Measurement of the Absolute Branching Fractions for $D_s^{-}\to {\ell }^{-}{\bar{\nu }}_{\ell }$ and Extraction of the Decay Constant $f_{D_s}$

Abstract

The absolute branching fractions for the decays $D_s^{-}\to {\ell }^{-}{\bar{\nu }}_{\ell }$ ($\ell =e$, $\mu$, or $\tau$) are measured using a data sample corresponding to an integrated luminosity of 521 fb${}^{-1}$ collected at center of mass energies near 10.58 GeV with the \mbox{\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the PEP-II $e^{+}{e}^{-}$ collider at SLAC. The number of $D_s^{-}$ mesons is determined by reconstructing the recoiling system $DKX\gamma$ in events of the type $e^{+}{e}^{-}\to DKX{D}_s^{\ast -}$, where $D_s^{\ast -}\to D_s^{-}\gamma$ and $X$ represents additional pions from fragmentation. The $D_s^{-}\to {\ell }^{-}{\bar{\nu }}_{\ell }$ events are detected by full or partial reconstruction of the recoiling system $DKX\gamma \ell$. The branching fraction measurements are combined to determine the $D_s^{-}$ decay constant $f_{D_s}=(258.6\pm 6.4\pm 7.5)$ MeV, where the first uncertainty is statistical and the second is systematic.

8 pages, 3 postscript figures

References in corpus (5)

• High Precision determination of the pi, K, D and D_s decay constants from lattice QCD
• Accumulating evidence for nonstandard leptonic decays of D_s mesons
• Measurement of B(Ds -> munu)
• Effect of H^\pm on B^\pm\to τ^\pmν_τand D^\pm_s\to μ^\pmν_μ,τ^\pmν_τ
• Decay constants of charm and beauty pseudoscalar heavy-light mesons on fine lattices