1. Discussion of “Coupled Channel Methods at High Q2”

2. Franz Gross

11. T. Sato, H. Kamano

12. Some remarks
Definition of resonance parameters with poles and residues.
Breit-Wigner mass and width
Proper definition based on scattering theory.
Consistent with resonance theory based on Gamow vectors
( eigenvalue problem of full Hamiltonian with purely outgoing b.c.).
One of the main subjects also in nuclear physics (complex scaling method, …).
Closely related to the developments of NON-Hermitian quantum mechanics.
(See, e.g., “Non-Hermitian Quantum Mechanics”, N. Moiseyev,
Cambridge University Press, 2011)
Highly model-dependent quantities
Can be a good approximation of resonance pole mass if and only if:
 the pole is isolated from any other singularities in complex-E plane
 small background contributions
## Not a small number of light-flavor hadrons do not satisfy this condition:
for example, Roper, f0(980), …
## One may analyze the data of real E with the BW parameterization, but
there is no guarantee that the resulting BW mass and width describe
the true resonance parameters.

13. Siggi Krewald

15. Victor Mokeev