Chiral imbalance in hadron matter : its manifestation in photon polarization asymmetries

Abstract: The possibility of the formation of a local parity breaking (LPB) in a quark-hadron medium is examined as a result of chiral symmetry violation, i.e, the appearance of difference between the average densities of right- and left-handed quarks in the fireball after heavy-ion collisions (HIC). Using the effective meson Lagrangian motivated by QCD extended to the chiral medium the properties of light scalar and pseudoscalar mesons are analyzed. It is establish that exotic decays of scalar mesons arise due to mixing of $\pi$ and $a_0$ vacuum states in the presence of chiral imbalance. The pion electromagnetic formfactor obtains a parity-odd supplement which generates a photon polarization asymmetry in pion polarizability. We conjecture that the above-mentioned properties of LPB can be revealed in experiments on LHC, RHIC, FAIR and NICA accelerators.