PION-NUCLEON SCATTERING IN THE N * ( 1440 ) RESONANCE REGION
Complete sets of measurements for pion-nucleon scattering in the N*(1440) resonance region have been made since 1980, when the landmark KarlsruheHelsinki (KH) and Carnegie Mellon-Berkeley (CMB) partial wave analyses (PWA) were completed. These measurements consist of differential cross sections and analyzing powers for elastic scattering and charge exchange and spin rotation parameters for elastic scattering in the momentum interval 0.4–0.7 GeV/c. The program culminated with measurements of π−p → Neutrals (charge exchange, multiple π final states, η production, and inverse photoproduction) by the Crystal Ball Collaboration at Brookhaven National Laboratory. Resonance parameters for the N*(1440) in the Review of Particle Physics by the Particle Data Group have been obtained from the KH and CMB analyses. The 2006 edition also includes the analysis by George Washington University (GWU), but the parameters were unchanged. An example of the data is presented along with comparisons to PWA.