Primakoff effect in -photoproduction off protons

A. Sibirtsev; J. Haidenbauer; S. Krewald; U. -G. Meißner

doi:10.1140/epja/i2010-10961-7

EPJ

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2023 Impact factor 2.6

Hadrons and Nuclei

Open Access

Eur. Phys. J. A (2010) 44: 169-173
https://doi.org/10.1140/epja/i2010-10961-7

Letter

Primakoff effect in $\eta$ -photoproduction off protons

A. Sibirtsev¹^,2^,3, J. Haidenbauer³^,4, S. Krewald³^,4 and U. -G. Meißner¹^,3^,4^*

¹ Helmholtz-Institut für Strahlen- und Kernphysik (Theorie) und Bethe Center for Theoretical Physics, Universität Bonn, D-53115, Bonn, Germany
² Excited Baryon Analysis Center (EBAC), Thomas Jefferson National Accelerator Facility, 23606, Newport News, VA, USA
³ Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425, Jülich, Germany
⁴ Institute for Advanced Simulation, Forschungszentrum Jülich, D-52425, Jülich, Germany

^* e-mail: meissner@hiskp.uni-bonn.de

Received: 6 January 2010
Revised: 4 March 2010
Accepted: 5 March 2010
Published online: 26 March 2010

Abstract

We analyse data on forward $\eta$ -meson photoproduction off a proton target and extract the $\eta$ $\rightarrow$ $\gamma$ $\gamma$ decay width utilizing the Primakoff effect. The hadronic amplitude that enters into our analysis is strongly constrained because it is fixed from a global fit to available $\gamma$ p $\rightarrow$ p $\eta$ data for differential cross-sections and polarizations. We compare our results with present information on the two-photon $\eta$ -decay from the literature. We provide predictions for future PrimEx experiments at Jefferson Laboratory in order to motivate further studies.