Unconventional phenomenology of a minimal two-Higgs-doublet model

Two-Higgs-doublet models (2HDM) are simple extensions of the Standard Model (SM) where the scalar sector is enlarged by adding a weak doublet. As a result, the Higgs potential depends in general on several free parameters which have to be carefully chosen to give predictions consistent with the current precision data. We consider a 2HDM invariant under a twisted custodial symmetry and depending only on three extra parameters beyond the SM ones. This model naturally features an inverted mass spectrum with a light pseudoscalar state and a heavy SM-like Higgs boson. We thoroughly analyze direct and indirect constraints and present a few unconventional though promising signatures at the LHC.