The CDF collaboration presents an updated measurement of the CP-violating parameter beta_s and of the decay width difference Delta Gamma_s using approximately 6500 Bs to J/Psi Phi decays collected by the dimuon trigger and reconstructed in a data sample corresponding to 5.2/fb of integrated luminosity. Besides exploiting the two-fold increase in the data sample with respect to the previous measurement, several improvements have been introduced in the analysis including a fully data-driven flavor tagging calibration and proper treatment of possible S-wave contributions. We find that the CP-violating phase is within the range beta_s in [0.02, 0.52] U [1.08,1.55] at 68C.L. The Standard Model p-value is 0.31. The decay width difference is found to be Delta Gamma_s = 0.075 +/- 0.035 (stat) +/- 0.01 syst 1/ps. In addition, we present the most precise mean Bs lifetime tau_s, polarization amplitudes |A_0|^2, |A_{\parallel}|^2 and |A_{\perp}|^2, as well as strong phase delta_perp: tau_s = 458.6 +/- 7.6$ (stat) +/- 3.6 (syst) microns |A_0|^2 = 0.524 +/- 0.013 (stat) +/- 0.015 (syst) |A_{\parallel}|^2 = 0.231 +/- 0.014 (stat) +/- 0.015 (syst) delta_perp = 2.95 +/- 0.64 (stat) +/- 0.07 (syst).
We present the first limit on Bs mixing frequency obtained using 360 pb^-1 of Tevatron Run II data with the CDF II detector. We derive Delta ms 7.9 ps^-1 @ 95 % C.L. with a sensitivity of 8.4 ps^-1. -
The measurements of the \Bs mixing parameter which describes the difference in width (the inverse of the lifetime) between the \Bs heavy and light states are described. These measurements include direct measurement of $ΔΓ_s$ and $Γ_s$ by resolving CP eigenstates by angular analysis and measurements in which the proportion of CP even and odd is known.
We report the final CDF measurement of the $B^0_s$ mixing phase, mean lifetime, and decay-width difference through the fit of the time evolution of flavor-tagged $B^0_s \rightarrow J/ψϕ$ decays. The measurement is based on the full data set of 1.96 TeV $p\bar{p}$ collisions collected between February 2002 and September 2011 by the CDF experiment. The results are consistent with the standard model and other experimental determinations and are amongst the most precise to date.
We present the CDF results using 1.0 fb^{-1} of data on the mixing frequency measurement in the B_s system and the lifetime measurements of several B hadrons. We obtain Δm_s=17.77 +- 0.1 +- 0.07 ps^{-1} and cτ(Λ_b)=473.8 +- 23.1 +- 3.5 μm. The later one is more than 3 sigma above the world average, but in reasonable agreement with HQE calculations.
The Collider Detector at Fermilab (CDF) experiment performed the first measurement of the time-evolution of flavor-tagged B0s->J/psiphi decays, which probes mixing-induced CP-violation in the B0s sector. Any sizable deviation from zero of the phase beta_s, accessible through interference of the bbar\to cbar c sbar quark-level process accompanied or not by B0s-aB0s mixing, would be unambiguous indication of physics beyond the Standard Model. I report CDF results obtained in 1.35/fb, a recent extension to a larger dataset corresponding to 2.8/fb, and future projections.
We review latest experimental results on the Bs mixing and lifetime difference measurements at CDF. We report on the latest beta_s and dGamma_s results from Bs->J/psi phi. We also discuss flavor specific dGamma_s measurements, including information from hadronic channels, Bs->DsDs and Bs->KK. We describe the new flavor tagging methodology and its calibration using the Bs oscillations.
A summary of the results of several recent studies of charm mixing is presented. A number of different methods were used, including the measurement of lifetime ratios for final states of different CP, time dependence of wrong-sign hadronic decays, fits to time-dependent Dalitz plots, and searches for wrong-sign semi-leptonic decays. Taken together, they suggest mixing is of order 1%. The status of searches for indirect CP violation is also reported.
We describe two measurements of Delta m_d. The first uses B -> nu l D(*) events and a same-side flavor tagging algorithm. The second uses dilepton events. From the average of these two measurements we find Delta m_d = 0.466 +- 0.037 +- 0.031 ps^{-1}.
