics)

Based on a data sample of 983 fb$$^{-1}$$ collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider, we present the study of the heavy-flavor-conserving decay $$Xi_{c}^{0}to Lambda_{c}^{+}pi^{-}$$ with $$Lambda_{c}^{+}$$ reconstructed via its $$pK^{-} pi^{+}$$ decay mode. The branching fraction ratio $$mathcal{B}(Xi_{c}^{0}to Lambda_{c}^{+}pi^{-})/mathcal{B}(Xi_{c}^{0}to Xi^{-}pi^{+})$$ is measured to be $$0.38 pm 0.04 pm 0.04$$. Combing with the world average value of $$mathcal{B}(Xi_{c}^{0}to Xi^{-}pi^{+})$$, the branching fraction $$mathcal{B}(Xi_{c}^{0}to Lambda_{c}^{+}pi^{-})$$ is deduced to be $$(0.54 pm 0.05 pm 0.05 pm 0.12)%$$. Here, the uncertainties above are statistical, systematic, and from $$mathcal{B}(Xi_c^{0} to Xi^{-}pi^{+})$$, respectively.

論文

Measurement of the branching fractions for Cabibbo-suppressed decays $$D^{+}to K^{+} K^{-}pi^{+}pi^{0}$$ and $$D_{(s)}^{+}to K^{+}pi^{-}pi^{+}pi^{0}$$ at Belle

Li, L. K.*; 谷田 聖; Belle Collaboration*; 他197名*

Physical Review D, 107(3), p.033003_1 - 033003_9, 2023/02

https://doi.org/10.1103/PhysRevD.107.033003
 被引用回数：0 パーセンタイル：0.00(Astronomy & Astrophysics)

We present measurements of the branching fractions for the singly Cabibbo-suppressed decays $$D^+to K^{+}K^{-}pi^{+}pi^{0}$$ and $$D_s^{+}to K^{+}pi^{-}pi^{+}pi^{0}$$, and the doubly Cabibbo-suppressed decay $$D^{+}to K^{+}pi^{-}pi^{+}pi^{0}$$, based on 980 $${rm fb}^{-1}$$ of data recorded by the Belle experiment at the KEKB $$e^{+}e^{-}$$ collider. We measure these modes relative to the Cabibbo-favored modes $$D^{+}to K^{-}pi^{+}pi^{+}pi^{0}$$ and $$D_s^{+}to K^{+}K^{-}pi^{+}pi^{0}$$. Our results for the ratios of branching fractions are $$B(D^{+}to K^{+}K^{-}pi^{+}pi^{0})/B(D^{+}to K^{-}pi^{+}pi^{+}pi^{0}) = (11.32 pm 0.13 pm 0.26)%$$, $$B(D^{+}to K^{+}pi^{-}pi^{+}pi^{0})/B(D^{+}to K^{-}pi^{+}pi^{+}pi^{0}) = (1.68 pm 0.11pm 0.03)%$$, and $$B(D_s^{+}to K^{+}pi^{-}pi^{+}pi^{0})/B(D_s^{+}to K^{+}K^{-}pi^{+}pi^{0}) = (17.13 pm 0.62 pm 0.51)%$$, where the uncertainties are statistical and systematic, respectively. The second value corresponds to $$(5.83pm 0.42)timestan^4theta_C$$, where $$theta_C$$ is the Cabibbo angle; this value is larger than other measured ratios of branching fractions for a doubly Cabibbo-suppressed charm decay to a Cabibbo-favored decay. Multiplying these results by world average values for $$B(D^{+}to K^{-}pi^{+}pi^{+}pi^{0})$$ and $$B(D_s^{+}to K^{+}K^{-}pi^{+}pi^{0})$$ yields $$B(D^{+}to K^{+}K^{-}pi^{+}pi^{0})= (7.08pm 0.08pm 0.16pm 0.20)times10^{-3}$$, $$B(D^{+}to K^{+}pi^{-}pi^{+}pi^{0})= (1.05pm 0.07pm 0.02pm 0.03)times10^{-3}$$, and $$B(D_s^{+}to K^{+}pi^{-}pi^{+}pi^{0}) = (9.44pm 0.34pm 0.28pm 0.32)times10^{-3}$$, where the third uncertainty is due to the branching fraction of the normalization mode. The first two results are consistent with, but more precise than, the current world averages. The last result is the first measurement of this branching fraction.

