Measurement of direct photon emission in $K^+ \to π^+ π^0 γ$ decay using stopped positive kaons
The radiative decay $K^+ \to π^+ π^0 γ$ ($K_{π2 γ}$) has been measured with stopped positive kaons. A $K_{π2 γ}$ sample containing 4k events was analyzed, and the $K_{π2 γ}$ branching ratio of the direct photon emission process was determined to be $[6.1\pm2.5({\rm stat})\pm1.9({\rm syst})]\times 10^{-6}$. No interference pattern with internal bremsstrahlung was observed.
hep-ex↗