The Pion Form Factor Within the Hidden Local Symmetry Model

Abstract

We analyze a pion form factor formulation which fulfills the Analyticity requirement within the Hidden Local Symmetry (HLS) Model. We show that it implies an $s$--dependent dressing of the $\ddot{I}-{\hat{I}}^3$ VMD coupling and an account of several coupled channels. The corresponding function $F_{\ddot{I}}€(s)$ provides nice fits of the pion form factor data from $s=-0.25$ to $s=1$ GeV${}^2$. It is shown that the coupling to $K\bar{K}$ has little effects, while $\omg π^0$ improves significantly the fit quality below the $\ddot{I}•$ mass. 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 $F_{\ddot{I}}€(s)$ at $s=0$ up to $\mathcal{O}(s^2)$ and with the phase shift data on $\hat{I}{´}_1^1(s)$ from threshold to somewhat above the $\ddot{I}•$ mass. The $\omg$ sector is also examined in relation with recent data from CMD--2.

26 pages, 4 eps figs