par Ahmed, Tauseef;Barth, Marie ;Coremans, Ghislaine ;Botterweck, F.;de Wolf, Els;Evrard, E.;Favart, Laurent ;Huet, Philippe ;Johnson, Denis;Marage, Pierre ;Panitch, Arkadi ;Roosen, Robert;van Esch, Patrick;Van Mechelen, Pierre; [et al.]
Référence Physics letters. Section B, 338, 4, page (507-518)
Publication Publié, 1994-11
Référence Physics letters. Section B, 338, 4, page (507-518)
Publication Publié, 1994-11
Article révisé par les pairs
Résumé : | We present a study of J ψ meson production in collisions of 26.7 GeV electrons with 820 GeV protons, performed with the H1-detector at the HERA collider at DESY. The J ψ mesons are detected via their leptonic decays both to electrons and muons. Requiring exactly two particles in the detector, a cross section of σ(ep → J ψX) = (8.8±2.0±2.2) nb is determined for 30 GeV ≤ Wγp ≤ 180 GeV and Q2 ≲ 4 GeV2. Using the flux of quasi-real photons with Q2 ≲ 4 GeV2, a total production cross section of σ(γp → J/ψX) = (56±13±14) nb is derived at an average Wγp=90 GeV. The distribution of the squared momentum transfer t from the proton to the J ψ can be fitted using an exponential exp(-b∥t∥) below a ∥t∥ of 0.75 GeV2 yielding a slope parameter of b = (4.7±1.9) GeV-2. © 1994. |