Towards high-precision predictions for the MSSM Higgs sector

The status of the evaluation of the MSSM Higgs sector is reviewed. The phenomenological impact of recently obtained corrections is discussed. In particular it is shown that the upper bound on mh within the MSSM is shifted upwards. Consequently, lower limits on tanb obtained by confronting the upper bound as function of tanb with the lower bound on mh from Higgs searches are significantly weakened. Furthermore, th e region in the MA-tanb-plane where the coupling of the lightest Higgs boson to down-type fermions is suppressed is modified. The presently not calculated higher-order corrections to the Higgs-boson mass matrix are estimated to shift the mass of the lightest Higgs boson by up to 3 GeV

Decoupling Coefficients and the Lightest CP-Even Higgs Boson Mass in the Minimal Supersymmetric Standard Model

In meiner Arbeit wurden Entkopplungskoeffizienten im Rahmen des Minimalen Supersymmetrischen Standardmodells berechnet um eine präzise Vorhersage der leichtesten CP-geraden Higgs-Boson-Masse zu ermöglichen

On the O(alpha_t^2) two-loop corrections to the neutral Higgs boson masses in the MSSM

We compute the O(alpha_t^2) two-loop corrections to the neutral CP-even Higgs boson mass matrix in the Minimal Supersymmetric Standard Model, for arbitrary values of mA and of the parameters in the stop sector, in the effective potential approach. In a large region of parameter space these corrections are sizeable, increasing the prediction for mh by several GeV. We present explicit analytical formulae for a simplified case. We discuss the inclusion of momentum-dependent corrections and some possible ways of assigning the input parameters.Comment: 23 pages, 6 figures; published versio

Higgs mass determination in supersymmetry

We present the state-of-the-art of the effective field theory computation of the MSSM Higgs mass, improving the existing ones by including extra threshold corrections. We show that, with this approach, the theoretical uncertainty is within 1 GeV in most of the relevant parameter space. We confirm the smaller value of the Higgs mass found in the EFT computations, which implies a slightly heavier SUSY scale. We study the large tan β region, finding that sbottom thresholds might relax the upper bound on the scale of SUSY. We present SusyHD, a fast computer code that computes the Higgs mass and its uncertainty for any SUSY scale, from the TeV to the Planck scale, even in Split SUSY, both in the D R ¯ $$\overline{\mathrm{DR}}$$ and in the on-shell schemes. Finally, we apply our results to derive bounds on some well motivated SUSY models, in particular we show how the value of the Higgs mass allows to determine the complete spectrum in minimal gauge mediation

Higgs mass and QCD axion properties at high precision

This thesis is dedicated to study the physical properties at high precision of two scalars of well-motivated beyond the standard model theories: the Higgs boson in the Minimal Supersymmetric Standard Model (MSSM) and the axion of the Peccei-Quinn mechanism. The discussion is divided in two parts. We make use of the advantages of the effective field theory framework. In the first part, we consider the state-of-the-art of the effective field theory computation of the MSSM Higgs mass, improving the existing ones by including extra threshold corrections. We perform a detailed estimate of the theoretical uncertainty. We study the large tangent beta region and we put emphasis on the allowed parameter space reproducing the experimental value of the Higgs mass. We present SusyHD, a fast computer code that computes the Higgs mass and its uncertainty for any supersymmetry (SUSY) scale, from the TeV to the Planck scale, even in Split SUSY, both in the DRbar and in the on-shell (OS) schemes. Finally, we apply our results to derive bounds on some well motivated SUSY models, in particular we show how the value of the Higgs mass allows to determine the complete spectrum in minimal gauge mediation. In the second part, we discuss how to extract several properties of the axion of Quantum Chromodynamics (QCD) with great accuracy using only first principle QCD computations. We obtained the axion potential, the mass and the coupling to photons by combining next to leading order (NLO) calculations in chiral perturbation theory (ChPT) with recent Lattice QCD results. Axion-nucleon interactions are also derived reliably. The method we have followed allows to further improve the precision as uncertainties on the light quark masses and the effective field theory couplings are reduced. We have also studied the finite temperature dependence of the axion potential and its mass, in connection with its role in determining the axion relic abundance

The Anatomy of Electro-Weak Symmetry Breaking. II: The Higgs bosons in the Minimal Supersymmetric Model

The second part of this review is devoted to the Higgs sector of the Minimal Supersymmetric Standard Model. The properties of the neutral and charged Higgs bosons of the extended Higgs sector are summarized and their decay modes and production mechanisms at hadron colliders and at future lepton colliders are reviewed.Comment: 340 pages, latex, many figures and tables. V2: many typos corrected, references added and some corrected, english improve