Precise Measurement of the Pion Axial Form Factor in the π+e+νγ Decay

E. Frlež et al.
Phys. Rev. Lett. 93, 181804 – Published 25 October 2004

Abstract

We have studied radiative pion decays π+e+νγ in three broad kinematic regions using the PIBETA detector and a stopped pion beam. Based on Dalitz distributions of 41 601 events we have evaluated absolute πeνγ branching ratios in the three regions. Minimum χ2 fits to the integral and differential (Ee+,Eγ) distributions result in the axial-to-vector weak form factor ratio of γFA/FV=0.443(15), or FA=0.0115(4) with FV=0.0259. However, deviations from standard model predictions in the high-Eγ–low-Ee+ kinematic region indicate the need for further theoretical and experimental work.

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  • Received 17 December 2003

DOI:https://doi.org/10.1103/PhysRevLett.93.181804

©2004 American Physical Society

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Precise Measurement of the π+π0e+ν Branching Ratio

D. Počanić et al.
Phys. Rev. Lett. 93, 181803 (2004)

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Vol. 93, Iss. 18 — 29 October 2004

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