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論文

First test of Lepton Flavor Universality in the charmed baryon decays $$Omega^{0}_{c} to Omega^{-} ell^{+} nu_{ell}$$ using data of the Belle experiment

Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他203名*

Physical Review D, 105(9), p.L091101_1 - L091101_7, 2022/05

https://doi.org/10.1103/PhysRevD.105.L091101
 被引用回数：12 パーセンタイル：72.70(Astronomy & Astrophysics)

We present the first observation of the $$Omega_{c}^{0} to Omega^{-} mu^{+} nu_{mu}$$ decay and present measurements of the branching fraction ratios of the $$Omega_{c}^{0} to Omega^{-} ell^{+} nu_{ell}$$ decays compared to the reference mode $$Omega_{c}^{0} to Omega^{-} pi^+$$, ($$ell = e$$ or $$mu$$). This analysis is based on 89.5 fb$$^{-1}$$, 711 fb$$^{-1}$$, and 121.1 fb$$^{-1}$$ data samples collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider at the center-of-mass energies of 10.52 GeV, 10.58 GeV, and 10.86 GeV, respectively. The $$Omega_{c}^{0}$$ signal yields are extracted by fitting $$M_{Omega^{-} ell^{+}}$$ and $$M_{Omega^{-}pi^+}$$ spectra. The branching fraction ratios $${cal B}(Omega_{c}^{0} to Omega^{-} e^{+} nu_{e})/{cal B}(Omega_{c}^{0} to Omega^{-} pi^+)$$ and $${cal B}(Omega_{c}^{0} to Omega^{-} mu^{+} nu_{mu})/{cal B}(Omega_{c}^{0} to Omega^{-} pi^+)$$ are measured to be $$1.98 pm0.13~({rm stat.}) pm 0.08~({rm syst.})$$ and $$ 1.94 pm 0.18~({rm stat.}) pm 0.10~({rm syst.})$$, respectively. The ratio of $${cal B}(Omega_{c}^{0} to Omega^{-} e^{+} nu_{e})/{cal B}(Omega_{c}^{0} to Omega^{-} mu^{+} nu_{mu})$$ is measured to be $$1.02 pm 0.10~({rm stat.}) pm 0.02~({rm syst.})$$, which is consistent with the expectation of lepton flavor universality.

論文

First determination of the spin and parity of the charmed-strange baryon $$Xi_{c}(2970)^+$$

Moon, T. J.*; 谷田 聖; Belle Collaboration*; 他203名*

Physical Review D, 103(11), p.L111101_1 - L111101_9, 2021/06

AA2022-0158.pdf:0.4MB

https://doi.org/10.1103/PhysRevD.103.L111101
 被引用回数：23 パーセンタイル：82.70(Astronomy & Astrophysics)

We report results from a study of the spin and parity of $$Xi_{c}(2970)^+$$ using a $$980~mathrm{fb^{-1}}$$ data sample collected by the Belle detector at the KEKB asymmetric-energy $$e^{+}e^{-}$$ collider. The decay angle distributions in the chain $$Xi_{c}(2970)^+ to Xi_c(2645)^{0}pi^{+} to Xi_c^{+}pi^{-}pi^{+}$$ are analyzed to determine the spin of this charmed-strange baryon. The angular distributions strongly favor the $$Xi_{c}(2970)^+$$ spin $$J =1/2$$ over $$3/2$$ or $$5/2$$, under an assumption that the lowest partial wave dominates in the decay. We also measure the ratio of $$Xi_{c}(2970)^+$$ decay branching fractions $$R={mathcal{B}[ Xi_{c}(2970)^+ to Xi_c(2645)^{0}pi^{+} ]} $$ / $${ mathcal{B}[ Xi_{c}(2970)^+ to Xi_c^{prime0}pi^{+} ]} $$ =1.67 $$pm 0.29mathrm{(stat.)}^{ +0.15}_{-0.09}mathrm{(syst.)} $$ $$pm 0.25mathrm{(IS)}$$, where the last uncertainty is due to possible isospin-symmetry-breaking effects. This $$R$$ value favors the spin-parity $$J^P=1/2^+$$ with the spin of the light-quark degrees of freedom $$s_{l}=0$$. This is the first determination of the spin and parity of a charmed-strange baryon.

