T. Chwalek

We report the observation of single top-quark production using 3.2 fb−1 of pp¯ collision data with s=1.96 TeV collected by the Collider Detector at Fermilab. The significance of the observed data is 5.0 standard deviations, and the expected sensitivity for standard model production and decay is in excess of 5.9 standard deviations. Assuming mt=175 GeV/c2, we measure a cross section of 2.3−0.5+0.6(stat+syst) pb, extract the CKM matrix-element value |Vtb|=0.91±0.11(stat+syst)±0.07(theory), and set the limit |Vtb|>0.71 at the 95% C.L.Received 4 March 2009DOI:https://doi.org/10.1103/PhysRevLett.103.092002©2009 American Physical Society

Evidence is reported for a narrow structure near the J/psivarphi threshold in exclusive B;{+} --> J/psivarphiK;{+} decays produced in p[over]p collisions at sqrt[s] = 1.96 TeV. A signal of 14 +/- 5 events, with statistical significance in excess of 3.8 standard deviations, is observed in a data sample corresponding to an integrated luminosity of 2.7 fb;{-1}, collected by the CDF II detector. The mass and natural width of the structure are measured to be 4143.0 +/- 2.9(stat) +/- 1.2(syst) MeV/c;{2} and 11.7_{-5.0};{+8.3}(stat) +/- 3.7(syst) MeV/c;{2}.

We present a search for new particles which produce narrow two-jet (dijet) resonances using proton-antiproton collision data corresponding to an integrated luminosity of $1.13\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with the CDF II detector. The measured dijet mass spectrum is found to be consistent with next-to-leading-order perturbative QCD predictions, and no significant evidence of new particles is found. We set upper limits at the 95% confidence level on cross sections times the branching fraction for the production of new particles decaying into dijets with both jets having a rapidity magnitude $|y|<1$. These limits are used to determine the mass exclusions for the excited quark, axigluon, flavor-universal coloron, ${E}_{6}$ diquark, color-octet techni-$\ensuremath{\rho}$, ${W}^{\ensuremath{'}}$, and ${Z}^{\ensuremath{'}}$.

In CDF we have observed the reactions p + p[over] --> p + X + p[over], with X being a centrally produced J/psi, psi(2S), or chi_{c0}, and gammagamma-->micro;{+}micro;{-} in pp[over] collisions at sqrt[s] = 1.96 TeV. The event signature requires two oppositely charged central muons, and either no other particles or one additional photon detected. Exclusive vector meson production is as expected for elastic photoproduction, gamma + p --> J/psi(psi(2S)) + p, observed here for the first time in hadron-hadron collisions. We also observe exclusive chi_{c0} --> J/psi + gamma. The cross sections dsigma/dy|_{y = 0} for J/psi, psi(2S), and chi_{c0} are 3.92 +/- 0.25(stat) +/- 0.52(syst) nb, 0.53 +/- 0.09(stat) +/- 0.10(syst) nb, and 76 +/- 10(stat) +/- 10(syst) nb, respectively, and the continuum is consistent with QED. We put an upper limit on the cross section for Odderon exchange in exclusive J/psi production.

We present a measurement of the tt[over ] differential cross section with respect to the tt[over ] invariant mass, dsigma/dM_{tt[over ]}, in pp[over ] collisions at sqrt[s]=1.96 TeV using an integrated luminosity of 2.7 fb;{-1} collected by the CDF II experiment. The tt[over ] invariant mass spectrum is sensitive to a variety of exotic particles decaying into tt[over ] pairs. The result is consistent with the standard model expectation, as modeled by PYTHIA with CTEQ5L parton distribution functions.

We present a search for high-mass neutral resonances using dimuon data corresponding to an integrated luminosity of 2.3 fb(-1) collected in pp[over ] collisions at sqrt[s]=1.96 TeV by the CDF II detector at the Fermilab Tevatron. No significant excess above the standard model expectation is observed in the dimuon invariant-mass spectrum. We set 95% confidence level upper limits on sigmaBR(pp-->X-->micromicro), where X is a boson with spin-0, 1, or 2. Using these cross section limits, we determine lower mass limits on sneutrinos in R-parity-violating supersymmetric models, Z' bosons, and Kaluza-Klein gravitons in the Randall-Sundrum model.

