Collider probes of the MSSM Higgs sector with explicit CP violation

We investigate the hadron collider phenomenology of the Minimal Supersymmetric Standard Model (MSSM) with explicit CP violation for Higgs bosons that can be observed in Standard Model search channels: W/ZH(i)(--> b (b) over bar) at the Tevatron, and gg --> H-i(--> gammagamma), t (t) over barH(i)(--> b (b) over bar) and WW --> H-i(--> tau(+)tau(-)) at the LHC. Our numerical analysis is based on a benchmark scenario proposed earlier called CPX, which has been designed to showcase the effects of CP violation in the MSSM, and on several variant benchmarks. In most of the CPX parameter space, these hadron colliders will find one of the neutral MSSM Higgs bosons. However, there are small regions of parameter space in which none of the neutral Higgs bosons can be detected in the standard channels at the Tevatron and the LHC. This occurs because the neutral Higgs boson with the largest coupling to W and Z bosons decays predominantly into either two lighter Higgs bosons or a Higgs boson and a gauge boson, whilst the lighter Higgs boson has only small couplings to the W and Z bosons and the top quark. For other choices of CP-violating parameters, all three neutral Higgs bosons can have significant couplings to TV and Z bosons, producing overlapping signatures: these may or may not be distinguishable from backgrounds. The existence of these regions of parameters provides a strong motivation for a detailed experimental simulation of these channels. (C) 2003 Elsevier Science B.V. All rights reserved.