Spin polarization and alignment in heavy-ion collisions

Abstract

We report the measurements of global spin polarization of hyperons ($P_{\Lambda }$) from FAIR, RHIC and LHC energies. The $P_{\Lambda }$ continue to follow an increasing trend at $\sqrt{s_{\mathrm{N}N}}$ < 7.7 GeV indicating that enormous vorticity prevail even in hadronic dominant region. New measurements of local spin polarization ($P_{z,2}$) from isobar collisions follow the same pattern observed in previous RHIC and LHC energies. An observable motivated by predicted baryonic Spin Hall Effect, the net local polarization ($P_{z,2}^{\mathrm{net}}$), shows negative value in Au+Au collisions at $\sqrt{s_{\mathrm{N}N}}$ = 19.6 and 27 GeV. The first $P_z$ measurement with respect to third order harmonic in 200 GeV RHIC isobar collisions show a non-zero sine modulation, indicating the presence of complex vortical structure in the medium. Surprising new patterns of spin alignment (${\rho }_{00}$) for various vector mesons ($K^{\ast 0}$, $K^{\ast \pm }$, $\varphi$ and $J/\psi$) emerged at both RHIC and LHC energies. The large deviation in ${\rho }_{00}$ of several species poses challenge to the theory.

arXiv commentSQM 2022 proceedings

References in corpus (10)

• The effects of topological charge change in heavy ion collisions: "Event by event P and CP violation"
• Global $\Lambda$ hyperon polarization in nuclear collisions: evidence for the most vortical fluid
• Globally Polarized Quark-gluon Plasma in Non-central A+A Collisions
• Angular momentum conservation in heavy ion collisions at very high energy
• Polarization of $\Lambda$ ($\bar{\Lambda }$) hyperons along the beam direction in Au+Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV
• Collective longitudinal polarization in relativistic heavy-ion collisions at very high energy
• Shear-induced spin polarization in heavy-ion collisions
• Evidence of spin-orbital angular momentum interactions in relativistic heavy-ion collisions
• Global polarization of $\Xi$ and $\Omega$ hyperons in Au+Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV
• Spin alignment measurements of the $K^{\ast 0}(892)$ and $\varphi (1020)$ vector mesons at RHIC

Cited by in corpus (2)

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