2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 13, 471-484
DOI 10.1007/s100520000308

Dispersive and chiral symmetry constraints
on the light meson form factors

I. Caprini

National Institute of Physics and Nuclear Engineering, POB MG 6, 76900 Bucharest, Romania

Received: 16 July 1999 / Published online: 6 March 2000 - © Springer-Verlag 2000

Abstract
The form factors of the light pseudoscalar mesons are investigated in a dispersive formalism based on hadronic unitarity, analyticity and the OPE expansion of the QCD Green functions. We propose generalizations of the original mathematical techniques, suitable for including additional low energy information provided by experiment or Chiral Perturbation Theory (CHPT). The simultaneous treatment of the electroweak form factors of the $\pi$ and K mesons allows us to test the consistency with QCD of a low energy CHPT theorem. By applying the formalism to the pion electromagnetic form factor, we derive quite strong constraints on the higher Taylor coefficients at zero momentum, using information about the phase and the modulus of the form factor along a part of the unitarity cut.


Copyright Società Italiana di Fisica, Springer-Verlag 2000