QCD corrections to the spin-dependent Drell-Yan process and a global subtraction scheme

Abstract

We present QCD corrections to the Drell-Yan process in the transversely polarized, longitudinally polarized, and unpolarized cases. The analytical results are presented in a form valid for all ndimensional regularization schemes. A universal mass factorization scheme is presented in which the results reduce to those of dimensional reduction. The connection between the parton distributions and fragmentation functions of dimensional reduction and those of dimensional regularisation is elucidated in a simple manner.Numerical results are presented for proton-proton collisions at energies relevant to ,the BNL Relativistic Heavy Ion Collider. The perturb&w stability of the transverse and longitudinal asymmetries is investigated.PACS number(s): 12.38. Bx, 13.75.Cs, 13.85.Qk, 13.88.+e

QCD corrections to double and single spin asymmetries in vector boson production at polarized hadron colliders

“…The QCD corrections to the total asymmetries (integrated over the vector boson rapidity y) in Drell-Yan process and vector boson production at RHIC have recently been studied in [18,19]. Comparison with these provides a strong cross-check of our results.…”

“…Having a complete calculation of the two-loop splitting functions available, it is now furthermore possible to define consistent scheme transformation prescriptions [20,23] for parton dis-tributions, splitting functions and parton level cross sections at next-to-leading order. Possible choices of the factorization scheme in polarized and unpolarized Drell-Yan process are elaborated in great detail in [18,19]. In our study, we shall only work in the MS scheme (with an appropriate correction for spurious terms generated due to the chosen representation of γ 5 ), which is identical to the scheme used in the recent determinations of polarized parton distributions at next-to-leading order [21,22].…”

Next-to-leading order evolution of polarized and unpolarized fragmentation functions

“…On the other hand, the 'γ 5 -effect' described above has been known to occur in the HVBM scheme for some time [37,38,35,39] and is purely artificial in the sense that it is related to helicity non-conservation at the quark-gluon tree-level vertex in d = 4 dimensions as expressed by the non-vanishing of the rhs of Eq. (46).…”

“…Once this is done, all remaining differences between the results for a NLO quantity in dimensional regularization and in dimensional reduction can only be due to the effects of mass singularities. They are fully accounted for [44,45,39] by the differences between the d-dimensional LO splitting functions (as to be obtained in dimensional regularization) and the four-dimensional ones (corresponding to dimensional reduction). In other words, the breakdown of the supersymmetric relation for dimensional regularization is entirely blamed on the breakdown of this relation in the ∼ ǫ-parts of the d-dimensional LO splitting functions of dimensional regularization.…”

“…For our purposes we only need to consider (39) in the combination appearing on the lhs of Eq. (62) and in the supersymmetric limit:…”