Quantitative constraints on the gluon distribution function in the proton from collider isolated-photon data

David d'Enterria, Juan Rojo

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The impact of isolated-photon data from proton–(anti)proton collisions at RHIC, SpView the MathML sourcep¯S, Tevatron and LHC energies, on the parton distribution functions of the proton is studied using a recently developed Bayesian reweighting method. The impact on the gluon density of the 35 existing isolated-γ measurements is quantified using next-to-leading order (NLO) perturbative QCD calculations complemented with the NNPDF2.1 parton densities. The NLO predictions are found to describe well most of the datasets from 200 GeV up to 7 TeV centre-of-mass energies. The isolated-photon spectra recently measured at the LHC are precise enough to constrain the gluon distribution and lead to a moderate reduction (up to 20%) of its uncertainties around fractional momenta x≈0.02x≈0.02. As a particular case, we show that the improved gluon density reduces the PDF uncertainty for the Higgs boson production cross section in the gluon-fusion channel by more than 20% at the LHC. We conclude that present and future isolated-photon measurements constitute an interesting addition to coming global PDF analyses.
Original languageEnglish
Pages (from-to)311-338
Number of pages28
JournalNuclear Physics B
Volume860
Issue number3
DOIs
Publication statusPublished - 8 Feb 2012

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distribution functions
partons
protons
photons
Higgs bosons
center of mass
quantum chromodynamics
fusion
momentum
collisions
energy
cross sections
predictions

Cite this

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title = "Quantitative constraints on the gluon distribution function in the proton from collider isolated-photon data",
abstract = "The impact of isolated-photon data from proton–(anti)proton collisions at RHIC, SpView the MathML sourcep¯S, Tevatron and LHC energies, on the parton distribution functions of the proton is studied using a recently developed Bayesian reweighting method. The impact on the gluon density of the 35 existing isolated-γ measurements is quantified using next-to-leading order (NLO) perturbative QCD calculations complemented with the NNPDF2.1 parton densities. The NLO predictions are found to describe well most of the datasets from 200 GeV up to 7 TeV centre-of-mass energies. The isolated-photon spectra recently measured at the LHC are precise enough to constrain the gluon distribution and lead to a moderate reduction (up to 20{\%}) of its uncertainties around fractional momenta x≈0.02x≈0.02. As a particular case, we show that the improved gluon density reduces the PDF uncertainty for the Higgs boson production cross section in the gluon-fusion channel by more than 20{\%} at the LHC. We conclude that present and future isolated-photon measurements constitute an interesting addition to coming global PDF analyses.",
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Quantitative constraints on the gluon distribution function in the proton from collider isolated-photon data. / d'Enterria, David; Rojo, Juan.

In: Nuclear Physics B, Vol. 860, No. 3, 08.02.2012, p. 311-338.

Research output: Contribution to JournalArticleAcademicpeer-review

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AU - Rojo, Juan

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AB - The impact of isolated-photon data from proton–(anti)proton collisions at RHIC, SpView the MathML sourcep¯S, Tevatron and LHC energies, on the parton distribution functions of the proton is studied using a recently developed Bayesian reweighting method. The impact on the gluon density of the 35 existing isolated-γ measurements is quantified using next-to-leading order (NLO) perturbative QCD calculations complemented with the NNPDF2.1 parton densities. The NLO predictions are found to describe well most of the datasets from 200 GeV up to 7 TeV centre-of-mass energies. The isolated-photon spectra recently measured at the LHC are precise enough to constrain the gluon distribution and lead to a moderate reduction (up to 20%) of its uncertainties around fractional momenta x≈0.02x≈0.02. As a particular case, we show that the improved gluon density reduces the PDF uncertainty for the Higgs boson production cross section in the gluon-fusion channel by more than 20% at the LHC. We conclude that present and future isolated-photon measurements constitute an interesting addition to coming global PDF analyses.

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