$c\to u γ$ in Cabibbo suppressed D meson radiative weak decays

Abstract

We investigate Cabibbo suppressed $D^{0}$, $D^{+}$ and $D^{+}_{s}$ radiative weak decays in order to find the best mode to test $c\to u γ$ decay. Combining heavy quark effective theory and the chiral Lagrangian approach we determine the decay widths. We calculate $Γ(D^{0}\to ρ^{0}/ωγ)/ Γ(D^{0}\to {\bar K}^{*0} γ)$ previously proposed to search for possible New Physics. However, we notice that there are large, unknown, corrections within the Standard Model. We propose a better alternative, the ratio $Γ(D_{s}^{+}\to K^{*+} γ)/ Γ(D_{s}^{+}\to ρ^{+} γ)$, and show that it is less sensitive to the Standard Model.