Nuclear systems with strangeness and baryon–baryon interactions

Abstract Research on hypernuclei plays an essential role in answering how the hierarchy of nuclei is constructed from quarks. In recent years, significant progress has been made in this research field, especially at J-PARC. One of the recent achievements is the realization of an accurate hyperon–nucleon scattering experiment. The differential cross sections of the $$\Sigma ^{+}p$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mi>Σ</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mi>p</mml:mi> </mml:mrow> </mml:math> , $$\Sigma ^{-}p$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mi>Σ</mml:mi> <mml:mo>-</mml:mo> </mml:msup> <mml:mi>p</mml:mi> </mml:mrow> </mml:math> elastic scatterings and $$\Sigma ^{-}p \rightarrow \Lambda n$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mi>Σ</mml:mi> <mml:mo>-</mml:mo> </mml:msup> <mml:mi>p</mml:mi> <mml:mo>→</mml:mo> <mml:mi>Λ</mml:mi> <mml:mi>n</mml:mi> </mml:mrow> </mml:math> inelastic scattering have been measured with unprecedented accuracy. These new data will be used as essential inputs to improve the theoretical descriptions of the two-body baryon–baryon interactions. Another achievement is the significant progress of research on double hypernuclei. A lot of information on double $$\Lambda $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Λ</mml:mi> </mml:math> hypernuclei and $$\Xi $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Ξ</mml:mi> </mml:math> hypernuclei has been accumulated through the observation of the double hypernuclear events in nuclear emulsions in the series of experiments at KEK and J-PARC. In this article, the progress of the hypernuclear program at J-PARC is described with a focus on these two experimental results. Future prospects are also discussed briefly.