Accumulating Hints for Flavour Violating Higgses at the Electroweak Scale

TL;DR

This paper proposes a two-Higgs-doublet model that can simultaneously explain multiple flavor anomalies and deviations in Higgs and top decays, predicting testable collider signatures for upcoming LHC data.

Contribution

It introduces a specific two-Higgs-doublet model that accounts for several flavor and Higgs anomalies while remaining consistent with existing bounds.

Findings

Model explains $h o e\tau$, $h\to \mu\tau$, and other anomalies.

Predicts a shift in Higgs coupling to tau leptons.

Forecasts a non-zero $t\to hc$ decay rate.

Abstract

We show that supplementing the Standard Model by only a second Higgs doublet, a combined explanation of $h\to e\tau$, $h\to \mu\tau$, $b\to s \ell^+ \ell^-$, the $W$ mass and $R({D^{(*)}})$ as well as the excess in $t\to bH^+(130\,{\rm GeV})\to b\overline{b}c$ is possible. While this requires flavour violating couplings, the stringent bounds from e.g. $\mu\to e\gamma$, $\tau\to \mu\gamma$, $B_s-\bar B_s$ mixing, $b\to s\gamma$, low mass di-jet and $pp\to H^+H^-\to \tau^+\tau^-\nu\bar\nu$ searches can be avoided. However, the model is very constrained, it inevitably predicts a shift in the SM Higgs coupling strength to tau leptons as well as a non-zero $t\to hc$ rate, as indeed preferred by recent measurements. We study three benchmark points providing such a simultaneous explanation and calculate their predictions, including collider signatures which can be tested with upcoming LHC run-3 data.