Drell-Yan double-spin asymmetry ALT in polarized p(p)over-bar collisions: Wandzura-Wilczek contribution

The longitudinal-transverse spin asymmetry A(LT) in the polarized Drell-Yan process depends on the twist-3 spin-dependent distributions of nucleon. In addition to the contributions expressed as matrix element of the twist-3 operators, these distributions contain the so-called Wandzura-Wilczek part, which is completely determined by a certain integral of the twist-2 spin-dependent parton distributions. We demonstrate that the recently obtained empirical information on the transversity distribution allows a realistic estimate of the Wandzura-Wilczek contribution to A(LT) for the case of polarized proton-antiproton collisions. In particular, our results in the Wandzura-Wilczek approximation indicate that rather large A(LT) can be observed in the proposed spin experiments at GSI, and its behavior as a function of dilepton mass obeys novel pattern, compared with the other double-spin asymmetries A(TT) and A(LL). Our results provide a guide for testing a signal of effects originating from the twist-3 operators associated with quark-gluon correlation. (C) 2008 Elsevier B.V. All rights reserved.