論文

First search for the weak radiative decays $$Lambda_c^+ to Sigma^+ gamma$$ and $$Xi_c^0 to Xi^0 gamma$$

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

Physical Review D, 107(3), p.032001_1 - 032001_11, 2023/02

https://doi.org/10.1103/PhysRevD.107.032001
 被引用回数：2 パーセンタイル：29.46(Astronomy & Astrophysics)

We present the first search for the weak radiative decays $$Lambda_c^+ to Sigma^+ gamma$$ and $$Xi_c^0 to Xi^0 gamma$$ using a data sample of 980~fb$$^{-1}$$ collected by the Belle detector operating at the KEKB asymmetric-energy $$e^+e^-$$ collider. There are no evident $$Lambda_c^+ to Sigma^+ gamma$$ or $$Xi_c^0 to Xi^0 gamma$$ signals. Taking the decays $$Lambda_c^+ to p K^- pi^+$$ and $$Xi_c^0 to Xi^- pi^+$$ as normalization channels, the upper limits at 90% credibility level on the ratios of branching fractions $${cal B}(Lambda_c^+ to Sigma^+ gamma)/{cal B}(Lambda_c^+ to p K^{-} pi^+) < 4.0 times 10^{-3}$$ and $${cal B}(Xi_c^0 to Xi^0 gamma)/{cal B}(Xi_c^0 to Xi^- pi^+) < 1.2 times 10^{-2}$$ are determined. We obtain the upper limits at 90% credibility level on the absolute branching fractions $${cal B}(Lambda_c^+ to Sigma^+ gamma) < 2.6 times 10^{-4}$$ and $${cal B}(Xi_c^0 to Xi^0 gamma) < 1.8 times 10^{-4}$$.

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

https://doi.org/10.1016/j.physletb.2022.137637
 被引用回数：10 パーセンタイル：79.31(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

Evidence for the singly Cabibbo-suppressed decay $$Omega^0_ctoXi^-pi^+$$ and search for $$Omega^0_ctoXi^-K^+$$ and $$Omega^-K^+$$ decays at Belle

Han, X.*; 谷田 聖; Belle Collaboration*; 他170名*

Journal of High Energy Physics (Internet), 2023(1), p.55_1 - 55_12, 2023/01

https://doi.org/10.1007/JHEP01(2023)055
 被引用回数：6 パーセンタイル：57.15(Physics, Particles & Fields)

Using a data sample of 980 fb$$^{-1}$$ collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider, we study for the first time the singly Cabibbo-suppressed decays $$Omega^0_ctoXi^{-}pi^{+}$$ and $$Omega^-K^+$$ and the doubly Cabibbo-suppressed decay $$Omega^0_cto Xi^- K^{+}$$. Evidence for an $$Omega^0_c$$ signal in the $$Omega^0_ctoXi^-pi^+$$ mode is reported with a significance of $$4.5sigma$$ including systematic uncertainties. The ratio of branching fractions to the normalization mode $$Omega_c^0to Omega^-pi^+$$ is measured to be $${cal B}(Omega_{c}^{0} to Xi^{-} pi ^{+} )/{cal B}(Omega_c^0to Omega^-pi^+)=0.253pm 0.053({rm stat.})pm 0.030({rm syst.}).$$ No significant signals of $$Omega^0_ctoXi^-K^+$$ and $$Omega^-K^+$$ modes are found. The upper limits at $$90%$$ confidence level on ratios of branching fractions are determined to be $${cal B}(Omega_{c}^{0} to Xi^{-} K ^{+})/{cal B}(Omega_c^0to Omega^-pi^+) < 0.070$$ and $${cal B}(Omega_{c}^{0} to Omega^{-}K^{+})/{cal B}(Omega_c^0to Omega^-pi^+) < 0.29.$$

論文

Study of $$e^{+}e^{-}toetaphi$$ via initial state radiation at Belle

Zhu, W. J.*; 谷田 聖; Belle Collaboration*; 他174名*

Physical Review D, 107(1), p.012006_1 - 012006_10, 2023/01

https://doi.org/10.1103/PhysRevD.107.012006
 被引用回数：2 パーセンタイル：29.46(Astronomy & Astrophysics)

