Running mass of the rho0 meson's implication for the dilepton mass spectrum and the mu+mu-/e+e- branching ratio in the K+ --> pi+l+l- decays

Abstract

We make an attempt to resolve the discrepancy of the observed e+e- mass spectrum in the K+ --> pi+e+e- decay with that predicted by meson dominance. To this end we investigate the properties of the rho0 propagator. We use dispersion relations to evaluate the running mass squared m_rho^2(t) of the rho0 resonance without adjustable parameters. To improve the convergence of the dispersion integral, the momentum dependence of strong vertices is taken from the flux-tube-breaking model of Kokoski and Isgur. The obtained behavior of m_rho^2(t) at small momentum squared t makes the K+ --> pi+e+e- form factor rise faster with increasing $t$ than in the original meson-dominance calculation and more in agreement with the published data. As a consequence, the meson-dominance prediction of the mu+mu-/e+e- branching ratio changes slightly, from 0.224 to 0.236. We do not see any possibility to accommodate into the meson-dominance approach an even steeper e+e- spectrum, indicated by the preliminary data of the E865 collaboration at BNL AGS.

13 pages, RevTeX, epsf.sty, 4 embedded figures

References in corpus (3)

• The Decays $K\to \pi {\ell }^{+}{\ell }^{-}$ beyond Leading Order in the Chiral Expansion
• Some implications of meson dominance in weak interactions
• Observation of the Decay K+ --> pi+ mu+ mu-

Cited by in corpus (10)

• New measurement of the K+- --> pi+-mu+mu- decay
• Precise measurement of the K+- --> pi+-e+e- decay
• A new measurement of the properties of the rare decay K -> pi+ e+ e-
• A New Measurement of the Rare Decay $K^{+}\to {\pi }^{+}{\mu }^{+}{\mu }^{-}$
• Forward-backward Asymmetry in $K^{+}\to {\pi }^{+}{\ell }^{+}{\ell }^{-}$
• Electron-positron annihilation into four charged pions and the a_1-rho-pi Lagrangian
• Vector meson dominance and the pi^0 transition form factor
• Linear representation of energy-dependent Hamiltonians
• Joint description of the e+e- annihilation into both four-pion channels
• Possible manifestation of the 2p pionium in particle physics processes