Single Heavy MSSM Higgs Production at e+e− Linear Collider

The measurement of the properties of the heavy Higgs bosons H, A and H± of Minimal Supersymmetric Standard Model (MSSM) could tell us a lot about the MSSM parameters. The mass of the heavy Higgses are related to the overall scale mA0 (CP-odd Higgs mass), with a distinctive mass relation between mA0 , mH0 andmH± in MSSM. The heavy Higgs couplings to the fermions are sensitive to tanβ (the ratio of the two Higgs vacuum expectation values) and Yukawa couplings, and its couplings to the sfermions are sensitive to the trilinear A-terms. Unlike the light CP-even Higgs h, whose couplings become increasingly insensitive to the MSSM parameters in the decoupling limit (mA0 mZ), the couplings of the heavy Higgs bosons are always sensitive to the MSSM parameters. Thus, measurements of the properties of the heavy MSSM Higgs bosons are very valuable, especially in the decoupling limit. Discovery of the heavy Higgs bosons, however, poses a special challenge at future colliders, contrary to the case of the light CP-even Higgs h, when the discovery is almost certain at current and future collider experiments. Run II of the Fermilab Tevatron, now in progress, has a limited reach for the neutral heavy MSSM Higgs bosons H and A at small mA0 and large tanβ. The charged Higgs boson H ± can be discovered in top quark decays for mH± mt and large tanβ [1, 2]. The CERN Large Hadron Collider (LHC) has a much greater reach for heavy MSSM Higgs boson discovery at moderate to large values of tan β via the process of H and A decays to τ pairs [3, 4] and the charged MSSM Higgs boson H± mode: gb → tH− with H− → τ ν̄ [4, 5]. The absence of a Higgs boson discovery at the CERN LEP-2 experiments implies that 0.5 < tanβ < 2.4 and mA0 < 91.9 GeV are excluded at 95% confidence level [6]. This leaves a wedge-shaped region of parameter space at moderate tanβ in which the heavy MSSM Higgs bosons could be missed at the LHC. At a future high energy e+e− linear collider (LC), the heavy Higgs bosons will be produced in pairs, if it is kinematically allowed. The dominant production modes are e+e− → HA and e+e− → H+H−. At large mA0 , mA0 mH0 mH± up to mass splittings of order mZ/mA0 , so that the pair-production modes are kinematically allowed only if mA0 0.5 √ s. In particular, the pair-production modes are limited to mA0 250 GeV (mA0 500 GeV) at a LC with √ s = 500 GeV ( √ s = 1000 GeV). In this talk we consider the production of one of the heavy Higgs bosons in association