Using $$980~fb^{-1}$$ of data collected on and around the $$Upsilon(nS)(n=1,2,3,4,5)$$ resonances with the Belle detector at the KEKB collider, we measure the cross section of $$e^{+}e^{-}to etaphi$$ from threshold to $$3.95~{rm GeV}/c^{2}$$ via initial-state radiation. From a multi-parameter fit assuming $$phi(2170)$$ exists in the $$etaphi$$ final state according to previous measurement by BESIII, the resonant parameters of $$phi(1680)$$ are determined to be $$m_{phi(1680)} = (1683 pm 7 pm 9)~{rm MeV}/c^{2}$$ (statistical and systematic errors, respectively), $$Gamma_{phi(1680)} = (149 pm 12 pm 13)~{rm MeV}$$ and, depending on the possible presence of interfering resonances, $$Gamma^{e^{+}e^{-}}_{phi(1680)}cdot {cal B}[phi(1680)toetaphi] = (122 pm 6 pm 13)~{rm eV}$$, $$(219 pm 15 pm 18)~{rm eV}$$, $$(163 pm 11 pm 13)~{rm eV}$$ or $$(203 pm 12 pm 18)~{rm eV}$$. The branching fraction of $$phi(1680)toetaphi$$ decay is determined to be approximately 20%. Additionally, the branching fraction for $$J/psitoetaphi$$ is measured to be $$(7.1pm 1.0 pm 0.5)times 10^{-4}$$. However, there is no significant observed $$phi(2170)$$ signal in the $$etaphi$$ final states in this analysis, and correspondingly the upper limit for $$Gamma^{e^{+}e^{-}}_{phi(2170)}cdot {cal B}(phi(2170)toetaphi)$$ is determined to be either $$0.17~{rm eV}$$ (for two fits), or $$18.6~{rm eV}$$ (remaining two fits), at 90% confidence level.

論文

Measurements of the branching fractions $$mathcal{B} (bar{B}{}^0 to D^{*+} pi^-)$$ and $$mathcal{B} (bar{B}{}^0 to D^{*+} K^-)$$ and tests of QCD factorization

Krohn, J.-F.*; 谷田 聖; Belle Collaboration*; 他198名*

Physical Review D, 107(1), p.012003_1 - 012003_12, 2023/01

https://doi.org/10.1103/PhysRevD.107.012003
 被引用回数：3 パーセンタイル：15.61(Astronomy & Astrophysics)

Using $$(771.6 pm 10.6) times 10^6$$ $$Bbar{B}$$ meson pairs recorded by the Belle experiment at the KEKB $$e^+ e^-$$ collider, we report the branching fractions $$mathcal{B}(bar{B}^0 to D^{*+} pi^-) = (2.62 pm 0.02 pm 0.09)times 10^{-3}$$ and $$mathcal{B}(bar{B}^0 to D^{*+} K^-) = (2.22 pm 0.06 pm 0.08)times 10^{-4}$$; the quoted uncertainties are statistical and systematic, respectively. A measurement of the ratio of these branching fractions is also presented, $$mathcal{R}_{K/pi}=mathcal{B}(bar{B} to D^{*+}K^-) /mathcal{B}(bar{B} to D^{*+}pi^-) = (8.41 pm 0.24 pm 0.13)times 10^{-2}$$, where systematic uncertainties due to the $$D^{*+}$$ meson reconstruction cancel out. Furthermore, we report a new QCD factorization test based on the measured ratios for $$bar{B} to D^{*+}h^-$$ and $$bar{B} to D^{*+}ell^-nu$$ decays at squared momentum transfer values equivalent to the mass of the $$h = pi$$ or $$K$$ hadron. The parameters $$|a_1(h)|$$ are measured to be $$|a_1(pi)|= 0.884 pm 0.004 pm 0.003 pm 0.016$$ and $$|a_1(K)|=0.913 pm 0.019 pm 0.008 pm 0.013$$, where the last uncertainties account for all external inputs. These values are approximately $$15%$$ lower than those expected from theoretical predictions. Subsequently, flavor $$SU(3)$$ symmetry is tested by measuring the ratios for pions and kaons, $$|a_1(K)|^2/ |a_1(pi)|^2=1.066 pm 0.042 pm 0.018 pm 0.023$$, as well as for different particle species. The ratio is consistent with unity and therefore no evidence for $$SU(3)$$ symmetry breaking effects is found at the $$5%$$ precision level.

