Geometric Scaling from GLAP evolution

We show that the geometric scaling of the total virtual photon-proton cross section data can be explained using standard linear GLAP perturbative evolution with generic boundary conditions in a wide kinematic region. This allows us to single out the region where geometric scaling may provide evidence for parton saturation.Comment: Final version, published in Phys. Rev. Letters. References and minor clarifications added. 4 pages, 5 figures, LaTeX with REVTe

Analytic results for color-singlet production at NNLO QCD with the nested soft-collinear subtraction scheme

We present analytic formulas that describe the fully-differential production of color-singlet final states in qq̄ and gg annihilation, including all the relevant partonic channels, through NNLO QCD. We work within the nested soft-collinear scheme, which allows the fully local subtraction of infrared divergences.We demonstrate analytic cancellation of soft and collinear poles and present formulas for the finite parts of all integrated subtraction terms. These results provide an important building block for calculating NNLO QCD corrections to arbitrary processes at hadron colliders within the nested soft-collinear subtraction scheme

Nested soft-collinear subtractions in NNLO QCD computations

We discuss a modification of the next-to-next-to-leading order (NNLO) subtraction scheme based on the residue-improved sector decomposition that reduces the number of double-real emission sectors from five to four. In particular, a sector where energies and angles of unresolved particles vanish in a correlated fashion is redundant and can be discarded. This simple observation allows us to formulate a transparent iterative subtraction procedure for double-real emission contributions, to demonstrate the cancellation of soft and collinear singularities in an explicit and (almost) process-independent way and to write the result of a NNLO calculation in terms of quantities that can be computed in four space-time dimensions. We illustrate this procedure explicitly in the simple case of O(α2s)O(αs2) gluonic corrections to the Drell–Yan process of qq¯qq¯ annihilation into a lepton pair. We show that this framework leads to fast and numerically stable computation of QCD corrections