The (π^-,γγ) program at TRIUMF

We report the first observation of the doubly-radiative decay mode of pionic hydrogen (π^- p → γγn) and deuterium (π^-d → γγX) using the RMC pair spectrometer at TRIUMF [1]. The process is interesting in the context of the π-Compton scattering [2] and the χPT predictions of the pion polarizability [3]. We present our preliminary values for the BR_{[π-p→γγn]} = 3.8 × 10^-5 and BR_{[π-d→γγX]} = 1-6 × 10^-5. Our π^-p data indicates the dominance of ππ → γγ mechanism. The π^-d data shows no evidence for the d*₁ dibaryon.