G. Moultaka

SuSpect: A Fortran code for the Supersymmetric and Higgs particle spectrum in the MSSM

We present the Fortran code SuSpect version 2.1, which calculates the Supersymmetric and Higgs particle spectrum in the Minimal Supersymmetric Standard Model (MSSM). The calculation can be performed in constrained models with universal boundary conditions at high scales such as the gravity (mSUGRA), anomaly (AMSB) or gauge (GMSB) mediated breaking models, but also in the non{universal MSSM case with R{parity and CP conservation. Care has been taken to treat important features such as the renormalization group evolution of parameters between low and high energy scales, the consistent implementation of radiative electroweak symmetry breaking and the calculation of the physical masses of the Higgs bosons and supersymmetric particles taking into account the dominant radiative corrections. Some checks of important theoretical and experimental features, such as the absence of non desired minima, large ne-tuning in the electroweak symmetry breaking condition, as well as agreement with precision measurements can be performed. The program is user friendly, simple to use, self{contained and can easily be linked with other codes; it is rather fast and flexible, thus allowing scans of the parameter space with several possible options and choices for model assumptions and approximations.

Higgs potential in the type II seesaw model

The Standard Model Higgs sector, extended by one weak gauge triplet of scalar elds with a very small vacuum expectation value, is a very promising setting to account for neutrino masses through the so-called type II seesaw mechanism. In this paper we consider the general renormalizable doublet/triplet Higgs potential of this model. We perform a detailed study of its main dynamical features that depend on ve

Gravitino dark matter in gauge mediated supersymmetry breaking

This paper investigates the parameter space of theories with gauge-mediated supersymmetry breaking leading to gravitino (cold) dark matter with mass m{sub 3/2}{approx}1 keV{yields}10 MeV. We pay particular attention to the cosmological role of messenger fields. Cosmology requires that these messengers decay to the visible sector if the lightest messenger mass M{sub X} > or approx. 30 TeV. We then examine the various possible messenger number violating interactions allowed by the symmetries of the theory and by phenomenology. Late messenger decay generally results in entropy production hence in the dilution of preexisting gravitinos. We find that in SU(5) grand unification only specific messenger-matter couplings allow to produce the required amount of gravitino dark matter particles. Gravitino dark matter with the correct abundance is, however, expected in larger gauge groups such as SO(10) for generic nonrenormalizable messenger-matter interactions and for arbitrarily high post-inflationary reheating temperatures.

Natural gravitino dark matter in SO(10) gauge mediated supersymmetry breaking

Abstract It is shown that gravitinos with mass m 3 / 2 ∼ 0.1 – 1 MeV may provide suitable cold dark matter candidates in scenarios of gauge mediated supersymmetry breaking (GMSB) under SO ( 10 ) grand unification coupled to supergravity, which accommodate a messenger sector of mass scale M X ∼ 10 6 GeV . This is due to the combined effects of renormalizable loop-suppressed operators and generic non-renormalizable ones governing the dilution of a pre-existing equilibrium gravitino abundance via messenger decay. The above range of gravitino and messenger masses can be accommodated in indirect GMSB scenarios. The gravitino abundance does not depend on the post-inflationary reheat temperature and it is shown that leptogenesis can generate successfully the baryon asymmetry.

Associated H− W+ production in high energy e+e− collisions

Abstract We study the associated production of charged Higgs bosons with W gauge bosons in high energy e + e − collisions at the one loop level. We present the analytical results and give a detailed discussion for the total cross section predicted in the context of a general Two Higgs Doublet Model (THDM).

Higgs Boson Production in Association with Scalar Top Quarks at Proton Colliders

We investigate the production of Higgs particles in association with the supersymmetric scalar partners of the top quark at proton colliders. In the minimal supersymmetric extension of the standard model, the cross sections for the lightest neutral Higgs boson production can be rather large, substantially exceeding the rate for the associated production with top quarks. If the lightest top squark is not much heavier than the top quark, this process will enhance the potential of the CERN Large Hadron Collider to discover the lightest neutral Higgs boson, and will open a window to the study of the Higgs-stop coupling, the potentially largest electroweak coupling in the supersymmetric theory.

Is natural fine tuning feasible in the standard model

Abstract A recent proposal for estimating the Higgs and the top masses from a naturalness requirement is reconsidered. We perform a calculation of the overall quadratic divergencies up to two loop order in the standard model, in general linear and non-linear renormalizable gauges R nl (a, b, E 0 , E w ) , and recover the necessary gauge invariance of the mass equations. However, our equations disagree slightly with those derived previously and actually jeopardize the whole procedure. Alternative solutions and open questions are also briefly discussed.

Virtual effects of the supersymmetric two-Higgs doublets model on the Z resonance

Abstract We analyse virtual effects due to the minimal supersymmetric two-Higgs doublets model on top of the Z resonance. We find that the precise measurement of the Z partial decay width into b quarks and the forward-backward asymmetry for b jets which will be performed at LEP, may allow for indirect signals of supersymmetric nature. If no deviation from the standard model predictions is felt by the two observables, one can improve the existing limits on the additional parameters of the model.

Associated production of Higgs bosons with scalar quarks at future hadron and e+e− colliders

Abstract We analyze the production of neutral Higgs particles in association with the supersymmetric scalar partners of the third generation quarks at future high-energy hadron colliders (upgraded Tevatron, LHC) and e+e− linear machines (including the γγ option). In the Minimal Supersymmetric extension of the Standard Model, the cross section for the associated production of the lightest neutral h boson with the lightest top squark pairs can be rather substantial at high energies. This process would open a window for the measurement of the h t t coupling, the potentially largest coupling in the supersymmetric theory.

MSSM radiative contributions to the WWγ and WWZ form factors

We evaluate one-loop contributions to the C and P conserving