# Simulating spin dynamics with spin-dependent cross sections in heavy-ion collisions

## TL;DR

This study integrates spin-dependent nucleon-nucleon cross sections into a transport model to analyze their effects on spin dynamics and collective flow observables in heavy-ion collisions.

## Contribution

It is the first to incorporate spin-dependent cross sections from phase-shift analyses into a transport model for heavy-ion collision simulations.

## Key findings

- Spin splitting of collective flows remains unaffected by spin-dependent cross sections.
- Spin-dependent cross sections reduce elliptic flows of free nucleons and light clusters.
- The results support the use of collective flows as probes of in-medium nuclear spin-orbit interactions.

## Abstract

We have incorporated the spin-dependent nucleon-nucleon cross sections into a Boltzmann-Uehling-Uhlenbeck transport model for the first time, using the spin-singlet and spin-triplet nucleon-nucleon elastic scattering cross sections extracted from the phase-shift analyses of nucleon-nucleon scatterings in free space. We found that the spin splitting of the collective flows is not affected by the spin-dependent cross sections, justifying it as a good probe of the in-medium nuclear spin-orbit interaction. With the in-medium nuclear spin-orbit mean-field potential that leads to local spin polarization, we found that the spin-averaged observables, such as elliptic flows of free nucleons and light clusters, becomes smaller with the spin-dependent differential nucleon-nucleon scattering cross sections.