Abstract
Using a counting scheme which treats the light pseudoscalar and the light vector-meson nonet on equal footing, the decays of the narrow light vector mesons into a pseudoscalar meson and a dilepton and of the 0 meson into an ! meson and a dielectron are calculated. Since all required parameters but one can be determined by other reactions, one has predictive power for the considered decay rates and form factors. The calculated partial decay widths are in good agreement with the available experimental data.
Highlights
According to the vector-meson dominance conjecture [1], electromagnetic reactions of hadrons can be described efficiently with dynamical vector meson degrees of freedoms
On the left-hand side in fig. 1, this form factor is plotted in comparison to the data taken by the NA60 collaboration and the vector-mesondominance model (VMD) form factor (7)
As already mentioned in the introduction, VMD fails to describe the data whereas our calculation misses only the last three data points
Summary
According to the vector-meson dominance conjecture [1], electromagnetic reactions of hadrons can be described efficiently with dynamical vector meson degrees of freedoms. A possible solution to this problem are effective field theories which use hadrons instead of quarks and gluons as relevant degrees of freedom. In the lowest energy range, such an effective theory is chiral perturbation theory (ChPT) [4, 5] which uses only the Goldstone bosons π, K and η as active degrees of freedom. We apply a novel counting scheme as proposed recently in [6, 3] The masses of both pseudoscalar and vector mesons, mP and mV , respectively, are regarded as light implying the universal counting rules mP, mV , Dμ ∼ Q (1).
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