We report the observation of electroweak single top quark production in $3.2\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collision data collected by the Collider Detector at Fermilab at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. Candidate events in the $W+\mathrm{\text{jets}}$ topology with a leptonically decaying $W$ boson are classified as signal-like by four parallel analyses based on likelihood functions, matrix elements, neural networks, and boosted decision trees. These results are combined using a super discriminant analysis based on genetically evolved neural networks in order to improve the sensitivity. This combined result is further combined with that of a search for a single top quark signal in an orthogonal sample of events with missing transverse energy plus jets and no charged lepton. We observe a signal consistent with the standard model prediction but inconsistent with the background-only model by 5.0 standard deviations, with a median expected sensitivity in excess of 5.9 standard deviations. We measure a production cross section of ${2.3}_{\ensuremath{-}0.5}^{+0.6}(\mathrm{stat}+\mathrm{sys})\text{ }\text{ }\mathrm{pb}$, extract the value of the Cabibbo-Kobayashi-Maskawa matrix element $|{V}_{tb}|={0.91}_{\ensuremath{-}0.11}^{+0.11}(\mathrm{stat}+\mathrm{sys})\ifmmode\pm\else\textpm\fi{}0.07\text{ }\text{ }(\mathrm{\text{theory}})$, and set a lower limit $|{V}_{tb}|>0.71$ at the 95% C.L., assuming ${m}_{t}=175\text{ }\text{ }\mathrm{GeV}/{c}^{2}$.

We present the first direct measurement of the W production charge asymmetry as a function of the W boson rapidity yW in p¯p collisions at √s=1.96 TeV. We use a sample of W→eν events in data from 1 fb−1 of integrated luminosity collected using the CDF II detector. In the region |yW|<3.0, this measurement is capable of constraining the ratio of up- and down-quark momentum distributions in the proton more directly than in previous measurements of the asymmetry that are functions of the charged-lepton pseudorapidity.Received 15 January 2009DOI:https://doi.org/10.1103/PhysRevLett.102.181801©2009 American Physical Society

We present an analysis of the mass of the X(3872) reconstructed via its decay to J/psi pi+ pi- using 2.4 fb^-1 of integrated luminosity from ppbar collisions at sqrt(s) = 1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. The possible existence of two nearby mass states is investigated. Within the limits of our experimental resolution the data are consistent with a single state, and having no evidence for two states we set upper limits on the mass difference between two hypothetical states for different assumed ratios of contributions to the observed peak. For equal contributions, the 95% confidence level upper limit on the mass difference is 3.6 MeV/c^2. Under the single-state model the X(3872) mass is measured to be 3871.61 +- 0.16 (stat) +- 0.19 (syst) MeV/c^2, which is the most precise determination to date.

We report on a search for inclusive production of squarks and gluinos in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$, in events with large missing transverse energy and multiple jets of hadrons in the final state. The study uses a CDF Run II data sample corresponding to $2\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity. The data are in good agreement with the standard model predictions, giving no evidence for any squark or gluino component. In an $R$-parity conserving minimal supergravity scenario with ${A}_{0}=0$, $\ensuremath{\mu}&lt;0$, and $\mathrm{tan}\ensuremath{\beta}=5$, 95% C.L. upper limits on the production cross sections in the range between 0.1 and 1 pb are obtained, depending on the squark and gluino masses considered. For gluino masses below $280\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, arbitrarily large squark masses are excluded at the 95% C.L., while for mass degenerate gluinos and squarks, masses below $392\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ are excluded at the 95% C.L.

Data collected in run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for ``bumps'' that could indicate resonant production of new particles, and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in $2.0\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ reveals no indication of physics beyond the standard model.

