Measurement of the Branching Fractions of the Radiative Charm Decays $D^0\to {\bar{K}}^{\ast 0}\gamma$ and $D^0\to \varphi \gamma$

Abstract

We present a measurement of the branching fractions for the Cabibbo-favored radiative decay, $D^0\to {\bar{K}}^{\ast 0}\gamma$, and the Cabibbo-suppressed radiative decay, $D^0\to \varphi \gamma$. These measurements are based on a data sample corresponding to an integrated luminosity of $387.1f{b}^{-1}$, recorded with the BaBar detector at the PEP-II $e^{+}{e}^{-}$ asymmetric-energy collider operating at center-of-mass energies 10.58 and 10.54 GeV. We measure the branching fractions relative to the well-studied decay $D^0\to K^{-}{\pi }^{+}$ and find $\mathcal{B}(D^0\to {\bar{K}}^{\ast 0}\gamma )/\mathcal{B}(D^0\to K^{-}{\pi }^{+})=(8.43\pm 0.51\pm 0.70)\times 10^{-3}$ and $\mathcal{B}(D^0\to \varphi \gamma )/\mathcal{B}(D^0\to K^{-}{\pi }^{+})=(7.15\pm 0.78\pm 0.69)\times 10^{-4}$, where the first error is statistical and the second is systematic. This is the first measurement of $\mathcal{B}(D^0\to {\bar{K}}^{\ast 0}\gamma )$.

8 pages, 5 postscript figures, submitted to Phys. Rev. D (Rapid Communications)