The small x gluon and b\bar{b} production at the LHC

TL;DR

This paper investigates open bar{b} production at the LHC to better understand the gluon distribution at very low x, proposing a method to reduce theoretical uncertainties and enabling experimental exploration of gluon behavior down to x ~ 10^{-5}.

Contribution

It introduces a selection criterion based on transverse momentum balance to significantly reduce factorization scale uncertainty in bar{b} production analysis.

Findings

Reduced scale uncertainty with the momentum balance cut.

Potential to study gluon distribution at x ~ 10^{-5}.

Cross section estimates using recent PDFs.

Abstract

We study open b\bar{b} production at large rapidity at the LHC in an attempt to pin down the gluon distribution at very low x. For the LHC energy of 7 TeV, at next-to-leading order (NLO), there is a large factorization scale uncertainty. We show that the uncertainty can be greatly reduced if events are selected in which the transverse momenta of the two B-mesons balance each other to some accuracy, that is |\vec p_{1T}+\vec p_{2T}| < k_0. This will fix the scale \mu_F \simeq k_0, and will allow the LHCb experiment, in particular, to study the x-behaviour of gluon distribution down to x ~ 10^{-5}, at rather low scales, \mu ~ 2 GeV. We evaluate the expected cross sections using, for illustrative purposes, various recent sets of Parton Distribution Functions.