Measurement of ${}^{3,4}$He($K^{-},{\pi }^0$)${}_{\Lambda }^{3,4}$H reaction cross section and evaluation of hypertriton $\Lambda$ binding energy

Abstract

Light $s$-shell hypernuclei (${}_{\Lambda }^{3,4}\text{H}$) and their ground-state properties are crucial benchmarks in hypernuclear physics. In particular, comparing the production cross sections of ${}_{\Lambda }^3\text{H}$ and ${}_{\Lambda }^4\text{H}$ provides insights into the $\Lambda N$ interaction in different isospin configurations, which can help address recent discrepancies in the reported $\Lambda$ binding energy of hypertriton. We present the first measurement of the production cross sections for ${}_{\Lambda }^3\text{H}$ and ${}_{\Lambda }^4\text{H}$ using the in-flight $(K^{-},{\pi }^0)$ reaction at a beam momentum of 1.0 GeV/$c$ with an identical experimental setup. The production cross sections in the laboratory frame, for the angular range from 0${}^{\circ }$ to 20${}^{\circ }$, are measured to be $15.0\pm 2.6(\text{stat.}){}_{-2.8}^{+2.4}(\text{syst.})\mu \text{b}$ and $49.9\pm 2.1(\text{stat.}){}_{-8.0}^{+7.8}(\text{syst.})\mu \text{b}$ for the ground-state of ${}_{\Lambda }^3\text{H}$ and ${}_{\Lambda }^4\text{H}$, respectively. Using the ratio of these cross sections and comparing it with theoretical calculations, we evaluate the $\Lambda$ binding energy of hypertriton, yielding a value consistent with the picture of a loosely bound system.

References in corpus (8)

• Measurement of the mass difference and the binding energy of the hypertriton and antihypertriton
• Pi-mesonic decay of the hypertriton
• Measurement of hyper triton lifetime in Au + Au collisions at the Relativistic Heavy-Ion Collider
• Measurement of the lifetime and $\Lambda$ separation energy of ${}_{\Lambda }^3\mathrm{H}$
• The simplest ``strange'' three-body halo
• The K1.8BR spectrometer system at J-PARC
• Binding energy of ${}_{\Lambda }^3\mathrm{H}$ and ${}_{\Lambda }^4\mathrm{H}$ via image analyses of nuclear emulsions using deep-learning
• Precise lifetime measurement of ${}_{\Lambda }^4$H hypernucleus using in-flight ${}^4$He$(K^{-},{\pi }^0{)}_{\Lambda }^4$H reaction