Core meets corona: Lambda and anti-Lambda polarization in peripheral high-energy heavy-ion collisions

by Prof. Alejandro Ayala (UNAM, Mexico City, Mexico)

Tuesday 8 Dec 2020, 19:30 → 21:30 Asia/Tehran

Online

Webinar on Quark Matter and Relativistic Hydrodynamics

Abstract:

The STAR Beam Energy Scan program has found a remarkable behavior for the global polarization of Lambdas and anti-Lambdas produced in peripheral high-energy Au + Au collisions: the latter is larger than the former for lower collision energies and the difference decreases with increasing collision energy. In this talk I show that a two-component source to model the collision region, consisting of a high density core and a lower density corona, can quantitatively describe the behavior of these polarizations as functions of the collision energy. The calculation makes use of the relaxation times that s-quarks and s-antiquarks produced in the core take to align with the thermal vorticity during the life-time of the quark-gluon plasma phase. We show that, in spite of the fact that s-antiquarks (that hadronize into anti-Lambdas) take longer to align their spins compared to s-quarks (that hadronize into Lambdas), when combining this information with the larger abundance of Lambdas compared to anti-Lambdas in the corona, the polarization excitation function can be well described.

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