Studies of Transverse-Momentum-Dependent distributions with A Fixed-Target ExpeRiment using the LHC beams (AFTER@LHC)

Massacrier, L.;Anselmino, M.;Arnaldi, R.;Brodsky, S. J.;Chambert, V.;den Dunnen, W.;Didelez, J. P.;Genolini, B.;Ferreiro, E. G.;Fleuret, F.;Gao, Y.;Hadjidakis, C.;Hřivnáčová, I.;Lansberg, J. P.;Lorcé, C.;Mikkelsen, R.;Pisano, C.;Rakotozafindrabe, A.;Rosier, P.;Schienbein, I.;Schlegel, M.;Scomparin, E.;Trzeciak, B.;Uggerhøj, U. I.;Ulrich, R.;Yang, Z.

2016-01-01

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Abstract

We report on the studies of Transverse-Momentum-Dependent distributions (TMDs) at a future fixed-target experiment - AFTER@LHC- using the p(+) or Pb ion LHC beams, which would be the most energetic fixed-target experiment ever performed. AFTER@LHC opens new domains of particle and nuclear physics by complementing collider-mode experiments, in particular those of RHIC and the EIC projects. Both with an extracted beam by a bent crystal or with an internal gas target, the luminosity achieved by AFTER@LHC surpasses that of RHIC by up to 3 orders of magnitude. With an unpolarised target, it allows for measurements of TMDs such as the Boer-Mulders quark distributions and the distribution of unpolarised and linearly polarised gluons in unpolarised protons. Using polarised targets, one can access the quark and gluon Sivers TMDs through single transverse-spin asymmetries in Drell-Yan and quarkonium production. In terms of kinematics, the fixed-target mode combined with a detector covering eta(lab) is an element of [1, 5] allows one to measure these asymmetries at large x(up arrow) in the polarised nucleon.