Higgs production at the LHC in warped extra-dimensional models
Résumé
The extra-dimensional model in which the bulk geometry is a slice of anti-de Sitter space is a particularly attractive extension of the Standard Model as it allows to address the gauge hierarchy problem, as well as the mass hierarchy prevailing among fermions. However, to allow for the masses of the Kaluza-Klein excitations of the known particles to be near the Terascale without conflicting with the high-precision electroweak data, one needs to promote the gauge symmetry to a left-right structure SU(2)_L x SU(2)_R x U(1) which incorporates a new quark b', the SU(2)_R doublet partner of the heavy top quark. We show that this new quark will contribute to the main production process of Higgs bosons at the LHC: the gluon-gluon fusion mechanism which proceeds through heavy quark triangular loops. In most of the parameter space in which the measured values of the heavy t,b quark masses are reproduced, the gg->Higgs production cross section is significantly altered, even if the b' quark is too heavy to be directly accessible, m_{b'} > ~1 TeV. In particular, the rate can be suppressed by an order of magnitude compared to the standard case as a result of the destructive interference of the t and b' contributions, rendering the Higgs search at the LHC more challenging.