Nuclear in-medium and isospin effects on subthreshold kaon production in heavy-ion collisions

TL;DR

This study investigates how in-medium and isospin effects influence subthreshold kaon production in neutron-rich heavy-ion collisions, providing insights into the nuclear equation of state at high densities.

Contribution

The paper introduces a transport model with a repulsive kaon-nucleon potential to analyze kaon yields and spectra, highlighting the impact of symmetry energy stiffness.

Findings

Hard symmetry energy increases the K$^{0}$/K$^{+}$ ratio at subthreshold energies.

In-medium effects enhance energetic kaon emission in heavy-ion collisions.

The model fits flow data and spectra, validating the approach.

Abstract

Subthreshold kaon (K$^{0}$ and K$^{+}$) production in neutron-rich nuclear reactions to probe the kaon-nucleon interaction in nuclear medium and to extract the isospin dependent part of the nuclear equation of state at high-baryon densities, is investigated within an isospin and momentum dependent transport model. A repulsive kaon-nucleon potential is implemented in the model through fitting the flow data and inclusive spectra in heavy-ion collisions, which enhances the energetic kaon emission squeezed out in the reaction zone and leads to a variation of the high-momentum spectrum of the K$^{0}$/K$^{+}$ yields. It is found that the stiffness of nuclear symmetry energy plays a significant role on the isospin ratio with decreasing the incident energy and a hard symmetry energy has a larger value of the K$^{0}$/K$^{+}$ ratio in the domain of subthreshold energies.