Nuclear dependence of the coherent eta photoproduction reaction in a relativistic approach

Abstract

We study the nuclear (or A) dependence of the coherent eta photoproduction reaction in a relativistic impulse approximation approach. We use a standard relativistic parameterization of the elementary amplitude, based on a set of four Lorentz- and gauge-invariant amplitudes, to calculate the coherent production cross section from He-4, C-12, and Ca-40. In contrast to nonrelativistic treatments, our approach maintains the full relativistic structure of the process. The nuclear structure affects the process through the ground-state tensor density. This density is sensitive to relativistic effects and depends on A in a different manner than the vector density used in nonrelativistic approaches. This peculiar dependence results in He-4 having a cross section significantly smaller than that of C-12---in contrast to existent nonrelativistic calculations. Distortion effects are incorporated through an eta-nucleus optical potential that is computed in a simple ``t rho'' approximation.

arXiv comment4 pages, 3 postscript figures. The replace is due to a misspelling in the Authors' list

References in corpus (5)

• Effective Lagrangian Approach to the Theory of Eta Photoproduction in the $N^{\ast }(1535)$ Region
• The $\eta$NN Coupling in Eta Photoproduction
• Extraction of the Ratio of the N^*(1535) Electromagnetic Helicity Amplitudes from Eta Photoproduction off Neutrons and Protons
• Coherent $\eta$-photoproduction on ${}^4$He and ${}^{12}$C in the near-threshold region
• Coherent eta-photoproduction from nuclei in a relativistic impulse approximation approach

Cited by in corpus (6)

• Neutrino-induced coherent pion production off nuclei reexamined
• Coherent Photoproduction of Eta-Mesons on Spin-Zero Nuclei in a Relativistic, Non-local Model
• Lessons to be learned from the coherent photoproduction of pseudoscalar mesons
• Quasifree kaon-photoproduction from nuclei in a relativistic approach
• Relativistic Calculations for Incoherent Photoproduction of Eta Mesons
• Non-locality and Medium Effects in the Exclusive Photoproduction of Eta Mesons on Nuclei