Gauge Singlet Scalars as Cold Dark Matter

In supersymmetric models whose gauge group includes an additional U(1) factor at the TeV scale, broken by the VEV of an standard model singlet S, the parameter space can accommodate a very light neutralino not ruled out experimentally. This higgsino-like fermion, stable if R-parity is conserved, can make a good cold dark matter candidate. We examine the thermal relic density of this particle and discuss the prospects for its direct detection if it forms part of our galactic h...

We study several aspects of electroweak vacuum metastability when an extra gauge singlet scalar, a viable candidate for a dark matter particle, is added to the standard model of particle physics, which is assumed to be valid up to the Planck scale. Phase diagrams are drawn for different parameter spaces, and based on that, we graphically demonstrate how the confidence level, at which stability of electroweak vacuum is excluded, depends on such new physics parameters.

We consider theories of flavored dark matter, in which the dark matter particle is part of a multiplet transforming nontrivially under the flavor group of the Standard Model in a manner consistent with the principle of Minimal Flavor Violation (MFV). MFV automatically leads to the stability of the lightest state for a large number of flavor multiplets. If neutral, this particle is an excellent dark matter candidate. Furthermore, MFV implies specific patterns of mass splitting...

We investigate non-gravitational signals of dark energy within the framework of gauge symmetry in the dark energy sector. Traditionally, dark energy has been primarily studied through gravitational effects within general relativity or its extensions. On the other hand, the gauge principles have played a central role in the standard model sector and dark matter sector. If the dark energy field operates under a gauge symmetry, it introduces the possibility of studying all major...

We investigate the phenomenology of singlet scalar dark matter in a simple $B-L$ gauge extension of the Standard Model where the dark matter particle is charged under the $U(1)_{B-L}$ symmetry. The non-trivial gauge anomalies are cancelled with the introduction of three exotic fermions with $B-L$ charges as $-4,-4,5$, instead of right-handed neutrinos $\nu_{Ri}~(i=1,2,3)$ with $B-L=-1$ in conventional $U(1)_{B-L}$ model. Without the need of any ad-hoc discrete symmetry, the $...

We analyze a simple extension of the Standard Model (SM) obtained by adding a complex singlet to the scalar sector (cxSM). We show that the cxSM can contain one or two viable cold dark matter candidates and analyze the conditions on the parameters of the scalar potential that yield the observed relic density. When the cxSM potential contains a global U(1) symmetry that is both softly and spontaneously broken, it contains both a viable dark matter candidate and the ingredients...

Following the unexpected theoretical discovery of a mass dimension one fermionic quantum field of spin one half, we now present first results on two _local_ versions. The Dirac and Majorana fields of the standard model of particle physics are supplemented by their natural counterparts in the dark matter sector. The possibility that a mass dimension transmuting symmetry may underlie a new standard model of particle physics is briefly suggested.

The origin of dark matter in the universe may be scalar particles produced by amplification of quantum fluctuations during a period of dilaton-driven inflation. We show, for the first time, that a single species of particles, depending on its mass and interactions, can be a source of both cold and hot dark matter simultaneously. Detection of such weakly interacting particles with masses below a fraction of an eV presents a new challenge for dark matter searches.

We investigate the possibility that Dark Matter (dm) could be made of scalar candidates and focus, in particular, on the unusual mass range between a few MeV's and a few GeV's. After showing why the Lee-Weinberg limit (which usually forbids a dm mass below a few GeV's) does not necessarily apply in the case of scalar particles, we discuss how light candidates (mdm < O(GeV)) can satisfy both the gamma ray and relic density constraints. We find two possibilities. Either dm is c...

We address the question of gravitino dark matter in the context of gauge mediated supersymmetry breaking models. A special emphasis is put on the role played by the MSSM singlet messenger in the case of SO(10) grand unification.