論文

Measurements of the branching fractions of $$Lambda_c^+ to p eta$$ and $$Lambda_c^+ to p pi^0$$ decays at Belle

Li, S. X.*; 谷田 聖; Belle Collaboration*; 他203名*

Physical Review D, 103(7), p.072004_1 - 072004_9, 2021/04

AA2022-0154.pdf:0.56MB

https://doi.org/10.1103/PhysRevD.103.072004
 被引用回数：15 パーセンタイル：67.89(Astronomy & Astrophysics)

We report measurements of the branching fractions of singly Cabibbo-suppressed decays $$Lambda_c^+ to p eta$$ and $$Lambda_c^+ to p pi^0$$ using the full Belle data sample corresponding to an integrated luminosity of 980.6 $$rm fb^{-1}$$. The data were collected by the Belle detector at the KEKB $$e^{+}$$$$e^{-}$$ asymmetric-energy collider. A clear $$Lambda_c^+$$ signal is seen in the invariant mass distribution of $$p eta$$. The signal yield of the $$Lambda_c^+ to p eta$$ process is $$7734 pm 263$$; from this, we measure the ratio of branching fractions $${cal B}(Lambda_c^+ to p eta)/{cal B}(Lambda_c^+ to p K^- pi^+) = (2.258 pm 0. 077(rm stat.) pm 0.136(rm syst.))times 10^{-2}$$, from which we infer the branching fraction $${cal B}(Lambda_c^+ to p eta) = (1.42 pm 0.05(rm stat.) pm 0.11(rm syst.)) times 10^{-3}$$. In addition, no significant signal for $$Lambda_c^+ to p pi^0$$ is found so an upper limit on the branching fraction of $${cal B}(Lambda_c^+ to p pi^0) < 8.0 times 10^{-5}$$ at 90% credibility level is set, more than three times better than the best current upper limit.

論文

Observation of $$B^{+} rightarrow pbar{Lambda} K^+ K^-$$ and $$B^{+} rightarrow bar{p}Lambda K^+ K^+$$

Lu, P.-C.*; 谷田 聖; Belle Collaboration*; 他203名*

Physical Review D, 99(3), p.032003_1 - 032003_9, 2019/02

AA2019-0533.pdf:1.04MB

https://doi.org/10.1103/PhysRevD.99.032003
 被引用回数：5 パーセンタイル：27.00(Astronomy & Astrophysics)

We report the study of $$B^{+} rightarrow pbar{Lambda} K^+ K^-$$ and $$B^{+} rightarrow bar{p}Lambda K^+ K^+$$ using a $$772 times 10^6$$ $$Bbar{B}$$ pair data sample recorded on the $$Upsilon({rm 4S})$$ resonance with the Belle detector at KEKB. These include the observations of decay modes with the corresponding branching fractions $$mathcal{B}$$($$B^{+} rightarrow pbar{Lambda} K^+ K^-$$) $$=$$ $$(4.22^{+0.45}_{-0.44}pm 0.51) times10^{-6}$$, $$mathcal{B}$$($$B^{+} rightarrow bar{p}Lambda K^+ K^+$$) $$=$$ $$(3.81^{+0.39}_{-0.37} pm 0.45)times 10^{-6}$$, $$mathcal{B}$$($$eta_c rightarrow p bar{Lambda} K^-$$) $$=$$ $$(2.9^{+0.4}_{-0.3}pm 0.4)times10^{-3}$$ and $$mathcal{B}$$($$B^{+} rightarrow pbar{Lambda} phi$$) $$=$$ $$(0.818 pm 0.215 pm 0.078)times10^{-6}$$, where $$mathcal{B}$$ denotes the decay branching fraction and the intermediate resonance decays are excluded in the four-body decay measurements.

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