Spin Effects in Heavy Ion Collisions at High Energies

Abstract

In non-central high energy heavy ion collisions, the colliding system possesses a huge orbital angular momentum along the normal direction of the reaction plane. Due to the spin orbit interaction in the system, such a huge orbital angular momentum leads to the spin polarization of quarks and anti-quarks in the quark matter system produced in the collision. Such an e ff ect, known as the global polarization e ff ect, was predicted many years ago and has been confirmed by the STAR collaboration at RHIC. The discovery of the global polarization e ff ect opens a new avenue in heavy ion physics in general and in studying the properties of quark-gluon plasma in particular. This talk will briefly review the original ideas and calculations that lead to the prediction and summarize progresses and problems in related aspects. + e − annihilations. The result shows that, in contrast to quark combination, ρ 00 obtained in fragmentation is larger than 1 / 3. This implies that the spin of ¯ q produced in the Among the most aspects, we particular: (i) GPE phenomenology including experimental and di ff erent phenomenological approaches; (ii) Spin-vortical e ff ects in strong interacting system; (iii) Spin-magnetic e ff ects in HIC including (a) the fine structure of GPE of di ff erent hadrons, (b) chiral magnetic e ff ect and (c) spin-electromagnetic e ff ects in ultra-peripheral collisions (UPC) in HIC; and (iv) Spin transport theory in relativistic quantum system to derive GPE, describe the spin transport, calculate the polarization and other related spin e ff ects directly from QCD.