Neutron-proton differential transverse flow in $^{132}$Sn + $^{124}$Sn collisions at 270 MeV/nucleon

TL;DR

This study uses a transport model to analyze how neutron-proton differential transverse flow in specific heavy-ion collisions can reveal information about the symmetry energy's slope at saturation density, considering uncertainties around this density.

Contribution

It introduces a detailed analysis of the sensitivity of neutron-proton differential transverse flow to the slope of symmetry energy at saturation density, accounting for uncertainties in its low-density behavior.

Findings

Flow is mainly sensitive to the slope L of symmetry energy at saturation density.

Low-density symmetry energy effects also influence the observable.

Measurements can complement spectral pion ratio constraints.

Abstract

Within a transport model, we study the neutron-proton differential transverse flow and its excitation function in central $^{132}$Sn + $^{124}$Sn collisions at 270 MeV/nucleon. To more accurately evaluate effects of the high-density behavior of symmetry energy \esym on this observable, we also consider the uncertainties of \esym around the saturation density $\rho_{0}$. It is shown that the neutron-proton differential transverse flow and its excitation function are mainly sensitive to the slope $L$ of \esym at $\rho_{0}$. However, the effects of low-density behavior of \esym on this observable should also be considered. Therefore, it is suggested that measurements of the neutron-proton differential transverse flow and its excitation function may provide useful complements to the constraints on $L$ extracted from the spectral pion ratio in S$\pi$RIT experiments.