Measurement of hypertriton lifetime at STAR

A precise measurement of the hypertriton lifetime and the ratio between the branching ratios of its two main decay channels has been made through the two body and three body decay channels with data of Au+Au collisions at √s_NN = 7.7, 11.5, 19.6, 27, 39, and 200 GeV at STAR. The hypertriton lifetime is 155_-22⁺²⁵(stat.)±31(syst.) ps with the combined channels. It is shorter than the lifetime of a free Λ and is consistent with recent results from HypHI experiment at GSI and ALICE experiment at LHC. The ratio of B.R._{(Λ³H→³He + π^-)}/B.R._{(Λ³H→d + p + π^-)} is 0.42_-0.06^+0.07(stat.)±0.12(syst.). It is consistent with the early results from helium bubble chamber experiments. (author)