Pinning down the linearly-polarised gluons inside unpolarised protons using quarkonium-pair production at the LHC

Pinning down the linearly-polarised gluons inside unpolarised protons using quarkonium-pair production at the LHC

We show that the production of J/ψ or ϒ pairs in unpolarised pp collisions is currently the best process to measure the momentum distribution of linearly-polarised gluons inside unpolarised protons through the study of azimuthal asymmetries. Not only the short-distance coefficients for such reaction...

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Bibliographic Details
Main Authors: Jean-Philippe Lansberg, Cristian Pisano, Florent Scarpa, Marc Schlegel
Format: Article
Language:English
Published: Elsevier 2018-09-01
Series:Physics Letters B
Online Access:http://www.sciencedirect.com/science/article/pii/S0370269318306075
Description
Summary:We show that the production of J/ψ or ϒ pairs in unpolarised pp collisions is currently the best process to measure the momentum distribution of linearly-polarised gluons inside unpolarised protons through the study of azimuthal asymmetries. Not only the short-distance coefficients for such reactions induce the largest possible cos⁡4ϕ modulations, but analysed data are already available. Among the various final states previously studied in unpolarised pp collisions within the TMD approach, di-J/ψ production exhibits by far the largest asymmetries, in the region studied by the ATLAS and CMS experiments. In addition, we use the very recent LHCb data at 13 TeV to perform the first fit of the unpolarised transverse-momentum-dependent gluon distribution.
ISSN:0370-2693

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