Higgs decay into two photons in a warped extra dimension

Abstract

A detailed five-dimensional calculation of the Higgs-boson decay into two photons is performed in both the minimal and the custodially protected Randall-Sundrum (RS) model, where the Standard Model (SM) fields propagate in the bulk and the scalar sector lives on or near the IR brane. It is explicitly shown that the [Formula: see text] gauge invariance of the sum of diagrams involving bosonic fields in the SM also applies to the case of these RS scenarios. An exact expression for the [Formula: see text] amplitude in terms of the five-dimensional (5D) gauge-boson and fermion propagators is presented, which includes the full dependence on the Higgs-boson mass. Closed expressions for the 5D [Formula: see text]-boson propagators in the minimal and the custodial RS model are derived, which are valid to all orders in [Formula: see text]. In contrast to the fermion case, the result for the bosonic contributions to the [Formula: see text] amplitude is insensitive to the details of the localization of the Higgs profile on or near the IR brane. The various RS predictions for the rate of the [Formula: see text] process are compared with the latest LHC data, and exclusion regions for the RS model parameters are derived.