Speaker
Description
The tantalising prospect that hints of scalars lighter than the 125 GeV Higgs boson may have already shown themselves at the LEP and LHC or will, at least, emerge during the run of the upcoming generation of colliders, has brought a renewed interest into scalar sectors with fields beyond the Standard Model. The addition of a second Higgs doublet stands as one of the simplest possible extensions, whose augmented parameter space, while opening the window to solutions to a few of the shortcomings of the current theory and to a plethora of new phenomena to be discovered, also comes with problems of its own: significant among those, the introduction of flavour-changing neutral currents at tree-level. These can be tackled with the imposition of specific Z2 symmetries on the model or, alternatively, by demanding the alignment of Yukawa couplings in flavour space, so that the diagonalisation of mass terms trims non-diagonal couplings of fermions with the additional neutral scalars as well. Setting out to ascertain whether current data allows two-Higgs-doublet models to accommodate low-mass scalars, we present here the results of new state-of-the-art global fits. Our numerical analyses make use of purely theoretical constraints, bounds from direct searches for neutral and charged scalars at the LEP and LHC, the signal strengths of the Higgs boson measured at the LHC, electroweak precision observables, and a set of flavour observables, all globally combined within HEPfit, a software with a Bayesian Markov Chain Monte Carlo approach to statistical inference.