Ambiguities in the definition of spin-dependent parton distributions

Abstract

<p>We investigate the ambiguities in defining polarized parton distributions. We point out that in addition to the well-known renormalization scheme dependence in the unpolarized case, there are extra ambiguities in defining polarized parton distributions. These include the definition of [gamma]5 in d-dimension and interpretation of the anomalous contribution. Here, a new renormalization/factorization scheme called UV Subtraction (UVS) is proposed. In the new UVS scheme, it exploits the freedom in renormalization to eliminate the ambiguities arising from [gamma]5 and anomalous contribution. We also discuss the consequences of these ambiguities on the calculable short-distance partonic hard parts and corresponding physical observables in processes like polarized DIS and Drell-Yan Production.</p>