Recent results and future prospects of kaonic nuclei at J-PARC

TL;DR

This paper reviews recent experimental progress at J-PARC on kaonic nuclei, demonstrating their production, observing deeply bound states like $K^-pp$, and proposing future systematic studies of light kaonic nuclei.

Contribution

It reports the first observation of deeply bound kaonic nuclei via in-flight reactions and proposes a series of experiments to systematically investigate light kaonic nuclei.

Findings

Observation of $K^-pp$ with deep binding energy

Successful production of kaonic nuclei using low-momentum kaon beams

Proposal of future experiments to explore $ar K N$ to $ar K NNN$ systems

Abstract

$\bar K$-nuclear bound systems, kaonic nuclei, have been widely discussed as products of the strongly attractive $\bar K N$ interaction in $I = 0$ channels. Recently, we demonstrated that kaonic nuclei can be produced via in-flight $(K^-,N)$ reactions using the low-momentum DC kaon beam at the J-PARC E15 experiment. We observed the simplest kaonic nuclei, $K^-pp$, having a much deeper binding energy than normal nuclei. For further studies, we have proposed a series of experimental programs for the systematic investigation of light kaonic nuclei, from $\bar K N$ ($\Lambda(1405)$) to $\bar K NNNN$. In the new experiment approved as J-PARC E80, we will measure the $\bar K NNN$ ($A=3$) system as a first step toward a comprehensive study.