Observability of the Lightest MSSM Higgs Boson with Explicit CP Violation via Gluon Fusion at the LHC

We investigate the observability of the lightest Higgs boson in the gluon–fusion channel at the CERN Large Hadron Collider (LHC) in the minimal supersymmetric Standard Model with explicit CP–violating mixing among three neutral Higgs bosons. The lightest Higgs boson with its mass less than 130 GeV can be detected at the LHC via its gluon–fusion production followed by the decay into two photons. The explicit CP violation can suppress both the production cross section and the two–photon decay branching fraction so significantly that the signal cross section may be more than ten times smaller than the SM signal. This reduction factor can be as small as 1/40 if the lightest Higgs boson mass is 115 GeV and its production cross section at LEP2 is more than 90 % that of the SM case.