We present improved bounds on the CP-violating phase β_s^{\Jpsiϕ} and on the decay-width difference ΔΓof the neutral B_s^0 meson system obtained by the CDF experiment at the Tevatron collider . We use 6500 B_s^0 --> J/psi phi decays collected by the dimuon trigger and reconstructed in a sample corresponding to integrated luminosity of 5.2 fb-1. Besides exploiting a two-fold increase in statistics with respect to the previous measurement, several improvements have been introduced in the analysis including a fully data-driven flavour-tagging calibration and proper treatment of possible S-wave co…
We measure the time dependence of the ratio of decay rates for the rare decay D0->K+pi- to the Cabibbo-favored decay D0->K-pi+. We use a signal of 12.7 x10^3 D0->K+pi decays with proper decay times between 0.75 and 10 mean D0 lifetimes. The data sample was recorded with the CDF II detector at the Fermilab Tevatron and corresponds to an integrated luminosity of 1.5 fb-1 of p-pbar collisions at sqrt(s) = 1.96 TeV. We search for D0-D0bar mixing and measure the mixing parameters to be Rd = (3.04 +/- 0.55) x10^{-3}, y' = (8.5 +/- 7.6) x10^{-3}, and x'^2 = (-0.12 +/- 0.35) x10^{-3}. We report Bayesi…
We report on the observation of $D^0$--$\bar{D}^0$ oscillations by measuring the time-dependent ratio of yields for the rare decay $D^0 \rightarrow K^+π^-$ to the favored decay $D^0 \rightarrow K^-π^+$ at the Collider Detector at Fermilab (CDF). Using 9.6 fb$^{-1}$ of integrated luminosity of $\sqrt{s}$ = 1.96 TeV $p$$\bar{p}$ collisions recorded in the full CDF Run II, the signals of $7.6 \times 10^6$ $D^0\rightarrow K^-π^+$ and $33 \times 10^3$ $D^0\rightarrow K^+π^-$ decays are reconstructed in $D^{*}$-tagged events, with proper decay times between 0.75 and 10 mean $D^0$ lifetimes. We measu…
We present the latest $B$ hadron lifetimes, $B^0_s$ mixing, and $D^0$ mixing measurements using up to 3.0 fb$^{-1}$ of data collected by CDF and D0 experiments at Fermilab. The $B^0_s$ lifetime is measured from both $J/ψϕ$ (CP admixture) and flavor specific channels, and the $B_c$ lifetime is obtained from semileptonic channels. Following the $B^0_s$ oscillation frequency measurement at CDF in 2006, the D0 collaboration now observes $B^0_s$ oscillation at a significance of about 3$σ$. Since the first $D^0$ mixing evidence established at $B$ factories in 2007, CDF has observed $D^0$ mixing at a…
We review the status of bottom quark physics at the CDF experiment. The measurements reported are based on about 110 pb-1 of data collected at the Fermilab Tevatron pp= Collider operating at sqrt{s} = 1.8 TeV. In particular, we review results on B hadron lifetimes, measurements of the time dependence of B0 B0= oscillations, and a search for CP violation in B0 --> J/Psi K0s decays. Prospects for future B physics at CDF in the next run of the Tevatron Collider starting in the year 2000 are also given.
The measurement of heavy quark cross-sections provides important tests of the QCD theory. This paper reviews recent measurements of single b-quark and correlated b-quark cross-sections at CDF. Two new measurements of the single b-quark production at CDF agree with the first result from CDF Run II. This clarifies the experimental situation and confirms the recent agreement of theoretical prediction with data. A new measurement of the correlated $b\bar{b}$ cross-section with dimuon events at CDF is presented. It agrees with theory and it does not confirm the anomalously large $b\bar{b}$ cross-se…
We present some recent measurements on electroweak physics using data collected by the CDF experiment at the Tevatron proton anti-proton collider ($\sqrt{s}=1.96\mathrm{TeV}$) at Fermilab (Batavia, Ill, USA).
We present results on hard diffraction obtained by the CDF Collaboration in Run II proton-antiproton collisions at the Fermilab Tevatron. Run I CDF results on hard diffraction are also reviewed.
We present recent CDF results on $B$ lifetimes, $B$ meson mass measurements, ratios of branching ratios, and rare decays. In addition, we present the first measurement of time-dependent $B_d$ mixing at CDF. Several results have been updated and a few new ones included since the workshop.
