One-loop $gg\to b\bar{b}$ effects in the main irreducible background to exclusive $H\to b\bar{b}$ production at the LHC

Abstract

We calculate the amplitude of $gg\to b\bar{b}$ production for the colour singlet, J z =0, di-gluon state at $\mathcal{O}(\alpha_{\mathrm{S}}^{2})$ order. We consider the cancellation and a realistic cut-off, of the infrared divergent terms. We show that the one-loop radiative QCD contributions effectively reduce the Born level result for the central exclusive $b\bar{b}$ cross section at the LHC. This process is essentially the only irreducible QCD background to the exclusive $H\to b\bar{b}$ signal.