https://doi.org/10.1140/epjc/s2003-01234-1
Original Paper
The pion form factor within the hidden local symmetry model
1
Laboratoire Européen pour la Recherche Nucléaire, CERN, 1211, Genève 23, Switzerland
2
Laboratoire Européen pour la Recherche Nucléaire, LPNHE des Universités Paris VI et VII-IN2P3, Paris, France
3
Laboratoire Européen pour la Recherche Nucléaire, Fermilab, PO Box 500 MS 109, IL 60510, Batavia, USA
We analyze a pion form factor formulation which fulfills the Analyticity requirement within the Hidden Local Symmetry (HLS) Model. This implies an s-dependent dressing of the $\rho-\gamma$ VMD coupling and an account of several coupled channels. The corresponding function $F_\pi(s)$ provides nice fits of the pion form factor data from s=-0.25 to s=1 GeV2. It is shown that the coupling to $K \overline{K}$ has little effect, while $\omega \pi^0$ improves significantly the fit probability below the $\phi$ mass. No need for additional states like $\rho(1450)$ shows up in this invariant-mass range. All parameters, except for the subtraction polynomial coefficients, are fixed from the rest of the HLS phenomenology. The fits show consistency with the expected behaviour of $F_\pi(s)$ at s=0 up to ${\cal O} (s^2)$ and with the phase shift data on $\delta_1^1(s)$ from threshold to somewhat above the $\phi$ mass. The $\omega$ sector is also examined in relation with recent data from CMD-2.
© Springer-Verlag, 2003