/ 99 07 43 3 v 1 2 0 Ju l 1 99 9 1 Precision determination of the π N scattering lengths and the charged π NN coupling constant

X iv : h ep - p h / 99 07 43 3 v 2 2 3 Ju l 1 99 9 1 Precision determination of the π N scattering lengths and the charged π NN coupling constant

We critically evaluate the isovector GMO sumrule for the charged πNN coupling constant using recent precision data from π − p and π − d atoms and with careful attention to systematic errors. From the π − d scattering length we deduce the pion-proton scattering lengths

A ug 1 99 9 Compton scattering on the charged pion and the process γγ → π 0 π 0

ar X iv : h ep - l at / 9 31 20 16 v 1 3 D ec 1 99 3 1 Lattice QCD Calculation of Hadron Scattering Lengths ∗

Method of calculating hadron multi-point functions and disconnected quark loop contributions which are not readily accessible through conventional techniques is proposed. Results are reported for π-π, π-N and N-N scattering lengths and the flavor singlet-non singlet meson mass splitting estimated in quenched QCD.

N ov 1 99 8 1 Precise strength of the π NN coupling constant

We report here a preliminary value for the πNN coupling constant deduced from the GMO sumrule for forward πN scattering. As in our previous determination from np backward differential scattering cross sections we give a critical discussion of the analysis with careful attention not only to the statistical, but also to the systematic uncertainties. Our preliminary evaluation gives g c (GMO) = 13...

ar X iv : h ep - p h / 98 07 39 5 v 1 1 6 Ju l 1 99 8 The low - energy constants of the πN system

Recent analyses of low-energy πN experimental data have provided clear evidence for the violation of the isospin symmetry of the strong interaction. In the present work, it is shown that the single-charge-exchange reaction (π − p → π 0 n) is the culprit for the effect. Given the present experimental uncertainties, no evidence for isospin breaking was found in the two elastic-scattering processe...