Abstract
We report on the opportunities for spin physics and Transverse-Momentum Dependent distribution (TMD) studies at a future multi-purpose fixed-target experiment using the proton or lead ion LHC beams extracted by a bent crystal. The LHC multi-TeV beams allow for the most energetic fixed-target experiments ever performed, opening new domains of particle and nuclear physics and complementing that of collider physics, in particular that of RHIC and the EIC projects. The luminosity achievable with AFTER@LHC using typical targets would surpass that of RHIC by more that 3 orders of magnitude in a similar energy region. In unpolarised proton-proton collisions, AFTER@LHC allows for measurements of TMDs such as the Boer-Mulders quark distributions, the distribution of unpolarised and linearly polarised gluons in unpolarised protons. Using the polarisation of hydrogen and nuclear targets, one can measure transverse single-spin asymmetries of quark and gluon sensitive probes, such as, respectively, Drell-Yan pair and quarkonium production. The fixed-target mode has the advantage to allow for measurements in the target-rapidity region, namely at large x^uparrow in the polarised nucleon. Overall, this allows for an ambitious spin program which we outline here.
Highlights
More than ten years ago, RHIC opened a new era in the study of spin physics at relativistic energies in being the first collider of polarised protons
A fixed-target experiment using the LHC beams can provide us with extremely complementary measurements to those made at RHIC and at lower energy fixed target projects, such as COMPASS and P1027 or P1039, which are dedicated to spin physics or Transverse-Momentum Dependent distribution (TMD) extraction
The fixed-target mode is very well adapted for measurements at large x in the target
Summary
More than ten years ago, RHIC opened a new era in the study of spin physics at relativistic energies in being the first collider of polarised protons. Much more can be done [6] if the multi-TeV proton LHC beams are extracted and sent to a fixed target, the latter being polarised or not In the former case, one can study a number of target (transverse) spin asymmetries, called single transverse spin asymmetries (STSA). EPJ Web of Conferences a fixed-target experiment allow for rather low transversemomentum measurements, one can perform a number of studies of Boer-Mulders function for the quark sector or of the distribution of polarised gluons in unpolarised nucleons. In this context, it is useful to recall the critical advantages of a fixed-target experiment compared to a collider one, i.e. These first two advantages are relevant for the topics to be discussed here and discussed in [7, 8], whereas the latter two are more relevant for heavy-ion physics previously discussed in [9,10,11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
