988 research outputs found
Fuchsia and Master Integrals for Energy-Energy Correlations at NLO in QCD
In this talk we discuss some aspects of the analytical calculation of energy
correlations in electron-positron annihilation at a next-to-leading order in
QCD. Our primary focus is on the most difficult task: the calculation of master
integrals for real-emission contributions, which are functions of two
dimensionless variables and the dimensional regulator. We use a method of
differential equations and their so-called epsilon-form which is constructed
with the help of the Fuchsia program based on Lee's algorithm.Comment: 11 pages, 1 figure. Presented at Matter to the Deepest Conference in
Podlesice (Poland) 3-8 Sep 2017 and at RADCOR Conference in St. Gilgen
(Austria) 24-29 Sep 201
Impact of SeaQuest data on PDF fits at large
We evaluate the impact of recent SeaQuest (E906 experiment) data on dimuon
production in proton-deuteron and proton-proton collisions on parton
distribution functions (PDFs). We find these data in a good agreement with the
QCD predictions based on PDFs fitted to the Tevatron and LHC data on forward
production of and bosons. As a basis for this study we use the ABMP16
PDF fits and show that they turn out to be compatible with the SeaQuest data,
and that these data have constraining power, allowing to reduce the
uncertainties on the isospin asymmetry of the light-sea-quark distribution at
large longitudinal momentum fraction . We discuss the nuclear corrections
needed to describe the deuteron and show that they affect the theoretical
description of the proton-deuteron Drell-Yan cross section at the level of
\%. We also comment on the compatibility of the SeaQuest
results with other state-of-the-art PDF fits and show that these data are in
clear disagreement with models proposing an SU(3)-flavor symmetric quark sea.
Finally, we perform a comparison between the second Mellin moments of the
light-quark PDFs and recent results from various lattice QCD computations,
which demonstrates good compatibility, albeit limited by the uncertainties
inherent in current lattice QCD simulations.Comment: 20 pages, 7 figures, 3 table
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