The pion-nucleon Sigma term is definitely large: results from a G.W.U. analysis of pion nucleon scattering data

摘要: A new result for the pion nucleon Sigma term from a George Washington University/TRIUMF group analysis of data is presented. The value Sigma=79$\pm$7 MeV was obtained, compared to canonical 64$\pm$8 found by Koch. difference explained simply PSI pionic hydrogen a(pi -p), latest results $\pi NN$ coupling onstant, and narrower Delta resonance. Many systematic effects have been investigated, including Coulomb corrections, database changes, our are be robust. In standard interpretation, implies strangeness fraction y/2~0.23. implausibility such large strange component suggests that relationship between ought re-examined.