Generalised parton distributions at small x

Martin, A. D.; Nockles, C.; Ryskin, M.G.; Shuvaev, A. G.; Teubner, T.

doi:10.1140/epjc/s10052-009-1087-y

Cited by 45 publications

(73 citation statements)

References 36 publications

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“…Since now we integrate over the |l 2 | < Q 2 0 < μ 2 F the correction does not depend on μ F . 7 This contribution is already included in the input value GPD(Q 0 ).…”

Section: Quark-induced Nlo Correctionmentioning

confidence: 99%

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The exclusive J/ $$\psi $$ ψ process at the LHC tamed to probe the low x gluon

et al. 2016

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The perturbative QCD expansion for J/ψ photoproduction appears to be unstable: the NLO correction is large (and of opposite sign) to the LO contribution. Moreover, the predictions are very sensitive to the choice of factorisation and renormalisation scales. Here we show that perturbative stability is greatly improved by imposing a 'Q 0 cut' on the NLO coefficient functions; a cut which is required to avoid double counting. Q 0 is the input scale used in the parton DGLAP evolution. This result opens the possibility of high precision exclusive J/ψ data in the forward direction at the LHC being able to determine the low x gluon distribution at low scales.

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“…Since now we integrate over the |l 2 | < Q 2 0 < μ 2 F the correction does not depend on μ F . 7 This contribution is already included in the input value GPD(Q 0 ).…”

Section: Quark-induced Nlo Correctionmentioning

confidence: 99%

“…Note that X is defined in (4) and β is given by (7). Recall that we are looking for the imaginary part of the amplitude (i.e.…”

Section: Gluon Nlo Correctionmentioning

confidence: 99%

The exclusive J/ $$\psi $$ ψ process at the LHC tamed to probe the low x gluon

et al. 2016

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“…Indeed in the case of modern NLO MS PDF sets, the fits tend to prefer a negative gluon, for example g(x, Q 2 0 = 1 GeV 2 ) < 0 for x < ∼ 10 −2 in the case of MSTW08 NLO. On the other hand there are some indications, for instance from J/ψ diffractive photoproduction data at HERA (which is not currently used in global PDF analyses), that the 'true' g(x, Q 2 ) at low x and Q 2 ∼ 2 − 3 GeV 2 is larger than the current NLO PDFs [82]. In contrast, the LO PDFs, which generally have a g(x, Q 2 0 ) which is positive at small x, do not give a particularly good description of the HERA F 2 (x, Q 2 ) data, and may in general be too large at low x and Q 2 in order to compensate for the non-negligible higher-order terms which are absent in the LO DGLAP evolution of the quark PDF.…”

Section: γγ Cep Revisitedmentioning

confidence: 99%

The phenomenology of central exclusive production at hadron colliders

et al. 2012

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Central exclusive production (CEP) processes in high-energy hadron-hadron collisions provide an especially clean environment in which to measure the nature and quantum numbers (in particular, the spin and parity) of new resonance states. Encouraged by the broad agreement between experimental measurements and theoretical predictions based on the Durham approach, we perform a detailed phenomenological analysis of γγ and meson pair CEP final states, paying particular attention to the theoretical uncertainties in the predictions, including those from parton distribution functions, higher-order perturbative corrections, and non-perturbative and proton dissociation contributions. We present quantitative cross-section predictions for these CEP final states at the RHIC, Tevatron and LHC colliders.

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“…Models or additional assumptions are generally needed to extract the diagonal GPD from the data. However, at x B ≪ 1 and sufficiently large Q 2 the "skewed" GPD can approximately be reconstructed from the diagonal limit [592,593]. In this case QCD evolution generates the GPD with x and x ′ from configurations at a lower scale with momentum fractions x 0 , x ′ 0 ≫ x, x ′ ; because the difference of the parton momentum fractions is preserved under evolution, the lower-scale GPD is effectively evaluated in the diagonal limit figure 3.8c).…”

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confidence: 99%

Gluons and the quark sea at high energies: distributions, polarization, tomography

Boer¹,

Diehl²,

Milner³

et al. 2011

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ForewordThe study of the fundamental structure of nuclear matter is a central thrust of physics research in the United States. As indicated in Frontiers of Nuclear Science, the 2007 Nuclear Science Advisory Committee long range plan, consideration of a future Electron-Ion Collider (EIC) is a priority and will likely be a significant focus of discussion at the next long range plan. We are therefore pleased to have supported the ten week program in fall 2010 at the Institute of Nuclear Theory which examined at length the science case for the EIC. This program was a major effort; it attracted the maximum allowable attendance over ten weeks.This report summarizes the current understanding of the physics and articulates important open questions that can be addressed by an EIC. It converges towards a set of "golden" experiments that illustrate both the science reach and the technical demands on such a facility, and thereby establishes a firm ground from which to launch the next phase in preparation for the upcoming long range plan discussions. We thank all the participants in this productive program. In particular, we would like to acknowledge the leadership and dedication of the five co-organizers of the program who are also the co-editors of this report.David Kaplan, Director, National Institute for Nuclear Theory Hugh Montgomery, Director, Thomas Jefferson National Accelerator Facility Steven Vigdor, Associate Lab Director, Brookhaven National Laboratory iii Preface This volume is based on a ten-week program on "Gluons and the quark sea at high energies", which took place at the Institute for Nuclear Theory (INT) in Seattle from September 13 to November 19, 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. Guiding questions were• What are the crucial science issues?• How do they fit within the overall goals for nuclear physics?• Why can't they be addressed adequately at existing facilities?• Will they still be interesting in the 2020's, when a suitable facility might be realized?The program started with a five-day workshop on "Perturbative and Non-Perturbative Aspects of QCD at Collider Energies", which was followed by eight weeks of regular program and a concluding four-day workshop on "The Science Case for an EIC".More than 120 theorists and experimentalists took part in the program over ten weeks. It was only possible to smoothly accommodate such a large number of participants because of the extraordinary efforts of the INT staff, to whom we extend our warm thanks and appreciation. We thank the INT Director, David Kaplan, for his strong support of the program and for covering a significant portion of the costs for printing this volume. We gratefully acknowledge additional financial support provided by BNL and JLab.The program w...

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Generalised parton distributions at small x

Cited by 45 publications

References 36 publications

The exclusive J/ $$\psi $$ ψ process at the LHC tamed to probe the low x gluon

The exclusive J/ $$\psi $$ ψ process at the LHC tamed to probe the low x gluon

The phenomenology of central exclusive production at hadron colliders

Gluons and the quark sea at high energies: distributions, polarization, tomography

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