Nuclear dependencies of azimuthal asymmetries in the Drell-Yan process

We study nuclear dependencies of azimuthal asymmetries in the Drell-Yan lepton pair production in nucleon-nucleus collisions with polarized nucleons. We use the “maximal two-gluon correlation approximation,” so that we can relate the transverse-momentum-dependent quark distribution in a nucleus to that in a nucleon by a convolution with a Gaussian broadening. We use the Gaussian ansatz for the transverse momentum dependence of such quark distribution functions and obtain the numerical results for the nuclear dependencies. These results show that the $q_T$-integrated azimuthal asymmetries are suppressed.

Figure 1

$R^{cos2\varphi }$ in Eq. (3.14) as a function of $\eta$ for different ${\widehat{q}}_T^{\alpha }$ and the relative width $\zeta$ of the TMD quark distributions.