Effective approaches within and beyond the MSSM : applications to Higgs Physics and Dark Matter observables

par Guillaume Drieu (LAPTh Annecy)

jeudi 12 juil. 2012, 14:30 → 15:30 Europe/Paris

Auditorium Vivargent (Annecy-le-Vieux)

We have explored in this thesis the use of Effective Field Theories in the case of models beyond the Standard Model. Indeed, the drawbacks (as the lack of particles accounting for dark matter and the Naturalness issue, among others) of the Standard Model have led to several expeditions in the extensions of the Standard Model, among which supersymmetry is one of the most popular. It is specially known to provide a good dark matter candidate with the lightest neutralino which can reproduce the correct relic density for dark matter. However such a statement is quite non-trivial since the measured value of the relic density is getting close to the percent accuracy, calling hence for a next-to leading order computation. In order to ease this long computation we have developed an effective approach to the neutralino couplings in the MSSM. We will discuss the performance of such an approach as compared to the full-one loop computation and show that a good agreement can be reached. Nevertheless, the recent results on the Higgs sector tell that the MSSM itself may not be our best guess for supersymmetry. Indeed, with a Higgs around 125 GeV, this model would appear in many cases fine-tuned, and to that respect we have developped an effective parametrisaiton for an extended supersymmetric Higgs sector, the BMSSM (Beyond the MSSM). We will see how the Standard Model Higgs searches can be recast in such a framework and in particular focus on the case of a Higgs signal at 125 GeV wih possible non standard couplings.

Slides DrieuLaRochelle