Higgs Phenomenology in Warped Extra-Dimensions with a 4th Generation

TL;DR

This paper explores how a warped extra-dimensional model with a fourth fermion family influences Higgs couplings, flavor violation, and collider signals, highlighting potential indirect detection avenues independent of KK particle discovery.

Contribution

It introduces the impact of a fourth fermion family on Higgs phenomenology and flavor violation in warped extra-dimensional models, emphasizing novel collider signatures.

Findings

Flavor misalignment is enhanced with a fourth family.

Flavor violating couplings affect Higgs decay patterns.

Potential collider signals from altered Higgs and fermion decays.

Abstract

We study a warped extra-dimension scenario where the Standard Model fields lie in the bulk, with the addition of a fourth family of fermions. We concentrate on the flavor structure of the Higgs couplings with fermions in the flavor anarchy ansatz. Even without a fourth family, these couplings will be generically misaligned with respect to the SM fermion mass matrices. The presence of the fourth family typically enhances the misalignment effects and we show that one should expect them to be highly non-symmetrical in the ${(34)}$ inter-generational mixing. The radiative corrections from the new fermions and their flavor violating couplings to the Higgs affect negligibly known experimental precision measurements such as the oblique parameters and $Z\to b {\bar b}$ or $Z \to \mu^+ \mu^-$. On the other hand, $\Delta F=1,2$ processes, mediated by tree-level Higgs exchange, as well as radiative corrections to $b \to s \gamma$ and $\mu \to e\gamma$ put some generic pressure on the allowed size of the flavor violating couplings. But more importantly, these couplings will alter the Higgs decay patterns as well as those of the new fermions, and produce very interesting new signals associated to Higgs phenomenology in high energy colliders. These might become very important indirect signals for these type of models as they would be present even when the KK mass scale is high and no heavy KK particle is discovered.