Quantum interferences in the reaction close to the vector meson production threshold

2005/03/31 by Matthias F. M. Lutz, Madeleine Soyeur · 7 citations
Physics and Astronomy · #Amplitude #High-Energy Particle Collisions Research #Meson #Nuclear physics #Nucleon #Pair production #Particle physics #Particle physics theoretical and experimental studies #Physics #Production (economics) #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Vector meson #Vector meson dominance #nucl-th

paper · pdf · doi:10.1016/j.nuclphysa.2005.05.199

published in Nuclear Physics A 760(1-2), 85-109 (Elsevier BV) · 28 pages, 12 figures

arxiv created 2005/03/31 · openalex publication_date 2005/06/30 · arxiv updated 2010/12/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

The exclusive photoproduction of e⁺e^- pairs from nucleons close to the vector meson production threshold (1.4<√ s <1.8 GeV) results from two main processes: the emission of Bethe-Heitler pairs and the photoproduction of ρ⁰- and ω-mesons decaying into e⁺e^- pairs. The Bethe-Heitler amplitudes are purely electromagnetic and reflect mostly the nucleon magnetic structure. The γN→ e⁺e^- N amplitudes arising from vector meson production and decay are derived from γN→ ρ⁰ N and γN → ωN amplitudes supplemented by the Vector Meson Dominance assumption. The vector meson photoproduction amplitudes are calculated using a relativistic and unitary coupled-channel approach to meson-nucleon scattering. They depend sensitively on the coupling of vector fields to baryon resonances. The γN → e⁺e^- N differential cross sections display interference patterns. The interference of Bethe-Heitler pair production with vector meson e⁺e^- decay is quite small in the domain of validity of our model for all angles of the emitted e⁺e^- pair. The interference of ρ⁰- and ω-mesons in the e⁺e^- channel can be large. It is constructive for the γp → e⁺e^- p reaction and destructive for the γn → e⁺e^- n reaction. We discuss the shape and magnitude of the e⁺e^- pair spectra produced in the γp → e⁺e^- p and γn → e⁺e^- n reactions as functions of the pair emission angle and of the total center of mass energy √ s.

Citations

• Backward electroproduction ofπ0mesons on protons in the region of nucleon resonances at four momentum transfer squaredQ2=1.0<mml:mspace width="0.3em"/>GeV2
• Polarization phenomena in small-angle photoproduction ofe+e−pairs and the Gerasimov-Drell-Hearn sum rule
• Relativistic chiral SU(3) symmetry, large-Nc sum rules and meson–baryon scattering
• Quantum interference of - and -mesons in the reaction
• Photoproduction of electron-positron pairs on the proton in the resonance region

Cited by

• Medium modifications of theρmeson in nuclear photoproduction