Azimuthal anisotropy and fundamental symmetries in QCD matter at RHIC

TL;DR

This paper reviews experimental results on azimuthal anisotropy in heavy ion collisions at RHIC, showing that the created matter behaves as a near-ideal liquid with significant jet quenching and potential symmetry violations.

Contribution

It provides a comprehensive analysis of azimuthal anisotropy, jet suppression, and symmetry considerations in QCD matter at RHIC for the first time.

Findings

Final state behaves as near-ideal liquid

Jet quenching depends on orientation to reaction plane

Evidence of possible P and CP symmetry violations

Abstract

A study of collective behavior in heavy ion collisions provides one of the most sensitive and promising probes for investigation of possible formation of new extreme state of strong interacting matter and elucidating its properties. Systematic of experimental results for final state azimuthal anisotropy is presented for heavy ion interactions at RHIC. Experimental data for azimuthal anisotropy indicate that the final state strongly interacting matter under extreme conditions behaves as near-ideal liquid rather, than ideal gas of quarks and gluons. The strong quenching of jets and the dramatic modification of jet-like azimuthal correlations, observed in ${Au+Au}$ collisions, are evidences of the extreme energy loss of partons traversing matter which contains a large density of color charges. For the first time, dependence of the jet suppression on orientation of a jet with respect to the reaction plane is found at RHIC experimentally. The model of compound collective flow and corresponding analytic approach are discussed. The possible violations of $\cal{P}$ and $\cal{CP}$ symmetries of strong interactions in heavy ion collisions at different initial energies are considered. Thus, now the fact is established firmly, that extremely hot and dense matter created in relativistic heavy ion collisions at RHIC differs dramatically from everything that was observed and investigated before.