Parton distributions incorporating QED contributions

Martin, A.; Roberts, Richard G.; Stirling, W.J.; Thorne, Robert S.

doi:10.1140/epjc/s2004-02088-7

Cited by 445 publications

(580 citation statements)

References 20 publications

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“…The electroweak corrections include a positive contribution from the irreducible, non-resonant photon-induced background, i.e., γ γ → e + e − . This contribution is estimated at leading order (LO) using the MRST2004qed [41] PDF, currently the only set available that includes QED corrections to the proton PDF, by taking the average of the predictions obtained under the current and constituent quark mass schemes. The symmetric difference between the average and either scheme is assigned as the corresponding uncertainty on this additive correction, being approximately 50% and representing a 3% uncertainty on the cross-section prediction in the highest m ee bin.…”

Section: Results and Comparison To Theorymentioning

confidence: 99%

Measurement of the high-mass Drell–Yan differential cross-section in pp collisions at s=7 TeV with the ATLAS detector

Aad¹,

Abajyan²,

Abbott³

et al. 2013

Physics Letters B

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This Letter reports a measurement of the high-mass Drell-Yan differential cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. Based on an integrated luminosity of 4.9 fb −1 , the differential cross-section in the Z /γ * → e + e − channel is measured with the ATLAS detector as a function of the invariant mass, m ee , in the range 116 < m ee < 1500 GeV, for a fiducial region in which both the electron and the positron have transverse momentum p T > 25 GeV and pseudorapidity |η| < 2.5.A comparison is made to various event generators and to the predictions of perturbative QCD calculations at next-to-next-to-leading order.© 2013 CERN. Published by Elsevier B.V. All rights reserved. IntroductionAt hadron colliders, the Drell-Yan (DY) process [1], proceeding at tree level via the s-channel exchange of a virtual photon or Z boson, can produce charged lepton pairs over a wide range of invariant mass. The differential cross-section as a function of the invariant mass is described by perturbative QCD (pQCD) calculations at next-to-next-to-leading order (NNLO). Given the simple experimental signature and the low backgrounds, a small experimental uncertainty can be achieved on the measured invariant mass distribution allowing for a precision test of pQCD. The mass spectrum is also sensitive to the parton distribution functions (PDFs), in particular to the poorly known distribution of antiquarks at large x [2], where x can be interpreted, at leading order, as the fraction of the proton momentum carried by the interacting parton. Additionally, the production of DY dilepton pairs is a source of background for other Standard Model (SM) measurements, and the mass spectrum may be modified by new physics phenomena giving rise to, e.g., narrow resonances or an excess of high-mass pairs inconsistent with the known PDFs.The differential cross-section for DY dilepton pair production in the high-mass range has been reported previously by the CMS [3], CDF [4] and D0 [5] Collaborations. With the ATLAS detector, total and differential cross-sections in a mass window of 66-116 GeV have been measured using the 2010 dataset [6]. In addition, searches for new physics in the high-mass range have been performed [7][8][9] and no deviations from the SM expectation were observed. This Letter reports an extension of these previous ✩ © CERN for the benefit of the ATLAS Collaboration.E-mail address: atlas.publications@cern.ch.analyses by providing a measurement of the DY cross-section, fully corrected for detector effects, in the dielectron channel as a function of the e + e − invariant mass, m ee , up to 1500 GeV. To minimise model-dependent theoretical uncertainties, the cross-section is not extrapolated to the full phase space but is reported in a phase space only slightly extended with respect to the fiducial acceptance of the e + and e − . The results are compared to NNLO pQCD calculations with next-to-leading-order (NLO) electroweak corrections from the FEWZ 3.1 [10,11] framework and to the predictions from ...

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Section: Results and Comparison To Theorymentioning

confidence: 99%

Measurement of the high-mass Drell–Yan differential cross-section in pp collisions at s=7 TeV with the ATLAS detector

Aad¹,

Abajyan²,

Abbott³

et al. 2013

Physics Letters B

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“…[60]: it could easily explain about a third of the observed discrepancy. In our fit, isospin symmetry is assumed, and furthermore [C − ] = 0.…”

Section: Pdf Corrections To the Paschos-wolfenstein Ratiomentioning

confidence: 94%

Precision determination of electroweak parameters and the strange content of the proton from neutrino deep-inelastic scattering

et al. 2009

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Abstract:We use recent neutrino dimuon production data combined with a global deep-inelastic parton fit to construct a new parton set, NNPDF1.2, which includes a determination of the strange and antistrange distributions of the nucleon. The result is characterized by a faithful estimation of uncertainties thanks to the use of the NNPDF methodology, and is free of model or theoretical assumptions other than the use of NLO perturbative QCD and exact sum rules. Better control of the uncertainties of the strange and antistrange parton distributions allows us to reassess the determination of electroweak parameters from the NuTeV dimuon data. We perform a direct determination of the |V cd | and |V cs | CKM matrix elements, obtaining central values in agreement with the current global CKM fit: specifically we find |V cd | = 0.244 ± 0.019 and |V cs | = 0.96 ± 0.07. Our result for |V cs | is more precise than any previous direct determination. We also reassess the uncertainty on the NuTeV determination of sin 2 θ W through the Paschos-Wolfenstein relation: we find that the very large uncertainties in the strange valence momentum fraction are sufficient to bring the NuTeV result into complete agreement with the results from precision electroweak data.1

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“…An improved approach how to include photons into inelastic processes was proposed some time ago by Martin, Roberts, Stirling and Thorne in ref. [37]. In their approach the photon is treated on the same footing as quarks, antiquarks and gluons.…”

Section: Jhep02(2015)098mentioning

confidence: 99%

“…Below we repeat the essential points of their formalism which includes combined QCD+QED evolution. They proposed a QED-corrected evolution equations for the parton distributions of the proton [37]:…”

Section: Jhep02(2015)098mentioning

confidence: 99%

W + W − pair production in proton-proton collisions: small missing terms

Łuszczak

Szczurek

Royon

2015

J. High Energ. Phys.

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W + W − production is one of the golden channels for testing the Standard Model as well for searches beyond the Standard Model. We discuss many new subleading processes for inclusive production of W + W − pairs generally not included in the literature so far. We focus on photon-photon induced processes. We include elastic-elastic, elastic-inelastic, inelastic-elastic and inelastic-inelastic contributions. We also calculate the contributions with resolved photons including the partonic substructure of the virtual photon. Predictions for the total cross section and differential distributions in W -boson rapidity and transverse momentum as well as W W invariant mass are presented. The γγ components constitute only about 1-2 % of the inclusive W + W − cross section but increases up to about 10 % at large W ± transverse momenta, and are even comparable to the dominant qq component at large M W W , i.e. are much larger than the gg → W + W − one.

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Parton distributions incorporating QED contributions

Cited by 445 publications

References 20 publications

Measurement of the high-mass Drell–Yan differential cross-section in pp collisions at s=7 TeV with the ATLAS detector

Measurement of the high-mass Drell–Yan differential cross-section in pp collisions at s=7 TeV with the ATLAS detector

Precision determination of electroweak parameters and the strange content of the proton from neutrino deep-inelastic scattering

W + W − pair production in proton-proton collisions: small missing terms

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