Strangeness in Quark Matter 2022 (SQM 2022)

Probing novel baryonic spin Hall effect using Λ spin polarization at STAR

POS-BLK-07

14 Jun 2022, 17:10

1h 50m

Metaverse

Board: BLK-07

Poster Bulk matter phenomena, QCD phase diagram, and Critical point Poster

Speakers

Qiang Hu (Institute of Modern Physics of Chinese Academy of Science) Qiang Hu

Description

The Spin Hall Effect (SHE) is a generation of spin polarization for moving spin carriers in materials under an external electric field and is instrumental in investigating quantum effects in many-body systems [1]. Recent theoretical calculations indicate that the gradient of baryonic chemical potential (analogous to the electric field) can induce a sizeable spin Hall current in Au+Au collisions at $\sqrt{s_{NN}}$ $\sim$ 10 GeV. Furthermore, at the RHIC Beam Energy Scan (BES) energies, the sign as well as the pattern of energy dependence of the difference between the harmonics of spin polarization of $\mathrm{\Lambda }$ and $\bar{\mathrm{\Lambda }}$ hyperons, can be significantly different with and without the presence of baryonic spin Hall current [2-4].

In this talk, we will present the harmonic coefficients of $\mathrm{\Lambda }$ hyperons' spin polarization ($P_x\sin (2\mathrm{\Delta }\varphi )$, $P_y\cos (2\mathrm{\Delta }\varphi )$, $P_z\sin (2\mathrm{\Delta }\varphi )$) as functions of transverse momentum, rapidity, and collision centrality in RHIC BES-II Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 14.6, 19.6, and 27 GeV. These measurements serve as the first experimental probe of the predicted baryonic SHE in heavy-ion collisions.

[1] Y. Kato el al., Science 306 (2004) 1910
[2] S. Liu et al., JHEP 07 (2021) 181
[3] B. Fu et al., Phys. Rev. Lett. 127 (2021) 142301
[4] B. Fu et al., arXiv: 2201.12970 (2022)

Presentation materials

QM2022_poster_QiangHu.pdf