Author/Authors :
Q2) Original Research Article
Pages 471-502
H1 Collaboration، نويسنده , , S. Aid، نويسنده , , A. V. Andreev، نويسنده , , B. Andrieu، نويسنده , , R.-D. Appuhn، نويسنده , , M. Arpagaus، نويسنده , , A. Babaev and NRMI Investigators، نويسنده , , Matthias J. Bahr، نويسنده , , J. B?n، نويسنده , , P. Ban، نويسنده , , P. Baranov، نويسنده , , E. Barrelet، نويسنده , , R. Barschke، نويسنده , , W. Bartel، نويسنده , , Joan M. Barth، نويسنده , , U. Bassler، نويسنده , , H.P. Beck، نويسنده , , H.-J. Behrend، نويسنده , , V. A. Belousov، نويسنده , , Ch. Berger، نويسنده , , et al.، نويسنده ,
Abstract :
The cross section for the elastic photoproduction of ϱ0 mesons (γp → ϱ0p) has been measured with the H1 detector at HERA for two average photon-proton centre-of-mass energies of 55 and 187 GeV. The lower energy point was measured by observing directly the ϱ0 decay giving a cross section of 9.1 ± 0.9 (stat.) ± 2.5 (syst.) μb. The logarithmic slope parameter of the differential cross section, dσ/dt, is found to be 10.9 ± 2.4 (stat.) ± 1.1 (syst.) GeV−2. The ϱ0 decay polar angular distribution is found to be consistent with s-channel helicity conservation. The higher energy cross section was determined from analysis of the lower part of the hadronic invariant mass spectrum of diffractive photoproduction and found to be 13.6 ± 0.8 (stat.) ± 2.4 (syst.) μb.
