Coherentρ0Photoproduction in Complex Nuclei

Abstract

The major purpose of this paper is a description of coherent p photoproduction which takes the rather substantial width of the p into proper account. The optical-model analysis due to Drell and Trefil is extended to include p decay inside the nucleus, as wcll as the subsequent absorption of the decay pio~ls. The eikonal method is used throughout, and is found to yield compact analytic expressions for the production amplitude. The decay effects produce an appreciable shift of the p peak towards lower mass for production in heavy nuclei and at the lower photon energies of current interest (2.7-4.5 GeV). On the whole, the differential cross sections are not significantly affected in either shapc or magnitude by the effects arising from p decay. In particular, the decay corrections do not appreciably influence the determination via vector dominance of the P-photon coupling constant. . Stairs, and J. Tenenbaum, Phys. Rev. Letters 15, 210 11 96.9 \ ----J .2 Aachen-Berlin-Bonn-Hamburg-Heidelberg-Munchen Collaboration, Nuovo Cimento 41A, 270 (1966).

Resonance propagation in heavy-ion scattering

“…ρ 0 is the typical nuclear density. Taking σ ρN T = 38 mb [4], α=0.7 and ρ 0 =0.17 fm −3 , we get the optical potential for the ρ meson to be, V v R =-(45+i64) MeV. For higher nuclear densities, these values would be higher.…”

Real Parts of Vector-Meson Scattering Amplitudes

“…Much of the A dependence has been suppressed by dividing by A 3 / 2 . The smooth curves are theoretical calculations with the parameters y p 2 /47r, a Ni and a. indicated (6). can be understood qualitatively.…”

“…The enhanced importance of a v in formula There is no difficulty in using formula (6) for comparison with the experimental results and this is done for p's in Fig. 1.…”

“…x exp[|a VN {\ -iot y)rp(b, z r )dz']; (6) q || is the momentum transfer along the beam. A 0 is the one-nucleon photoproduction amplitude.…”

Forward coherent ω and ϕ mesons production in the photonuclear reaction on nuclei

“…The semi-hadronic decays of the ρ 0 and ω mesons coherently photoproduced in the nucleus demonstrates the enhancement in the cross section away from the peak region due to the interference of these mesons [15]. The coherent ρ meson photoproduction from the nucleus was studied to extract the informations about the ρ − N coupling constant, ρ − N scattering amplitude and N − N correlation in the nucleus [16]. The modification of the hadronic parameters (i.e., mass and width) is looked for the ρ and ω mesons coherently produced in the photonuclear reactions [17].…”