High statistics study of the reaction $\gamma p\to p2{\pi }^0$

Abstract

The photoproduction of 2${\pi }^0$ mesons off protons was studied with the Crystal Barrel/TAPS experiment at the electron accelerator ELSA in Bonn. The energy of photons produced in a radiator was tagged in the energy range from 600\,MeV to 2.5\,GeV. Differential and total cross sections and $p{\pi }^0{\pi }^0$ Dalitz plots are presented. Part of the data was taken with a diamond radiator producing linearly polarized photons, and beam asymmetries were derived. Properties of nucleon and $\Delta$ resonances contributing to the $p{\pi }^0{\pi }^0$ final state were determined within the BnGa partial wave analysis. The data presented here allow us to determine branching ratios of nucleon and $\Delta$ resonances for their decays into $p{\pi }^0{\pi }^0$ via several intermediate states. Most prominent are decays proceeding via $\Delta (1232)\pi$, $N(1440)1/2^{+}\pi$, $N(1520)3/2^{-}\pi$, $N(1680)5/2^{+}\pi$, but also $p{f}_0(500)$, $p{f}_0(980)$, and $p{f}_2(1270)$ contribute to the reaction.

28 pages, 17 figures, 7 tables

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• Baryon Spectroscopy - Recent Results from the CBELSA/TAPS Experiment