Effects of the high-momentum tail of nucleon momentum distribution on the isospin-sensitive observables

TL;DR

This study investigates how the high-momentum tail of nucleon momentum distribution influences isospin-sensitive observables in heavy-ion collisions, revealing selective sensitivities among various flow and pion production measurements.

Contribution

It provides new insights into the impact of the high-momentum tail on specific isospin-sensitive observables in nuclear reactions.

Findings

Nucleon transverse flow and neutron-proton flow difference are less affected by the HMT.

Isospin-sensitive nucleon elliptic flow difference is significantly influenced by the HMT.

Pion yield ratios are sensitive to the HMT at most kinetic energies.

Abstract

Based on the Isospin-dependent transport model Boltzmann-Uehling-Uhlenbeck (IBUU), effects of the high momentum tail (HMT) of nucleon momentum distribution in colliding nuclei on some isospin-sensitive observables are studied in the semi-central $^{197}\rm {Au}+^{197}\rm {Au}$ reactions at incident beam energy of 400 MeV/nucleon. It is found that the nucleon transverse flow, the difference of neutron and proton transverse flows, the nucleon elliptic flow and free neutron to proton ratio are all less sensitive to the HMT, while the isospin-sensitive nucleon elliptic flow difference is clearly affected by the HMT. Except at very high kinetic energies, the kinetic energy distributions of $\pi^{-}$, $\pi^{+}$ and charged pion ratio $\pi^{-}/\pi^{+}$ are all sensitive to the HMT.