# Observation of X(3872) production in $pp$ collisions at $\sqrt{s}=7$ TeV

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## Abstract

Using 34.7 pb-1 of data collected with the LHCb detector, the inclusive production of the X(3872) meson in pp collisions at sqrt(s) = 7 TeV is observed for the first time. Candidates are selected in the X(3872) -> J/psi pi+ pi- decay mode, and used to measure sigma(pp -> X(3872) + anything) B(X(3872)-> J/psi pi+ pi-) = 5.4 +- 1.3 (stat) +- 0.8 (syst) nb, where sigma(pp -> X(3872) + anything) is the inclusive production cross-section of X(3872) mesons with rapidity in the range 2.5-4.5 and transverse momentum in the range 5-20 GeV/c. In addition the masses of both the X(3872) and psi(2S) mesons, reconstructed in the J/psi pi+ pi- final state, are measured to be m(X(3872)) = 3871.95 +- 0.48 (stat) +- 0.12 (syst) MeV/c2 and m(psi(2S)) = 3686.12 +- 0.06 (stat) +- 0.10 (syst) MeV/c2

## Figures and captions

 Invariant mass distribution of $J/\psi \pi^+ \pi^-$ (points with statistical error bars) and same-sign $J/\psi \pi^{\pm} \pi^{\pm}$ (filled histogram) candidates. The curves are the result of the fit described in the text. The inset shows a zoom of the $X(3872)$ region. Fig1_V2.pdf [61 KiB] HiDef png [358 KiB] Thumbnail [92 KiB] *.C file Animated gif made out of all figures. PAPER-2011-034.gif Thumbnail

## Tables and captions

 Results of the fit to the $J/\psi \pi^+ \pi^-$ invariant mass distribution of Fig. 1. Table_1.pdf [41 KiB] HiDef png [76 KiB] Thumbnail [11 KiB] tex code Systematic uncertainties on the $\psi(2S)$ and $X(3872)$ mass measurements. Table_2.pdf [35 KiB] HiDef png [94 KiB] Thumbnail [15 KiB] tex code Relative systematic uncertainties on the $X(3872)$ production cross-section measurement. The total uncertainty is the quadratic sum of the individual contributions. Table_3.pdf [50 KiB] HiDef png [197 KiB] Thumbnail [29 KiB] tex code

Created on 19 April 2019.Citation count from INSPIRE on 24 April 2019.