Private Higgs at the LHC

Abstract

We study the LHC phenomenology of a general class of "Private Higgs" (PH) models, in which fermions obtain their masses from their own Higgs doublets with $\op(1)$ Yukawa couplings, and the mass hierarchy is translated into a dynamical chain of vacuum expectation values. This is accomplished by introducing a number of light gauge-singlet scalars, the "darkons," some of which could play the role of dark matter. These models allow for substantial modifications to the decays of the lightest Higgs boson, for instance through mixing with TeV-scale PH fields and light darkons: the simplest version of the model predicts the ratios of partial widths to satisfy $\G(h \to VV^*)_{\text{PH}}/\G(h \to VV^*)_{\text{SM}} \approx \G(h \to \g\g)_{\text{PH}}/\G(h \to \g\g)_{\text{SM}} \leq 1$ and $\G(h \to b\bar b)_{\text{PH}}/\G(h \to b\bar b)_{\text{SM}} \sim \op(1)$, where the inequalities are saturated only in the absence of Higgs mixing with light darkons. An extension of the model proposed previously for generating nonzero neutrino masses can also contribute substantially to $h \to \g\g$ without violating electroweak precision constraints. If the Higgs coupling to fermions is found to deviate from the Standard Model (SM) expectation, then the PH model may be a viable candidate for extending the SM.