Scalar f0(980) and meson exchange in decays intoA. Bramon1, R. Escribano1, 2, J.L. Lucio M.3, M. Napsuciale3 and G. Pancheri4
1 Grup de Física Teòrica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
2 IFAE, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
3 Instituto de Física, Universidad de Guanajuato, Lomas del Bosque #103, Lomas del Campestre, 37150 León, Guanajuato, Mexico
4 INFN-Laboratori Nazionali di Frascati, P.O. Box 13, 00044 Frascati, Italy
(Received: 14 May 2002 / Revised version: 25 July 2002 / Published online: 18 October 2002 )
The complementarity between chiral perturbation theory and the linear sigma model is exploited to study production in radiative decays, where the effects of the f0(980) scalar resonance, and those of its more controversial partner, should become manifest via the decay chain. The recently reported data on coming from the VEPP-2M e+ e- collider in Novosibirsk and the DA NE -factory in Frascati can be reasonably described in our approach, which we propose as a promising first step towards more detailed analyses. The f0(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 coupling and an coupling suppressed by almost ideal - f0 mixing. Indeed, the mixing angle in the flavor basis is found to be , if the f0 propagator is approximated by a simple Breit-Wigner expression, or , if an improved two-channel analysis is performed. The 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 and thus quite small.
© Società Italiana di Fisica, Springer-Verlag 2002