Search for CP violation and measurement of branching fractions and decay asymmetry parameters for Λc+→Λh+ and Λc+→Σ0h+ (h=K,π)

L. K., Li; Shan, W.; Kinoshita, K.; Adachi, I.; Aihara, H.; Asner, D. M.; Atmacan, H.; Aushev, T.; Babu, V.; Bahinipati, S.; Banerjee, S.; Behera, P.; Bennett, J.; Bessner, M.; Bhardwaj, V.; Bhuyan, B.; Bilka, T.; Bobrov, A.; Bodrov, D.; Borah, J.; Bracko, M.; Branchini, P.; Budano, A.; Campajola, M.; Cervenkov, D.; Chang, M. -C.; Chang, P.; Chekelian, V.; Chen, A.; Cheon, B. G.; Chilikin, K.; Cho, H. E.; Cho, K.; Cho, S. -J.; Choi, S. -K.; Choi, Y.; Choudhury, S.; Cinabro, D.; Dash, N.; De Nardo, G.; De Pietro, G.; Dhamija, R.; Capua, F. D.; Dolezal, Z.; Dong, T. V.; Epifanov, D.; Ferber, T.; Frey, A.; Fulsom, B. G.; Gaur, V.; Garmash, A.; Giri, A.; Goldenzweig, P.; Gong, G.; Graziani, E.; Gu, T.; Guan, Y.; Gudkova, K.; Hadjivasiliou, C.; Hayasaka, K.; Hayashii, H.; Hedges, M. T.; Hou, W. -S.; Hsu, C. -L.; Inami, K.; Ishikawa, A.; Itoh, R.; Jacobs, W. W.; Jang, E. -J.; Q. P., Ji; Jia, S.; Jin, Y.; Joo, K. K.; Kiesling, C.; Kim, C. H.; Kim, D. Y.; Kim, K. -H.; Kodys, P.; Konno, T.; Korobov, A.; Korpar, S.; Kovalenko, E.; Krokovny, P.; Kuhr, T.; Kumar, R.; Kumara, K.; Kuzmin, A.; Kwon, Y. -J.; Lai, Y. -T.; Lam, T.; Lange, J. S.; Lee, S. C.; Li, J.; S. X., Li; Li, Y.; Y. B., Li; Gioi, L. L.; Libby, J.; Lieret, K.; Masuda, M.; Maurya, S. K.; Merola, M.; Metzner, F.; Miyabayashi, K.; Mizuk, R.; Mussa, R.; Nakao, M.; Natkaniec, Z.; Natochii, A.; Nayak, L.; Nayak, M.; Niiyama, M.; Nisar, N. K.; Nishida, S.; Ogawa, S.; Ono, H.; Oskin, P.; Pakhlova, G.; Pardi, S.; Park, H.; Park, S. -H.; Passeri, A.; Patra, S.; Paul, S.; Pedlar, T. K.; Pestotnik, R.; Piilonen, L. E.; Podobnik, T.; Prencipe, E.; Prim, M. T.; Rostomyan, A.; Rout, N.; Russo, G.; Sahoo, D.; Sakai, Y.; Sandilya, S.; Sangal, A.; Savinov, V.; Schnell, G.; Schueler, J.; Schwanda, C.; Schwartz, A. J.; Seino, Y.; Senyo, K.; Sevior, M. E.; Shapkin, M.; Sharma, C.; Shen, C. P.; Shiu, J. -G.; Singh, J. B.; Sokolov, A.; Solovieva, E.; Staric, M.; Sumihama, M.; Sumisawa, K.; Sumiyoshi, T.; Sutcliffe, W.; Takizawa, M.; Tamponi, U.; Tanida, K.; Tenchini, F.; Uchida, M.; Uglov, T.; Unno, Y.; Uno, S.; Usov, Y.; Vahsen, S. E.; van Tonder, R.; Varner, G.; Vinokurova, A.; Vossen, A.; Waheed, E.; Wang, E.; Wang, X. L.; Watanabe, M.; Watanuki, S.; Werbycka, O.; Won, E.; Xu, X.; Yabsley, B. D.; Yan, W.; Yang, S. B.; Yelton, J.; Yin, J. H.; Yook, Y.; Yuan, C. Z.; Zhang, Z. P.; Zhilich, V.; Zhukova, V.

doi:10.1016/j.scib.2023.02.017

We report a study of Λc+→Λh+ and Λc+→Σ0h+ (h=K,π) decays based on a data sample of 980fb-1 collected with the Belle detector at the KEKB energy-asymmetric e+e- collider. The first results of direct CP asymmetry in two-body singly Cabibbo-suppressed (SCS) decays of charmed baryons are measured, ACPdir(Λc+→ΛK+)=+0.021±0.026±0.001 and ACPdir(Λc+→Σ0K+)=+0.025±0.054±0.004. We also make the most precise measurement of the decay asymmetry parameters (α) for the four modes of interest and search for CP violation via the α-induced CP asymmetry (ACPα). We measure ACPα(Λc+→ΛK+)=-0.023±0.086±0.071 and ACPα(Λc+→Σ0K+)=+0.08±0.35±0.14, which are the first ACPα results for SCS decays of charmed baryons. We search for Λ-hyperon CP violation in Λc+→(Λ,Σ0)π+ and find ACPα(Λ→pπ-)=+0.013±0.007±0.011. This is the first time that hyperon CP violation has been measured via Cabibbo-favored charm decays. No evidence of baryon CP violation is found. We also obtain the most precise branching fractions for two SCS Λc+ decays, B(Λc+→ΛK+)=(6.57±0.17±0.11±0.35)×10-4 and B(Λc+→Σ0K+)=(3.58±0.19±0.06±0.19)×10-4. The first uncertainties are statistical and the second systematic, while the third uncertainties come from the uncertainties on the world average branching fractions of Λc+→(Λ,Σ0)π+.