Effective Approaches in and Beyond the MSSM : applications to Higgs Physics and Dark Matter observables

Abstract

In this thesis we use the Effective Field Theory approach for supersymmetric theories, applied to two experimental domains : the search for the Higgs bosons at colliders and the Dark Matter observables. The reason for introducing an effective approach in the Higgs physics is that the simple supersymmetric extension of the Standard Model (the MSSM) is known to have a tightly constrained Higgs sector, in particular with a lightest Higgs mass difficult to raise without introducing some fine-tuning. Many specific expansions (as the NMSSM for instance) allow for a richer Higgs sector. In this case however, the effective approach is handy since it encompasses many different specific ultraviolet completions. We have added to the Kahler and superpotential of the MSSM all possible terms of dimensions 5 and 6 including only Higgs superfields. The phenomenology of the resulting Higgs sector appears to be much richer, and we analyse our model in view of the latest LHC results. On the other side, supersymmetry is known for providing a Dark Matter candidate, so we have also worked to improve the accuracy of the computation of the relic density in the MSSM. Indeed the impressive accuracy on the experimental side (around 6%) calls for a precise computation including radiative corrections. Those one-loop computations being rather long in the MSSM, thus often overlooked, we have used again the effective approach by introducing new effective vertices that aim at accounting for the one-loop correction. We show on a specific process (neutralinos annihilation to muons) the agreement between the effective approach and the full one-loop computation.

PhD Thesis, 187p

References in corpus (23)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• FeynRules - Feynman rules made easy
• Combined results of searches for the standard model Higgs boson in pp collisions at sqrt(s) = 7 TeV
• A Tentative Gamma-Ray Line from Dark Matter Annihilation at the Fermi Large Area Telescope
• Search for the Standard Model Higgs boson in the diphoton decay channel with 4.9 fb-1 of pp collisions at sqrt(s) = 7 TeV with ATLAS
• Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
• Strong constraints on the rare decays Bs -> mu+ mu- and B0 -> mu+ mu-
• Higgs Physics as a Window Beyond the MSSM (BMSSM)
• Search for Dark Matter and Large Extra Dimensions in pp Collisions Yielding a Photon and Missing Transverse Energy
• Full one-loop corrections to the relic density in the MSSM: A few examples
• Automatised full one-loop renormalisation of the MSSM I: The Higgs sector, the issue of tan(beta) and gauge invariance
• Automatised full one-loop renormalisation of the MSSM II: The chargino-neutralino sector, the sfermion sector and some applications
• MSSM with Dimension-five Operators (MSSM_5)
• Neutralino Annihilation into Massive Quarks with SUSY-QCD Corrections
• SUSY-QCD effects on neutralino dark matter annihilation beyond scalar or gaugino mass unification
• Radiative corrections to co-annihilation processes
• Vacuum (Meta)Stability Beyond the MSSM
• Feynman Diagram Calculations with FeynArts, FormCalc, and LoopTools
• Constraints on invisible Higgs decay in MSSM in the light of diphoton rates from the LHC
• The Supersymmetric Higgs
• BMSSM Implications for Cosmology
• Effect of SUSY-QCD corrections to neutralino annihilation on the cold dark matter relic density in the Higgs funnel
• Radiative corrections to neutralino annihilation: Recent developments