We present results from electroweak precision measurements at CDF. These include the measurement of the Z boson rapidity distribution using di-electron events, the W boson charge asymmetry measurement in the electron-neutrino decay and the direct measurement of the W boson mass and width in both the electron-neutrino and muon-neutrino decay channels.
We present recent top physics results in the CDF including updates of top mass, \ttbar cross section, single top search, forward-backward asymmetry, and the differential cross section of \ttbar. Most of measurements utilize close to the integrated luminosity of 3 fb$^{-1}$.
We review the results of measurements on hard diffractive processes performed by the CDF Collaboration and report preliminary CDF results on two soft diffractive processes with a leading antiproton and a rapidity gap in addition to that associated with the antiproton. All results have been obtained from data collected in Run I of the Fermilab Tevatron $\bar pp$ collider.
This document was written as part of the PANIC 2008 conference proceedings in Eilat Israel. We review top mass measurements performed at CDF Run II through October of 2008. The basic algorithms used in many mass measurements are discussed as are some common systematic difficulties. Mass results in combination with the D0 Collaboration are presented, and the implications on the Standard Model Higgs mass are discussed.
Recently, the B factory experiments BABAR and Belle as well as the CDF collaboration found evidence for mixing in the D meson system. The current status (beginning of summer 2008) of the experimental results of D mixing is summarized.
We have measured the W-boson mass MW using data corresponding to 2.2/fb of integrated luminosity collected in proton-antiproton collisions at 1.96 TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470126 W->enu candidates and 624708 W->munu candidates yield the measurement MW = 80387 +- 12 (stat) +- 15 (syst) = 80387 +- 19 MeV. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined.
A measurement of Delta m_d is performed using inclusive lepton+vertex events at CDF. A probability based Same-Side Tagger was developed to tag the initial b-flavor of the B^0_d, which suppresses tagging on B-decay products. We find Delta m_d = 0.42 +/- 0.09 +/- 0.03 ps^-1.
The CDF collaboration has analyzed ~200/pb of Tevatron Run II data taken between February 2002 and September 2003 to measure the W boson mass. With a sample of 63964 W->e nu decays and 51128 W->mu nu decays, we measure M_W = 80413+-34(stat)+-34(syst) MeV. The total measurement uncertainty of 48 MeV makes this result the most precise single measurement of the W boson mass to date.
We present a measurement of the mass difference m(D+_s) - m(D+), where both the D+_s and D+ are reconstructed in the phi pi+ decay channel. This measurement uses 11.6 pb-1 of data collected by CDF II using the new displaced-track trigger. The mass difference is found to be: 99.41 +- 0.38 (stat) +- 0.21 (syst) MeV/c^2.
We present recent W and charged lepton asymmetry measurements from the CDF and D0 experiments. Theoretical predictions agree with the CDF W asymmetry, measured using a new matrix element technique. These theoretical predictions are less consistent with the latest lepton asymmetry measurements from D0 and CDF, especially for high charged lepton transverse momentum.
Measurement of Orbitally Excited D-Mesons at CDF II Igor V. Gorelov (For the CDF Collaboration) Talk given on behalf of the CDF Collaboration at the First Meeting of the APS Topical Group on Hadronic Physics, GHP 2004, 24-26 October 2004, FERMILAB. Results on the first measurement of orbitally excited neutral D-meson states, D*_2 and D_1, produced in hadron collisions at Tevatron are presented. Using data from the displaced track trigger, CDF II collects the largest world sample of these states in decay modes D*+ pi-, D+ pi-. Masses and widths of both states have been measured with precision b…
Measurements of production cross sections and polarizations are essential inputs for a theoretical understanding of heavy vector meson production. In this article the CDF measurement of the Y(1S) polarization in the kinematic range |y|<0.6 and 2 < pT [GeV/c] < 40 using a data sample of 2.9/fb is described. Compared to the CDF Run I measurement, with which it agrees, it extends the covered pT range, allowing for a better comparison to predictions in the perturbative regime. The observed trend towards longitudinal polarization at high transverse momentum disagrees with predictions based on non-r…
Results on inclusive jet production in proton-antiproton collisions at sqrt(s) =1.96 TeV based on 1 fb-1 of CDF Run II data are presented. Measurements are preformed using the k_T algorithm in a wide range of jet transverse momentum and jet rapidity. The measured cross sections are compared to next-to-leading order perturbative QCD calculations.
