Double-Spin Asymmetry A_{LT} for Polarized Drell-Yan Process in p\bar{p} Collisions: Wandzura-Wilczek Contribution

The longitudinal-transverse spin asymmetry $A_{LT}$ in the polarized Drell-Yan process depends on twist-3 quark distributions of nucleon. In addition to the contributions associated with the twist-3 operators, these distributions contain the "Wandzura-Wilczek (WW)" part, which is determined by a certain integral of twist-2 distributions. The recently obtained empirical information on the transversity allows a realistic estimate of the WW contribution to $A_{LT}$ for the polarized $p\bar{p}$ collisions. Our results indicate that rather large $A_{LT}$ ($\sim 10$%) can be observed in the proposed spin experiments at GSI, with novel pattern as a function of dilepton mass compared with $A_{TT}$ and $A_{LL}$.
Comment: 4 pages, 2 figures; to appear in the proceedings of the 18th International Symposium on Spin Physics (SPIN20008), October 6 - 11, 2008, Charlottesville, Virginia, USA