Decoupling behaviour of O(m_t^4) corrections to the h^0 self-couplings

The decoupling behaviour of the leading one-loop Yukawa-coupling contributions of O(m_t^4) to the lightest MSSM Higgs boson self-couplings, when the top-squarks are heavy as compared to the electroweak scale, are discussed. As shown analytically and numerically, the large corrections can almost completely be absorbed into the h^0-boson mass and therefore, the h^0 self-couplings remain similar to the coupling of the SM Higgs boson for a heavy top-squark sector.Comment: LaTeX, 5 pages, 3 figures included; typos corrected. Uses npb.sty. Talk given by S.P. at the RADCOR 2002/Loops and Legs in Quantum Field Theory 2002, September 8 to 13, Kloster Banz, German

Yukawa coupling quantum corrections to the self couplings of the lightest MSSM Higgs boson

A detailed analysis of the top-quark/squark quantum corrections to the lightest CP-even Higgs boson (h^0) self-couplings is presented in the MSSM. By considering the leading one-loop Yukawa-coupling contributions of O(m_t^4), we discuss the decoupling behaviour of these corrections when the top-squarks are heavy compared to the electroweak scale. As shown analytically and numerically, the large corrections can almost completely be absorbed into the h^0-boson mass. Our conclusion is that the h^0 self-couplings remain similar to the coupling of the SM Higgs boson for a heavy top-squark sector.Comment: LaTeX, 19 pages, 3 figures included. A few minor changes and references adde

On the electroweak symmetry breaking in the Littlest Higgs model

In the SU(5)/SO(5) little Higgs models radiative corrections give rise to the SU(2)_L x U(1)_Y symmetry breaking. In this work we start a program for a detailed determination of the relevant terms of the Higgs effective potential by computing the contribution of the b, t and T quarks at the one-loop level, as an starting point for higher-loops computation. In spite of the fact that some two-loop level contributions are well known to be important, we use our preliminary one-loop result to illustrate that, by demanding the effective potential to reproduce exactly the Standard Model Higgs potential, and in particular the relation m_H^2= 2 lambda v^2= 2 mu^2, it will be possible to set new constraints on the parameter space of the Littlest Higgs model when the computation of all the relevant contributions to the Higgs effective potential is completed.Comment: LaTex, 20 pages, 3 figures. Comments added. Published version in Eur.Phys.J.

Distinguishing Higgs models in H -> b b-bar / H -> tau^+ tau^-

We analyze the ratio of branching ratios R=BR(H->b b-bar)/BR(H->tau^+ tau^-) of Higgs boson decays as a discriminant quantity between supersymmetric and non-supersymmetric models. This ratio receives large renormalization-scheme independent radiative corrections in supersymmetric models at large \tan\beta, which are absent in the Standard Model or Two-Higgs-doublet models. These corrections are insensitive to the supersymmetric mass scale. A detailed analysis in the effective Lagrangian approach shows that, with a measurement of +-21% accuracy, the Large Hadron Collider can discriminate between models if the CP-odd Higgs boson mass is below 900 GeV. An e+e- Linear Collider at 500 GeV center of mass energy can discriminate supersymmetric models up to a CP-odd Higgs mass of ~ 1.8 TeV.Comment: LaTeX, 10 pages, 4 figures. Uses cite.sty. Comments and references adde

Les Houches physics at TeV colliders 2005 beyond the standard model working group: Summary report

The work contained herein constitutes a report of the Beyond the Standard Model'' working group for the Workshop Physics at TeV Colliders, Les Houches, France, 2-20 May, 2005. We present reviews of current topics as well as original research carried out for the workshop. Supersymmetric and non-supersymmetric models are studied, as well as computational tools designed in order to facilitate their phenomenology