The heavy neutral Higgs signature in the $\gamma \gamma \to Z Z $ process

G.J. Gounaris; P.I. Porfyriadis; F.M. Renard

doi:doi:10.1007/s100520100589

2022 Impact factor 4.4

Particles and Fields

Eur. Phys. J. C 19, 57-76
DOI: 10.1007/s100520100589

The heavy neutral Higgs signature in the $\gamma \gamma \to Z Z$ process

G.J. Gounaris¹, P.I. Porfyriadis¹ and F.M. Renard²

¹ Department of Theoretical Physics, Aristotle University of Thessaloniki, 54006, Thessaloniki, Greece
² Physique Mathématique et Théorique, UMR 5825, Université Montpellier II, 34095 Montpellier Cedex 5, France

(Received: 20 October 2000 / Revised version: 5 January 2001 / Published online: 23 February 2001 -© Springer-Verlag 2001)

Abstract
If the standard model (SM) Higgs particle is sufficiently heavy, then its contribution to $\gamma \gamma \to Z Z$ should be largely imaginary, interfering with the also predominantly imaginary SM "background"generated by the W loop. For standard model Higgs masses in the region $200\lesssim m_H \lesssim 500$ GeV, this interference is found to be constructive and increasing the Higgs signal. In the minimal SUSY case an interference effect should also appear for the contribution of the heavier CP-even neutral Higgs boson H⁰, provided it is sufficiently heavy. The effect is somewhat reduced, though, by the smallness of the H⁰ width and the $\gamma\gamma$ and ZZ branching ratios. The interference is again found to be constructive for part of the parameter space corresponding to sfermion masses at the TeV scale and maximal stop mixing. For both the SM and the SUSY case, regions of the parameter space exist, though, where the interference may be destructive. It is therefore essential to take these effects into account when searching for possible scalar Higgs-like candidates. To this aim, we present the complete analytic expressions for both resonance and background amplitudes.