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Measurement of $J/\psi$ production in $pp$ collisions at $\sqrt{s}=2.76$ TeV

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Abstract

The production of J/psi mesons is studied with the LHCb detector using data from pp collisions at sqrt(s)=2.76 TeV corresponding to an integrated luminosity of 71 nb^-1. The differential cross-section for inclusive J/psi production is measured as a function of its transverse momentum pT. The cross-section in the fiducial region 0<pT<12 GeV/c and rapidity 2.0<y<4.5 is measured to be 5.6 +/- 0.1(stat) +/- 0.4 (syst) mub, with the assumption of unpolarised J/psi production. The fraction of J/psi production from b-hadron decays is measured to be (7.1 +/- 0.6 (stat) +/- 0.7 (syst)) %.

Figures and captions

Dimuon mass distributions, with fit results superimposed, in bins of $p_{\rm T}$ . Results for $ p_{\rm T} >7 {\mathrm{\,GeV\!/}c} $ are merged in the last bin.

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Distributions of the data with projections of the fit superimposed for (left) the dimuon invariant mass and (right) $t_z$. The thick blue line is the total fit function and the hatched area the background component.

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Acceptance (orange circles), reconstruction (upward-facing red triangles), trigger (downward-facing green triangles) and total (blue squares) $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ efficiency, as a function of $p_{\rm T}$ . The efficiencies are evaluated from a Monte Carlo simulation in which the $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ is produced unpolarised.

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Differential production cross-section for inclusive $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ production in the rapidity range $2.0<y<4.5$ as a function of $p_{\rm T}$ . The vertical error bars are the quadratic sums of the statistical and systematic uncertainties.

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Animated gif made out of all figures.

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Tables and captions

Relative systematic uncertainties on the luminosity (%).

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Relative systematic uncertainties on the cross-section results and on the fraction of $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ mesons from $b$-hadron decay (%).

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Differential cross-section ${\rm d}\sigma / {\rm d} p_{\rm T} $ at $\sqrt{s}=2.76\mathrm{\,TeV} $ for inclusive $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ production in bins of $p_{\rm T}$ . The rapidity range covered is $2.0<y<4.5$. The first uncertainty is statistical and the second is systematic.

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Created on 09 December 2018.Citation count from INSPIRE on 18 December 2018.