Measurement of the $b$-quark production cross-section in 7 and 13 TeV $pp$ collisions

TL;DR

This paper reports measurements of b-quark production cross-sections at 7 and 13 TeV in proton-proton collisions, comparing results with theoretical models and analyzing the dependence on pseudorapidity within the LHCb detector acceptance.

Contribution

It provides the first detailed measurement of b-quark production cross-sections at these energies as a function of pseudorapidity, using semileptonic decay channels.

Findings

Cross-sections are 72.0 μb at 7 TeV and 144 μb at 13 TeV.

The cross-section ratio between 13 TeV and 7 TeV is 2.00.

Good agreement with theory at 7 TeV, some discrepancy at 13 TeV.

Abstract

Measurements of the cross-section for producing \bquark quarks in the reaction $pp\to b\bar{b} X$ are reported in 7 and 13 TeV collisions at the LHC as a function of the pseudorapidity $\eta$ in the range $2<\eta<5$ covered by the acceptance of the LHCb experiment. The measurements are done using semileptonic decays of $b$-flavored hadrons decaying into a ground-state charmed hadron in association with a muon. The cross-sections in the covered $\eta$ range are $72.0\pm 0.3\pm6.8~\mu$b and $144\pm 1\pm 21~\mu$b for 7 and 13 TeV. The ratio is $2.00\pm0.02\pm0.26$, where the quoted uncertainties are statistical and systematic, respectively. The agreement with theoretical expectation is good at 7 TeV, but differs somewhat at 13 TeV. The measured ratio of cross-sections is larger at lower $\eta$ than the model prediction.