Abstract
Based on previous studies of hard exclusive leptoproduction of pions in which the essential role of the pion pole and the transversity generalized parton distributions (GPDs) has been pointed out, we present predictions for the four partial cross sections of the exclusive Drell–Yan process, π−p→l−l+n.
Highlights
In recent years hard exclusive leptoproduction of mesons and photons have been studied intensively by both experimentalists and theoreticians
The data on the cross section for π+ leptoproduction [5, 6] demonstrate the prominent role of the contribution from the pion pole at small invariant momentum transfer, t, and it became evident that it is to be calculated as an one-particle-exchange (OPE) term rather than from the generalized parton distributions (GPDs) E [7]
Second important observation has been made in [3, 4]: The interpretation of the transverse target spin asymmetries in π+ leptoproduction measured by the HERMES collaboration [8] necessitates contributions from transversely polarized photons which are to be modelled by transversity GPDs within the handbag approach
Summary
In recent years hard exclusive leptoproduction of mesons and photons have been studied intensively by both experimentalists and theoreticians. Future data on the exclusive pion-induced Drell-Yan process may reveal whether or not our present understanding of hard exclusive processes in terms of convolutions of GPDs and hard subprocesses holds for time-like photons. This is a non-trivial issue because the physics in the time-like region is complicated and often not understood. Even the semiinclusive Drell-Yan process was difficult to understand It took a long time before the discrepancy between the theoretical predictions and experiment, known as the K-factor, has been explained as threshold logarithms [14, 15] representing gluon radiation resummed to next-leading-log (NLL) accuracy
Sign-in/Register to view highlights & summary 
Published Version (
Free)
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 call