Quarkonium Physics at a Fixed-Target Experiment using the LHC Beams

• Published in: Few-body systems Vol. 53; no. 1-2; pp. 11 - 25
• Main Authors: Lansberg, J. P., Brodsky, S. J., Fleuret, F., Hadjidakis, C.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.07.2012; Springer Nature B.V
• Subjects: Atomic; Hadrons; Heavy Ions; Molecular; Nuclear Physics; Optical and Plasma Physics; Particle and Nuclear Physics; Particle physics; Physics; Physics and Astronomy; Gluon Distribution; Large Hadron Collider; PbPb Collision; Quarkonium Production; Charmonium Production
• ISSN: 0177-7963; 1432-5411
• DOI: 10.1007/s00601-012-0445-8

We outline the many quarkonium-physics opportunities offered by a multi-purpose fixed-target experiment using the p and Pb Large Hadron Collider (LHC) beams extracted by a bent crystal. This provides an integrated luminosity of 0.5 fb −1 per year on a typical 1 cm-long target. Such an extraction mode does not alter the performance of the collider experiments at the LHC. With such a high luminosity, one can analyse quarkonium production in great details in pp , pd and pA collisions at GeV and at GeV in Pb A collisions. In a typical pp ( pA ) run, the obtained quarkonium yields per unit of rapidity are 2–3 orders of magnitude larger than those expected at RHIC and about, respectively, 10(70) times larger than for ALICE. In Pb A , they are comparable. By instrumenting the target-rapidity region, the large negative- x F domain can be accessed for the first time, greatly extending previous measurements by Hera-B and E866. Such analyses should help resolving the quarkonium-production controversies and clear the way for gluon PDF extraction via quarkonium studies. The nuclear target-species versatility provides a unique opportunity to study nuclear matter and the features of the hot and dense matter formed in Pb A collisions. A polarised proton target allows the study of transverse-spin asymmetries in J / ψ and production, providing access to the gluon and charm Sivers functions.