Observation of charmonium pairs produced exclusively in $pp$ collisions

Unknown, Article, Preprint English OPEN
LHCb Collaboration ; Bernet, R ; Müller, K ; Steinkamp, O ; Straumann, U ; Vollhardt, A ; et al (2014)
  • Publisher: IOP Publishing
  • Journal: volume 41, page 115,002
  • Related identifiers: doi: 10.1088/0954-3899/41/11/115002, doi: 10.5167/uzh-108253
  • Subject: QC | Particle Physics - Experiment | hep-ex | LHCb - Abteilung Hofmann | High Energy Physics - Experiment | Physics Institute | info:eu-repo/classification/arxiv/High Energy Physics::Experiment | Física nuclear | 530 Physics
    arxiv: High Energy Physics::Experiment

A search is performed for the central exclusive production of pairs of charmonia produced in proton proton collisions. Using data corresponding to an integrated luminosity of 3{\rm f}{{{\rm b}}^{ 1}} collected at centre of mass energies of 7 and 8 TeV J/\psi J/\psi and J/\psi \psi (2S) pairs are observed which have been produced in the absence of any other activity inside the LHCb acceptance that is sensitive to charged particles in the pseudorapidity ranges ( 3.5 1.5) and (1.55.0). Searches are also performed for pairs of P wave charmonia and limits are set on their production. The cross sections for these processes where the dimeson system has a rapidity between 2.0 and 4.5 are measured to be \begin{array}{rcl} {{\sigma }^{{\rm J}/\psi {\rm J}/\psi }} = 58\pm 10({\rm stat})\pm 6({\rm syst})\;{\rm pb} \\ {{\sigma }^{{\rm J}/\psi \psi (2S)}} = 63_{ 18}^{+27}({\rm stat})\pm 10({\rm syst})\;{\rm pb} \\ {{\sigma }^{\psi (2S)\psi (2S)}} \lt 237\;{\rm pb} \\ {{\sigma }^{{{\chi }_{{\rm c}0}}{{\chi }_{{\rm c}0}}}} \lt 69\;{\rm nb} \\ {{\sigma }^{{{\chi }_{{\rm c}1}}{{\chi }_{{\rm c}1}}}} \lt 45\;{\rm pb} \\ {{\sigma }^{{{\chi }_{{\rm c}2}}{{\chi }_{{\rm c}2}}}} \lt 141\;{\rm pb} \\ \end{array} where the upper limits are set at the 90 confidence level. The measured {\rm J}/\psi {\rm J}/\psi and {\rm J}/\psi \psi (2S) cross sections are consistent with theoretical expectations.
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