The coupling of the lightest SUSY Higgs boson to two photons in the decoupling regime
Laboratoire de Physique Mathématique et Théorique, UPRES-A 5032, Université de Montpellier II, F-34095, Montpellier Cedex 5, France
2 Institut für Theoretische Physik, Universität Karlsruhe, D-76128, Karlsruhe, Germany
Published online: 27 February 2005
We analyze the contribution of the SUSY particles to the coupling of the lightest Higgs boson to two photons in supersymmetric theories. We discuss to what extent these contributions can be large enough to allow for a discrimination between the lightest SUSY and the standard Higgs particles in the decoupling limit where all other Higgs bosons are very heavy and no supersymmetric particle has been discovered at future colliders. We find that only chargino and top squark loops can generate a sizeable difference between the standard and the SUSY Higgs-photon couplings. For masses above 250 GeV, the effect of chargino loops on the two-photon width is however smaller than ≈ 10% in the entire SUSY parameter space. Top squarks heavier than 250 GeV can induce deviations larger than 10% only if their couplings to the Higgs boson are large. Since top squark contributions can be sizeable, we derive the two-loop QCD correction to squark loops and show that they are well under control.
© Springer-Verlag, 1998