Forward analysis of $\pi$N scattering with an expansion method

Understand

The $\pi$N forward scattering data are analyzed using an expansion method, where the invariant amplitudes are represented by expansions satisfying the forward dispersion relations.

• The experimental errors of the data are taken into account through the covariance matrix of the coefficients of the expansions in a careful error analysis.
• From the results, some coefficients, $c_{n0}^\pm$, of the subthreshold expansions have been calculated with proper error bars.