Impact of the top quark cross-section data on parton distribution functions

Azizi, M.; Khorramian, Ali N.; Abdolmaleki, Hamed; Mehdiabadi, S. Paktinat

doi:10.1142/s0217751x18501427

Cited by 6 publications

(3 citation statements)

References 116 publications

(145 reference statements)

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“…Also, attributed to including 8 TeV differential topquark data, the NNPDF3.1 fit has large-x gluons suppressed compared to CT14 and MMHT14 [31]. In addition, a recent reweighting study using multiple top-production data sets found very similar CT14 modifications as we do here [32]. Thus, we have evidence that the CT14 gluon distribution is simply too hard to be able to fully describe jet and top-quark measurements.…”

Section: Proton-proton Dijet Spectra and Ct14 Reweightingsupporting

confidence: 56%

Non-quadratic improved Hessian PDF reweighting and application to CMS dijet measurements at 5.02 TeV

2019

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Hessian PDF reweighting, or "profiling", has become a widely used way to study the impact of a new data set on parton distribution functions (PDFs) with Hessian error sets. The available implementations of this method have resorted to a perfectly quadratic approximation of the initial χ 2 function before inclusion of the new data. We demonstrate how one can take into account the first non-quadratic components of the original fit in the reweighting, provided that the necessary information is available. We then apply this method to the CMS measurement of dijet pseudorapidity spectra in proton-proton (pp) and proton-lead (pPb) collisions at 5.02 TeV. The measured pp dijet spectra disagree with next-to-leading order (NLO) theory calculations using the CT14 NLO PDFs, but upon reweighting the CT14 PDFs, these can be brought to a much better agreement. We show that the needed proton-PDF modifications also have a significant impact on the predictions for the pPb dijet distributions. Taking the ratio of the individual spectra, the proton-PDF uncertainties effectively cancel, giving a clean probe of the PDF nuclear modifications. We show that these data can be used to further constrain the EPPS16 nuclear PDFs and strongly support gluon nuclear shadowing at small x and antishadowing at around x ≈ 0.1. arXiv:1903.09832v2 [hep-ph] 26 Sep 20191 The intricacies of choosing an appropriate value for ∆ χ 2 are outside the scope of this article, see Refs. [17,21,22] for discussion.

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Section: Proton-proton Dijet Spectra and Ct14 Reweightingsupporting

confidence: 56%

Non-quadratic improved Hessian PDF reweighting and application to CMS dijet measurements at 5.02 TeV

2019

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“…For both cases, the obtained modifications are significant, especially at large x, where a large suppression with respect to the original central set would be preferred. Similar results have recently been found in reweighting CT14 with top-production data [9], and hence seeing such effects here is not entirely unexpected.…”

Section: Issue With Proton Pdfssupporting

confidence: 90%

Impact of CMS dijets in 5.02 TeV pPb and pp collisions on EPPS16 nuclear PDFs

Eskola¹,

Paakkinen²,

Paukkunen³

2018

Preprint

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The CMS measurement of dijet pseudorapidity distributions in pPb versus pp collisions at 5.02 TeV provides a direct probe on nuclear gluon PDFs. We show that while the predicted pPb pseudorapidity distributions suffer from sizable free-proton PDF uncertainties, the ratios of the pPb and pp distributions are practically insensitive to scale and free-proton PDF choices. We find the CMS data on pPb to pp ratios to be in good agreement with the EPPS16 nuclear modifications. Using a non-quadratic extension of the Hessian PDF reweighting method, we study the impact of these data on the EPPS16 nuclear PDFs. Relative to EPPS16, we find stronger evidence for mid-x gluon antishadowing as well as indication for larger gluon shadowing at small x. The data are also able to further constrain the gluon PDF in the EMC region.

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“…Refs. [60][61][62][63][64][65], we have used the xFitter package for different QCD analyses. Very recently, we presented also a new set of PDFs considering the intrinsic charm content of the proton using this package [66].…”

Section: Introductionmentioning

confidence: 99%

QCD analysis of structure functions in deep inelastic neutrino-nucleon scattering without using the orthogonal polynomials approach

2019

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A nonsinglet QCD analysis of neutrino-nucleon structure function is performed based on all the data for charged current neutrino-nucleon deep inelastic scattering (DIS) corresponds to NLO and NNLO approximations, with taking into account the nuclear and higher twist corrections. In this analysis, we extract xu v (x, Q 2 ) and xd v (x, Q 2 ) valence parton distribution functions (PDFs) in a wide range of x and Q 2 , and determine their parametrization with the correlated errors using the xFitter framework. Our results regarding valence-quark densities with their uncertainties are compared to the prediction extracted using other PDF sets from different groups. We determine α s (M 2 Z )= 0.1199 ± 0.0031 and 0.1185 ± 0.0023 with considering the nuclear and higher twist corrections at the NLO and NNLO, respectively, and perform a comparison with other reported results. The extracted results regarding valence-quark distributions and the value of α s (M 2 Z ) are in good agreement with available theoretical models.

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Impact of the top quark cross-section data on parton distribution functions

Cited by 6 publications

References 116 publications

Non-quadratic improved Hessian PDF reweighting and application to CMS dijet measurements at 5.02 TeV

Non-quadratic improved Hessian PDF reweighting and application to CMS dijet measurements at 5.02 TeV

Impact of CMS dijets in 5.02 TeV pPb and pp collisions on EPPS16 nuclear PDFs

QCD analysis of structure functions in deep inelastic neutrino-nucleon scattering without using the orthogonal polynomials approach

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