Speaker
Francesco Hautmann
(University of Oxford)
Description
Collinear and transverse momentum dependent (TMD) parton densities are obtained from fits to precision measurements of deep inelastic scattering (DIS) cross sections at HERA. The parton densities are evolved
by DGLAP evolution with next-to-leading-order (NLO) splitting functions using the parton branching method, allowing one to determine simultaneously collinear and TMD densities for all flavors over a wide range in
x, μ2 and kt, relevant for predictions at the LHC. The DIS cross section is computed from the parton
densities using perturbative NLO coefficient functions. Parton densities satisfying angular ordering
conditions are presented. Two sets of parton densities are obtained, differing in the renormalization
scale choice for the argument in the strong coupling αs. This is taken to be either the evolution
scale μ or the transverse momentum qt. While both choices yield similarly good χ2 values for the fit to
DIS measurements, especially the gluon density turns out to differ between the two sets. The TMD densities
are used to predict the transverse momentum spectrum of Z–bosons at the LHC.
Primary author
Francesco Hautmann
(University of Oxford)
