We study a conformal version of the Standard Model (SM), which apart from SM sector, containing a U D (1) dark sector with a vector dark matter candidate and a scalar field (scalon). In this model the dark sector couples to the SM sector via a Higgs portal. The theory is scaleinvariant in lowest order, therefore the spontaneous symmetry breaking of scale invariance entails the existence of a scalar particle, scalon, with vanishing zeroth-order mass. However, one-loop corrections break scale invariance, so they give mass to the scalon. Because of the scale invariance, our model is subjected to constraints which remove many of the free parameters. We put constraints to the two remaining parameters from the Higgs searches at the LHC, dark matter relic density and dark matter direct detection limits by PandaX-II. The viable mass region for dark matter is about 1-2 TeV. We also obtain the finite temperature one-loop effective potential of the model and demonstrate that finite temperature effects, for the parameter space constrained by dark matter relic density, induce a strongly first-order electroweak phase transition. * syaser.ayazi@semnan.ac.ir † a.mohamadnejad@ut.ac.ir and fermionic loop contributions to the Higgs mass within supersymmetry can also explain the hierarchy problem. However, concerning the null results at the first and second LHC runs [3,4], and other popular theoretical resolutions of the hierarchy problem, such as large extra dimensions, investigating alternative approaches are appealing.As it was mentioned, one approach of addressing the hierarchy problem is the radical assumption that the fundamental theory describing Nature does not have any scale. This idea is well worth considering for its potential to be an sparing solution to the hierarchy problem. The CW mechanism with a Higgs does not work for the electroweak symmetry breaking because the large top mass does not permit radiative breaking of the electroweak symmetry, but, simple extensions of the Higgs sector with additional bosonic degrees of freedom are known to be phenomenologically viable (see, e.g., ). On the other hand, the scale-invariant extension of the Higgs sector, is a generic feature of many DM models with scalar [27][28][29][30][31][32][33][34][35][36][37][38], fermionic [39][40][41][42][43][44][45] and vector [46-52] DM candidates.There are plenty astronomical and cosmological evidences that around 27 percent of the Universe is made of DM. According to the dominant paradigm, DM consists of weakly interacting massive particles (WIMPs) that successfully explain the large scale structures in our Universe.However, the nature of DM is not well understood, and its particle properties such as spin, mass and interactions all are unknown. Therefore, it is not surprising that despite many previous models, there are still opportunities for DM model building.In this paper we consider spin one (vector) gauge fields as DM candidates. Without concerning scale invariance, vector DM [53-72] and some of its theoretical and phenomenological aspe...

In this paper, we study freeze-in production of fermionic dark matter with a pseudo scalar as the mediator between dark sector and Standard Model (SM). While the fermionic DM is non-thermal, we will explain two scenarios in which production of pseudo-scalar particles are either thermal or non thermal. We'll present elaborate discussion to derive yield quantity and relic density and illustrate these values for the different range of model parameters. We'll investigate constraints on parameters space coming from invisible Higgs decay at LHC. For the case of extremely small couplings and zero mixing between SM Higgs field with pseudo scalar field which pseudo scalar boson can play role of DM, we will justify recent observation of merging galaxies with a case of self-interacting DM. We'll show that influence of DM annihilation in this case, would provide a better fit to the AMS-02 data of positron flux.

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We study a scale invariant extension of the standard model which can explain simultaneously dark matter and the hierarchy problem. In our set-up, we introduce a scalar and a spinor as two-component dark matter in addition to scalon field as a mediator. Interesting point about our model is that due to scale invariant conditions, compared to other two-component dark matter models, it has lower independent parameters. Possible astrophysical and laboratory signatures of two-component dark matter candidate are explored and it is shown that the most contribution of observed relic density of dark matter can be determined by spinor dark matter. Detectability of these dark matter particles is studied and the direct and invisible Higgs decay experiments are used to rule out part of the parameter space of the model. In addition, the dark matter self-interactions are considered and shown that their contribution saturate this constraint in the resonant regions.

The possibility of cancellation between different contributions to d e , d n and d Hg is reconsidered with special emphasis on the region that is phenomenologically interesting (intermediate values of tan and sub-TeV sfermion masses). It is found that in the range favored by electroweak baryogenesis (i.e., jj ' M 1 or jj ' M 2 ), sin M 1 1 can be compatible with the EDM bounds even for slepton masses below 500 GeV. Such large values of the phases promise a successful electroweak baryogenesis. The possibility of large CP-odd effects at linear collider is also discussed.