Speaker
Description
The hyperon puzzle of neutron stars refers to the problem that most of the equations of state with hyperons are not sufficiently stiff to support the observed massive neutron stars. One promising solution to the puzzle is that the three-body interaction between hyperon and medium nucleons produces so strong repulsion that $\Lambda$'s do not appear in neutron stars. The $\Lambda$ potential in nuclear matter which fulfills the $\Lambda$-suppressing scenario is calculated by using chiral effective field theory with a decuplet saturation model [1]. This $\Lambda$ potential is highly repulsive compared to the conventional ones, and it should verified its consistency with existing experimental data.
We found that the repulsive $\Lambda$ potential derived from chiral effective field theory is consistent with the $\Lambda$ directed flow of heavy-ion collision [2] and the $\Lambda$ hypernuclear spectroscopy [3]. On the other hand, the conventional attractive $\Lambda$ potential is found to explain both the $\Lambda$ directed flow and the $\Lambda$ binding energy data at the same level of accuracy. In this talk, we will discuss what is needed to distinguish the repulsive and attractive $\Lambda$ potentials from experimental data.
[1] D. Gerstung, N. Kaiser, and W. Weise, Eur. Phys. J. A 56 (2020) 175.
[2] Y. Nara, A. Jinno, K. Murase, and A. Ohnishi, Phys. Rev. C 106 (2022) 044902.
[3] A. Jinno, K. Murase, Y. Nara, and A. Ohnishi, Phys. Rev. C 108 (2023) 065803.
