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Differential cross section measurements for γ n → π− p above the first nucleon resonance region

The quasifree γd → π− p(p) differential cross section has been measured with CLAS at photon beam energies Eγ from 0.445 to 2.510 GeV (corresponding to W from 1.311 to 2.366 GeV) for pion center-of-mass angles cos θc.m. from −0.72 to 0.92. A correction for final state interactions has been applied to these data to extract the γn → π−p differential cross sections. These cross sections are quoted in 8428 (Eγ, cos θc.m.) bins, a factor of nearly 3 increase in the world statistics for this channel in this kinematic range. These new data help to constrain coupled-channel analysis fits used to disentangle the spectrum of N∗ resonances and extract their properties. Selected photon decay amplitudes N∗ → γn at the resonance poles are determined for the first time and are reported here.

pion photoproduction ; differential cross section ; partial wave analysis ; hadron spectroscopy

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