論文

Evidence of a new excited charmed baryon decaying to $$Sigma_{c}(2455)^{0,++} pi^{pm}$$

Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他194名*

Physical Review Letters, 130(3), p.031901_1 - 031901_7, 2023/01

https://doi.org/10.1103/PhysRevLett.130.031901
 被引用回数：16 パーセンタイル：91.49(Physics, Multidisciplinary)

We present the study of $$bar{B}^{0} to Sigma_{c}(2455)^{0,++} pi^{pm} bar{p}$$ decays based on $$772times 10^{6}$$ $$Bbar{B}$$ 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 $$Lambdapi^{+}$$ 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 $${cal B}(bar{B}^{0} to Sigma_{c}(2455)^{++} pi^{-} bar{p}) = (1.84pm 0.11 pm 0.12)times 10^{-4}$$, 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 $$4.2sigma$$ 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 $$(51.8pm20.0 pm 18.8)$$ 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.

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

https://doi.org/10.1051/epjconf/202227103001

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

Recent progress and future prospects of hyperon nucleon scattering experiment

三輪 浩司*; 藤田 真奈美; 原田 健志; 長谷川 勝一; 細見 健二; 市川 真也; 今井 憲一*; 佐甲 博之; 佐藤 進; 田村 裕和; et al.

EPJ Web of Conferences, 271, p.04001_1 - 04001_7, 2022/11

https://doi.org/10.1051/epjconf/202227104001

A new hyperon-proton scattering experiment, dubbed J-PARC E40, was performed to measure differential cross sections of the $$Sigma^+ p$$, $$Sigma^- p$$ elastic scatterings and the $$Sigma^- p to Lambda n$$ scattering by identifying a lot of $$Sigma $$ particles in the momentum ranging from 0.4 to 0.8 GeV/$$c$$ produced by the $$pi^{pm}p to K^+Sigma^{pm}$$ reactions. We successfully measured the differential cross sections of these three channels with a drastically improved accuracy with a fine angular step. These new data will become important experimental constraints to improve the theories of the two-body baryon-baryon interactions. Following this success, we proposed a new experiment to measure the differential cross sections and spin observables by using a highly polarized $$Lambda$$ beam for providing quantitative information on the $$Lambda N$$ interaction. The results of three $$Sigma p$$ channels and future prospects of the $$Lambda p$$ scattering experiment are described.

論文

J-PARC Hadron Experimental Facility extension project

佐久間 史典*; 田村 裕和; 谷田 聖; 山本 剛史; 他39名*

EPJ Web of Conferences, 271, p.11001_1 - 11001_7, 2022/11

https://doi.org/10.1051/epjconf/202227111001

The J-PARC Hadron Experimental Facility was constructed with an aim to explore the origin and evolution of matter in the universe through experiments with intense particle beams. In the past decade, many results from particle and nuclear physics experiments have been obtained at the present facility. To expand the physics programs to as yet unexplored regions, the extension project of the Hadron Experimental Facility has been extensively discussed. This contribution presents the physics of the extension of the Hadron Experimental Facility to resolve issues related to strangeness nuclear physics, hadron physics, and flavor physics.

論文

Strangeness physics programs by S-2S at J-PARC

後神 利志*; 江端 健悟; 藤田 真奈美; 原田 健志; 長谷川 勝一; 細見 健二; 市川 裕大; 今井 憲一*; Kim, S.; 七村 拓野; et al.

EPJ Web of Conferences, 271, p.11002_1 - 11002_7, 2022/11

https://doi.org/10.1051/epjconf/202227111002

In the K1.8 beam-line at Hadron Experimental Facility of J-PARC, a new magnetic spectrometer S-2S is being installed. S-2S was designed to achieve a high momentum resolution of $$Delta p/p = 6 times 10^{-4}$$ in FWHM. Several strangeness-physics programs which require the high resolution will be realized by S-2S. The present article introduces J-PARC E70 (missing-mass spectroscopy of $$_{Xi}^{12}$$Be) and E94 (missing-mass spectroscopy of $$_{Lambda}^7$$Li, $$_{Lambda}^{10}$$B, and $$_{Lambda}^{12}$$C) experiments.

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