Effects of Extra Dimensions on Unitarity and Higgs Boson Mass

TL;DR

This paper investigates how extra dimensions influence unitarity constraints on Higgs boson scattering, revealing that Kaluza-Klein states significantly affect bounds on the Higgs mass depending on energy ratios.

Contribution

It introduces the impact of extra dimensions and Kaluza-Klein states on unitarity bounds for Higgs boson mass, extending standard model analyses.

Findings

Unitarity constraints are relaxed at high energy ratios due to extra dimensions.

Kaluza-Klein states significantly affect the partial wave amplitude.

Higgs mass bounds are not drastically changed under perturbative validity up to maximal energy ratios.

Abstract

We study the unitarity constraint on the two body Higgs boson elastic scattering in the presence of extra dimensions. The contributions from exchange of spin-2 and spin-0 Kaluza-Klein states can have large effect on the partial wave amplitude. Unitarity condition restrict the maximal allowed value for the ratio $r$ of the center of mass energy to the gravity scale to be less than one. Although the constraint on the standard Higgs boson mass for $r$ of order one is considerably relaxed, for small $r$ the constraint is similar to that in the Standard Model. The resulting bound on the Higgs boson mass is not dramatically altered if perturbative calculations are required to be valid up to the maximal allowed value for $r$.