Abstract
The resonancelike signal with axial-vector quantum numbers at a mass of 1420 MeV and a width of 140 MeV, recently observed by the COMPASS and VES experiments in the final state and tentatively called , is discussed. Instead of a genuine new meson, we interpret this signal as a dynamical effect due to a singularity (branching point) in the triangle diagram formed by the processes , , and (). The amplitude for this diagram is calculated. The result exhibits a peak in the intensity with a sharp phase motion with respect to the dominant -wave decay, in good agreement with the data. The branching ratio of via the triangle diagram is estimated and compared to the dominant decay .
2 More- Received 17 March 2015
DOI:https://doi.org/10.1103/PhysRevD.91.094015
© 2015 American Physical Society