The CDF experiment at the Tevatron p-pbar collider established that extensive and detailed exploration of the b-quark dynamics is possible in hadron collisions, with results competitive and supplementary to those from e+e- colliders. This provides an unique, rich, and highly rewarding program that is currently reaching full maturity. I report a few recent world-leading results on rare decays, CP-violation in Bs mixing, and b-> s penguin decays.
This paper describes the determination of the direct CP observables R_cp and A_cp, related to the CKM angle gamma, using B- to D0 K- decays in 1.0 inverse fb of data collected with the CDF II detector. This is the first measurement of these CP observables made at a hadron collider in this decay mode. The results presented are consistent with the measurements of these quantities made by the Belle and BABAR collaborations.
Recent results on Bs mixing, lifetime difference and rare decays obtained by the CDF and DO collaborations using the data samples collected at the Tevatron Collider in the period 2002 - 2005 are presented.
Preliminary results of ttbar cross section measurements and single top exclusion limits of the Tevatron experiments CDF and D0 are presented. The different measurements are based on a dataset between 140 and 200 inverse pb corresponding to a data taking period from spring 2002 to September 2003. The ttbar cross section measurements are consistent with each other and the Standard Model prediction. Data and Monte-Carlo prediction are in good agreement in the search for single top quark. Its observation is anticipated with roughly 2 inverse fb integrated luminosity.
We present the most recent CDF results in the measurements of the decay and production vertex of the top-quark. New results on forward-backward asymmetry in top-antitop events are presented. Also, recent measurements of the branching fractions of top-quark are discussed. Finally, measurements in single top events, where top-quark is produced through electroweak processes, are presented. Despite the much larger number of top events collected at the LHC, due to the symmetric initial state and the better signal-to-background ratio in specific channels, some results will be lasting heritage of the…
The top quark with its mass of about 172 GeV/c^2 is the most massive fundamental particle observed by experiment. In this talk we highlight the most recent measurements of several top quark properties performed with the CDF detector based on data samples corresponding to integrated luminosities up to 1 fb-1. These results include a search for top quark pair production via new massive resonances, measurements of the helicity of the W boson from top-quark decay, and a direct limit on the lifetime of the top quark.
We present the status of the forward-backward charge asymmetry measurement for W boson production using early Run 2 data collected with the Collider Detector at Fermilab (CDF). Tracking for forward electrons is a critical component of this measurement, and we describe a new technique which combines the position and energy measurements from the calorimeter with position measurements in the silicon detector to provide tracking and charge determination for electron candidates. The performance of this algorithm is described and the sensitivity for the W charge asymmetry measurement with Run 2 data…
I report recent measurements in b-hadron decays reconstructed in the full data set of \sqrt{s} = 1.96 TeV proton-antiproton collisions collected by the CDF experiment at the Tevatron. These include the final CDF results on: measurements of CP asymmetries in two-body charmless decays of the Bd, Bs, and Λ^0_b hadrons; bounds on the Bs mixing phase and on the decay width difference of Bs mass eigenstates; and updated measurements of branching ratios of Bs->Jpsi Phi and Bs->Ds(*)Ds(*) decays. All measurements are among the most precise from a single experiment and in agreement with the standard mo…
We present a reanalysis of CDF data to extend limits on individual fourth-generation quark masses from particular flavor-mixing rates to the entire space of possible mixing values. Measurements from CDF have set individual limits on masses, $m_{b'}$ and $m_{t'}$, at the level of $335$--$385$ GeV assuming specific and favorable flavor-mixing rates. We consider the space of possible values for the mixing rates and find that the CDF data imply limits of $290$ GeV and greater over a wide range of mixing scenarios. We also analyze the limits from the perspective of a four-generation CKM matrix. We …
The forward-backward charge asymmetry ($A_{FB}$) of $\ppbar \to e^{+}e^{-} X$ is sensitive to the vector and axial-vector couplings of the initial state quarks and final state leptons. Based on the measurement in $72 pb^{-1}$ of CDF Run II data, we measure the coupling constants of the $Z$ boson to quarks and electron. The electroweak mixing angle, $\sin^2θ_{W}$, is also measured through its relation to the coupling constants.