A search for high-mass resonances in the ${e}^{+}{e}^{\ensuremath{-}}$ final state is presented based on $2.5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ $p\overline{p}$ collision data from the CDF II detector at the Fermilab Tevatron. The largest excess over the standard model prediction is at an ${e}^{+}{e}^{\ensuremath{-}}$ invariant mass of $240\text{ }\text{ }\mathrm{GeV}/{c}^{2}$. The probability of observing such an excess arising from fluctuations in the standard model anywhere in the mass range of $150--1000\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ is 0.6% (equivalent to $2.5\ensuremath{\sigma}$). We exclude the standard model coupling ${Z}^{\ensuremath{'}}$ and the Randall-Sundrum graviton for $k/{\overline{M}}_{\mathrm{Pl}}=0.1$ with masses below 963 and $848\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ at the 95% credibility level, respectively.

We performed a signature-based search for long-lived charged massive particles produced in $1.0\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$, collected with the CDF II detector using a high transverse-momentum (${p}_{T}$) muon trigger. The search used time of flight to isolate slowly moving, high-${p}_{T}$ particles. One event passed our selection cuts with an expected background of $1.9\ifmmode\pm\else\textpm\fi{}0.2$ events. We set an upper bound on the production cross section and, interpreting this result within the context of a stable scalar top-quark model, set a lower limit on the particle mass of $249\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ at 95% C.L.

We report the observation of the bottom, doubly-strange baryon Omega^-_b through the decay chain Omega^-_b -> J/psi Omega^-, where J/psi -> mu^+ mu^-, Omega^- -> Lambda K^-, and Lambda -> p pi^-, using 4.2 fb^{-1} of data from p\bar p collisions at sqrt{s}=1.96 TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability of arising from a background fluctuation is 4.0 * 10^{-8}, or 5.5 Gaussian standard deviations. The Omega^-_b mass is measured to be 6054.4 +/- 6.8 (stat.) +/- 0.9 (syst.) MeV/c^2. The lifetime of the Omega^-_b baryon is measured to be 1.13^{+0.53}_{-0.40}(stat.) +/- 0.02(syst.)$ ps. In addition, for the \Xi^-_b baryon we measure a mass of 5790.9 +/- 2.6(stat.) +/- 0.8(syst.) MeV/c^2 and a lifetime of 1.56^{+0.27}_{-0.25}(stat.) +/-0.02(syst.) ps. Under the assumption that the \Xi_b^- and \Omega_b^- are produced with similar kinematic distributions to the \Lambda^0_b baryon, we find sigma(Xi_b^-) B(Xi_b^- -> J/psi Xi^-)}/ sigma(Lambda^0_b) B(Lambda^0_b -> J/psi Lambda)} = 0.167^{+0.037}_{-0.025}(stat.) +/-0.012(syst.) and sigma(Omega_b^-) B(Omega_b^- -> J/psi Omega^-)/ sigma(Lambda^0_b) B(Lambda^0_b -> J/psi Lambda)} = 0.045^{+0.017}_{-0.012}(stat.) +/- 0.004(syst.) for baryons produced with transverse momentum in the range of 6-20 GeV/c.

We report a measurement of the ratio of the tt to Z/γ{*} production cross sections in sqrt[s]=1.96 TeV pp collisions using data corresponding to an integrated luminosity of up to 4.6 fb{-1}, collected by the CDF II detector. The tt cross section ratio is measured using two complementary methods, a b-jet tagging measurement and a topological approach. By multiplying the ratios by the well-known theoretical Z/γ{*}→ll cross section predicted by the standard model, the extracted tt cross sections are effectively insensitive to the uncertainty on luminosity. A best linear unbiased estimate is used to combine both measurements with the result σ{tt}=7.70±0.52 pb, for a top-quark mass of 172.5 GeV/c{2}.

We study the underlying event in proton-antiproton collisions by examining the behavior of charged particles produced in association with a large transverse momentum jet ($\ensuremath{\sim}2.2\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$) or with a Drell-Yan lepton pair ($\ensuremath{\sim}2.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$) in the $Z$-boson mass region [$70&lt;M(\mathrm{\text{pair}})&lt;110\text{ }\text{ }\mathrm{GeV}/{c}^{2}$] as measured by CDF at 1.96 TeV center-of-mass energy. We use the direction of the lepton pair or the leading jet in each event to define regions of $\ensuremath{\eta}\mathrm{\text{\ensuremath{-}}}\ensuremath{\phi}$ space that are sensitive to the modeling of the underlying event. The data are corrected to the particle level to remove detector effects and are then compared with several QCD Monte Carlo models.

