Speaker
Description
The medium produced at RHIC Beam Energy Scan (BES) energies is baryon-rich. This enhanced baryon stopping not only leads to a splitting in the yields of baryons and anti-baryons, but has also been observed experimentally to produce a splitting in their flow coefficients. Hydrodynamic models have struggled to reproduce this baryon-antibaryon flow splitting with the correct magnitude and sign, largely because of inadequate modeling of the initial net-baryon profile. In this work, we propose a novel baryon deposition ansatz that goes beyond the commonly employed factorization approach, in which the transverse and longitudinal components of the deposition are treated independently. Instead, our model allows the rapidity extent of the baryon profile to depend explicitly on the transverse position. Specifically, we introduce a density-dependent baryon stopping prescription in which the rapidity loss of a participant nucleon depends on the local density of participants from the opposing nucleus. When this initial condition is combined with a tilted energy deposition and incorporated into a hydrodynamic framework with finite baryon density and baryon diffusion, it successfully captures the splitting of both $v_1$ and $v_2$ between baryons and anti-baryons, a feature that theoretical models have long struggled to explain. This combined initial condition and hydrodynamic framework therefore provides a robust baseline for predictions relevant to the search for the QCD critical point and for electromagnetic field signatures and future measurements.
