arXiv:nucl-th/9912034·v1·Nuclear Theory
New Result for the Pion-Nucleon Sigma Term from an Updated VPI/GW Pion-Nucleon Partial-Wave and Dispersion Relation Analysis
M.M. Pavan (1) · R.A. Arndt (2) · I.I Strakovsky · R.L. Workman (3) ((1) Lab for Nuclear Science, M.I.T., Cambridge, MA ; (2) Dept. of Physics, V.P.I., Blacksburg, VA ; (3) Dept. of Physics, The George Washington University, Washington, D.C.)
Abstract
A new result for the nucleon sigma term from an updated pion-nucleon partial-wave and dispersion relation analysis of the Virginia Polytechnic Institute (now George Washington University) group is discussed. Using a method similar to that of Gasser, Leutwyler, Locher, and Sainio, we obtain Sigma=90 +/- 8 MeV (preliminary), in disagreement with the canonical result 64 +/- 8 MeV, but consistent with expectations based on new information on the NN coupling constant, pionic atoms, and the Delta resonance width.
Comments: Proceedings of the 8th International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon, Zuoz, Switzerland, August 1999. 5 pages, 4 figures