Speaker
Description
We investigate the angular momentum in heavy-ion collisions applying the hadronic transport approach SMASH. In contrast to geometrical models (e.g. a Glauber approach) our transport approach allows to access the full phase-space information of every particle at any time. The importance of understanding the non-equilibrium angular momentum transferred to the fireball and in turn the quark-gluon plasma (QGP) was highlighted by recent results of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The spin polarization measurement of the $\Lambda$-hyperon revealed a high angular momentum of the heavy ions and provided experimental evidence for vorticity in the QGP for the first time. Therefore, a systematic exploration of the angular momentum within a dynamic calculation for beam energies from $\sqrt{s}_{NN}= 2.41GeV$ to $\sqrt{s}_{NN}= 200GeV$ is a crucial step towards the full description of vorticity as a fundamental property of the QGP. Results for the angular momentum of Au-Au collisions as function of the impact parameter are presented and the influence of the initial Fermi momentum is studied. Moreover, it is shown that the angular momentum exhibits a distinct maximum for a specific impact parameter, independent of the beam energy. We show that the remaining angular momentum $L_r$ of the system grows with increasing system size in a range of $A=16$ $(^{16}_8O)$ to $A=208$ $(^{208}_{82}Pb)$ while we observe that for smaller beam energies a larger fraction of the initial angular momentum is transferred to $L_r$. The findings are important to guide future experimental programs and indicate where the largest transfer of angular momentum is expected.
