INFN - Laboratori Nazionali di Frascati, May 1995
From: The Second DAFNE Physics Handbook
Chapter 10: Two Photon Initiated Processes
Eds. L. Maiani, G. Pancheri, N. Paver
Supported by the INFN, by the EC under the HCM contract number CHRX-CT920026 and by the authors home institutions.
at DA
NE
Centre for Particle Theory, University of Durham,
Durham DH1 3LE, U.K.
Dispersion relations provide a framework for the model-independent
determination of key parameters of hadron dynamics from
measurements of 
scattering. This framework is outlined.
Particular attention is paid to the range
of applicability of approximations made in practical calculations and
the consequent uncertainty in predictions or quantities extracted.
Precise measurements at DA
NE of the reactions 
and 
at low energies over
as complete an angular coverage as possible will impose constraints on
phases,
test Chiral Perturbation Theory and provide a firmer basis for the
determination of two photon couplings of the I=0 scalar resonances at
higher 
masses and so help to solve the enigma of their structure.