Search for evidence of (3)(Lambda)n by observing d + pi(-) and t + pi(-) final states in the reaction of Li-6+C-12 at 2A GeV

The experimental data obtained from the reaction of Li-6 projectiles at 2A GeV on a fixed graphite target were analyzed to study the invariant mass distributions of d + pi(-) and t + pi(-). Indications of a signal in the d + pi(-) and t + pi(-) invariant mass distributions were observed with significances of 5.3 sigma and 5.0 sigma, respectively, when including the production target, and 3.7 sigma and 5.2 sigma, respectively, when excluding the target. The estimated mean values of the invariant mass for d + pi(-) and t + pi(-) signal were 2059.3 +/- 1.3 +/- 1.7 MeV/c(2) and 2993.7 +/- 1.3 +/- 0.6 MeV/c(2) respectively. The lifetime estimation of the possible bound states yielding to d + pi(-) and t + pi(-) final states were deduced to be as 181(-24)(+30) +/- 25 ps and 190(-35)(+47) +/- 36 ps, respectively. Those final states may be interpreted as the two-body and three-body decay modes of a neutral bound state of two neutrons and a Lambda hyperon, (3)(Lambda)n.