Nuclear Dependence of Azimuthal Asymmetry in Semi-Inclusive Deep Inelastic Scattering

Semi-inclusive deeply inelastic scattering (SIDIS) cross sections can be expressed as a series of products of colinear hard parts and transverse-momentum-dependent (TMD) parton distributions and correlations within the framework of a generalized factorization in the small transverse momentum region. Within such framework, the aszimuthal asymmetry of unpolarized SIDIS in the small transverse momentum region will depend on twist-2, 3 and 4 TMD quark distributions in target nucleons or nuclei. Nuclear broadening of these twist 2, 3, and 4 quark distributions due to final-state multiple scattering in nuclei is investigated and the nuclear dependence of the azimuthal asymmetry is studied. It is shown that the azimuthal asymetry is suppressed by multiple parton scattering and the transverse momentum dependence of the suppression depends on the relative shape of the different quark distributions in the nucleon