Reduced branching ratio for H -> AA -> 4 tau from A - eta_b mixing

Abstract

Models with an extended Higgs sector, as the NMSSM, allow for scenarios where the Standard Model-like CP-even Higgs boson H decays dominantly as H -> AA -> 4 tau where A is a light CP-odd Higgs boson. Tight constraints on this scenario in the form of lower bounds on M_H have recently been published by the ALEPH group. We show that, due to A - eta_b mixing, the branching ratio H -> AA -> 4 tau is strongly reduced for M_A in the range 9 - 10.5 GeV. This is the range of M_A in which the tension between the observed eta_b(1S) mass and its prediction based on QCD can be resolved due to mixing, and which is thus still consistent with a light CP-even Higgs boson H satisfying LEP constraints with a mass well below 114 GeV. This result is practically independent from the coupling of A to b quarks.