NLO Dispersion Laws for Slow-Moving Quarks in HTL QCD

We determine the next-to-leading order dispersion laws for slow-moving quarks in hard-thermal-loop perturbation of high-temperature QCD where weak coupling is assumed. Real-time formalism is used. The next-to-leading order quark self-energy is written in terms of three and four HTL-dressed vertex functions. The hard thermal loops contributing to these vertex functions are calculated ab initio and expressed using the Feynman parametrization which allows the calculation of the solid-angle integrals involved. We use a prototype of the resulting integrals to indicate how finite results are obtained in the limit of vanishing regularizer.Comment: 28 pages, 7 figures. Changes made to the text. References adde

Constraining the Parameters of a Model for Cold Dark Matter

This chapter aims at reviewing how modeling cold dark matter as weakly interacting massive particles (WIMPs) gets increasingly constrained as models have to face stringent cosmological and phenomenological experimental results as well as internal theoretical requirements like those coming from a renormalization-group analysis. The review is based on the work done on a two-singlet extension of the Standard Model of elementary particles. We conclude that the model stays viable in physically meaningful regions that soon will be probed by direct-detection experiments

A Two-Singlet Model for Light Cold Dark Matter

We extend the Standard Model by adding two gauge-singlet $\mathbb{Z}_{2}$% -symmetric scalar fields that interact with visible matter only through the Higgs particle. One is a stable dark matter WIMP, and the other one undergoes a spontaneous breaking of the symmetry that opens new channels for the dark matter annihilation, hence lowering the mass of the WIMP. We study the effects of the observed dark matter relic abundance on the annihilation cross section and find that in most regions of the parameters space, light dark matter is viable. We also compare the elastic scattering cross-section of our dark matter candidate off nucleus with existing (CDMSII and XENON100) and projected (SuperCDMS and XENON1T) experimental exclusion bounds. We find that most of the allowed mass range for light dark matter will be probed by the projected sensitivity of XENON1T experiment.Comment: 30 pages, 17 figure

Phenomenology of a Light Cold Dark Matter Two-Singlet Model

We study the implications of phenomenological processes on a two-singlet extension of the Standard Model we introduced in a previous work to describe light cold dark matter. We look into the rare decays of $\Upsilon$ and $B$ mesons, most particularly the invisible channels, and study the decay channels of the Higgs particle. Preferred regions of the parameter space are indicated, together with others that are excluded. Comments in relation to recent Higgs searches and finds at the LHC are made.Comment: 16 pages, 8 figure