Speaker
Description
We investigate the possible emergence of chiral-spin symmetry, $SU(2)_\mathrm{CS}$, in hot QCD using lattice simulations with [$N_f = 2+1$ fermions] at temperatures [$T \approx 1.2$–$3\,T_\mathrm{pc}$]. Chiral-spin symmetry has been proposed as an approximate emergent symmetry of QCD in an intermediate-temperature regime above the chiral crossover and may shed light on the nature of strongly interacting matter there. We study spatial screening correlators in several mesonic channels. These allow us to examine the effective restoration of chiral $SU(2)_L \times SU(2)_R$ and $U(1)_A$ symmetry, and to test the degeneracy patterns among the vector, axial-vector, tensor, and axial-tensor channels predicted by $SU(2)_\mathrm{CS}$. Ratios of screening correlators are compared with free-quark expectations, in which chiral-spin symmetry is explicitly broken. We find clear signals of $SU(2)_L \times SU(2)_R$ and effective $U(1)_A$ restoration above $T_\mathrm{pc}$, while the $SU(2)_\mathrm{CS}$-related channels show only partial degeneracy. These results constrain the extent to which chiral-spin symmetry emerges in the high-temperature QCD medium.