Higgs–Boson Production Induced by Bottom Quarks

Bottom quark–induced processes are responsible for a large fraction of the LHC discovery potential, in particular for supersymmetric Higgs bosons. Recently, the discrepancy between exclusive and inclusive Higgs boson production rates has been linked to the choice of an appropriate bottom factorization scale. We investigate the process kinematics at hadron colliders and show that it leads to a considerable decrease in the bottom factorization scale. This effect is the missing piece needed to understand the corresponding higher order results. Our results hold generally for charged and for neutral Higgs boson production at the LHC as well as at the Tevatron. The situation is different for single top quark production, where we find no sizeable suppression of the factorization scale. Turning the argument around, we can specify how large the collinear logarithms are, which can be resummed using the bottom parton picture. I. HIGGS BOSONS AT THE LHC The combined LEP precision measurements [1] suggest the existence of a light Higgs boson. In the case of a single Standard Model Higgs boson the LHC promises multiple coverage for any Higgs boson mass, which will enable us to measure its different decay modes and extract the couplings [2]. For a supersymmetric Higgs sector this coverage has to rely on fewer Higgs boson decay channels [2,3]. This is a direct consequence of the structure of the Higgs sector: while the Minimal Supersymmetric Standard Model (MSSM) predicts a light Higgs boson, it also predicts an enhancement of the coupling to down-type fermions, at the expense of the branching fractions to gauge bosons. This enhancement is an outcome from the two Higgs doublet structure in the MSSM: one doublet is needed to give mass to up-type, the other to down-type fermions. The vacuum expectation values of the two doublets are different, parameterized by tanβ = v2/v1. In addition to a light scalar Higgs boson, the two Higgs doublet model includes a heavy scalar, a pseudoscalar, and a charged Higgs boson. None of these additional particles have a mass bounded from above, apart from triviality or unitarity bounds. Of course, observables linked to properties of a light Higgs boson can serve as a probe if a new scalar particle is indeed consistent with the Standard Model Higgs boson [4,5]. There is, however, only one way to conclusively tell the supersymmetric Higgs sector from its Standard Model counterpart: to discover the additional heavy Higgs bosons and determine their properties.