Observation of a narrow meson decaying to $D_s^{+}{\pi }^0\gamma$ at a mass of $2.458\mathrm{GeV}{/c}^2$

A narrow state, which we label $D_{\mathrm{sJ}}{\mathrm{}\left(2458\right)\mathrm{}}^{+},$ with a mass $2458.0\pm 1.0\left(\mathrm{stat}\right)\pm 1.0\left(\mathrm{syst}\right)\mathrm{MeV}{/c}^2,$ is observed in the inclusive $D_s^{+}{\pi }^0\gamma$ mass distribution in $91{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data recorded by the BABAR detector at the SLAC PEP-II asymmetric-energy $e^{+}{e}^{-}$ storage ring. The observed width is consistent with the experimental resolution. The data favor decay through $D_s^{*}{\mathrm{}\left(2112\right)\mathrm{}}^{+}{\pi }^0$ rather than through $D_{\mathrm{sJ}}^{*}{\mathrm{}\left(2317\right)\mathrm{}}^{+}\gamma .$ An analysis of $D_s^{+}{\pi }^0$ data accounting for the influence of the $D_{\mathrm{sJ}}{\mathrm{}\left(2458\right)\mathrm{}}^{+}$ produces a $D_{\mathrm{sJ}}^{*}{\mathrm{}\left(2317\right)\mathrm{}}^{+}$ mass of $2317.3\pm 0.4\left(\mathrm{stat}\right)\pm 0.8\left(\mathrm{syst}\right)\mathrm{MeV}{/c}^2.$