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 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 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 -boson propagators in the minimal and the custodial RS model are derived, which are valid to all orders in . In contrast to the fermion case, the result for the bosonic contributions to the 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 process are compared with the latest LHC data, and exclusion regions for the RS model parameters are derived.

Higgs couplings and phenomenology in a warped extra dimension

“…In models with a brane-localized Higgs field, the inverse characteristic width of the Higgs field along the extra dimension ∆ h is assumed to be much larger than the inherent UV cutoff near the IR brane, i.e. ∆ h ≫ Λ TeV ∼ several M KK [33]. It is well known that quantum fields can be strictly localized on orbifold fixed points, and in such a scenario the quantity ∆ h can indeed be infinite or arbitrarily large.…”

“…In order to eliminate this sensitivity to the localization mechanism one would need to consider models in which the Higgs lives inside the bulk of the extra dimension, for which ∆ h ∼ M KK [34,35]. In some papers [22,33,37], the UV sensitivity to the localization mechanism of RS models in which the Higgs sector is localized on or near the IR brane is treated as a model dependence. In other work [36], the narrow bulk-Higgs…”

“…For the W -boson zero mode, one finds 10) JHEP02 (2015)008 where here and below the ellipses denote terms of order v 4 /M 4 KK and higher. Note, in particular, that for the zero mode one encounters a correction factor [33] …”

Impact of warped extra dimensions on the dipole coefficients in b → sγ transitions

“…In this work we focus on the RS model with a brane-localized Higgs field, where the inverse characteristic width ∆ h of the Higgs field along the extra dimension is assumed to be much larger than the inherent UV cutoff near the IR brane, i.e. ∆ h Λ TeV ∼ several M KK [28]. It is well known that quantum fields can be strictly localized on orbifold fixed points, and in such a scenario the quantity ∆ h can indeed be infinite or arbitrarily large.…”

“…The propagator function (3.4) can be calculated in closed form, see [28] for more details on the derivation and the solution. The 5D quark propagators in (3.2) can be decomposed into four functions differing in chirality and Lorentz structure [16,21,[32][33][34],…”