The New Δq(x) at HERMES

摘要

Since the HERMES Collaboration published its 5-flavor Δq(x) extraction in 2005 [1], several aspects of the analysis and its related longitudinal double-spin asymmetries have been revisited. Work has been done to improve statistical uncertainties, more precisely determine previously overestimated systematic uncertainties, and to extract new related quantities. This presentation deals with two features of this new analysis. First, the phi dependence of the asymmetry A_1 is presented. No ph dependence is observed within the precision of the vailable statistics. Second, a novel approach for estimating the systematic uncertainty contribution to the extracted Δq(x) values from uncertainty in the tune of the fragmentation model has been developed and is discussed.