2006/10/24 by Andrea Bianconi, Marco Radici
Physics and Astronomy · #Asymmetry #Azimuth #Function (biology) #High-Energy Particle Collisions Research #Kinematics #Parametrization (atmospheric modeling) #Particle physics theoretical and experimental studies #Parton #Pion #Quantum Chromodynamics and Particle Interactions #Valence (chemistry) #hep-ph
paper · pdf · doi:10.1088/0954-3899/34/7/002
published as J.Phys.G34:1595-1610,2007 · 13 pages, 9 figures in eps format
arxiv created 2006/10/24 · openalex publication_date 2007/05/02 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We perform numerical simulations of the Sivers effect from single-spin asymmetries in Drell–Yan processes on transversely polarized protons. We consider colliding antiprotons and pions at different kinematic conditions of interest for the future planned experiments. We conventionally name 'framework I' the results obtained when properly accounting for the various flavour-dependent polarized valence contributions in the numerator of the asymmetry and for the unpolarized nonvalence contribution in its denominator. We name 'framework II' the results obtained when taking a suitable flavour average of the valence contributions and neglecting the nonvalence ones. We compare the two methods, also with respect to the input parametrization of the Sivers function which is extracted from data with approximations sometimes intermediate between frameworks I and II. Deviations between the two approaches are found to be small except for dilepton masses below 3 GeV. The Sivers effect is used as a test case; the arguments can be generalized to other interesting azimuthal asymmetries in Drell–Yan processes, such as the Boer–Mulders effect.