The latest results for the measurement of the CP violating phase beta_s in B0s -> J/psi phi decays, from 5.2 fb-1 integrated luminosity of CDF data are presented. For the first time, this measurement includes the contribution of B0s -> J/psi K+K- or B0s -> J/psi f0 events to the signal sample, where the f0 and non-resonant K+K- are S-wave states. Additional improvements to the analysis include more than doubling the signal sample, improved selection and particle ID, and fully calibrated flavour tagging for the full dataset. Additionally, the world's most precise single measurements of the B0s …
We report on recent measurements of the top quark mass using t t-bar candidate events selected in ~320/pb of data from the "Run II" operation period of the Tevatron p p-bar collider. More emphasis is given on the best single measurement to date Mtop = 173.5 +3.9 -3.8 GeV/c^2, provided by CDF using the "lepton plus jets" channel, where one W decays to a lepton-neutrino pair and the other into quarks (top quarks decay to Wb almost 100% of the time).
Using data collected during the 1992-93 collider run at Fermilab, CDF has made measurements of correlated $b$ quark cross section where one $b$ is detected via a muon from semileptonic decay and the second $b$ is detected with secondary vertex techniques. We report on measurements of the cross section as a function of the momentum of the second $b$ and as a function of the azimuthal separation of the two $b$ quarks, for transverse momentum of the initial $b$ quark greater than 15 GeV. Results are compared to QCD predictions.
Using data samples in excess of 1 fb^-1 collected by the CDF II detector we present several world's best measurements of B hadron lifetimes. They include B_s meson lifetime in a flavor-specific decay mode, combining fully and partially reconstructed hadronic decays, B_c^+ meson lifetimes in semileptonic B_c^+ -> J/psi l+ X, l+=mu+,e+ decays and Lambda_b baryon lifetime in Lambda_c^+ pi- fully-reconstructed decays. In addition, we introduce a Monte Carlo independent technique for measuring B hadron lifetimes in data samples biased by displaced vertex triggers.
We report a preliminary measurement of the CP violating asymmetry in D0->pi+pi- using approximately 215,000 decays reconstructed in about 5.94/fb of CDF data. We use the strong D*+->D0pi+ decay ("D* tag") to identify the flavor of the charmed meson at production time and exploit CP-conserving strong c-cbar pair-production in p-pbar collisions. Higher statistic samples of Cabibbo-favored D0->K-pi+ decays with and without D* tag are used to highly suppress systematic uncertainties due to detector effects. The result is the world's most precise measurement to date.
A summary of the most up-to-date top quark mass measurements at CDF is presented. These analyses use top-antitop candidate events detected in the CDF experiment at the Tevatron collider with an integrated luminosity of up to ~3/fb. The combination of all those measurements together with the corresponding top mass measurements from the concurrently running D0 experiment at the Tevatron yields a world average of M_t=[173.1+/-0.6(stat.)+/-1.1(syst.)] GeV/c^2.
Measurements of the ttbar production cross-section at \sqrt{s} = 1.96TeV in proton-antiproton collisions were performed by the CDF and Dzero collaborations using ttbar final states where both W's decay hadronically. Each experiment uses luminosity of about 160pb^-1 of data collected during Run II of the Fermilab Tevatron collider. Beside kinematical observables both experiments take advantage of identifying b-jets based on lifetime tagging. While CDF counts the number of b-tags over background after a cut based analysis, Dzero counts the excess of events after a neural network based kinematica…
Recent measurements of jet and multijet production cross sections from ppbar collisions recorded with the Collider Detector at Fermilab (CDF) are summarized. First Run II results of the inclusive one jet cross section at sqrt(s) = 1.96 TeV as well as prospects for future extensions of this measurement are presented. We also studied the properties of three-jet events in Run Ib data at sqrt(s) = 1.8 TeV. All results are compared to predictions of Quantum Chromodynamics at next-to-leading order perturbation theory.
The mass of the top quark M_top is interesting both as a fundamental parameter of the standard model and as an important input to precision electroweak tests. The Collider Detector at Fermilab (CDF) has a robust program of top quark mass analyses, including the most precise single measurement, M_top = 173.4 +/- 2.8 GeV/c^2, using 680 pb^-1 of ppbar collision data. A combination of current results from CDF gives M_top = 172.0 +/- 2.7 GeV/c^2, surpassing the stated goal of 3 GeV/c^2 precision using 2 fb^-1 of data. Finally, a combination with current D0 results gives a world average top quark ma…
Results on physics of heavy flavour at CDF are reported. Selected measurements of Branching Ratios and CP asymmetry in $B^0$ and $B_s^0$, lifetime difference of $B^0_s$ CP eigenstates and a precise measurement of the $B_c$ mass are presented.
