Global spin alignment of ɸ and K*0 vector mesons in Au+Au collisions from RHIC BES-II program

Abstract

Global spin alignment is a preferential alignment of a particle’s spin along the orbital angular momentum produced in heavy-ion collisions. The global spin alignment of vector mesons (JP = 1−) ϕ and K*0 may be sensitive to the vorticity in the medium and hadronization mechanisms. The second phase of RHIC Beam Energy Scan (BES-II) program provides higher statistics data sets for Au+Au collisions at √SNN = 7.7 - 19.6 GeV. From this data, we can make high precision measurements of ϕ and K*0 global spin alignment, allowing for more differential studies not possible with the BES-I data. We can also compare global spin alignment between ϕ and K*0, where the lifetime of ϕ is roughly ten times larger than that of K*0 and the latter is more sensitive to hadronic rescattering. We report high precision measurements for the global spin alignment of ϕ at √SNN = 19.6 GeV from BES-II.