Exclusive J/ψ and ψ(2S) production in pp collisions at √s=7 TeV

The paper is available here.

J. Phys. G40 (2013) 045001

arXiv:1301.7084

More detailed information: ANA note 2012-059

Abstract

Exclusive $J/\psi$ and $\psi(2S)$ vector meson production has been observed in the dimuon channel using the LHCb detector. The cross-section times branching fractions to two muons with pseudorapidities between 2.0 and 4.5 are measured to be

$\sigma_{pp\rightarrow J/\psi (\rightarrow \mu^{+} \mu^{-})} (2.0 <\eta_{\mu^{\pm}}< 4.5) = 307 \pm 21 \pm 36~\text{pb},$

$\sigma_{pp\rightarrow \psi(2S) (\rightarrow \mu^{+} \mu^{-})} (2.0 <\eta_{\mu^{\pm}}< 4.5) = 7.8 \pm 1.3 \pm 1.0~\text{pb},$

where the first uncertainties are statistical and the second are systematic. The measurements are found to be in good agreement with results from previous experiments and theoretical predictions. The $J/\psi$ photoproduction cross-section has been measured as a function of the photon-proton centre-of-mass energy. The results are consistent with measurements obtained at HERA and confirm a similar power law behaviour for the photoproduction cross-section.

Figures

(Note, pdf versions are available under attachments).

Caption Figure

Number of tracks in the forward region for dimuon triggered events which in the backward region have one or more tracks. Fig1a.png
Number of tracks in the forward region for dimuon triggered events which in the backward region have no tracks. Fig1b.png
Invariant mass distribution in the region of the $J/\psi$ mass peak for events with exactly two tracks, no photons and a dimuon with pt below 900 MeV. The overall fit to the data is shown by the full curve while the dashed curve shows the background contribution. Fig2a.png
Invariant mass distribution in the region of the $\psi(2S)$ mass peak for events with exactly two tracks, no photons and a dimuon with pt below 900 MeV. The overall fit to the data is shown by the full curve while the dashed curve shows the background contribution. Fig2b.png
Feynman diagrams displaying (a) exclusive $J/\psi$ photoproduction and (b) inelastic $J/\psi$ photoproduction where a small number of additional particles are produced due to gluon radiation and (c,d) proton dissociation. Fig3.png
Transverse momentum distribution for exclusive $J/\psi$ candidates with exactly two tracks and no photons. The points represent the data. The fit contains an exclusive signal component (short-dashed green curve) as estimated by SuperChic and an inelastic background component (long-dashed red curve) as estimated from data. Fig4.png
Transverse momentum distribution in $J/\psi$ events with no backward tracks and no photons when there are three (black squares) and eight (red open circles) forward tracks. The results of fitting a Novosibirsk function to the three and eight forward track data are represented by the dashed black and the full red curves respectively. Fig5a.png
The values for P0 of the $J/\psi$ pt distribution are shown as a function of the number of forward tracks. Fig5b.png
The values for sigma of the $J/\psi$ pt distribution are shown as a function of the number of forward tracks. Fig5c.png
The values for alpha of the $J/\psi$ pt distribution are shown as a function of the number of forward tracks. Fig5d.png
Dependence of $J/\psi$ photoproduction cross-section on the centre-of-mass energy of the photon-proton system.The blue (red) triangles represent the data from H1 (ZEUS). The black dots and squares are derived from the LHCb differential cross-section as a function of rapidity. The dashed and full lines are the power law dependences determined from the HERA and LHCb data, respectively.The uncertainty on the LHCb power law determination is shown by the shaded band. Fig6.png

-- Main.Dermot Moran - 05 Feb 2013

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf Fig1a.pdf r1 manage 14.3 K 2013-02-05 - 12:01 DermotMoran1  
PNGpng Fig1a.png r1 manage 15.4 K 2013-02-05 - 12:07 DermotMoran1  
PDFpdf Fig1b.pdf r1 manage 14.3 K 2013-02-05 - 12:01 DermotMoran1  
PNGpng Fig1b.png r1 manage 14.9 K 2013-02-05 - 12:07 DermotMoran1  
PDFpdf Fig2a.pdf r1 manage 23.2 K 2013-02-05 - 12:22 DermotMoran1  
PNGpng Fig2a.png r1 manage 15.5 K 2013-02-05 - 12:09 DermotMoran1  
PDFpdf Fig2b.pdf r1 manage 18.0 K 2013-02-05 - 12:22 DermotMoran1  
PNGpng Fig2b.png r1 manage 14.4 K 2013-02-05 - 12:09 DermotMoran1  
PDFpdf Fig3.pdf r1 manage 27.4 K 2013-02-05 - 12:23 DermotMoran1  
PNGpng Fig3.png r1 manage 12.1 K 2013-02-05 - 12:23 DermotMoran1  
PDFpdf Fig4.pdf r1 manage 20.6 K 2013-02-05 - 12:23 DermotMoran1  
PNGpng Fig4.png r1 manage 16.6 K 2013-02-05 - 12:23 DermotMoran1  
PDFpdf Fig5a.pdf r1 manage 22.0 K 2013-02-05 - 13:10 DermotMoran1  
PNGpng Fig5a.png r1 manage 18.6 K 2013-02-05 - 13:04 DermotMoran1  
PDFpdf Fig5b.pdf r1 manage 14.5 K 2013-02-05 - 13:10 DermotMoran1  
PNGpng Fig5b.png r1 manage 10.7 K 2013-02-05 - 13:04 DermotMoran1  
PDFpdf Fig5c.pdf r1 manage 14.4 K 2013-02-05 - 13:10 DermotMoran1  
PNGpng Fig5c.png r1 manage 9.6 K 2013-02-05 - 13:09 DermotMoran1  
PDFpdf Fig5d.pdf r1 manage 14.4 K 2013-02-05 - 13:10 DermotMoran1  
PNGpng Fig5d.png r1 manage 9.7 K 2013-02-05 - 13:04 DermotMoran1  
PDFpdf Fig6.pdf r1 manage 19.0 K 2013-02-05 - 13:11 DermotMoran1  
PNGpng Fig6.png r1 manage 20.6 K 2013-02-05 - 13:11 DermotMoran1  
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