Nuclear Physics B71 (1974) 461-480. North-Holland Publishing Company A MODEL FOR CHARGED nN AND nA PHOTOPRODUCTION * Gary GOLDSTEIN and Joseph F. OWENS III Physics Dept., Tufts Univ., Medford, Mass. 02155 Received August 17 1973 Abstract: A model, consisting of absorptively corrected, exchange degenerate lr-B and p-A2 Regge trajectories, is constructed for charged n-nucleon photoproduction. A fit is obtained to the existing data, and it is found that there are two significant features of the model that disagree with the data. The addition of Regge-Regge cut effects and a reduction of absorp- tive corrections away from the forward direction strikingly improve the fit. Using the Sto- dolsky-Sakurai model for pNA coupling the same improved model is applied to 7rA photo- production from deuterons. Excellent agreement is obtained with the existing data. 1. Introduction In recent years the Regge pole model has proved to be a valuable aid in helping to understand two-body and quasi-two-body reactions at high energy [ 1]. The ad- dition of absorptive corrections has yielded successful fits to many reactions [2]. In particular, absorption model calculations for charged 7rN photoproduction have been made by many authors [3-13]. These calculations have shown that the ab- sorption model provides a simple explanation for the forward peak in do/dt for 7P ~ zr+n. Furthermore, the data for the polarized photon asymmetry, Y..(+), and the polarized target asymmetry, A(+), can be correctly described for small t values. While it is possible to describe the major features of the charged nN data with the basic absorption model, there are still discrepancies between the calculations and the fine structure of the data, i.e. the precise location and shape of dips, bumps, etc. In the most detailed calculation to date, Worden has performed a fit to the data for 3'P ~ ~r+n, 7n ~ 7r-p, 719 ~ 7r0p and 7P ~ r/p as well as the constraints provided by finite energy sum rules [13]. The results show that by allowing a moderate t de- pendence for the Regge pole residues and by using a modified absorption profile, it is possible to improve the description of the fine structure apparent in the data. However, upon close examination of the results, it can be seen that some of the problems present in the basic absorption model calculations are still present, al- * Work supported in part by the Atomic Energy Commission.