Measurement of the HΛ3 lifetime in Au+Au collisions at the BNL Relativistic Heavy Ion Collider

Author(s): Adamczyk, L; Adams, JR; Adkins, JK; Agakishiev, G; Aggarwal, MM; Ahammed, Z; Ajitanand, NN; Alekseev, I; Alford, J; Anderson, DM; Aoyama, R; Aparin, A; Arkhipkin, D; Aschenauer, EC; Ashraf, MU; Attri, A; Averichev, GS; Bai, X; Bairathi, V; Barish, K; Behera, A; Bellwied, R; Bhasin, A; Bhati, AK; Bhattarai, P; Bielcik, J; Bielcikova, J; Bland, LC; Bordyuzhin, IG; Bouchet, J; Brandenburg, JD; Brandin, AV; Brown, D; Bryslawskyj, J; Bunzarov, I; Butterworth, J; Caines, H; Calderon De La Barca Sanchez, M; Campbell, JM; Cebra, D; Chakaberia, I; Chaloupka, P; Chang, Z; Chankova-Bunzarova, N; Chatterjee, A; Chattopadhyay, S; Chen, X; Chen, X; Chen, JH; Cheng, J; Cherney, M; Christie, W; Contin, G; Crawford, HJ; Das, S; Dedovich, TG; Deng, J; Deppner, IM; Derevschikov, AA; Didenko, L; Dilks, C; Dong, X; Drachenberg, JL; Draper, JE; Dunlop, JC; Efimov, LG; Elsey, N; Engelage, J; Eppley, G; Esha, R; Esumi, S; Evdokimov, O; Ewigleben, J; Eyser, O; Fatemi, R; Fazio, S; Federic, P; Federicova, P; Fedorisin, J; Feng, Z; Filip, P; Finch, E; Fisyak, Y; Flores, CE; Fujita, J | Abstract: An improved measurement of the HΛ3 lifetime is presented. In this paper, the mesonic decay modes HΛ3→He3 + π- and HΛ3→d+p+π- are used to reconstruct the HΛ3 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=142-21+24(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.(He3+π-)/(B.R.(He3+π-)+B.R.(d+p+π-))=0.32±0.05(stat.)±0.08(syst.). Our ratio result favors the assignment J(HΛ3)=12 over J(HΛ3)=32. These measurements will help to constrain models of hyperon-baryon interactions.