Studies of hypernuclei with heavy-ion beams, nuclear emulsions and machine learning

¹ High Energy Nuclear Physics Laboratory, RIKEN, Wako, Japan
² GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany
³ School of Nuclear Physics and Technology, Lanzhou University, China

^* e-mail: takehiko.saito@riken.jp

Published online: 9 November 2022

Abstract

The lightest hypernucleus, the hypertriton, has been a benchmark in the field of hypernuclear physics. However, some of recent experiments employing energetic heavy-ion beams have revealed that the hypertriton lifetime is significantly shorter than 263 ps which is expected by considering the known weakly binding nature of the hypertriton. The STAR collaboration has also measured the hypertriton binding energy, and the deduced value is contradicting to its formerly known small binding energy. These measurements have indicated that the fundamental physics quantities of the hypertriton such as its lifetime and binding energy have not been understood, therefore, they have to be measured very precisely. Furthermore, an unprecedented Λnn bound state observed by the HypHI collaboration has to be studied in order to draw a conclusion whether or not such a bound state exists. These three-body hypernuclear states are studied by the heavy-ion beam data in theWASA-FRS experiment and by analysing J-PARC E07 nuclear emulsion data with machine learning.