This Letter describes the current most precise measurement of the $W$ boson pair production cross section and most sensitive test of anomalous $WW\ensuremath{\gamma}$ and $WWZ$ couplings in $p\overline{p}$ collisions at a center-of-mass energy of 1.96 TeV. The $WW$ candidates are reconstructed from decays containing two charged leptons and two neutrinos. Using data collected by the CDF II detector from $3.6\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity, a total of 654 candidate events are observed with an expected background of $320\ifmmode\pm\else\textpm\fi{}47$ events. The measured cross section is $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}{W}^{+}{W}^{\ensuremath{-}}+X)=12.1\ifmmode\pm\else\textpm\fi{}0.9(\mathrm{stat}{)}_{\ensuremath{-}1.4}^{+1.6}(\mathrm{syst})\text{ }\text{ }\mathrm{pb}$, which is in good agreement with the standard model prediction. The same data sample is used to place constraints on anomalous $WW\ensuremath{\gamma}$ and $WWZ$ couplings.

The cross section for jets from b quarks produced with a W boson has been measured in pp collision data from 1.9 fb(-1) of integrated luminosity recorded by the CDF II detector at the Tevatron. The W+b-jets process poses a significant background in measurements of top quark production and prominent searches for the Higgs boson. We measure a b-jet cross section of 2.74+/-0.27(stat)+/-0.42(syst) pb in association with a single flavor of leptonic W boson decay over a limited kinematic phase space. This measured result cannot be accommodated in several available theoretical predictions.

We report on the first search for top-quark production via flavor-changing neutral-current (FCNC) interactions in the non-standard-model process u(c)+g -> t using ppbar collision data collected by the CDF II detector. The data set corresponds to an integrated luminosity of 2.2/fb. The candidate events feature the signature of semileptonic top-quark decays and are classified as signal-like or background-like by an artificial neural network trained on simulated events. The observed discriminant distribution is in good agreement with the one predicted by the standard model and provides no evidence for FCNC top-quark production, resulting in a Bayesian upper limit on the production cross section sigma (u(c)+g -> t) < 1.8 pb at the 95% confidence level. Using theoretical predictions we convert the cross-section limit to upper limits on FCNC branching ratios: BR (t -> u+g) < 3.9 x 10{-4}$ and BR (t -> c+g) < 5.7 x 10^{-3}.

We present new limits on resonant tb[over] production in pp[over] collisions at sqrt[s] = 1.96 TeV, using 1.9 fb;{-1} of data recorded with the CDF II detector at the Fermilab Tevatron. We reconstruct a candidate tb[over] mass in events with a lepton, neutrino candidate, and two or three jets, and search for anomalous tb[over] production as modeled by W;{'} --> tb[over]. We set a new limit on a right-handed W;{'} with standard model-like coupling, excluding any mass below 800 GeV/c;{2} at 95% C.L. The cross section for any narrow, resonant tb[over] production between 750 and 950 GeV/c;{2} is found to be less than 0.28 pb at 95% C.L. We also present an exclusion of the W;{'} coupling strength versus W;{'} mass over the range 300-950 GeV/c;{2}.

We have measured the differential cross section for the inclusive production of psi(2S) mesons decaying to mu^{+} mu^{-1} that were produced in prompt or B-decay processes from ppbar collisions at 1.96 TeV. These measurements have been made using a data set from an integrated luminosity of 1.1 fb^{-1} collected by the CDF II detector at Fermilab. For events with transverse momentum p_{T} (psi(2S)) &gt; 2 GeV/c and rapidity |y(psi(2S))| &lt; 0.6 we measure the integrated inclusive cross section sigma(ppbar -&gt; psi(2S)X) Br(psi(2S) -&gt; mu^{+} mu^{-}) to be 3.29 +- 0.04(stat.) +- 0.32(syst.) nb.

