A Possible Arena for Searching New Physics - the $Γ(D^0 \to ρ^0 γ)/Γ(D^0 \to ωγ)$ Ratio

Abstract

We propose to investigate flavour changing neutral currents in the $c \to u γ$ transition through the measurement of the difference between $Γ(D^0 \to ρ^0 γ)$ and $Γ(D^0 \to ωγ)$. This is based on the observation that $D^0 \to (d \bar d) γ$ is due to long distance physics while $D^0 \to (u \bar u) γ$ arises from the $c \to u γ$ transition. The effect of $ρ- ω$ mixing is included. A difference in the decay widths of more than about 30% would be indicative of new physics.