Measurement of the cross-section ratio sigma(psi(2S))/sigma(J/psi(1S)) in deep inelastic exclusive ep scattering at HERA

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 View the MathML source 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 View the MathML source  and t. The results are compared to predictions of QCD-inspired models of exclusive vector-meson production

Further studies of isolated photon production with a jet in deep inelastic scattering at HERA

Isolated photons with high transverse energy have been studied in deep inelastic ep scattering with the ZEUS detector at HERA, using an integrated luminosity of 326 pb−1 in the range of exchanged-photon virtuality 10-350 GeV2. Outgoing isolated photons with transverse energy 4 ≺ E T γ  ≺ 15 GeV and pseudorapidity − 0.7 ≺ η γ  ≺ 0.9 were measured with accompanying jets having transverse energy and pseudorapidity 2.5≺ E T jet ≺ 35 GeV and −1.5 ≺ ηjet ≺ 1.8, respectively. Differential cross sections are presented for the following variables: the fraction of the incoming photon energy and momentum that is transferred to the outgoing photon and the leading jet; the fraction of the incoming proton energy transferred to the photon and leading jet; the differences in azimuthal angle and pseudorapidity between the outgoing photon and the leading jet and between the outgoing photon and the scattered electron. Comparisons are made with theoretical predictions: a leading-logarithm Monte Carlo simulation, a next-to-leading-order QCD prediction, and a prediction using the k T -factorisation approach

Combination of differential D*(+/-) cross-section measurements in deep-inelastic ep scattering at HERA

H1 and ZEUS have published single-differential cross sections for inclusive D∗±-meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q2&gt; 5 GeV2, electron inelasticity 0.02 &lt; y &lt; 0.7 and the D∗± meson’s transverse momentum pT(D∗) &gt; 1.5 GeV and pseudorapidity |η(D∗)| &lt; 1.5. The combination procedure takes into account all correlations, yielding significantly reduced experimental uncertainties. Double-differential cross sections d2σ/dQ2dy are combined with earlier D∗± data, extending the kinematic range down to Q2&gt; 1.5 GeV2. Perturbative next-to-leading-order QCD predictions are compared to the results

Combination of Differential D^{*\pm} Cross-Section Measurements in Deep-Inelastic ep Scattering at HERA

H1 and ZEUS have published single-differential cross sections for inclusive D^{*\pm}-meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q2 > 5 GeV2, electron inelasticity 0.02 1.5 GeV and pseudorapidity |eta(D^*)| 1.5 GeV2. Perturbative next-to-leadingorder QCD predictions are compared to the results.H1 and ZEUS have published single-differential cross sections for inclusive D$^{∗±}$-meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q$^{2}$ > 5 GeV$^{2}$, electron inelasticity 0.02 1.5 GeV and pseudorapidity |η(D$^{∗}$)| 1.5 GeV$^{2}$. Perturbative next-to-leading-order QCD predictions are compared to the results.H1 and ZEUS have published single-differential cross sections for inclusive D^{*\pm}-meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q2 > 5 GeV2, electron inelasticity 0.02 1.5 GeV and pseudorapidity |eta(D^*)| 1.5 GeV2. Perturbative next-to-leadingorder QCD predictions are compared to the results