Dilepton production from polarized hadron hadron collisions

Abstract

In this paper we present a comprehensive formalism for dilepton production from the collision of two polarized spin-1 2 hadrons by identifying the general angular distribution of the cross section in combination with a complete set of structure functions. The various structure functions are computed in the parton model approximation where we mainly consider the case when the transverse momentum of the dilepton pair is much smaller than its invariant mass. In this kinematical region dilepton production can be described in terms of transverse momentum dependent parton distributions.

QCD corrections of all structure functions in transverse momentum dependent factorization for Drell-Yan processes

“…Here, the dot product of two vectors is defined with the metric g µν ⊥ and q 2 = q µ q ν g µν ⊥ . Through a carful comparison our results by taking the tree-level result of H = 1 agree with the existing results of factorized form factors in [26,27].…”

“…In the subtractive approach one only calculates in detail the contributions to the structure functions subtracted with the contributions of TMD parton distributions. At leading twist of TMD factorization, the symmetric part of the hadronic tensor has 24 structure functions [26,27]. With the work presented here, it turns out that the one-loop correction is the same for all structure functions.…”

Angular correlations in the double Drell-Yan process

“…Useful information about this frame can e.g. be found in [62,63]. By contrast, we define x axes (and thus the azimuthal angles ϕ i ) starting from a fixed direction in space, whereas in the Collins-Soper frame the x axis is defined such that the proton momenta lie in the x-z plane.…”

Azimuthal asymmetries in single polarized proton-proton Drell-Yan processes

“…[39] and [63]; right panel: definition of azimuthal angles in Ref. [38]. Using the replacements φ → −φ and φS → φS − φ, the definition in the left panel is transformed to that in the right panel.…”

“…Here φ and φ S are the azimuthal angles of the dilepton pair and proton transverse spin with respect to the hadron plane, and we use the convention for the angle definition introduced in Ref. [38]. These types of the asymmetries arise from the coupling of two different chiral-odd parton distributions.…”