Two component Higgs-portal dark matter

In this paper, we construct two component dark matter model and revisit fine-tuning, unitarity and vacuum stability problem in this framework. Through Higgs-portal interactions, the additional scalar and vector singlet fields can interact with the SM particles. The parameter space of the model are severely constraint by observed relic density and direct detection experiments. We found that, unlike the SM, the fine-tuning problem is relaxed due to the modified Veltman condition. The vacuum stability problem is addressed, the additional contributions from two DM singlets to the beta function make the Higgs quartic coupling lambda(mu) be positive up to Planck scale in some parameter space. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.