On the search for a second scalar doublet at the LHC

TL;DR

This paper explores the search for a second scalar doublet at the LHC within a general Yukawa alignment framework, offering a more flexible approach that encompasses various models with natural flavour conservation and better aligns with experimental constraints.

Contribution

It introduces a Yukawa alignment framework for analyzing additional scalars at the LHC, broadening the scope beyond traditional models with fixed flavour structures.

Findings

Yukawa alignment allows for sizable new physics effects in the scalar sector.

The framework includes models with natural flavour conservation as special cases.

It provides a more general analysis compatible with flavour experiment constraints.

Abstract

Motivated by the principle of natural flavour conservation, searches for signatures of a second scalar doublet at the LHC are usually limited to models with a very restricted Yukawa structure. Strong correlations between the scalar couplings to fermions are fixed in these models due to the underlying flavour principle, making the results obtained from such analyses highly model dependent. Moreover, constraints derived from flavour experiments also vary radically within the different models considered. The hypothesis of Yukawa alignment provides a suitable framework to perform a more general analysis of 125 GeV boson data and searches for additional scalars at the LHC, allowing for sizable new physics effects to be observed in the scalar sector while accommodating the stringent limits from flavour experiments at the same time. This general setting includes the different models with natural flavour conservation as particular cases.