We search for new charmless decays of neutral b-hadrons to pairs of charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using a data sample corresponding to 1 fb-1 of integrated luminosity, we report the first observation of the B0s-&gt;K-pi+ decay, with a significance of 8.2 sigma, and measure BR(B0s-&gt;K-pi+)= (5.0+-0.7(stat)+-0.8(syst))*10^{-6}. We also report the first observation of charmless b-baryon decays in the channels Lambda_b -&gt; p pi and Lambda_b -&gt; pK with significances of 6.0 sigma and 11.5 sigma respectively, and we measure BR(Lambda_b-&gt;p pi-) = (3.5+-0.6(stat)+-0.9(syst))*10^{-6} and BR(Lambda_b-&gt;p K-) = (5.6+-0.8(stat)+-1.5(syst))*10^{-6}. No evidence is found for the decays B0-&gt;K+K- and B0s -&gt; pi+pi-, and we set an improved upper limit BR(B0s -&gt; pi+pi-) &lt; 1.2*10^{-6}$ at the 90% confidence level. All quoted branching fractions are measured using BR(B0-&gt;K+pi-)$ as a reference.

A measurement of the cross section for the inclusive production of isolated photons by the CDF experiment at the Fermilab Tevatron collider is presented. The measurement covers the pseudorapidity region |ηγ|<1.0 and the transverse energy range EγT>30 GeV and is based on 2.5 fb−1 of integrated luminosity. The sample is almost a factor of 7 larger than those used for recent published results and extends the EγT coverage by 100 GeV. The result agrees with next-to-leading order perturbative QCD calculations within uncertainties over the range 50<EγT<400 GeV, though the energy spectrum in the data shows a steeper slope at lower EγT.Received 20 October 2009DOI:https://doi.org/10.1103/PhysRevD.80.111106©2009 American Physical Society

We report a measurement of resonance parameters of the orbitally excited ($L=1$) narrow ${B}^{0}$ mesons in decays to ${B}^{(*)+}{\ensuremath{\pi}}^{\ensuremath{-}}$ using $1.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected by the CDF II detector at the Fermilab Tevatron. The mass and width of the ${B}_{2}^{*0}$ state are measured to be $m({B}_{2}^{*0})={5740.2}_{\ensuremath{-}1.8}^{+1.7}(\mathrm{stat}{)}_{\ensuremath{-}0.8}^{+0.9}(\mathrm{syst})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ and $\ensuremath{\Gamma}({B}_{2}^{*0})={22.7}_{\ensuremath{-}3.2}^{+3.8}(\mathrm{stat}{)}_{\ensuremath{-}10.2}^{+3.2}(\mathrm{syst})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$. The mass difference between the ${B}_{2}^{*0}$ and ${B}_{1}^{0}$ states is measured to be ${14.9}_{\ensuremath{-}2.5}^{+2.2}(\mathrm{stat}{)}_{\ensuremath{-}1.4}^{+1.2}(\mathrm{syst})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, resulting in a ${B}_{1}^{0}$ mass of ${5725.3}_{\ensuremath{-}2.2}^{+1.6}(\mathrm{stat}{)}_{\ensuremath{-}1.5}^{+1.4}(\mathrm{syst})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$. This is currently the most precise measurement of the masses of these states and the first measurement of the ${B}_{2}^{*0}$ width.

We present the results of a search for Higgs bosons predicted in two-Higgs-doublet models, in the case where the Higgs bosons decay to tau lepton pairs, using $1.8\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity of $p\overline{p}$ collisions recorded by the CDF II experiment at the Fermilab Tevatron. Studying the mass distribution in events where one or both tau leptons decay leptonically, no evidence for a Higgs boson signal is observed. The result is used to infer exclusion limits in the two-dimensional space of $\mathrm{tan}\ensuremath{\beta}$ versus ${m}_{A}$ (the ratio of the vacuum expectation values of the two Higgs doublets and the mass of the pseudoscalar boson, respectively).

