Initial state interactions and single spin asymmetries in Drell-Yan processes
By S. Brodsky, D. Hwang, I. Schmidt. 2002
239 citations recorded by the source corpus.
We show that the initial-state interactions from gluon exchange between the incoming quark and the target spectator system lead to leading-twist single-spin asymmetries in the Drell-Yan process H{sub 1}H{sub 2}{sup {up_arrow}} {yields} {ell}{sup +}{ell}{sup -}X. The QCD initial-state interactions produce a T-odd spin-correlation {rvec S}{sub H{sub 2}} {center_dot} {rvec P}{sub H{sub 1}} x {rvec Q} between the target spin and the virtual photon production plane which is not power-law suppressed in the Drell-Yan scaling limit at large photon virtuality Q{sup 2} at fixed x{sub F}. The single-spin asymmetry which arises from the initial-state interactions is not related to the target or projectile transversity distribution {delta}q{sub H}. The origin of the single-spin asymmetry in {pi}p{up_arrow} {ell}{sup +}{ell}{sup -} is a phase difference between two amplitudes coupling the proton target with J{sub p}{sup z} = {+-} 1/2 to the same final-state, the same amplitudes which are necessary to produce a nonzero proton anomalous magnetic moment. The calculation requires the overlap of target light-front wavefunctions with different orbital angular momentum: {Delta}L{sup z} = 1; thus the SSA in the Drell-Yan reaction provides a direct measure of orbital angular momentum in the QCD bound state. The single-spin asymmetry predicted for the Drell-Yan process {pi}p{up_arrow}more » {yields} {ell}{sup +}{ell}{sup -}X is similar to the single-spin asymmetries in deep inelastic semi-inclusive leptoproduction {ell}p{up_arrow} {yields} {ell}{prime}{pi}X which arises from the final-state rescattering of the outgoing quark. The Bjorken-scaling single-spin asymmetries predicted for the Drell-Yan and leptoproduction processes high-light the importance of initial- and final-state interactions for QCD observables.« less
Subfields: Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/bda973cc646b058b10bb38b9be189a8252c3263b
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In Nuclear and High Energy Physics
Citations in the corpus
- k T factorization is violated in production of high-transverse-momentum particles in hadron-hadron collisions (2007, methodology): “Then we review the differences that give factorization with an exact sign reversal in the Sivers function for the Drell-Yan process [9, 10].”