Interference of Higgs boson resonances in μ+μ-→χ0iχ0j with longitudinal beam polarization

We study the interference of resonant Higgs boson exchange in neutralino production in μ+μ- annihilation with longitudinally polarized beams. We use the energy distribution of the decay lepton in the process χ0j→l±l± to determine the polarization of the neutralinos. In the CP-conserving minimal supersymmetric standard model a non-vanishing asymmetry in the lepton energy spectrum is caused by the interference of Higgs boson exchange channels with different CP-eigenvalues. The contribution of this interference is large if the heavy neutral bosons Hand Aare nearly degenerate. We show that the asymmetry can be used to determine the couplings of the neutral Higgs bosons to the neutralinos. In particular, the asymmetry allows one to determine the relative phase of the couplings. We find large asymmetries and cross sections for a set of reference scenarios with nearly degenerate neutral Higgs bosons. (orig.)