Phenomenology of Light MSSM Higgs Boson Scenario

We have found that in the MSSM, the possibility for the lightest CP-even Higgs boson to be lighter than $Z$ boson (as low as about 60 GeV) is, contrary to the usual belief, not yet excluded by LEP2 Higgs search nor any direct searches for supersymmetric particles at high energy colliders. The Light Higgs boson scenario (LHS) is realised when the $ZZh$ coupling and the decay branching ratio ${\rm Br}(h/A\to b\bar{b})$ are simultaneously suppressed as a result of generic supersymmetric loop corrections. Consequently, the $W^\pm H^\mp h$ coupling has to be large due to the sum rule of Higgs couplings to weak gauge bosons and as we demonstrate, the associate neutral and charged Higgs boson production process, $pp\to H^\pm h (A)$, at the LHC can completely probe the LHS.