74 research outputs found

    Three pseudoscalar meson production in e+e−e^+ e^- annihilation

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    We study, at leading order in the large number of colours expansion and within the Resonance Chiral Theory framework, the odd-intrinsic-parity e+e−→π+π−(π0,η)e^+ e^- \rightarrow \pi^+ \pi^- (\pi^0, \eta) cross-sections in the energy regime populated by hadron resonances, namely 3 \, m_{\pi} \lsim E \lsim 2 \, \mbox{GeV}. In addition we implement our results in the Monte Carlo generator PHOKHARA 7.0 and we simulate hadron production through the radiative return method.Comment: 39 pages, 5 figure

    Theoretical inputs and errors in the new hadronic currents in TAUOLA

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    The new hadronic currents implemented in the TAUOLA library are obtained in the unified and consistent framework of Resonance Chiral Theory: a Lagrangian approach in which the resonances exchanged in the hadronic tau decays are active degrees of freedom included in a way that reproduces the low-energy results of Chiral Perturbation Theory. The short-distance QCD constraints on the imaginary part of the spin-one correlators yield relations among the couplings that render the theory predictive. In this communication, the obtaining of the two- and three-meson form factors is sketched. One of the criticisms to our framework is that the error may be as large as 1/3, since it is a realization of the large-N_C limit of QCD in a meson theory. A number of arguments are given which disfavor that claim pointing to smaller errors, which would explain the phenomenological success of our description in these decays. Finally, other minor sources of error and current improvements of the code are discussed.Comment: 5 pages, no figures, contribution to the Proceedings of the QCD@Work12 Conferenc
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