Dark energy and QCD axion from approximate U(1)_de and U(1)_PQ

by Jihn E. Kim (Kyung Hee University)

Tuesday 1 Apr 2014, 15:00 → 16:00 Europe/Berlin

Semiar room 2, Bldg. 2A (DESY Hamburg)

Quantum gravity effects do not favor global symmetries, which was the basis for discrete gauge symmetries at the bottom approach. String theory contains gravity and must be free of such quantum gravity problems. Indeed, string theory does not allow global symmetries except a global U(1) descending from the anomalous U(1) gauge symmetry. In this talk, we discuss two gauge symmetries. One anomalous U(1) and a U(1)-DE gauge symmetry. The U(1)-DE gauge symmetry can be broken to a discrete symmetry such as to Z_N. This Z_N must be exact to not have any quantum gravity dilemma. Z_N symmetric models can allow global symmetries, one is interpreted as the PQ symmetry and the as a DE-symmetry. We discuss this framework in a non-technical manner.