Variation of the cross section for e+e- --> W+H- in the Minimal Supersymmetric Standard Model

We study the loop-induced process e+e- --> W+H- in the Minimal Supersymmetric Standard Model (MSSM). This process allows the charged Higgs boson to be produced in e+e- collisions when its mass is larger than half the center-of-mass energy, so that e+e- --> H+H- is kinematically forbidden. By scanning over the MSSM parameters subject to experimental constraints we examine the range of values possible for this cross section. We find that, in regions of parameter space where this cross section is large enough to be of interest, the contributions from supersymmetric particles typically increase the cross section by 50-100% compared to the non-supersymmetric two Higgs doublet model result. Choosing a few typical MSSM parameter sets, we show the regions in the m_{H^{\pm}}-tan(beta) plane in which at least 10 W^{\pm}H^{\mp} events would be produced at the e+e- collider for m_{H^{\pm}} >= sqrt(s)/2. We also show that including radiative corrections to the MSSM Higgs sector has only a small effect on the cross section.