This is not exactly my area of expertise, so you can probably get a better answer from someone else (perhaps Lubos). But based on a quick overview of the relevant papers, the presence of a Randall-Sundrum radion as originally proposed would not eliminate the need for a Higgs boson. In order to allow gauge invariance, the Higgs mechanism basically requires a ring-shaped potential minimum, which means you need a field with at least two degrees of freedom. The first RS paper mostly only works with the case of one extra dimension, so you would need to generalize the model to additional dimensions, and given that these extra dimensions are supposed to be individually periodic, I'm not seeing how you could get the sort of structure required to produce a Higgs mechanism out of it. Of course, a *lot* of people have done work that builds on Randall's and Sundrum's papers, so perhaps someone has determined some way to do it, but it seems unlikely to me. (In fact, in the original paper, around equations 17 and 18 they talk about a fundamental Higgs field which is separate from the radion field, so evidently the authors themselves did not consider the radion as a stand-in for the Higgs.)

The LHC experiments have searched the entire allowed mass range for the standard model Higgs, from the lower limit set by LEP to the upper limit set by unitarity bounds, and everything except this region around $125\text{ GeV}$ is excluded at 95% confidence level. So if this bump turns out not to be the Higgs boson, the standard model Higgs is ruled out and we would have to start looking at rather more exotic model which predict Higgs masses in excess of $600\text{ GeV}$. I don't know of any particular model of this sort which has generated much interest among particle physicists.

And another thought: even just based on the data presented in the paper by Cheung and Yuan, the branching ratio excesses measured by CMS have *huge* uncertainties. It seems pretty premature to me to dismiss the identification of the observed excesses with the Higgs boson, since with more data, the numbers could easily converge to the SM Higgs expectations.

This post imported from StackExchange Physics at 2014-03-17 03:22 (UCT), posted by SE-user David Z