Low-mass dilepton production in pppp and AAAA collisions

We adopt a factorized QCD formalism to describe the transverse momentum distribution of low-mass lepton pairs produced in $pp$ collisions, when the pair transverse momentum $Q_T \gg Q$, with the pair's invariant mass $Q$ as low as $Q \sim \Lambda_{\mathrm{QCD}}$. We extend this formalism to dilepton production in $AA$ collisions by including the nuclear-dependent power correction due to parton multiple scattering.Comment: 4 pages, 1 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse