More detailed properties of rho and phi mesons from QCD sum rules.

Abstract

We reexamine the genuine Borel QCD sum rules for the $\ensuremath{\rho}$ and $\ensuremath{\varphi}$ mesons using a simple numerical method to flatten the sum-rule ${M}^{2}$ dependence in a wide range of ${M}^{2}$. Following Das et al., the imaginary part of the corresponding polarization operator is written in terms of the pion or kaon electromagnetic form factor, which we parametrize by means of simple formulas obeying requirements of analyticity and depending on the mass, the width, and the vector-meson-dominance coupling-constant ratio for the given vector meson. The determined resonance parameters are close to their experimental values. Furthermore, the influence of the "nonstandard" values of the gluon and four-quark condensates on the vector-meson properties is also studied.