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新山 雅之 所属 京都産業大学 理学部 物理科学科 職種 教授 |
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| 発行・発表の年月 | 2022/08 |
| 形態種別 | その他 |
| 標題 | Search for $C\!P$ violation and measurement of branching fractions and decay asymmetry parameters for $Λ_c^+\toΛh^+$ and $Λ_c^+\toΣ^{0} h^+$ ($h\!=\!K,\,π$) |
| 執筆形態 | その他 |
| 著者・共著者 | Belle Collaboration,L. K. Li,W. Shan,K. Kinoshita,I. Adachi,H. Aihara,D. M. Asner,H. Atmacan,T. Aushev,V. Babu,S. Bahinipati,Sw. Banerjee,P. Behera,J. Bennett,M. Bessner,V. Bhardwaj,B. Bhuyan,T. Bilka,A. Bobrov,D. Bodrov,J. Borah,M. Bračko,P. Branchini,A. Budano,M. Campajola,D. Červenkov,M. -C. Chang,P. Chang,V. Chekelian,A. Chen,B. G. Cheon,K. Chilikin,H. E. Cho,K. Cho,S. -J. Cho,S. -K. Choi,Y. Choi,S. Choudhury,D. Cinabro,N. Dash,G. De Nardo,G. De Pietro,R. Dhamija,F. Di Capua,Z. Doležal,T. V. |
| 概要 | We report a study of $\Lambda_c^+\to\Lambda h^+$ and
$\Lambda_c^+\to\Sigma^{0} h^+$ ($h\!=\!K,\,\pi$) decays based on a data sample of 980~${\rm fb}^{-1}$ collected with the Belle detector at the KEKB energy-asymmetric $e^+e^-$ collider. The first results of direct $C\!P$ asymmetry in two-body singly Cabibbo-suppressed (SCS) decays of charmed baryons are measured, $A_{C\!P}^{\rm{dir } }(\Lambda_c^+\to\Lambda K^+)\!=\!+0.021\pm0.026\pm0.001$ and $A_{C\!P}^{\rm{dir } }(\Lambda_c^+\to\Sigma^0K^+)\!=\!+0.025\pm0.054\pm0.004$. We also make the most precise measurement of the decay asymmetry parameters ($\alpha$) for the four modes of interest and search for $C\!P$ violation via the $\alpha$-induced $C\!P$ asymmetry ($A_{C\!P}^{\alpha}$). We measure $A_{C\!P}^{\alpha}(\Lambda_c^+\to\Lambda K^+)\!=\!{-0.023\pm0.086\pm0.071}$ and $A_{C\!P}^{\alpha}(\Lambda_c^+\to\Sigma^0K^+)\!=\!{+0.08\pm 0.35\pm 0.14}$, which are the first $A_{C\!P}^{\alpha}$ results for SCS decays of charmed baryons. We search for $\Lambda$-hyperon $C\!P$ violation in $\Lambda_c^+\to(\Lambda,\,\Sigma^0)\pi^+$ and find $A_{C\!P}^{\alpha}(\Lambda\to p\pi^{-})\!=\!{+0.013\pm0.007\pm0.011}$. This is the first time that hyperon $C\!P$ violation has been measured via Cabibbo-favored charm decays. No evidence of baryon $C\!P$ violation is found. We also obtain the most precise branching fractions for two SCS $\Lambda_c^+$ decays, $\mathcal{B}(\Lambda_c^+\to\Lambda K^+)\!=\!(6.57\pm0.17\pm0.11\pm0.35)\times10^{-4}$ and $\mathcal{B}(\Lambda_c^+\to\Sigma^0K^+)\!=\!(3.58\pm0.19\pm0.06\pm0.19)\times10^{-4}$. The first uncertainties are statistical and the second systematic, while the third uncertainties come from the uncertainties on the world average branching fractions of $\Lambda_c^+\to(\Lambda,\,\Sigma^0)\pi^+$. |
| DOI | 10.1016/j.scib.2023.02.017 |
| PermalinkURL | http://arxiv.org/abs/2208.08695v2 |
| researchmap用URL | http://arxiv.org/pdf/2208.08695v2 |