Higgs-radion unification: radius stabilization by an SU(2) bulk doublet and the 126 GeV scalar

Abstract

We investigate a Randall-Sundrum model with an SU(2) doublet propagating in the bulk. Upon calculating its gravitational effect we find that a stabilized radius can be generated without the use of an additional scalar, as needed for example in the Goldberger-Wise (GW) mechanism, and with no additional fine-tuning other than the inescapable one due to the cosmological constant; similar tuning is also present in the GW mechanism. The lowest scalar excitation in this scenario, the counterpart of the radion of the GW mechanism, has both radion-like and Higgs-like couplings to the SM fields. It, thus, plays a dual role and we, therefore, denote it as the "Higgs-radion" ($h_r$). As opposed to the GW radion case, our Higgs-radion is found to be compatible with the 126 GeV scalar recently discovered at the LHC, at the level of $1\sigma$, with a resulting $95\%$ CL bound on the KK-gluon mass of: $4.48TeV<M_{KKG}<5.44TeV$. An important consequence of our setup should be accentuated: the radion of the traditional RS scenarios simply does not exist, so that our Higgs-radion is not the conventional mixed state between the GW radion and the Higgs.

Comments: latex, 23 pages, 2 figures, 2 tables. In V2: 2 figures and 1 table added, new references added and differences with previous works are further elaborated