Evidence for 6{\Lambda}H

TL;DR

This paper reports experimental evidence for the neutron-rich hypernucleus 6ΛH, measuring its production rate and binding energy, and suggests an excitation state based on systematic energy differences.

Contribution

First experimental observation and measurement of 6ΛH's production rate and binding energy, providing new insights into hypernuclear physics.

Findings

Production rate of (2.9±2.0)×10⁻⁶ per K-

Binding energy BΛ(6ΛH) = (4.0±1.1) MeV

Indication of an excited state at 0+ to 1+ transition

Abstract

Evidence for the neutron-rich hypernucleus 6{\Lambda}H is presented from the FINUDA experiment at DA{\Phi}NE, Frascati, studying ({\pi}+, {\pi}-) pairs in coincidence from the K- +6Li \rightarrow 6 H+{\pi}+ production reaction followed by 6{\Lambda}H \rightarrow 6He + {\pi}- weak decay. The production rate of 6{\Lambda}H undergoing this two-body {\pi}- decay is determined to be (2.9\pm2.0)\cdot10-6/K-. Its binding energy, evaluated jointly from production and decay, is B{\Lambda}(6{\Lambda}H) = (4.0\pm1.1) MeV with respect to 5H+{\Lambda}. A systematic difference of (0.98 \pm 0.74) MeV between B{\Lambda} values derived separately from decay and from production is tentatively assigned to the 6{\Lambda}H 0+g.s. \rightarrow 1+ excitation.