[Hybrid RBRC seminar] Local equilibrium and Lambda polarization in high energy heavy-ion collisions

by Andrea Palermo (Stony Brook University)

Thursday 30 Nov 2023, 12:30 → 13:30 US/Eastern

2-160 (https://bnl.zoomgov.com/j/1619458475?pwd=Z1VDdXVXcWF1eUhsRDZObVJnME4rUT09)

The polarization of the $\Lambda$ hyperon has become an important probe of the Quark-Gluon Plasma produced in heavy-ion collisions. Recently, it has been found that polarization receives a substantial contribution from a term proportional to the symmetric derivative of the four-temperature, the thermal shear tensor. We review the theoretical derivation of this result using the local equilibrium density operator, and discuss numerical computations for Au-Au collisions at 200 GeV. It is shown that, provided that the hadronization hypersurface is isothermal, the thermal shear can restore the agreement between the experimental measurements and the predictions of the hydrodynamic model, solving the long-standing "polarization sign-puzzle".