LHC explores what LEP hinted at: CP-violating type-I 2HDM

Abstract

The Large Hadron Collider is shown to have great scope for a light charged Higgs discovery, in the context of the CP-violating type-I two Higgs doublet model. This scenario with similar masses of $H^{\pm }$ and W was suggested by the puzzling departure from charged current lepton universality found in the LEP data. With the lightest neutral Higgs mass set to 125 GeV, the charged-neutral Higgs associated production mechanism can cause a significant excess in the $\tau \nu b\bar{b}$ events over a vast range of tan beta as long as the Higgs mixing pattern avoids a few limiting cases. Thanks to the low $H^{\pm }$ mass, the charged Higgs loop can play a striking role in neutral Higgs decays into $\gamma \gamma$, thereby compensating for a suppressed gluon-gluon fusion rate. The effect of scalar-pseudo-scalar mixing on loop-induced Higgs signals is also discussed.

Comments: 25 pages, corrected a numerical error in Fig. 4 and a typo, conclusions unchanged