Using data collected during the 1992-1993 collider run at Fermilab, CDF has made measurements of correlated $b$ quark cross sections where one $b$ is detected from the lepton from semileptonic decay and the second $b$ is detected with secondary vertex techniques. We report on measurements of the cross section as a function of the momentum of the second $b$ and as a function of the azimuthal separation of the two $b$ quarks, for transverse momentum of the initial $b$ quark greater than 15 GeV. The vertex reconstruction techniques are valid over a large range in transverse momentum, starting at …
The CDF experiment at the Tevatron $p\bar{p}$ collider has pioneered and established the role of hadron collisions in exploring flavor physics through a broad program that is now at its full maturity. We report new results sensitive to physics beyond the standard model, obtained using the whole CDF data set; including new bounds on the \Bs\ mixing phase and the decay width difference of \Bs\ mass-eigenstates and a measurement of the difference of CP asymmetries in $K^+K^-$ and $π^+π^-$ decays of $D^0$ mesons. We also present a new measurement of the $\Bs \rightarrow D^{(*)+}_s D^{(*)-}_s$ bran…
The angular distributions of Upsilon(1S) to mu+ mu- decays are analyzed using a sample of Upsilon(1S) mesons in 2.9 fb^{-1} of data collected at sqrt{s} = 1.96TeV. The results of the one-dimensional angular analysis suggest that Upsilon(1S) may be longitudinal polarized at high transverse momentum. This observation is largely inconsistent with NRQCD prediction that predicts transverse polarization at high p_T.
We report a combination of the CDF and D0 measurements of the inclusive single top quark production cross section in the s- and t-channels in ppbar collisions at a center of mass energy of 1.96TeV. The total integrated luminosity included in CDF's analysis is 3.2 fb^-1 and D0's analysis has 2.3 fb^-1. A Bayesian analysis is used to extract the cross section from the distributions of multivariate discriminants provided by the collaborations. For a top quark mass m_t=170 GeV/c^2, we measure a cross section of 2.76 +0.58 -0.47 pb. We extract the CKM matrix element |Vtb|=0.88+-0.07 with a 95% C.L.…
We summarize and combine the results on the direct measurements of the mass of the W boson in data collected by the Tevatron experiments CDF and D0 at Fermilab. Earlier results from CDF Run-0 (1988--1989), D0 and CDF Run-I (1992--1995) and D0 results from 1/fb (2002--2006) of Run-II data are now combined with two new, high statistics Run-II measurements: a CDF measurement in both electron and muon channels using 2.2/fb of integrated luminosity collected between 2002 and 2007, and a D0 measurement in the electron channel using 4.3/fb collected between 2006 and 2009. As in previous combinations,…
The ttbar spin correlation at production is a fundamental prediction of QCD and a potentially incisive test of new physics coupled to top quarks. We measure the ttbar spin state in ppbar collisions at sqrt(s) = 1.96 TeV using 1001 candidate events in the lepton plus jets decay channel reconstructed in the CDF II detector. In the helicity basis, for a top-quark mass of 172.5 GeV/c^2, we find a spin correlation coefficient kappa = 0.60 +/- 0.50 (stat) +/- 0.16 (syst), consistent with the QCD prediction, kappa ~= 0.40.
We report on measurements of the Upsilon(1S), Upsilon(2S) and Upsilon(3S) differential and integrated cross sections in pp(bar) collisions at sqrt(s)=1.8 TeV. The three resonances were reconstructed through the decay Upsilon-->mu(+)mu(-). The cross section measurements are compared to theoretical models of direct bottomonium production.
We present a measurement of R_B, the ratio of the branching fraction for the rare decay D0 -> K+ pi- to that for the Cabibbo-favored decay D0 -> K- pi+. Charge conjugate decays are implicitly included. A signal of 2005 +/- 104 events for the decay D0 -> K+ pi- is obtained using the CDF II detector at the Fermilab Tevatron collider. The data set corresponds to an integrated luminosity of 0.35 1/fb produced in p-bar/p collisions at sqrt{s}=1.96 TeV. Assuming no mixing, we find R_B = [ 4.05 +/- 0.21 (stat) +/- 0.11 (syst) ] x 10(-3). This measurement is consistent with the world average, and comp…
