Hyperon polarization in relativistic heavy ion collisions and axial U(1) symmetry breaking at high temperature
Experiments at the Relativistic Heavy Ion Collider have measured the net polarization of $$\text{Λ}$$ and $$\bar{Λ}$$ hyperons and attributed it to a coupling between their spin and the vorticity of the fluid created in heavy ion collisions, but how the spin comes to equilibrium with vorticity is an open problem. Recently, we found that vorticity fluctuations and helicity flip of strange quarks in quark-gluon plasma through perturbative QCD processes resulted in equilibration times far too long to be relevant. Here, we consider the Nambu-Jona-Lasinio model with the inclusion of the six-quark Kobayashi-Maskawa–'t Hooft interaction which breaks axial U(1). In this work, using instanton inspired models for the temperature dependence of the axial symmetry breaking, we find that constituent strange quarks can reach spin equilibrium at temperatures below about 170 MeV, just before they hadronize to form hyperons.
- Research Organization:
- Univ. of Minnesota, Minneapolis, MN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF); Heising-Simons Foundation
- Grant/Contract Number:
- FG02-87ER40328; PHY-1630782; 2017-228
- OSTI ID:
- 1800660
- Alternate ID(s):
- OSTI ID: 1605637
- Journal Information:
- Physical Review. C, Vol. 101, Issue 3; ISSN 2469-9985
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Hyperon–anti-hyperon polarization asymmetry in relativistic heavy-ion collisions as an interplay between chiral and helical vortical effects
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journal | January 2022 |
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