Quantized vortices in pionic superfluid

Oleg Teryaev,Valentin Zakharov,A Rothkopf,N Brambilla,D Röhrich,K Tywoniuk,L Tolos,A Kurkela,J.O Andersen,A Tranberg

doi:10.1051/epjconf/202225810008

Abstract

The interplay between classical vorticity being the main undisputed source of polarization in heavy-ion collisions (HIC) and quantized vortices is considered. The vortex tubes emerging in the rotating pionic (super) fluid polarize the baryons in their cores and explain the emerging global polarization. The appearance of vortices in the region separating participants and spectators in non-central HIC is similar to that for sliding layers of liquid helium. From the other side, it is also the region where the classical vorticity was earlier found to be large forming the vortex sheets. The formation of tubes manifests a threshold at certain critical vorticity implying the vanishing polarization at lower energies. For central HIC the compact jet-like flows may lead to formation of vortex rings related to local polarization. The P-odd momentum correlations for their experimental investigation are suggested. The role of shear and viscosity in the emergence of polarization is discussed.

Highlights

Observation of non-vanishing polarization of Λ(Λ)-hyperons in heavy ion collisions by the STAR Collaboration [1] is considered to be one of most remarkable experimental findings of recent years
The transition of the rotation to spin happens in the cores of these vortices via the heavy baryonic degrees of freedom. This process is accompanied by the dissipation which may be considered as a counterpart if absorptive phases
In the present paper we consider the mechanisms of quantized vortices production in the core-corona border region which was earlier found [13] to produce the femto-vortex sheets ("femto-cyclones") corresponding to classical vorticity

Summary

Introduction

Observation of non-vanishing polarization of Λ(Λ)-hyperons in heavy ion collisions by the STAR Collaboration [1] is considered to be one of most remarkable experimental findings of recent years. The crucial problem is the transition of rotation to spin which may be realized either through the thermal equilibration of spin with rotating matter [4, 5] or by the making use [2, 6] of axial anomaly in effective theory [7] which naturally led to the predicrion of both polarization decrease with energy [2] and its estimate [3] to be of percent order at several GeV energy The latter approach in confined phase may be realized via the quantum vortices in pionic supeerfluid [8]. The transition of the rotation to spin happens in the cores of these vortices via the heavy baryonic degrees of freedom This process is accompanied by the dissipation which may be considered as a counterpart if absorptive phases. In the present paper we consider the mechanisms of quantized vortices production in the core-corona border region which was earlier found [13] to produce the femto-vortex sheets ("femto-cyclones") corresponding to classical vorticity. We will discuss the role of shear and viscosity in polarization emergence

Sliding layers and quantized vortices

Conclusions and outlook