Search for the semileptonic decays $\Xi_c^0 \to \Xi^0\ell^+\ell^-$ at
Belle
Belle Collaboration,I. Adachi,H. Aihara,S. Al Said,D. M. Asner,T. Aushev,R. Ayad,V. Babu,S. Bahinipati,Sw. Banerjee,M. Bauer,P. Behera,K. Belous,J. Bennett,M. Bessner,B. Bhuyan,T. Bilka,D. Biswas,A. Bobrov,D. Bodrov,J. Borah,M. Bračko,P. Branchini,T. E. Browder,A. Budano,M. Campajola,D. Červenkov,M. -C. Chang,B. G. Cheon,K. Chilikin,K. Cho,S. -K. Choi,Y. Choi,S. Choudhury,S. Das,N. Dash,G. De Nardo,G. De Pietro,R. Dhamija,F. Di Capua,J. Dingfelder,Z. Doležal,T. V. Dong,S. Dubey,P. Ecker,D. Epifanov,T. Ferber,D. Ferlewicz,B. G. Fulsom,R. Garg,V. Gaur,A. Garmash,A. Giri,P. Goldenzweig,E. Graziani,K. Gudkova,C. Hadjivasiliou,S. Halder,K. Hayasaka,H. Hayashii,S. Hazra,D. Herrmann,W. -S. Hou,C. -L. Hsu,K. Inami,N. Ipsita,A. Ishikawa,R. Itoh,M. Iwasaki,W. W. Jacobs,S. Jia,Y. Jin,D. Kalita,C. Kiesling,D. Y. Kim,K. -H. Kim,Y. -K. Kim,K. Kinoshita,P. Kodyš,A. Korobov,S. Korpar,E. Kovalenko,P. Križan,P. Krokovny,T. Kuhr,D. Kumar,R. Kumar,Y. -J. Kwon,T. Lam,S. C. Lee,L. K. Li,Y. Li,Y. B. Li,L. Li Gioi,J. Libby,D. Liventsev,Y. Ma,M. Masuda,D. Matvienko,S. K. Maurya,F. Meier,M. Merola,K. Miyabayashi,R. Mizuk,R. Mussa,M. Nakao,Z. Natkaniec,A. Natochii,L. Nayak,S. Nishida,S. Ogawa,H. Ono,P. Oskin,P. Pakhlov,G. Pakhlova,S. Pardi,H. Park,J. Park,S. -H. Park,S. Patra,S. Paul,T. K. Pedlar,R. Pestotnik,L. E. Piilonen,T. Podobnik,M. T. Prim,N. Rout,G. Russo,S. Sandilya,L. Santelj,V. Savinov,G. Schnell,C. Schwanda,Y. Seino,K. Senyo,M. E. Sevior,W. Shan,C. Sharma,C. P. Shen,J. -G. Shiu,A. Sokolov,E. Solovieva,M. Starič,Z. S. Stottler,M. Sumihama,M. Takizawa,K. Tanida,F. Tenchini,R. Tiwary,T. Uglov,Y. Unno,S. Uno,Y. Usov,A. Vinokurova,M. -Z. Wang,S. Watanuki,E. Won,B. D. Yabsley,W. Yan,J. Yelton,J. H. Yin,L. Yuan,Z. P. Zhang,V. Zhilich,V. Zhukova
arxiv（2023）
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摘要
Using the full data sample of 980 $\mathrm{fb}^{-1}$ collected with the Belle detector at the KEKB asymmetric energy electron-positron collider, we report the results of the first search for the rare semileptonic decays $\Xi_c^0 \to \Xi^0\ell^+\ell^-$ ($\ell=e$ or $\mu)$. No significant signals are observed in the $\Xi^0\ell^+\ell^-$ invariant-mass distributions. Taking the decay $\Xi_c^0 \to \Xi^- \pi^+$ as the normalization mode, we report 90\% credibility upper limits on the branching fraction ratios ${\cal{B}} (\Xi_c^0 \to \Xi^0 e^+ e^-) / {\cal{B}}(\Xi_c^0\to \Xi^-\pi^+) < 6.7 \times 10^{-3}$ and ${\cal{B}} (\Xi_c^0 \to \Xi^0 \mu^+ \mu^-) / {\cal{B}}(\Xi_c^0\to \Xi^-\pi^+) < 4.3 \times 10^{-3}$ based on the phase-space assumption for signal decays. The 90\% credibility upper limits on the absolute branching fractions of ${\cal{B}} (\Xi_c^0 \to \Xi^0 e^+ e^-)$ and ${\cal{B}} (\Xi_c^0 \to \Xi^0 \mu^+ \mu^-)$ are found to be $9.9 \times 10^{-5}$ and $6.5 \times 10^{-5}$, respectively.
