ZU–TH 5/98 PM–98/1 GDR–S–011 hep-ph/9806301 LOWER BOUNDS ON CHARGED HIGGS BOSONS FROM LEP AND THE TEVATRON

We point out that charged Higgs bosons can decay into final states different from τντ and cs̄, even when they are light enough to be produced at LEP II or at the Tevatron through top quark decays. These additional decay modes are overlooked in ongoing searches even though they alter the existing lower bounds on the mass of the charged Higgs bosons that are present in supersymmetric and two Higgs doublets models. The discovery of a charged Higgs boson would be an unambiguous signal of an extended Higgs sector and possibly of supersymmetry. In supersymmetric models, at least two Higgs doublets are needed to give mass to all fermions: one is coupled only to down-type quarks and leptons; the other, only to up-type quarks. A Two Higgs Doublet Model (2HDM) is said of Type II if the doublets are coupled as in supersymmetric models with minimal particle content. It is said of Type I if one Higgs doublet does not couple to fermions at all and the other couples as the Standard Model (SM) doublet. After electroweak symmetry breaking, five physical states remain: two CP-even Higgs bosons h and H (with mh < mH), a CP-odd Higgs boson A, and two charged states H . The charged-Higgses–fermions interactions, can then be comprehensively expressed as: L = g √ 2 {( mdi MW ) X uLjVji dRi + ( mui MW ) Y uRiVij dLj + ( mli MW )