Models for polarization asymmetry in inclusive hadron production

Abstract

The parton-recombination model plus SU(6) symmetry is used to relate polarizations in inclusive baryon production to those of the underlying constituent subprocesses. A description of the origin of the polarization asymmetry in terms of Thomas precession of the quarks' spins in the recombination process accounts for all of the qualitative features of the baryon and antibaryon polarization data.

Low energy pion-hyperon interaction

“…As explained there, the anti-hyperon polarization cannot be understood in terms of the usual models [9][10][11][12][13], because all of them are based on the leadingparticle effect and an anti-hyperon cannot be a leading particle. In [15] it has been proposed that anti-hyperons are polarized when interacting with the surrounding particles, which are predominantly pions, that make the environment where they are produced.…”

“…It is by now well known that in highenergy proton-nucleus collisions, the inclusively produced hyperons appear usually polarized [6][7][8]. Several models have been proposed to explain this phenomenon [9][10][11][12][13], which at least qualitatively, or even quantitatively, can account for the hyperon polarization. However, as for the anti-hyperons which are generally produced also with polarization [7,8], no one of these models are applicable, since all of them are based on some leading-particle effect in which the incident proton is transformed into a leading hyperon.…”

Global Λ polarization in high energy collisions

“…From the partonic micro-perspective, the initial angular momentum is transferred to the partons through the interaction of spin-orbit coupling in viscous QGP [11], and then the global polarized quarks are recombined into hadrons, in which the Thomas precession of the quark spin was applied [25].…”

Λpolarization in an exact rotating and expanding fluid dynamical model for peripheral heavy ion reactions

“…In single p + p collisions forward production in small-transverse-momentum fragmentation was theoretically studied and also observed. These reactions did result in much higher polarizations up to about 30% [20].…”