QCD Factorized Drell-Yan Cross Section at Large Transverse Momentum

We derive a new factorization formula in perturbative quantum chromodynamics for the Drell-Yan massive lepton-pair cross section as a function of the transverse momentum QT of the pair. When QT is much larger than the pair’s invariant mass Q, this factorization formula systematically resums the logarithmic contributions of the type αs ln (QT /Q 2) to all orders in the strong coupling αs. When QT ∼ Q, our formula yields the same Drell-Yan cross section as conventional fixed order QCD perturbation theory. We show that resummation is important when the collision energy √ S is large enough and QT ≫ Q, and we argue that perturbative expansions are more stable and reliable in terms of the modified factorization formula. PACS Numbers: 12.38.Bx, 12.38.cy, 13.85.Qk, 14.70.Bh Typeset using REVTEX 1