Four-pion production in $e^+e^-$ annihilation

G. Ecker; R. Unterdorfer

doi:doi:10.1007/s10052-002-0960-8

EPJ

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2021 Impact factor 4.991

Particles and Fields

Eur. Phys. J. C 24, 535-545 (2002)
DOI: 10.1007/s10052-002-0960-8

Four-pion production in e⁺e^- annihilation

G. Ecker and R. Unterdorfer

Institut für Theoretische Physik, Universität Wien, Boltzmanngasse 5, 1090 Vienna, Austria

(Received: 8 March 2002 / Published online: 14 June 2002 )

Abstract
We calculate the processes $e^+ e^- \to 4\pi$ and $\tau \to \nu_\tau 4 \pi$ to O(p⁴) in the low-energy expansion of the standard model. The chiral amplitudes of O(p⁴) can be extended via resonance exchange to energies around 1 GeV. Higher-order effects have been included in the form of $\omega$ , a₁ and double $\rho$ exchange and by performing a resummation of the pion form factor. The predicted cross sections and the branching ratios ${\mathrm {BR}}(\rho^0 \to 4 \pi)$ are in good agreement with the available data.