Eur. Phys. J. C (2004) 33: 505-509
https://doi.org/10.1140/epjc/s2004-01666-y
https://doi.org/10.1140/epjc/s2004-01666-y
experimental physics
The pion nucleon coupling constant
Queen Mary, University of London, E1 4NS, London, UK
The latest 
elastic scattering data are re-analysed to determine the coupling constant g
c
of the charged pion, using the dispersion relation for the invariant amplitude B
(+ ). Depending on the choice of data-base, values 
to 13.65 are obtained with errors of 
. The mass difference between charge states of 
is 
MeV, close to twice the mass difference between neutron and proton. The difference in widths on resonance is 
MeV. One may account for a width difference of 4.5 MeV from phase space for decays and the extra channel 
.
© Springer-Verlag, 2004
