https://doi.org/10.1140/epjc/s10052-019-6943-9
Regular Article - Theoretical Physics
A dispersive analysis of the pion vector form factor and 
decay
1
CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, China
2
Department of Physics, Indiana University, Bloomington, IN, 47405, USA
3
Center for Exploration of Energy and Matter, Indiana University, Bloomington, IN, 47408, USA
4
Departamento de Física, Centro de Investigación y Estudios Avanzados del IPN, Apdo. Postal 14-740, 07000, Mexico City, Mexico
* e-mail: sgonzalez@itp.ac.cn
Received:
17
February
2019
Accepted:
12
May
2019
Published online:
23
May
2019
We explore the potential of a combined analysis of the decays 
and in the determination of the 
and 
resonance properties in the frame of resonance Chiral Theory supplemented by dispersion relations. On the one hand, we take advantage of the very precise data on the modulus squared of the pion vector form factor 
obtained by Belle to carry out a very dedicated analysis of the region where these resonances come up into play. Our study provides an improved treatment of the systematic theoretical errors and, as a most important result, we conclude that they dominate over the fit uncertainties in the determination of the and pole parameters and tend to be larger than in other determinations quoted in the literature where these errors were ignored or underestimated. The results of our analysis are summarized in numerical tables for the form factor modulus and phase, including both statistical and systematic errors, that can be found as ancillary material of this paper. As a byproduct, we also determine the low-energy observables of the pion vector form factor and the 
-pole position. On the other hand, we benefit from the recent experimental data for the transition released by BaBar to perform a first analysis of its decay spectrum and discuss the role of these resonances in this decay. We point out that higher-quality data on the 
decay channel will allow to compete with the ones and improve the determination of the and resonance parameters as a result of a combined analysis. We hope our study to be of interest for present and future experimental analysis of these decays.
© The Author(s), 2019
