Charged Higgs phenomenology in the lepton-specific two Higgs doublet model

Abstract

We study the "lepton-specific" two Higgs doublet model, in which one doublet Phi_l gives mass to charged leptons and the other Phi_q gives mass to both up- and down-type quarks. We examine the existing experimental constraints on the charged Higgs boson mass and the parameter tan(beta) \equiv <Phi_q^0>/<Phi_l^0>. The most stringent constraints come from LEP-II direct searches and lepton flavour universality in tau decays. The former yields M_H+ \geq 92.0 GeV; the latter yields two allowed regions, 0.61 tan(beta) GeV \leq M_H+ \leq 0.73 tan(beta) GeV or M_H+ \geq 1.4 tan(beta) GeV, and excludes parameter regions beyond the LEP-II bound for tan(beta) \gtrsim 65. We present the charged Higgs decay branching fractions and discuss prospects for charged Higgs discovery at the LHC in this model.