Four-pion production in e(+) e(-) annihilation

por Gerhard Ecker (Institut fur Theoretische Physik (Wien))

jueves 18 abr. 2002 12:30 → 13:30 Europe/Madrid

Sala Seminarios IFIC (Edf. Institutos de Investigación)

We have calculated the processes e(+) e(-) -> 4 pion and tau -> nu_tau 4 pion to O(p^4) in the low-energy expansion of the standard model. The chiral amplitudes of O(p^4) can be extended via resonance exchange to energies arount 1 GeV. Higher-order effects have been included in the form of w(782), a_1(1260) and double rho exchange and by performing a resummation of the pion form factor. The predicted cross sections and the branching ratios BR(rho^0 -> 4pion) are in good agreement with available data.