Production of light non-minimal neutral Higgs bosons via gluon-gluon fusion at HERA

Gluon-gluon fusion can be a significant source of light non-minimal neutral Higgs bosons in certain non-supersymmetric models in which the coupling of the Higgs particles to the down-type quarks is enhanced. We study this mechanism for the HERA collider where it occurs through the hadronic interaction of quasi-real photons with protons. The cross section is calculated for the case of fixed energy γp scattering with energy Eγp = 170 GeV and for the ep scattering. We find that the rate is large for small Mh and tan β ∼ O(mtmb). In the region Mh ≲ 30 GeV, gg fusion dominates over the photon-gluon production mechanism where the Higgs boson is produced by bremsstrahlung off a b-quark. In the tagged γp case we expect a clear signature for the τ+τ− final state for tan β ⋍ 30 and 5 ≲ Mh ≲ 30 GeV at positive centre-of-mass rapidities of the Higgs particle.