Spin Hydrodynamic Generation in the Charged Subatomic Swirl

Abstract

Recently there have been significant interests in the spin hydrodynamic generation phenomenon from multiple disciplines of physics. Such phenomenon arises from global polarization effect of microscopic spin by macroscopic fluid rotation and is expected to occur in the hot quark-gluon fluid (the "subatomic swirl") created in relativistic nuclear collisions. This was indeed discovered in experiments which however revealed an intriguing puzzle: a polarization difference between particles and anti-particles. We suggest a novel application of a general connection between rotation and magnetic field: a magnetic field naturally arises along the fluid vorticity in the charged subatomic swirl. We establish this mechanism as a new way for generating long-lived in-medium magnetic field in heavy ion collisions. Due to its novel feature, this new magnetic field provides a nontrivial explanation to the puzzling observation of a difference in spin hydrodynamic generation for particles and anti-particles in heavy ion collisions.

A study of $$\varLambda $$ and $$\bar{\varLambda }$$ polarization splitting by meson field in PICR hydrodynamic model

“…For the case of 7.7 GeV, the polarization difference from our model could be as significant as ΔP J ≈ 3.5%, which is already larger than the lower boundary of experimental measurement of 3%. Up to now several mechanisms were proposed, and quantitative calculations were performed to explain the Λ andΛ polarization splitting [28,29,38,39], but none of them can achieve 3% difference at 7.7 GeV. More specifically, our result for 7.7 GeV case is about 3 times larger than the upper boundary estimate in Ref.…”

“…More specifically, our result for 7.7 GeV case is about 3 times larger than the upper boundary estimate in Ref. [28]. As discussed before that the values of density quantity and the vorticity between our model and the 1 To compare vorticity herein with the thermal vorticity = 1 2 ∇ × (γ v/T ) defined in Ref.…”

“…Besides, as indicated by Relativistic Magneto-hydrodynamics, the magnetic field can also be induced by charged particles in vortical Quark-Gluon-Plasma (QGP), and in this scenario the magnetic field could last long enough until freeze-out, but problem still exists: the charge density might not be large enough to produce a magnetic field that is strong enough. e.g., the upper limits of the estimated polarization difference at 7.7 GeV is below 1%, which is far away from the lower boundary of experimentally observed 3% difference [28].…”

“…[37], one could estimate the freeze-out temperature as around 170 MeV at √ s =39-200 GeV [34], and thus the factor AMPT model are very close, the reason why we have much larger polarization splitting effect than that in Ref. [28] lies on the coefficient…”

Ellipticity of photon emission from strongly magnetized hot QCD plasma

“…It is reasonable to expect that a strong magnetic field, produced in noncentral heavy-ion collisions, can affect the photon emission [36][37][38]. Since the magnetic field is likely to be present during an extended period of the evolution of the fireball [1,2,39,40], all known sources of photon emission could be affected. Here we will concentrate primarily on the direct photon emission from the quarkgluon plasma.…”