A study ofAxion Dark Matter in a Pecci-Quinn Symmetry Breaking Scenario

Abstract

We analyze the possibility of invisible axion part icle as a cold dark matter (CDNI) candidate. Axions are generated due to the spontaneous breaking of Peccei-Quinn symmetry as a Pscudo-Nambu-Goldstone boson. T his global chiral symmetry ap pears as an incidental symmetry of an exact ZN symmetry in t he extensions of St an dard Model (SM). For N = 9 alld 10 we check t he illvari ance of KSVZ and DFSZ axion models. The spontaneol1s breaking of U (1 ) PQ symmetry is achieved via the semi-classical gravity effects, under both N = 9 and N = 10. We consider the axion effective potent ial with higher dimensiona.l Pl allck's suppressed operators whi ch induces t he U (1)pQ symmetry breaking at Planck's energy scale and a charge-parity violating term. We find DFSZ axion models to be phenomenologically plausible for both N = 9 or 10. T he right amount of t he axion dark matter reli c abundance is ob tained for both KSVZ and DFSZ models. The remnant axion dark matt er (ADM) abundance is cal cul at ed by taking into account t he impacts h'olll topological defect degradation and assuming the PQ symmetry to be broken aft er inflation. In DFSZ axion model, the axion mass for N = 10 case t urns out to be 7nA ~ (3.5 - 4.2) /-LeV in accordance wit h a viable range for a cold dark matter candidate, This mass range is also relevant in the study of anomalous cooling of white dwarfs. Fin ally, we discuss the various constraints on axion mass 7nA and U (1)PQ symmetry breaking parameter fA from different running experiments.