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## Measurement of $B_d$ mixing using opposite-side flavor tagging

### Abstract

19 pages, 17 figures, submitted to Phys. Rev. D - D0We report on a measurement of the $B^0_d$ mixing frequency and the calibration of an opposite-side flavor tagger in the D{\O}experiment. Various properties associated with the $b$ quark on the opposite side of the reconstructed $B$ meson were combined using a likelihood-ratio method into a single variable with enhanced tagging power. Its performance was tested with data, using a large sample of reconstructed semileptonic $B \to \mu \dzero X$ and $B \to \mu \dst X$ decays, corresponding to an integrated luminosity of approximately 1 fb$^{-1}$. The events were divided into groups depending on the value of the combined tagging variable, and an independent analysis was performed in each group. Combining the results of these analyses, the overall effective tagging power was found to be eD^2 = (2.48 \pm 0.21 (stat.) ^{+0.08}_{-0.06} (syst.))%. The measured $B^0_d$ mixing frequency dmd = 0.506 \pm 0.020 {\rm (stat) \pm 0.016 (syst) ps}^{-1} is in good agreement with the world average value

Topics: 12.15.Hh, [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex]
Publisher: American Physical Society
Year: 2006
DOI identifier: 10.1103/PhysRevD.74.112002
OAI identifier: oai:HAL:in2p3-00097162v1
Provided by: Hal-Diderot