Effects of the initialization of nucleon momentum in heavy-ion collisions at medium energies

TL;DR

This study investigates how the initial high momentum tails of nucleon distributions influence isospin-sensitive observables in heavy-ion collisions, revealing certain observables are sensitive to these initial conditions.

Contribution

It demonstrates the sensitivity of high-momentum neutron-proton ratios and pion yields to the form of the nucleon momentum distribution's high momentum tail in heavy-ion collisions.

Findings

High-momentum neutron-proton ratio depends on the HMT form.

Pion yields and ratios are sensitive to the HMT form.

Certain flow observables are less affected by the HMT.

Abstract

Based on the Isospin-dependent transport model Boltzmann-Uehling-Uhlenbeck (IBUU), effects of the difference of the high momentum tails (HMTs) of nucleon momentum distribution in colliding nuclei on some isospin-sensitive observables are studied in the $^{197}\rm {Au}+^{197}\rm {Au}$ reactions at incident beam energy of 400 MeV/nucleon. It is found that the nucleon transverse and elliptic flows, the free neutron to proton ratio at low momenta are all less sensitive to the specific form of the HMT, while the free neutron to proton ratio at high momenta and the yields of $\pi^{-}$ and $\pi^{+}$ as well as the $\pi^{-}/\pi^{+}$ ratio around the Coulomb peak are sensitive to the specific form of the HMT. Combining the present studies with the experimental measurements at rare-isotope reaction facilities worldwide, one may get more insights into the nuclear short-range correlations in heavy nuclei or nuclear matter.