Publications by Roman Walczak

Measurement of the cross-section ratio σψ(2S)/σJ/ψ(1S) in deep inelastic exclusive ep scattering at HERA

Nuclear Physics B Elsevier (2016)

H Abramowicz, I Abt, L Adamczyk, M Adamus, S Antonelli, V Aushev, Y Aushev, O Behnke, U Behrens, A Bertolin, I Bloch, EG Boos, K Borras, I Brock, NH Brook, R Brugnera, A Bruni, PJ Bussey, A Caldwell, M Capua, CD Catterall, J Chwastowski, J Ciborowski, R Ciesielski, AM Cooper-Sarkar

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.

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