New searches for the C-noninvariant decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup></mrow></math>→3γ and the rare decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup></mrow></math>→4γ

J. McDonough; V. L. Highland; W. K. McFarlane; R. D. Bolton; M. D. Cooper; J. S. Frank; A. L. Hallin; P. Heusi; C. M. Hoffman; G. E. Hogan; F. G. Mariam; R. E. Mischke; L. E. Piilonen; V. D. Sandberg; U. Sennhauser; R. D. Werbeck; R. A. Williams; S. L. Wilson; D. P. Grosnick; S. C. Wright

doi:10.1103/PhysRevD.38.2121

New searches for the C-noninvariant decay $π^{0}$ →3γ and the rare decay $π^{0}$ →4γ

J. McDonough, V. L. Highland, W. K. McFarlane, R. D. Bolton, M. D. Cooper, J. S. Frank, A. L. Hallin, P. Heusi, C. M. Hoffman, G. E. Hogan, F. G. Mariam, R. E. Mischke, L. E. Piilonen, V. D. Sandberg, U. Sennhauser, R. D. Werbeck, R. A. Williams, S. L. Wilson, D. P. Grosnick, and S. C. Wright

Phys. Rev. D 38, 2121 – Published 1 October 1988

Abstract

A search for the charge-conjugation-noninvariant decay $π^{0}$ →3γ has been made using the Crystal Box of the Los Alamos Meson Physics Facility. No signal in excess of background was observed, resulting in a branching-ratio upper limit of 3.1× $10^{- 8}$ (90% C.L.). A new upper limit of 2× $10^{- 8}$ (90% C.L.) was also established for the allowed decay $π^{0}$ →4γ.