Drell-Yan phenomenology in the color dipole picture revisited

Abstract

An extensive phenomenological study of the Drell-Yan (DY) process in $pp$ collisions at various energies is performed in the color dipole framework. Besides previously studied ${\ensuremath{\gamma}}^{*}$ production we also include the ${Z}^{0}$ contribution relevant at large dilepton invariant masses. We investigate the DY cross section differential in invariant mass, rapidity and transverse momentum of the dilepton pair in $pp$ collisions at the RHIC and LHC. We consider three different phenomenological models for the dipole cross section and find a reasonable agreement with the available data. As a further test of the color dipole formalism, we also study the correlation function in azimuthal angle between the dilepton pair and a forward pion $\mathrm{\ensuremath{\Delta}}\ensuremath{\phi}$ for different energies, dilepton rapidities and invariant masses. The characteristic double-peak structure of the correlation function around $\mathrm{\ensuremath{\Delta}}\ensuremath{\phi}\ensuremath{\simeq}\ensuremath{\pi}$ found for very forward pions and low-mass dilepton pairs is sensitive to the saturation effects and can be tested by future DY measurements in $pp$ collisions.