2001/10/18 by J. A. Crittenden, J. Crittenden, H1 Collaboration +1
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1088/0954-3899/28/5/330
published as J.Phys.G28:1103-1112,2002 · Contributed to the proceedings of the Ringberg Workshop on New Trends in HERA Physics 2001, 17-22 June 2001, Ringberg Castle, Tegernsee, Germany (11 pages including 9 figures) Transparencies are available at http://www-zeus.physik.uni-bonn.de/~critten/ringberg/talk/ringt/index.html
arxiv created 2001/10/18 · openalex publication_date 2002/04/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Abstract. We discuss results on the diffractive production of the vector mesons ρ 0, φ and ω reported by the H1 and ZEUS collaborations at HERA. Unique to such studies is the experimental accessibility to the polarization of the vector mesons and hence to the spin-density matrix elements arising in vacuum-exchange processes. We emphasize the relation between the observed dependence on momentum transfer and the polarization state of the vector meson. The diffractive nature of the production mechanism is investigated via extraction of the Pomeron trajectory at high Q 2. Flavor symmetry is observed in the φ/ρ 0 ratios in the same region of momentum transfer where the powerlaw scaling becomes similar. The multivariable helicity analyses impose stringent constraints on models for the vacuum-exchange production mechanism. Semi-exclusive photoproduction of transverse ρ 0 and φ mesons at momentum transfers far exceeding their mass scale exhibit a hard scaling behavior which appears to violate the QCD helicity selection rules in a two-gluon exchange model.