Observation of the Decay B-→Ds(*)+K-ℓ-ν̅ ℓ

• Main Authors: Fisher, Peter H. (Contributor), Cowan, Ray Franklin (Contributor), Dujmic, Denis (Contributor), Sciolla, Gabriella (Contributor), Zhao, M. (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor), Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: American Physical Society, 2011-11-30T18:35:51Z.
• Subjects: Article
• Online Access: Get fulltext

 We report the observation of the decay B[superscript -]→D[subscript s][superscript (*)+]K[superscript -]ℓ[superscript -]ν̅ ℓ based on 342  fb[superscript -1] of data collected at the Υ(4S) resonance with the BABAR detector at the PEP-II e[superscript +]e[superscript -] storage rings at SLAC. A simultaneous fit to three D[subscript s][superscript +] decay chains is performed to extract the signal yield from measurements of the squared missing mass in the B meson decay. We observe the decay B[superscript -]→D[subscript s][superscript (*)+]K[superscript -]ℓ[superscript -]ν̅ ℓ with a significance greater than 5 standard deviations (including systematic uncertainties) and measure its branching fraction to be B(B[superscript -]→D[subscript s][superscript (*)+]K[superscript -]ℓ[superscript -]ν̅ ℓ)=[6.13[subscript -1.03][superscript +1.04](stat)±0.43(syst)±0.51(B(D[subscript s]))]×10[superscript -4], where the last error reflects the limited knowledge of the D[subscript s] branching fractions.