Light dark matter from the U(1)X sector in the NMSSM with gauge mediation

Abstract

Cosmic ray anomalies observed by PAMELA and Fermi-LATexperiments may be interpreted by heavy (TeV-scale) dark matterannihilation enhanced by Sommerfeld effects mediated by a verylight (sub-GeV) U(1)X gauge boson, while the recent directsearches from CoGeNT and DAMA/LIBRA experiments may indicate arather light ( ∼ 7 GeV) dark matter with weak interaction.Motivated by these apparently different scales, we consider agauge mediated next-to-the minimal supersymmetric standard model(NMSSM) entended with a light U(1)X sector plus a heavy sector (H̄h,Hh), which can provide both a light ( ∼ 7 GeV) and aheavy (TeV-scale) dark matter without introducing any ad hoc newscale. Through the Yukawa coupling between Hh and the messagerfields, the U(1)X gauge symmetry is broken around the GeV scaleradiatively and a large negative mS2 is generated for theNMSSM singlet S. Furthermore, the small kinetic mixing parameterbetween U(1)X and U(1)Y is predicted to be θ ∼ 10−5−10−6 after integrating out the messengers. Such alight dark matter, which can have a normal relic density from thelate decay of the right-handed sneutrino (assumed to be theordinary next-to-the lightest supersymmetric particle andthermally produced in the early Universe), can serve a goodcandidate to explain the recent CoGeNT and DAMA/LIBRA results.