We present the results of a search for supersymmetry with gauge-mediated breaking and $\NONE\to\gamma\Gravitino$ in the $\gamma\gamma$+missing transverse energy final state. In 2.6$\pm$0.2 \invfb of $p{\bar p}$ collisions at $\sqrt{s}$$=$1.96 TeV recorded by the CDF II detector we observe no candidate events, consistent with a standard model background expectation of 1.4$\pm$0.4 events. We set limits on the cross section at the 95% C.L. and place the world's best limit of 149\gevc on the \none mass at $\tau_{\tilde{\chi}_1^0}$$<<$1 ns. We also exclude regions in the \none\ mass-lifetime plane for $\tau_{\tilde{\chi}_1^0}$$\lesssim$2 ns.

A measurement of the b jet production cross section is presented for events containing a Z boson produced in p¯p collisions at √s=1.96 TeV, using data corresponding to an integrated luminosity of 2 fb−1 collected by the CDF II detector at the Tevatron. Z bosons are selected in the electron and muon decay modes. Jets are considered with transverse energy ET>20 GeV and pseudorapidity |η|<1.5 and are identified as b jets using a secondary vertex algorithm. The ratio of the integrated Z+b jet cross section to the inclusive Z production cross section is measured to be 3.32±0.53(stat)±0.42(syst)×10−3. This ratio is also measured differentially in jet ET, jet η, Z-boson transverse momentum, number of jets, and number of b jets. The predictions from leading-order Monte Carlo generators and next-to-leading-order QCD calculations are found to be consistent with the measurements within experimental and theoretical uncertainties.2 MoreReceived 21 January 2009DOI:https://doi.org/10.1103/PhysRevD.79.052008©2009 American Physical Society

We report results from a search for the lepton flavor violating decays B_{s};{0} --> e;{+} micro;{-} and B;{0} --> e;{+} micro;{-}, and the flavor-changing neutral-current decays B_{s};{0} --> e;{+} e;{-} and B;{0} --> e;{+} e;{-}. The analysis uses data corresponding to 2 fb;{-1} of integrated luminosity of pp[over ] collisions at sqrt[s] = 1.96 TeV collected with the upgraded Collider Detector (CDF II) at the Fermilab Tevatron. The observed number of B0 and B_{s};{0} candidates is consistent with background expectations. The resulting Bayesian upper limits on the branching ratios at 90% credibility level are B(B_{s};{0} --> e;{+} micro;{-}) < 2.0 x 10;{-7}, B(B;{0} --> e;{+} micro;{-}) < 6.4 x 10;{-8}, B(B_{s};{0} --> e;{+} e;{-}) < 2.8 x 10;{-7}, and B(B;{0} --> e;{+} e;{-}) < 8.3 x 10;{-8}. From the limits on B(B_{(s)};{0} --> e;{+} micro;{-}), the following lower bounds on the Pati-Salam leptoquark masses are also derived: M_{LQ}(B_{s};{0} --> e;{+} micro;{-}) > 47.8 TeV/c;{2}, and M_{LQ}(B;{0} --> e;{+} micro;{-}) > 59.3 TeV / c;{2}, at 90% credibility level.

We present a search for a standard model Higgs boson produced in association with a W boson using 2.7 fb−1 of integrated luminosity of p¯p collision data taken at √s=1.96 TeV. Limits on the Higgs boson production rate are obtained for masses between 100 and 150 GeV/c2. Through the use of multivariate techniques, the analysis achieves an observed (expected) 95% confidence level upper limit of 5.6 (4.8) times the theoretically expected production cross section for a standard model Higgs boson with a mass of 115 GeV/c2.Received 2 July 2009DOI:https://doi.org/10.1103/PhysRevLett.103.101802©2009 American Physical Society

