Speaker
Samuel F. Romera
(University of the Basque Country UPV/EHU)
Description
Transverse-momentum-dependent (TMD) parton distribution functions encode the three-dimensional structure of the proton, but the gluon sector remains far less constrained than the quark one. Double $J/\psi$ production at the LHCb is a particularly clean probe of gluon TMDs: at LHCb kinematics it is dominated by gluon-gluon fusion, and in the region of small pair transverse momentum it is sensitive, within TMD factorisation, to the unpolarised gluon distribution $f_1^g$ and, through azimuthal modulations, to the linearly polarised one, $h_1^{\perp g}$. We present a first determination of $f_1^g$ from a fit to LHCb measurements of $J/\psi$-pair production in pp collisions at $\sqrt{s} = 13 \,$TeV.
Author
Samuel F. Romera
(University of the Basque Country UPV/EHU)