Spin transport in intermediate-energy heavy-ion collisions as a probe of in-medium spin–orbit interactions

Abstract

The spin up-down splitting of collective flows in intermediate-energy heavy-ion collisions as a result of the nuclear spin-orbit interaction is investigated within a spin-and isospin-dependent Boltzmann-Uehing-Uhlenbeck transport model SIBUU12. Using a Skyrme-type spin-orbit coupling quadratic in momentum, we found that the spin splittings of the directed flow and elliptic flow are largest in peripheral Au+Au collisions at beam energies of about 100-200 MeV/nucleon, and the effect is considerable even in smaller systems especially for nucleons with high transverse momenta. The collective flows of light clusters of different spin states are also investigated using an improved dynamical coalescence model with spin. Our study can be important in understanding the properties of in-medium nuclear spin-orbit interactions once the spin-dependent observables proposed in this work can be measured.

Λ hyperon polarization in relativistic heavy ion collisions from a chiral kinetic approach

“…To study this effect requires a hadronic transport model that includes explicitly their spin degrees of freedom, such as in Refs. [49][50][51], and is beyond the present study. Also, Λ andΛ have same polarization in our study because they are described by the same chiral kinetic equations of motion and modified collisions.…”

Spectra and flow of light nuclei in relativistic heavy ion collisions at energies available at the BNL Relativistic Heavy Ion Collider and at the CERN Large Hadron Collider

“…The statistical factors and values of the width parameters in the Wigner functions for deuteron and helium-3 as well as the empirical values of their charge radii and resulting oscillator constants are given in TABLE I. We note that as in most studies on application of the coalescence model for deuteron production , the statistical factors given in TABLE I do not include that due to isospin, which would reduce the value for p + n → d by a factor of 2 and the value for p + p + n → 3 He by a factor of 3 [45,50,51]. Since whether to include isospin in determining the statistical factors in the coalescence model is still an unresolved question, we give in Appendix A our arguments for not including this in our consideration.…”

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

“…1 of Ref. [10]) as well as the spin splitting of collective flows of free nucleons and light clusters [6,9,10].…”

“…We found this model is useful in studying the spin dynamics in intermediate-energy heavy-ion collisions [8]. In particular, it was observed that the spin splittings of collective flows of free nucleons and light clusters can be good probes of the in-medium spin-orbit interaction [9,10]. However, in our previous studies, we applied the spin-dependent mean-field potential for nucleons but employed the spin-averaged nucleon-nucleon scattering cross sections.…”