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arXiv · 2006.13857

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

Chris A. Flett·Alan D. Martin·Misha G. Ryskin·Thomas Teubner
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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.

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Chris A. Flett, Alan D. Martin, Misha G. Ryskin, Thomas Teubner. 2020-06-24. Very low $x$ gluon density determined by LHCb exclusive $J/\psi$ data. https://doi.org/10.1103/physrevd.102.114021

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