An improved measurement of the 3ΛH lifetime is presented. In this paper, the mesonic decay modes 3ΛH → 3He + π− and 3ΛH → d + p + π− are used to reconstruct the 3ΛH from Au+Au collision data collected by the STAR collaboration at Relativistic Heavy Ion Collider (RHIC). A minimum χ2 estimation is used to determine the lifetime of τ = 142+24−21(stat.) ± 29(syst.) ps. This lifetime is about 50% shorter than the lifetime τ = 263 ± 2 ps of a free Λ, indicating strong hyperon-nucleon interaction in the hypernucleus system. The branching ratios of the mesonic decay channels are also determined to satisfy B.R.(3He+π−)/(B.R.(3He+π−) + B.R.(d + p + π−)) = 0.32 ± 0.05(stat.) ± 0.08(syst.). Our ratio result favors the assignment J(3ΛH) = 12 over J(3ΛH) = 32. These measurements will help to constrain models of hyperon-baryon interactions.
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This work was supported in part by the Office of Nuclear Physics within the US DOE Office of Science, the US National Science Foundation, the Ministry of Education and Science of the Russian Federation, National Natural Science Foundation of China, Chinese Academy of Science, the Ministry of Science and Technology of China (973 Program No. 2014CB845400) and the Chinese Ministry of Education, the National Research Foundation of Korea, GA and MSMT of the Czech Republic, Department of Atomic Energy and Department of Science and Technology of the Government of India, the National Science Centre of Poland, National Research Foundation, the Ministry of Science, Education and Sports of the Republic of Croatia, RosAtom of Russia and German Bundesministerium fur Bildung, Wissenschaft, Forschung and Technologie (BMBF), and the Helmholtz Association.
Adamczyk, L.; Adams, J. R.; Adkins, James K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Ajitanand, N. N.; Alekseev, I.; Alford, J.; Anderson, D. M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Barish, K.; Behera, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Fatemi, Renee H.; and Ramachandran, Suvarna, "Measurement of the 3ΛH Lifetime in Au+Au Collisions at the BNL Relativistic Heavy Ion Collider" (2018). Physics and Astronomy Faculty Publications. 577.