Energy-independent multipole analysis of pi /sup 0/, pi /sup +/ and pi /sup -/ photoproduction in the first resonance region

Extending previous work on an multipole analysis of pi /sup 0/ and pi /sup +/ photoproduction, the authors report on an analysis of pi /sup 0/, pi /sup +/ and pi /sup -/ photoproduction, using the very recent and accurate data of the pi /sup -// pi /sup +/ ratio measured at Bonn. The analysis also uses the most recent pi N phase shifts from the CERN analysis. The results are compared to two dispersion theoretic calculations. Discrepancies between theory and the analysis occur in particular for M/sub 1-/(3/2), for M/sub 1+/(3/2), E/sub 0+ /(0) and M/sub 1+/(1/2) while the other multipoles agree more or less with at least one calculation. All data are described satisfactorily without inclusion of an isotensor term in the electromagnetic current. (17 refs)