Tarasov, VE; Briscoe, WJ; Gao, H; Kudryavtsev, AE; Strakovsky, II, *Extracting the photoproduction cross section off the neutron $\gamma n \rightarrow \pi^- p$ from deuteron data with FSI effects*,
Phys. Rev. C, vol. 84 no. 3
(2011),
pp. 035203 [doi] .
**Abstract:**

*The incoherent pion photoproduction reaction Î³dâ†’Ï€ -pp is considered theoretically in a wide energy region E thâ‰¤EÎ³â‰¤2700 MeV. The model applied contains the impulse approximation as well as the NN and Ï€N final-state-interaction (FSI) amplitudes. The aim of the paper is to study a reliable way for getting the information on elementary Î³nâ†’Ï€-p reaction cross sections beyond the impulse approximation for Î³dâ†’Ï€-pp. For the elementary Î³Nâ†’Ï€N, NNâ†’NN, and Ï€Nâ†’Ï€N amplitudes, the results of The George Washington University (GW) Data Analysis Center (DAC) are used. There are no additional theoretical constraints. The calculated cross sections dÏƒ/dÎ©(Î³dâ†’Ï€-pp) are compared with existing data. The procedure used to extract information on the differential cross section dÏƒ/dÎ©(Î³nâ†’Ï€ -p) on the neutron from the deuteron data using the FSI correction factor R is discussed. The calculations for R versus Ï€-p center-of-mass (CM) angle Î¸1 of the outgoing pion are performed at different photon-beam energies with kinematic cuts for a "quasifree" process Î³nâ†’Ï€-p. The results show a sizable FSI effect Râ‰ 1 from the S-wave part of pp-FSI at small angles close to Î¸1âˆ¼0: this region narrows as the photon energy increases. At larger angles, the effect is small (|R-1| 1) and agrees with estimations of FSI in the Glauber approach. Â© 2011 American Physical Society.*