Muon anomalous magnetic moment and positron excess at AMS-02 in a gauged horizontal symmetric model

Abstract

We studied an extension of the standard model with a fourth generation of fermions to explain the discrepancy in the muon $(g-2)$ and explain the positron excess seen in the AMS-02 experiment. We introduce a gauged $SU(2{)}_{HV}$ horizontal symmetry between the muon and the 4th generation lepton families. The 4th generation right-handed neutrino is identified as the dark matter with mass $\sim 700$ GeV. The dark matter annihilates only to $({\mu }^{+}{\mu }^{-})$ and $({\nu }_{\mu }^c{\nu }_{\mu })$ states via $SU(2{)}_{HV}$ gauge boson. The $SU(2{)}_{HV}$ gauge boson with mass $\sim 1.4$ TeV gives an adequate contribution to the $(g-2)$ of muon and fulfill the experimental constraint from BNL measurement. The higgs production constraints from 4th generation fermions is evaded by extending the higgs sector.

Comments: Journal version, to appear in JHEP