# Topologically induced local P and CP violation in QCD x QED - High Energy Physics - Phenomenology

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Abstract: The existence of topological solutions and axial anomaly open a possibilityof P and CP violation in QCD. For a reason that has not yet been establishedconclusively, this possibility is not realized in strong interactions - theexperimental data indicate that a global P and CP violation in QCD is absent.Nevertheless, the fluctuations of topological charge in QCD vacuum, althoughnot observable directly, are expected to play an important role in the breakingof $U A1$ symmetry and in the mass spectrum and other properties of hadrons.Moreover, in the presence of very intense external electromagnetic fieldstopological solutions of QCD can induce local P- and CP-odd effects in the$SU c3\times U {em}1$ gauge theory that can be observed in experimentdirectly. Here I show how these local parity-violating phenomena can bedescribed by using the Maxwell-Chern-Simons, or axion, electrodynamics as aneffective theory. Local P- and CP- violation in hot QCD matter can be observedin experiment through the -chiral magnetic effect- the separation of electriccharge along the axis of magnetic field. Very recently, STAR Collaborationpresented an observation of the electric charge asymmetry with respect toreaction plane in relativistic heavy ion collisions at RHIC.

Author: ** Dmitri E. Kharzeev**

Source: https://arxiv.org/