First observation of the hyper superheavy hydrogen 6{\Lambda}H

TL;DR

This paper reports the first observation of the hyper superheavy hydrogen isotope 6ΛH, using the FINUDA experiment, providing measurements of its production rate and binding energy, and discussing implications for hypernuclear physics.

Contribution

The study presents the first experimental evidence of 6ΛH, including its production rate and binding energy, advancing understanding of neutron-rich hypernuclei.

Findings

Three candidate events identified for 6ΛH.

Measured binding energy BΛ = (4.0 ± 1.1) MeV.

Observed excitation energy difference of (0.98 ± 0.74) MeV.

Abstract

Three candidate events of the neutron-rich hypernucleus 6{\Lambda}H were uniquely identified in the FINUDA experiment at DA{\Phi}NE, Frascati, by observing {\pi}+ mesons from the (K-stop,{\pi}+) production reaction on 6Li targets, in coincidence with {\pi}-mesons from 6{\Lambda}H \rightarrow 6He+{\pi}- weak decay. Details of the experiment and the analysis of its data are reported, leading to an estimate of (2.9\pm2.0)\cdot10-6/K- stop for the 6{\Lambda}H production rate times the two-body {\pi}- weak decay branching ratio. The 6{\Lambda}H binding energy with respect to 5H + {\Lambda} was determined jointly from production and decay to be B{\Lambda} = (4.0 \pm 1.1) MeV, assuming that 5H is unbound with respect to 3H + 2n by 1.7 MeV. The binding energy determined from production is higher, in each one of the three events, than that determined from decay, with a difference of (0.98 \pm 0.74) MeV here assigned to the 0+g.s. \rightarrow 1+ excitation. The consequences of this assignment to {\Lambda} hypernuclear dynamics are briefly discussed.