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Title: Search for b^0s oscillations in semileptonic b decays

Journal Article ·
OSTI ID:899704

This note describes a search for B{sub s}{sup 0} oscillations using semileptonic B decays recorded by the CDF detector during Run II of the Fermilab Tevatron Collider on about 1 fb{sup -1} of data, as it was in April 2006. Opposite-side and same-side b flavor taggers are used in this analysis. First they measure the B{sup 0} oscillation frequency and calibrate opposite-side b flavor taggers on a sample of semileptonic B decays. A simultaneous analysis of B{sup 0} and B{sup +} decays to {ell}D{sup 0}, {ell}D{sup +} and {ell}D* final states has been performed. Beginning with tagger calibrations available from earlier analyses on the {ell} + SVT samples, they use the high statistic {ell}D sample to derive scale factors for predicted dilutions of the soft muon, soft electron and jet charge opposite-side taggers. Secondly they reconstruct B{sub s}{sup 0} {yields} {ell}{sup +}D{sub s}{sup -}X decays in three different D{sub s}{sup -} channels, namely {phi}{pi}{sup -}, K*{sup 0} K{sup -} and {pi}{sup +}{pi}{sup -}{pi}{sup -}. D mass, lepton-D mass and lifetime parameters for signal and backgrounds are determined with unbinned maximum likelihood fits. They validate their fitter and obtain sensitivity projections with toy Monte Carlo samples. The {Delta}m{sub s} sensitivity on the semileptonic sample is 17.3 ps{sup -1}. With the combination of the semileptonic and hadronic analyses they observe a signature consistent with B{sub s}{sup 0} - {bar B}{sup s}{sup 0} oscillations. The probability that random tags background could fluctuate to mimic such a signature is 0.5%. Under the hypothesis that this is a signal for B{sub s}{sup 0} - {bar B}{sup s}{sup 0} oscillations, they measure {Delta}m{sub s} = 17.31{sub -0.18}{sup -0.33}(stat.) {+-} 0.07(syst.) ps{sup -1}.

Research Organization:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC02-07CH11359
OSTI ID:
899704
Report Number(s):
FERMILAB-PUB-06-514-E; TRN: US200711%%529
Country of Publication:
United States
Language:
English