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Scalar f 0 (980) and \(\sigma (500)\) meson exchange in \(\phi\) decays into \(\pi^0\pi^0\gamma\)

  • A. Bramon
  • R. Escribano
  • J.L. Lucio M.
  • M. Napsuciale
  • G. Pancheri
Theoretical Physics

Abstract.

The complementarity between chiral perturbation theory and the linear sigma model is exploited to study \(\pi^0\pi^0\) production in \(\phi\) radiative decays, where the effects of the f 0 (980) scalar resonance, and those of its more controversial \(\sigma (500)\) partner, should become manifest via the \(\phi\rightarrow K^+ K^- (\gamma)\rightarrow\pi^0\pi^0\gamma \) decay chain. The recently reported data on \(\phi\rightarrow\pi^0\pi^0\gamma\) coming from the VEPP-2M e + e - collider in Novosibirsk and the DA\(\Phi\)NE \(\phi\)-factory in Frascati can be reasonably described in our approach, which we propose as a promising first step towards more detailed analyses. The f 0 (980) contribution, which appears as a moderately narrow peak at the high part of the dipion mass spectrum, can be interpreted as the isoscalar member of the scalar nonet with a large \(f_0 K\bar{K}\) coupling and an \(f_0\pi\pi\) coupling suppressed by almost ideal \(\sigma\)-f0 mixing. Indeed, the mixing angle in the flavor basis is found to be \(\phi_{S}\approx - 6^\circ\), if the f0 propagator is approximated by a simple Breit-Wigner expression, or \(\phi_{S}\approx -9^\circ\), if an improved two-channel analysis is performed. The \(\sigma (500)\) resonance, which is then strongly coupled to pion pairs, yields a tiny contribution because, in our approach, its coupling to kaon pairs is proportional to \(m^2_\sigma-m^2_K\) and thus quite small.

Keywords

Sigma Model Narrow Peak Radiative Decay Decay Chain Chiral Perturbation Theory 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg / Società Italiana di Fisica 2002

Authors and Affiliations

  • A. Bramon
    • 1
  • R. Escribano
    • 1
  • J.L. Lucio M.
    • 2
  • M. Napsuciale
    • 2
  • G. Pancheri
    • 3
  1. 1.Grup de Física Teòrica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain ES
  2. 2. Instituto de Física, Universidad de Guanajuato, Lomas del Bosque #103, Lomas del Campestre, 37150 León, Guanajuato, Mexico MX
  3. 3. INFN-Laboratori Nazionali di Frascati, P.O. Box 13, 00044 Frascati, Italy IT

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