We report the observation of the exclusive decay Bs0-->Ds-Ds+ at the 7.5 standard deviation level using 355 pb(-1) of data collected by the CDF II detector in pp collisions at sqrts=1.96 TeV at the ...Fermilab Tevatron. We measure the relative branching ratio B(Bs0-->Ds-Ds+)/B(B0-->D-Ds+)=1.44(-0.44)(+0.48). Using the world average value for B(B0-->D-Ds+), we find B(Bs0-->Ds-Ds+)=(9.4(-4.2)(+4.4))x10(-3). This provides a lower bound DeltaGammasCP/Gammas>or=2B(Bs0-->Ds-Ds+)>1.2x10(-2) at 95% C.L.
We report the observation of B{sub s}{sup 0}-B{sub s}{sup 0} oscillations from a time-dependent measurement of the B{sub s}{sup 0}-B{sub s}{sup 0} oscillation frequency {delta}m{sub s}. Using a data ...sample of 1 fb{sup -1} of pp collisions at {radical}(s)=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron, we find signals of 5600 fully reconstructed hadronic B{sub s} decays, 3100 partially reconstructed hadronic B{sub s} decays, and 61 500 partially reconstructed semileptonic B{sub s} decays. We measure the probability as a function of proper decay time that the B{sub s} decays with the same, or opposite, flavor as the flavor at production, and we find a signal for B{sub s}{sup 0}-B{sub s}{sup 0} oscillations. The probability that random fluctuations could produce a comparable signal is 8x10{sup -8}, which exceeds 5{sigma} significance. We measure {delta}m{sub s}=17.77{+-}0.10(stat){+-}0.07(syst) ps{sup -1} and extract vertical bar V{sub td}/V{sub ts} vertical bar =0.2060{+-}0.0007({delta}m{sub s}){sub -0.0060}{sup +0.0081}({delta}m{sub d}+theor)
Cosmic ray (CR) interactions can be a challenging source of background for neutrino oscillation and cross-section measurements in surface detectors. We present methods for CR rejection in ...measurements of charged-current quasielastic-like (CCQE-like) neutrino interactions, with a muon and a proton in the final state, measured using liquid argon time projection chambers (LArTPCs). Using a sample of cosmic data collected with the MicroBooNE detector, mixed with simulated neutrino scattering events, a set of event selection criteria is developed that produces an event sample with minimal contribution from CR background. Depending on the selection criteria used a purity between 50 and 80% can be achieved with a signal selection efficiency between 50 and 25%, with higher purity coming at the expense of lower efficiency. While using a specific dataset and selection criteria values optimized for the MicroBooNE detector, the concepts presented here are generic and can be adapted for various studies of exclusive
ν
μ
CCQE interactions in LArTPCs.
For a large liquid-argon time-projection chamber (LArTPC) operating on or near the Earth’s surface to detect neutrino interactions, the rejection of cosmogenic background is a critical and ...challenging task because of the large cosmic-ray flux and the long drift time of the time-projection chamber. We introduce a superior cosmic background rejection procedure based on the Wire-Cell three-dimensional (3D) event reconstruction for LArTPCs. From an initial 1:20 000 neutrino to cosmic-ray background ratio, we demonstrate these tools on data from the MicroBooNE experiment and create a high-performance generic neutrino event selection with a cosmic contamination of 14.9% (9.7%) for a visible energy region greater than O(200) MeV. The neutrino interaction selection efficiency is 80.4% and 87.6% for inclusive νμ charged-current and νe charged-current interactions, respectively. Here, this significantly improved performance compared with existing reconstruction algorithms marks a major milestone toward reaching the scientific goals of LArTPC neutrino oscillation experiments operating near the Earth’s surface.
We present a measurement of the W-boson mass, M sub(W), using data corresponding to 2.2 fb super(-1) of integrated luminosity collected in pp collisions at radicals = 1.96 TeV with the CDF II ...detector at the Fermilab Tevatron. The selected sample of 470 126 W arrow right enu candidates and 624 708 W arrow right mu nu candidates yields the measurement M sub(W) = 80387 + or - 12 (stat) + or - 15 (syst) = 80387 + or - 19 MeV /c super(2). This is the most precise single measurement of the W-boson mass to date.
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