Speaker
Description
We develop a new parametric 3-dimensional initial condition for low-energy heavy-ion collisions based on collision geometry for a multistage hybrid framework. The longitudinal structure of the collision profile is constrained by rapidity-dependent experimental measurements, especially the directed flow of pions and protons (i.e., $v_1(y)$). We introduce a baryon stopping parameter which controls the initial rapidity distribution of baryon charge after the nuclei interpenetration, and the amount of energy and momentum deposited from the incoming nucleons into the produced quark-gluon plasma. The energy-momentum and net baryon charge conservation impose correlations among the initial energy, baryon distributions, and longitudinal flow.
The (3+1)-dimensional hydrodynamic evolution shows that the baryon density distribution and baryon diffusion can change the sign of identified particles’ directed flow coefficients. Furthermore, the rapidity-dependent $v_1(y)$ is affected by the longitudinal diffusive baryon transport and flow velocity. We further quantify how the rescattering between mesons and baryons affect their $v_1(y)$ slopes in the hadronic stage. Finally, we will present a systematic study of $v_1(y)$ in Au+Au collisions at different centrality classes, various beam energies, and additional identified species (kaons and lambdas) to test our hybrid model. Our results shed light on the initial baryon stopping and the hydrodynamic baryon transport, and are relevant for the model-to-data comparison in the BES-II.
