New analysis of the low-energy π±p differential cross-sections of the CHAOS Collaboration

In a previous paper, we reported the results of a partial-wave analysis (PWA) of the pion-nucleon (pi N) differential cross-sections (DCSs) of the CHAOS Collaboration and came to the conclusion that the angular distribution of their pi(+)p data sets is incompatible with the rest of the modern (meson factory) database. The present work, re-addressing this issue, has been instigated by a number of recent improvements in our analysis, namely regarding the inclusion of the theoretical uncertainties when investigating the reproduction of experimental data sets on the basis of a given "theoretical" solution, modifications in the parametrization of the form factors of the proton and of the pion entering the electromagnetic part of the pi N amplitude, and the inclusion of the effects of the variation of the sigma-meson mass when fitting the ETH model of the pi N interaction to the experimental data. The new analysis of the CHAOS DCSs confirms our earlier conclusions and casts doubt on the value for the pi N Sigma term, which Stahov, Clement and Wagner have extracted from these data.