Dispersive and chiral symmetry constraints on the light meson form factors

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.

29 pages, 3 figures

Cited by in corpus (10)

• Vector Meson Dominance as a first step in a systematic approximation: the pion vector form factor
• Stringent constraints on the scalar K pi form factor from analyticity, unitarity and low-energy theorems
• Implications of unitarity and analyticity for the Dπform factors
• Test of analyticity and unitarity for the pion form-factor data around the $\rho$ resonance
• Constraining the low energy pion electromagnetic form factor with space-like data
• Constraining the low energy Pion electromagnetic form factor with space-like and phase of time-like data
• New constraints on the Pion EM form factor using Pi'(-Q^2)
• Constraining Form Factors with the Method of Unitarity Bounds
• Advanced parametrisations for hadronic form factors
• Bounds on the spacelike pion electromagnetic form factor from analyticity and unitarity