Absolute Measurement of Hadronic Branching Fractions of the $D_s^{+}$ Meson

The branching fractions of $D_s^{\pm }$ meson decays serve to normalize many measurements of processes involving charm quarks. Using $298{\mathrm{pb}}^{-1}$ of $e^{+}{e}^{-}$ collisions recorded at a center of mass energy of 4.17 GeV, we determine absolute branching fractions for eight $D_s^{\pm }$ decays with a double tag technique. In particular we determine the branching fraction $\mathcal{B}(D_s^{+}\to K^{-}{K}^{+}{\pi }^{+})=(5.50\pm 0.23\pm 0.16)\%$, where the uncertainties are statistical and systematic, respectively. We also provide partial branching fractions for kinematic subsets of the $K^{-}{K}^{+}{\pi }^{+}$ decay mode.

Figure 1

Invariant masses of the $D_s^{\pm }$ candidates in data in ST modes. Charge-conjugate modes are combined. The fits for yields are shown as the dashed red lines (background component) and solid blue lines (signal plus background). The total ST yield is $(30.9\pm 0.3)\times {10}^3$ events.

Figure 2

Masses of the $D_s^{-}$ and $D_s^{+}$ candidates for all 64 DT modes in data. The rectangles show the signal region (center) and two sideband regions (diagonally offset). There are 1089 events in the signal region and 339 events in the combined sideband regions.

Figure 3

Yields of $D_s^{\pm }\to K^{\mp }{K}^{\pm }{\pi }^{\pm }$ single tag events versus $K^{-}{K}^{+}$ invariant mass; no efficiency corrections have been applied. The ST fit procedure for the full $K^{-}{K}^{+}{\pi }^{+}$ sample is applied here to the subsample of each bin of $M(K^{-}{K}^{+})$ and the resulting yields plotted, hence backgrounds have been subtracted and the yields shown are signal. A $\varphi$ peak is visible above an additional broad signal component. The lines show the mass window boundaries for the partial branching fractions in Table 2.