Measurement of the H-3(Lambda) lifetime in Au plus Au collisions at the BNL Relativistic Heavy Ion Collider

An improved measurement of the H-3(Lambda) lifetime is presented. In this paper, the mesonic decay modes H-3(Lambda) -> He-3 + pi(-) and H-3(Lambda) -> d + p + pi(-) are used to reconstruct the H-3(Lambda) from Au+Au collision data collected by the STAR collaboration at Relativistic Heavy Ion Collider (RHIC) A minimum chi(2) estimation is used to determine the lifetime tau = 142(+21)(-24 )(stat.)+/- 29 (syst.) ps. This lifetime is about 50% shorter than the lifetime tau = 263 +/- 2 ps of a free A, indicating strong hyperon-nucleon interaction in the hypernucleus system. The branching ratios of the mesonic decay channels are also determined to satisfy B.R.(He-3+ pi(-))/(B.R.(H-3+pi(-))/B.R.((d+p+pi))) = 0.32 +/- 0.05 (stat.)+/- 0.08 (syst.). Our ratio result favors the assignment J(H-3(Lambda)) = 1/2 over J(H-3(Lambda)) = 3/2. These measurements will help to constrain models of hyperon-baryon interactions.