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The $(π^-,γγ)$ program at TRIUMF

Piotr A. Zolnierczuk
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Abstract

We report the first observation of the doubly-radiative decay mode of pionic hydrogen (pi- p --> gamma gamma n) and and deuterium (pi- d --> gamma gamma X) using the RMC pair spectrometer at TRIUMF. The process is interesting in the context of the pi-Compton scattering and the chiPT predictions of the pion polarizability We present our preliminary values for the B.R.(pi- p --> gamma gamma n)=3.8x10^-5 and B.R.(pi- d --> gamma gamma X)=1.6x10^-5. Our pi- p data indicates the dominance of pi pi --> gamma gamma mechanism. The pi- d data shows no evidence for the d1* dibaryon.

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Piotr A. Zolnierczuk. 2000-07-11. The $(π^-,γγ)$ program at TRIUMF. https://arxiv.org/abs/nucl-ex/0007011

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