Spin studies via Drell-Yan processes at PANDA

摘要

The nucleon structure is still not completely understood. A transverse momentum dependent description of the nucleon structure is a crucial milestone for several forthcoming studies in a wide range of experimental scenarios. By means of antiproton beams, possibly polarized in a later stage of the project, with a beam momentum up to 15 GeV/c, which will be available at the future FAIR facility, the nonperturbative region of QCD is planned to be investigated. One of the main goals of the forthcoming experiments at FAIR is the study of Drell-Yan lepton pairs by means of proton-antiproton annihilations, taking also advantage of the expected high luminosity. The Drell-Yan production is a unique tool to access the spin dependent properties of the nucleon, and in particular its transverse degrees of freedom. Transverse Momentum Dependent (TMD) Parton Distribution Functions (PDFs), i.e. the Boer-Mulders function, the Sivers function, and the Transversity, could be deeply investigated by means of experimental angular asymmetries. In later stages of FAIR, single- and double-spin asymmetries could be investigated as well. The Drell-Yan physics program which could be accessed at FAIR with the PANDA experiment will be discussed in details, in the light of existing results in the field.