Measurement of the cross-section ratio σ ψ (2 S ) / σ J / ψ (1 S ) in deep inelastic exclusive ep scattering at HERAстатья
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Дата последнего поиска статьи во внешних источниках: 28 октября 2016 г.
Аннотация:The exclusive deep inelastic electroproduction of ψ(2S) and J/ψ(1S) at an ep centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range 2<Q2<80 GeV2 , 30<W<210 GeV and |t|<1 GeV2 , where Q2 is the photon virtuality, W is the photon–proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The data for 2<Q2<5 GeV2 were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb −1 . The data for 5<Q2<80 GeV2 are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb −1 . The decay modes analysed were μ+μ− and J/ψ(1S)π+π− for the ψ(2S) and μ+μ− for the J/ψ(1S) . The cross-section ratio σψ(2S)/σJ/ψ(1S) has been measured as a function of Q2,W and t . The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.