Journal article

Publication year: 2017

Journal: Physical Review D

Volume number: 96

Issue number: 1

ISSN: 2470-0010

eISSN: 2470-0029

Open access status: Green

DOI Link: https://doi.org/10.1103/PhysRevD.96.014021

Publisher: American Physical Society

Abstract: 
We complement studies of the neutral pion transition form factor pi(0) -> gamma(()*())gamma(()*()) with calculations for the electromagnetic decay widths of the processes pi(0) -> e(+)e(-), pi(0) -> e(+)e(-)gamma and pi(0) -> e(+)e(-)e(+)e(-). Their common feature is that the singly or doubly virtual transition form factor serves as a vital input that is tested in the nonperturbative low-momentum region of QCD. We determine this form factor from a well-established and symmetry-preserving truncation of the Dyson-Schwinger equations. Our results for the three-and four-body decays match results of previous theoretical calculations and experimental measurements. For the rare decay we employ a numerical method to calculate the process directly by deforming integration contours, which in principle can be generalized to arbitrary integrals as long as the analytic structure of the integrands are known. Our result for the rare decay is in agreement with dispersive calculations but still leaves a 2 sigma discrepancy between theory and experiment.

Harvard Citation style: Weil, E., Eichmann, G., Fischer, C. and Williams, R. (2017) Electromagnetic decays of the neutral pion, Physical Review D, 96(1), Article 014021. https://doi.org/10.1103/PhysRevD.96.014021

APA Citation style: Weil, E., Eichmann, G., Fischer, C., & Williams, R. (2017). Electromagnetic decays of the neutral pion. Physical Review D. 96(1), Article 014021. https://doi.org/10.1103/PhysRevD.96.014021