Radion phenomenology with 3 and 4 generations

Abstract

We study radion phenomenology in an warped extra-dimension scenario with Standard Model fields in the bulk, with and without an additional fourth family of fermions. The radion couplings with the fermions will be generically misaligned with respect to the Standard Model fermion mass matrices, therefore producing some amount of flavor violating couplings and potentially influencing production and decay rates of the radion. Simple analytic expressions for the radion-fermion couplings are obtained with three or four families. We also update and analyze the current experimental limits on radion couplings and on the model parameters, again with both three and four families scenarios. We finally present the modified decay branching ratios of the radion with an emphasis on the new channels involving flavor diagonal and flavor violating decays into fourth generation quarks and leptons.

Randall–Sundrum reality at the LHC

“…Similar analyses were done in ref. [5,28,29,30,31,32,33,34]. We refine the calculations appropriate to the LHC experiments at 7 TeV (LHC7), and consider the possibility of finding φ in the ongoing LHC Higgs searches.…”

Saving the fourth-generation Higgs boson with radion mixing

“…We perform the same analysis, this time for the flavor-diagonal couplings, in Table III for m τ = 100 GeV and in Table IV [20], and if observed, they will give a clear indication for the warped space model.…”

“…where the couplings a ij andã ij , of the original unmixed Higgs and radion, have been previously obtained in [24,27] in the case of three generations and in [20,25] with four generations.…”

“…In a recent study, we have shown that if the fourth generation is incorporated into the framework of warped space models, both the production and decay patterns of the Higgs bosons can be altered significantly with respect to the patterns expected in the standard model with four generations, thus giving rise to distinguishing signals at the colliders [20].…”

“…It has been shown that a tree-level misalignment between the flavor structure of the Yukawa couplings of the radion and the fermion mass matrix will appear when the fermion bulk parameters are not all degenerate in both three [24] and four generations [25].…”