https://doi.org/10.1140/epjc/s10052-020-08576-6
Regular Article - Theoretical Physics
and 
transition form factor revisited
1
Theory Center, Thomas Jefferson National Accelerator Facility, 23606, Newport News, VA, USA
2
Institut für Kernphysik and PRISMA+ Cluster of Excellence, Johannes Gutenberg Universität, 55099, Mainz, Germany
3
Department of Physics, Indiana University, 47405, Bloomington, IN, USA
4
Center for Exploration of Energy and Matter, Indiana University, 47403, Bloomington, IN, USA
5
Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, 04510, Mexico City, Mexico
6
Departamento de Física Teórica, Universidad Complutense de Madrid and IPARCOS, 28040, Madrid, Spain
7
CERN, 1211, Geneva 23, Switzerland
8
European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*) and Fondazione Bruno Kessler, 38123, Villazzano, Trento, Italy
9
INFN Sezione di Genova, 16146, Genoa, Italy
10
INFN Sezione di Roma, I-00185, Roma, Italy
Received:
5
June
2020
Accepted:
19
October
2020
Published online:
2
December
2020
In light of recent experimental results, we revisit the dispersive analysis of the decay amplitude and of the 
transition form factor. Within the framework of the Khuri–Treiman equations, we show that the Dalitz-plot parameters obtained with a once-subtracted amplitude are in agreement with the latest experimental determination by BESIII. Furthermore, we show that at low energies the transition form factor obtained from our determination of the amplitude is consistent with the data from MAMI and NA60 experiments.
© The Author(s) 2020
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