High-energy factorization for the Drell-Yan process in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mover accent="true"><mml:mi>p</mml:mi><mml:mo stretchy="false">¯</mml:mo></mml:mover></mml:math> collisions with new unintegrated PDFs
Maxim Nefedov, V. A. Saleev
Abstract
The formalism for uniform description of the Drell-Yan transverse-momentum spectrum is presented in a framework of high-energy factorization, which smoothly interpolates between Collins-Soper-Sterman formalism at $|{\mathbf{q}}_{T}|\ensuremath{\ll}Q$ and usual collinear parton model at $|{\mathbf{q}}_{T}|\ensuremath{\sim}Q\ensuremath{\ll}\sqrt{S}$. The new formula for deriving unintegrated parton distribution functions (UPDFs) from collinear ones is introduced, which leads to excellent description of the shape of $Z$-boson $|{\mathbf{q}}_{T}|$-spectrum at high energies up to $|{\mathbf{q}}_{T}|/\sqrt{S}\ensuremath{\simeq}0.02$. Description of normalized $|{\mathbf{q}}_{T}|$-distributions at low energies is achieved via the fit of nonperturbative parameters of quark UPDFs. Reasonable description of angular distributions of leptons in the dilepton center-of-mass frame is also obtained with new UPDFs.