Cacciari, Matteo Gluon PDF constraints from the ratio of forward heavy-quark production at the LHC at [Formula: see text] and 13 TeV. [electronic resource] - The European physical journal. C, Particles and fields - 610 p. digital Publication Type: Journal Article ISSN: 1434-6044 Standard No.: 10.1140/epjc/s10052-015-3814-x doi