Effects of light scalar mesons in η→3π decay -: art. no. 054001

We study the role of a possible nonet of light scalar mesons in the still interesting eta-->3pi decay process, with the primary motivation of learning more about the scalars themselves. The framework is a conventional nonlinear chiral Lagrangian of pseudoscalars and vectors, extended to include the scalars. The parameters involving the scalars were previously obtained to fit the s-wave pipi and piK scatterings in the region up to about 1 GeV as well as the strong decay eta'-->etapipi. At first, one might expect a large enhancement from diagrams including a light sigma(560). However there is an amusing cancellation mechanism which prevents this from occurring. In the simplest model there is an enhancement of about 13 percent in the eta-->3pi decay rate due to the scalars. In a more complicated model which includes derivative type symmetry breakers, the cancellation is modified and the scalars contribute about 30 percent of the total decay rate (although the total is not significantly changed). The vectors do not contribute much. Our model produces a reasonable estimate for the related a(0)(980)-f(0)(980) mixing strength, which has been a topic of current interest. Promising directions for future work along the present line are suggested.