Measurement of the anti-quark flavor asymmetry in the nucleon sea

Awes, T. C.; Beddo, M. E.; Brown, C. N.; Bush, J. D.; NuSea,; Geesaman, D. F.; Kaufman, S.; Makins, N.; Mueller, B.

doi:10.2172/1155653

Cited by 45 publications

(87 citation statements)

References 20 publications

(35 reference statements)

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“…The E866 experiment at Fermilab measured the ratio σ pd /σ pp at high (projectile) proton momentum fractions x 1 and low target momentum fraction x 2 , where at leading order in the strong coupling constant α s it is approximately given by [7] …”

Section: Su(2) Flavor Asymmetry Of the Seamentioning

confidence: 99%

“…The large-x behavior in the SMRS parametrization [25] was consistent with the ∼ (1 − x) form indicated by the data. Comparison of the pion model fits to thed −ū data from the E866 experiment [7] with the t-dependent exponential form factor(2.7) for the valence pion PDFs from the SMRS [25] and ASV [26] parametrizations.…”

Section: Su(2) Flavor Asymmetry Of the Seamentioning

confidence: 99%

“…3 in fitting the HERA leading neutron production data [1,2], and the compatibility of the results with thed −ū asymmetry extracted from the E866 Drell-Yan measurement [7]. While some dedicated analyses [37] have attempted to describe the HERA leading neutron spectra at all kinematics, our aim here was instead to maximize the sensitivity to the basic one-pion exchange contribution, which has the most direct connection to the chiral effective theory.…”

Section: Efficacy Of the Pion Exchange Model In Leading Neutron Produmentioning

confidence: 99%

“…Our analysis has sought to determine whether both thed −ū asymmetry in the proton extracted from the E866 Drell-Yan data [7] and the HERA leading neutron cross sections [1,2,3] can be obtained consistently within a common pion exchange framework. Rather than relying on assumptions about specific forms for the pion distributions in the nucleon, we have addressed the model dependence empirically, by performing the first comprehensive statistical analysis of the combined HERA leading neutron and E866 data sets, for a wide range of prescriptions adopted in the literature for regularizing the pion-nucleon amplitudes.…”

Section: Future Directionmentioning

confidence: 99%

“…In particular, we have recently addressed [6] the question of whether one can reduce the model dependence of F π 2 extracted from the HERA data [1,2,3] by using additional constraints from the data on the SU(2) flavor asymmetryd −ū, especially those from the E866 Drell-Yan experiment [7]. Because the E866 data are at relatively high x values compared with the HERA measurements, within the pion exchange framework they are sensitive to the pion PDFs at large x π , where these are well determined from pion-nucleon Drell-Yan data [8,9,10].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Pion structure function and SU(2) flavor asymmetry

Ji¹

2017

Proceedings of QCD Evolution 2016 — PoS(QCDEV2016)

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We refine the computation of thed −ū flavor asymmetry in the proton sea with a complementary effort to reveal the dynamics of pion exchange in high-energy processes. In particular, we discuss the efficacy of pion exchange models to simultaneously describe leading neutron electroproduction at HERA along with thed −ū flavor asymmetry in the proton. A detailed χ 2 analysis of the ZEUS and H1 cross sections, when combined with constraints on the pion flux from Drell-Yan data, allows regions of applicability of one-pion exchange to be delineated. The analysis disfavors several models of the pion flux used in the literature, and yields an improved extraction of the pion structure function and its uncertainties at parton momentum fractions in the pion of 4 × 10 −4 x π 0.05 at a scale of Q 2 = 10 GeV 2 . Based on the fit results, we also address a possible estimate for leading proton structure functions in upcoming tagged deep-inelastic scattering experiments at Jefferson Lab on the deuteron with forward protons.

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Section: Su(2) Flavor Asymmetry Of the Seamentioning

confidence: 99%

Section: Su(2) Flavor Asymmetry Of the Seamentioning

confidence: 99%

Section: Efficacy Of the Pion Exchange Model In Leading Neutron Produmentioning

confidence: 99%

Section: Future Directionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Pion structure function and SU(2) flavor asymmetry

Ji¹

2017

Proceedings of QCD Evolution 2016 — PoS(QCDEV2016)

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Pinning down the large-x gluon with NNLO top-quark pair differential distributions

Czakon

Hartland

Mitov

et al. 2017

J. High Energ. Phys.

100

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Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work we study the impact on the large-x gluon of top-quark pair differential distributions measured by ATLAS and CMS at √ s = 8 TeV. Our analysis, performed in the NNPDF3.0 framework at NNLO accuracy, allows us to identify the optimal combination of LHC top-quark pair measurements that maximize the constraints on the gluon, as well as to assess the compatibility between ATLAS and CMS data. We find that differential distributions from top-quark pair production provide significant constraints on the large-x gluon, comparable to those obtained from inclusive jet production data, and thus should become an important ingredient for the next generation of global PDF fits.

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The impact of the LHC Z-boson transverse momentum data on PDF determinations

Boughezal

Guffanti

Petriello

et al. 2017

J. High Energ. Phys.

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Abstract:The LHC has recently released precise measurements of the transverse momentum distribution of the Z-boson that provide a unique constraint on the structure of the proton. Theoretical developments now allow the prediction of these observables through next-to-next-to-leading order (NNLO) in perturbative QCD. In this work we study the impact of incorporating these latest advances into a determination of parton distribution functions (PDFs) through NNLO including the recent ATLAS and CMS 7 TeV and 8 TeV p Z T data. We investigate the consistency of these measurements in a global fit to the available data and quantify the impact of including the p Z T distributions on the PDFs. The inclusion of these new data sets significantly reduces the uncertainties on select parton distributions and the corresponding parton-parton luminosities. In particular, we find that the p Z T data ultimately leads to a reduction of the PDF uncertainty on the gluon-fusion and vector-boson fusion Higgs production cross sections by about 30%, while keeping the central values nearly unchanged.

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Measurement of the anti-quark flavor asymmetry in the nucleon sea

Cited by 45 publications

References 20 publications

Pion structure function and SU(2) flavor asymmetry

Pion structure function and SU(2) flavor asymmetry

Pinning down the large-x gluon with NNLO top-quark pair differential distributions

The impact of the LHC Z-boson transverse momentum data on PDF determinations

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