Transverse emission of isospin ratios as a probe of high-density symmetry energy in isotopic nuclear reactions

TL;DR

This study investigates how transverse emission ratios in isotopic nuclear reactions can serve as sensitive probes for the high-density behavior of nuclear symmetry energy, using a transport model to analyze various particle ratios.

Contribution

It introduces the use of double ratios of emitted particles as a reliable observable to determine the high-density symmetry energy in nuclear reactions.

Findings

Transverse momentum distribution of isospin ratios depends on symmetry energy stiffness.

Collision centrality influences the distribution structure of ratios.

Mass splitting of neutrons and protons affects the ratios but not the symmetry energy influence.

Abstract

Transverse emission of preequilibrium nucleons, light clusters (complex particles) and charged pions from the isotopic $^{112,124}$Sn+$^{112,124}$Sn reactions at a beam energy of 400\emph{A} MeV, to extract the high-density behavior of nuclear symmetry energy, are investigated within an isospin and momentum dependent transport model. Specifically, the double ratios of neutron/proton, triton/helium-3 and $\pi^{-}/\pi^{+}$ in the squeeze-out domain are analyzed systematically, which have the advantage of reducing the influence of the Coulomb force and less systematic errors. It is found that the transverse momentum distribution of isospin ratios strongly depend on the stiffness of nuclear symmetry energy, which would be a nice observable to extract the high-density symmetry energy. The collision centrality and the mass splitting of neutron and proton in nuclear medium play a significant role on the distribution structure of the ratios, but does not change the influence of symmetry energy on the spectrum.