Warm dark matter in low scale left-right theory

Abstract

We investigate the viability of having dark matter in the minimal left-right\nsymmetric theory. We find the lightest right-handed neutrino with a mass around\nkeV as the only viable candidate consistent with a TeV scale of left-right\nsymmetry. In order to account for the correct relic density with such low\nscales, the thermal overproduction of the dark matter in the early universe is\ncompensated by a sufficient late entropy production due to late decay of\nheavier right-handed neutrinos. We point out that the presence of the\nright-handed charge-current interactions, operative around the QCD phase\ntransition, has a crucial impact on the amount of dilution, as does the nature\nof the phase transition itself. A careful numerical study, employing the\nBoltzmann equations, reveals the existence of a narrow window for the\nright-handed gauge boson mass, possibly within the reach of LHC (in\ndisagreement with a previous study). We also elaborate on a variety of\nastrophysical, cosmological and low energy constraints on this scenario.\n