Experimental review of hypernuclear physics: recent achievements and future perspectives

Abstract

Since the shutdown of several old proton synchrotrons, which played a fundamental role in the second generation experiments in hypernuclear physics performed in Europe, USA and Japan, some new experimental setups aiming to achieve sub-MeV energy resolution have been operating for a long time. Over the last decade the hypernuclear physics community has been committed to carrying out several third generation experiments by exploiting the potential offered by new accelerators, such as a continuous electron beam machine and a ϕ-factory. Large data samples were collected on specific items thanks to dedicated facilities and experimental apparatuses. The attention was mainly focused on both high-resolution spectroscopy and the decay mode study of single Λ-hypernuclei. Nowadays this phase is over but, until recently, important and, to some extent, unexpected results were achieved. An updated review of selected experimental results is presented, as well as a survey of perspectives for future studies.

Experimental Studies on the Weak Decay of Λ-Hypernuclei

“…where BR(p) is the branching ratio for process (2), N p is the number of protons in each of the blue hatched areas of Fig. 1, N 2N is the number of protons from (4) (≲ 2%), N hyp is the number of produced Table I.…”

“…Actually, the most suitable production reaction to pursue this ambitious program appears to be the (π + ,K + ) at 1.05 -1.10 GeV/c at forward angles. Either the long-used Superconducting Kaon Spectrometer (SKS) [46] or the soon available S-2S magnetic spectrometer [2] are capable of performing missing-mass Λ C hypernuclei. The existing experimental data for Γ TOT /Γ Λ , Γ π − /Γ Λ , Γ π 0 /Γ Λ and Γ p /Γ Λ are showed in the first four rows of columns 2-5.…”

“…Such a strong interest is testified by several review papers on the subject from both the experimental [1][2][3] and the theoretical [4,5] point of view (just to mention the most recently published).…”

Construction Status of a New Spectrometer “S-2S” for Spectroscopy of Multi-Strangeness Systems at J-PARC

“…While the study of Λ-and Σ-hypernuclei has been making good progress experimentally and theoretically [1], experimental data on hypernuclei with strangeness (S ) = −2 are very limited. There exist various interaction models which predict different spectra of hypernuclei with S = −2.…”

Spectroscopy of Nuclei with Multi-Strangeness by Using New S-2S Spectrometer at J-PARC

“…Many species of Λ hypernuclei up to the mass number of A = 209 have been measured to investigate the interaction for the S = −1 system so far [1][2][3]. On the other hand, there is no clear observation of S = −2 nucleus except for few cases such as NAGARA [4,5] (double Λ hypernucleus) and KISO [6] (Ξ − hypernucleus) events measured in the emulsion experiment (KEK-E373) at KEK.…”