Very low $x$ gluon density determined by LHCb exclusive $J/\psi$ data

Abstract

The low $x$ behaviour of the gluon density $xg(x,{\mu }^2)$ at scale ${\mu }^2=2.4$ GeV${}^2$ is determined using exclusive $J/\psi$ production data from HERA and LHCb within the framework of collinear factorisation at next-to-leading order (NLO). It is shown that in the interval $3\times 10^{-6}<x<10^{-3}$ the gluon distribution function grows as $xg(x,{\mu }^2)\propto x^{-\lambda }$ with $\lambda =0.135\pm 0.006$. The impact this experimental data will have for the global parton distribution function (PDF) analyses in this low $x$ domain is quantified. No indication in favour of parton density saturation is observed.

arXiv comment18 pages, 8 figures. Text added, version to be published in Phys. Rev. D

References in corpus (37)

• Parton distributions for the LHC Run II
• Operator expansion for high-energy scattering
• LHAPDF6: parton density access in the LHC precision era
• New parton distribution functions from a global analysis of quantum chromodynamics
• Small-x F_2 Structure Function of a Nucleus Including Multiple Pomeron Exchanges
• Parton distributions in the LHC era: MMHT 2014 PDFs
• Exclusive photoproduction of J/psi mesons at HERA
• Elastic J/Psi Production at HERA
• Off-diagonal distributions fixed by diagonal partons at small $x$ and $\xi$
• The QCD Pomeron with Optimal Renormalization
• Exclusive electroproduction of J/psi mesons at HERA
• Prompt charm production in pp collisions at sqrt(s)=7 TeV
• Measurements of prompt charm production cross-sections in $pp$ collisions at $\sqrt{s}=13\mathrm{TeV}$
• Updated measurements of exclusive $J/\psi$ and $\psi (2S)$ production cross-sections in $pp$ collisions at $\sqrt{s}=7$ TeV
• Fitting Parton Distribution Data with Multiplicative Normalization Uncertainties
• Exclusive photoproduction of a heavy vector meson in QCD
• Impact of heavy-flavour production cross sections measured by the LHCb experiment on parton distribution functions at low x
• Neutrino Telescopes as QCD Microscopes
• The hard to soft Pomeron transition in small x DIS data using optimal renormalization
• Precision determination of the small-$x$ gluon from charm production at LHCb
• Description of F2 and FL at small x using a collinearly-improved BFKL resummation
• Central exclusive production of $J/\psi$ and $\psi (2S)$ mesons in $pp$ collisions at $\sqrt{s}=13$TeV
• Diffraction at the LHC
• Relativistic corrections to the vector meson light front wave function
• Wavefunction corrections and off-forward gluon distributions in diffractive J/psi electroproduction
• QCD evolution based evidence for the onset of gluon saturation in exclusive photo-production of vector mesons
• Exclusive $J/\psi$ and ${\rm Y}$ photoproduction and the low $x$ gluon
• Solution of the off-forward leading logarithmic evolution equation based on the Gegenbauer moments inversion
• Next-to-leading order corrections in exclusive meson production
• The exclusive $J/\psi$ process at the LHC tamed to probe the low $x$ gluon
• How to include exclusive $J/\psi$ production data in global PDF analyses
• High Energy Elastic and Diffractive Cross Sections
• Gluon PDF constraints from the ratio of forward heavy quark production at the LHC at \sqrt{S}=7 and 13 TeV
• Generalised parton distributions at small x
• Exclusive $J/\psi$ production at the LHC in the $k_T$ factorization approach
• Open charm production and low x gluons
• Understanding forward $B$ hadron production

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