Spin Physics with a fixed-target experiment at the LHC

Echevarria, Miguel G.; Brodsky, Stanley J.; Cavoto, G.; Da Silva, C.; Donato, F.; Ferreiro, E.G.; Hadjidakis, C.; Hřivnác\v ová, I.; Kikoła, D.; Klein, A.; Kurepin, A.; Kusina, A.; Lansberg, J.P.; Lorcé, C.; Lyonnet, F.; Makdisi, Y.; Massacrier, L.; Porteboeuf, S.; Quintans, C.; Rakotozafindrabe, A.; Robbe, P.; Scandale, W.; Schienbein, I.; Seixas, J.; Shao, H.S.; Signori, A.; Topilskaya, N.; Trzeciak, Barbara; Uras, A.; Wagner, J.; Yamanaka, N.; Yang, Z.; Zelenski, A.

doi:10.22323/1.346.0063

Abstract

The multi-TeV proton and ion beams of the LHC would allow for the most energetic fixed-target experiment ever.
In particular, $pp$, $p$d and $p$A collisions could be performed at $\sqrt{s_{NN}}$ = 115~GeV, as well as Pb$p$ and PbA collisions at $\sqrt{s_{NN}}$ = 72~GeV, in a parasitic way by making use of the already existing LHCb and ALICE detectors in fixed-target mode.
This would offer the possibility to carry out a ground-breaking physics program, to study the nucleon and nuclear structure at high $x$, the spin content of the nucleon and the phases of the nuclear matter from a new rapidity viewpoint.
In this talk I focus on the spin physics axis of the full program developed so far by the AFTER@LHC study group.