Precision Determination of the Small-x Gluon from Charm Production at LHCb

Gauld, Rhorry; Rojo, Juan

Abstract

The small-x gluon in global fits of parton distributions is affected by large uncertainties from the lack of direct experimental constraints. In this Letter, we provide a precision determination of the small-x gluon from the exploitation of forward charm production data provided by LHCb for three different center-ofmass (c.m.) energies: 5 TeV, 7 TeV, and 13 TeV. The LHCb measurements are included in the parton distribution function (PDF) fit by means of normalized distributions and cross-section ratios between data taken at different c.m. values, R13=7 and R13=5. We demonstrate that forward charm production leads to a reduction of the PDF uncertainties of the gluon down to x ≃ 10−6 by up to an order of magnitude, with implications for high-energy colliders, cosmic ray physics, and neutrino astronomy.

• Journal Article Type: Article
• Acceptance Date: Nov 4, 2016
• Online Publication Date: Feb 15, 2017
• Publication Date: Feb 15, 2017
• Deposit Date: Jul 26, 2017
• Publicly Available Date: Jul 26, 2017
• Journal: Physical Review Letters
• Print ISSN: 0031-9007
• Electronic ISSN: 1079-7114
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 118
• Issue: 7
• Article Number: 072001
• DOI: https://doi.org/10.1103/physrevlett.118.072001
• Public URL: https://durham-repository.worktribe.com/output/1353524