Jun 5 – 9, 2023
Genova, Italy
Europe/Rome timezone

p- and sd-shell Λ-hypernuclei with shell model approach

Jun 6, 2023, 3:30 PM
30m
DAD - Room 1A (Genova, Italy)

DAD - Room 1A

Genova, Italy

Invited Hypernuclei and kaonic atoms Hypernuclei and kaonic atoms

Speaker

Prof. Atsushi Umeya (Nippon Institute of Technology)

Description

Hypernuclear structure studies have been progressing steadily through the $K$- and $\pi$-induced production reaction experiments, especially by the recent $\gamma$-ray coincidence measurements with the large volume Ge detector. Moreover a series of recent $(e,e' K^+)$ reaction experiments from the Jefferson Laboratory provide high-resolution data of the low-lying energy levels for $p$-shell hypernuclei. These data are quite helpful in better understanding of hyperon-nucleon interactions, though the data are still limited to about ten hypernuclear species.

As the next stage of hypernuclear studies, new projects of high-intensity and high-resolution $(K^-, \pi^- \gamma)$ and $(\pi^+, K^+ \gamma)$ reaction experiments are being scheduled at the J-PARC facility. New experiments are also planned at the Jefferson Laboratory.

In order to meet these experimental projects, updated theoretical studies are needed for prediction and/or comparison with the coming quality data. So far we have made detailed theoretical analyses of hypernuclear level stuctures, $\gamma$-transition rates, and the production cross sections by employing the extended shell models for $_{\;\;\;\;\;\Lambda}^{9,10,11}$Be, $_{\;\;\;\,\Lambda}^{11,12}$B, $_{\,\Lambda}^{19}$F, etc.

In this talk we focus our attention on the interplay between the hyperon motion and the nuclear core states. First, we discuss that the extended shell-model calculation is successful in explaining the new peak observed in the $^{10}$B $(e,e' K^+)$ $^{10}_{\,\Lambda}$Be experiment. It is attributed to the lowering of $p_{\Lambda}$ (perpendicular) state due to the strong coupling with $\alpha$-$\alpha$ like nuclear core deformation as already known in the case of $_{\Lambda}^{9}$Be. Second, we will show the results of new calculations for an $sd$-shell hypernuclear structure of $_{\,\Lambda}^{27}$Mg, in which the even-even core nucleus $^{26}$Mg is shown to have rotational bands. Thus we see coupling of the $p_{\Lambda}$ orbital and the core deformation. For the $^{27}$Al $(\gamma, K^+)$ $_{\,\Lambda}^{27}$Mg reaction, we also discuss the DWIA cross-section spectra that are calculated with the microscopic shell-model wave functions.

Primary author

Prof. Atsushi Umeya (Nippon Institute of Technology)

Presentation materials