The rapidity gap Higgs signal at LHC

Abstract

We compare the W W and pomeron-pomeron fusion mechanisms for the doublediffractive production of a Higgs boson. We determine the suppression of the 'rapidity gap' pomeron-pomeron fusion events due to QCD radiative effects. In particular we use leading log techniques to estimate the cross sections for both exclusive and inclusive double-diffractive Higgs production at LHC energies. The same approach can be applied to the double-diffractive central production of large E T dijets. These two processes provide one of the most justified applications of various aspects of leading logarithm QCD techniques.

Rates for rapidity gap Higgs production

“…As in Refs. [4,6,7,8,12,15], we adopt the two-gluon exchange picture of the Pomeron, where the amplitude for the double-diffractive process is shown in Fig. 1.…”

“…Either non-perturbative gluons are used in which the propagator is modified so as to reproduce the total cross section [4,8], or a perturbative QCD estimate is made [7] using an unintegrated, skewed gluon density that is determined from the conventional gluon obtained in global parton analyses. In this respect, it has been emphasized [16] (see also [6,7] that the non-perturbative normalisation based on the value of the elastic or total cross section fixes the diagonal gluon density atx ∼ ℓ T / √ s where the transverse momentum ℓ T is small, namely ℓ T < 1 GeV. Thus the value ofx is even smaller than…”

“…S 2 is the probability that the gaps are not filled by secondary particles generated by soft rescattering, see for instance [2,3,5,6,7,14,17,18,19]. The second factor, T 2 , is the price to pay for not having gluon radiation in the hard subprocess gg → M. The estimates of the survival factor S 2 strongly depend on the models for soft hadron rescattering, which causes the main uncertainty in evaluation of the double-diffractive cross section.…”

“…is given in [6,7,15], where it was found that the event rate is much larger. However, in the inclusive case the large multiplicity of secondaries poses an additional problem in identifying the Higgs boson.…”

“…In order to use the 'missing-mass' method to search for an intermediate mass Higgs boson, via the H → bb decay mode, we have to estimate the QCD background which arises from 3 Moreover, the effective anomalous dimension, γ, of the gluon distribution (xg(x, Q 2 T ) ∼ (Q 2 T ) γ ) additionally suppresses the contribution from the low Q 2 T domain [6]. 4 The only exceptions are our results in Refs.…”