Jun 13 – 17, 2011
Europe/Berlin timezone
Proceedings are now available online at <a href="http://www.slac.stanford.edu/econf/C110613/">eConf</a>

About the contact term in the omega->3 pion process from the Vector Dominance point of view.

Jun 14, 2011, 6:20 PM
1h 10m
Millerzimmer (Künstlerhaus)



poster Poster Session Poster Session


David Garcia (Instituto de Física, UNAM)


The omega->3 pion process is known to be dominated by the omega-rho-pi transition, followed by the decay of the rho meson into two pions. However, this does not deny the possibility of the need of a contact term, as can be seen in other works, to reproduce the experimental value of the decay width of the omega meson into three pions. In this work, we revisit the omega->3 pion process under the Vector Meson Dominance scheme (VMD). We obtain its width by considering only the rho channel, fixing the omega-rho-pi coupling from radiative decays. We restate the possible need of the contact term to account for the deviations from the experimental value. Using the VMD ideas, we mimic the contact term by a higher resonance (namely the rho′(1450) meson) which, in contrast with previous works, possess a structure at high energies, while at low energies behaves as a constant. We have found that under such considerations the numerical value of the contact term is similar to the other estimates and therefore satisfy the corresponding requirements. We also determine at which extent it is possible to ignore such contact term in the VMD scheme while being consistent with other observables. In order to do so, we have calculated the cross section for the e+ e− ->omega->3 pi process. By comparing with the experimental data when excluding/including the contact term and varying the omega-rho-pi coupling within the corresponding error bars, we have found that a value of 12.39±1.5 GeV^-1 for this coupling is in agreement with both the e+ e− ->omega->3 pi cross section, the omega->3 pi decay width and the related radiative decays by VMD. Due to the large uncertainties involved it is not possible to be conclusive about the contact term.

Primary author

David Garcia (Instituto de Física, UNAM)


Dr Genaro Toledo (Instituto de Física, UNAM)

Presentation materials