New parton distribution functions from a global analysis of quantum chromodynamics

Abstract

We present new parton distribution functions (PDFs) at next-to-next-to-leading order (NNLO) from the CTEQ-TEA global analysis of quantum chromodynamics. These differ from previous CT PDFs in several respects, including the use of data from LHC experiments, and the new DØ charged lepton rapidity asymmetry data, as well as the use of a more flexible parametrization of PDFs that, in particular, allows a better fit to different combinations of quark flavors. Predictions for important LHC processes, especially Higgs boson production at 13 TeV, are presented. These CT14 PDFs include a central set and error sets in the Hessian representation. For completeness, we also present the CT14 PDFs determined at the leading order (LO) and the next-to-leading order (NLO) in QCD.Besides these general-purpose PDF sets, we provide a series of (N)NLO sets with various αs values and additional sets in general-mass variable flavor number (GM-VFN) schemes, to deal with heavy partons, with up to 3, 4, and 6 active flavors.

Two-loop QED corrections to the Altarelli-Parisi splitting functions

“…Along this work we will present the expressions for the splitting functions including QCD and QED corrections. Thus, we expand them according to 6) where the upper indices indicate the (QCD,QED) order of the calculation, while…”

“…Both for leptons and quarks, the QED coupling is proportional to their EM charges. In consequence, the replacement 6) has to be implemented in all the contributions arising from quark loops in the pure QCD kernels.…”

“…The calculation of the NNLO corrections to the splitting functions performed in [1][2][3][4] and the development of modern parton distribution analysis [5][6][7][8][9][10] allows to achieve the required precision in QCD.…”

The landscape of W± and Z bosons produced in pp collisions up to LHC energies

“…In the CT14 model [13] this factor for valence distributions is represented in terms of a linear combination 1 It turns out that X − 0u and X − 0d were found almost identical. 2 In Ref.…”

Measurement of forward W and Z boson production in association with jets in proton-proton collisions at s = 8 $$ \sqrt{s}=8 $$ TeV

“…Additional fixed-order predictions are generated using Fewz [25] at O(α 2 s ) with the NNPDF3.0, CT14 [26] and MMHT14 [27] PDF sets.…”