We present the results of a search for pair production of the supersymmetric partner of the top quark (the top squark ${\stackrel{\texttildelow{}}{t}}_{1}$) decaying to a $b$ quark and a chargino ${\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1}^{\ifmmode\pm\else\textpm\fi{}}$ with a subsequent ${\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1}^{\ifmmode\pm\else\textpm\fi{}}$ decay into a neutralino ${\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1}^{0}$, lepton $\ensuremath{\ell}$, and neutrino $\ensuremath{\nu}$. Using a data sample corresponding to $2.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity of $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ collected by the CDF II detector, we reconstruct the mass of top squark candidate events and fit the observed mass spectrum to a combination of standard model processes and ${\stackrel{\texttildelow{}}{t}}_{1}{\overline{\stackrel{\texttildelow{}}{t}}}_{1}$ signal. We find no evidence for ${\stackrel{\texttildelow{}}{t}}_{1}{\overline{\stackrel{\texttildelow{}}{t}}}_{1}$ production and set 95% C.L. limits on the masses of the top squark and the neutralino for several values of the chargino mass and the branching ratio $\mathcal{B}({\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{\stackrel{\texttildelow{}}{\ensuremath{\chi}}}_{1}^{0}{\ensuremath{\ell}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\nu})$.

We report measurements of the polarization of W bosons from top-quark decays using 2.7 fb{-1} of pp collisions collected by the CDF II detector. Assuming a top-quark mass of 175 GeV/c{2}, three measurements are performed. A simultaneous measurement of the fraction of longitudinal (f{0}) and right-handed (f{+}) W bosons yields the model-independent results f{0}=0.88±0.11(stat)±0.06(syst) and f{+}=-0.15±0.07(stat)±0.06(syst) with a correlation coefficient of -0.59. A measurement of f{0} [f{+}] constraining f{+} [f{0}] to its standard model value of 0.0 [0.7] yields f{0}=0.70±0.07(stat)±0.04(syst) [f{+}=-0.01±0.02(stat)±0.05(syst)]. All these results are consistent with standard model expectations. We achieve the single most precise measurements of f{0} for both the model-independent and model-dependent determinations.

We report two complementary measurements of the WW+WZ cross section in the final state consisting of an electron or muon, missing transverse energy, and jets, performed using p¯p collision data at √s=1.96 TeV collected by the CDF II detector. The first method uses the dijet invariant mass distribution while the second more sensitive method uses matrix-element calculations. The result from the second method has a signal significance of 5.4σ and is the first observation of WW+WZ production using this signature. Combining the results gives σWW+WZ=16.0±3.3 pb, in agreement with the standard model prediction.Received 24 November 2009DOI:https://doi.org/10.1103/PhysRevLett.104.101801©2010 American Physical Society

Using data from $2.9\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity collected with the CDF II detector at the Tevatron, we search for resonances decaying into a pair of on-shell gauge bosons, $WW$ or $WZ$, where one $W$ decays into an electron and a neutrino, and the other boson decays into two jets. We observed no statistically significant excess above the expected standard model background, and we set cross section limits at 95% confidence level on ${G}^{*}$ (Randall-Sundrum graviton), ${Z}^{\ensuremath{'}}$, and ${W}^{\ensuremath{'}}$ bosons. By comparing these limits to theoretical cross sections, mass exclusion regions for the three particles are derived. The mass exclusion regions for ${Z}^{\ensuremath{'}}$ and ${W}^{\ensuremath{'}}$ are further evaluated as a function of their gauge coupling strength.

We present a measurement of the mass of the top quark using data corresponding to an integrated luminosity of 1.9fb^-1 of ppbar collisions collected at sqrt{s}=1.96 TeV with the CDF II detector at Fermilab's Tevatron. This is the first measurement of the top quark mass using top-antitop pair candidate events in the lepton + jets and dilepton decay channels simultaneously. We reconstruct two observables in each channel and use a non-parametric kernel density estimation technique to derive two-dimensional probability density functions from simulated signal and background samples. The observables are the top quark mass and the invariant mass of two jets from the W decay in the lepton + jets channel, and the top quark mass and the scalar sum of transverse energy of the event in the dilepton channel. We perform a simultaneous fit for the top quark mass and the jet energy scale, which is constrained in situ by the hadronic W boson mass. Using 332 lepton + jets candidate events and 144 dilepton candidate events, we measure the top quark mass to be mtop=171.9 +/- 1.7 (stat. + JES) +/- 1.1 (syst.) GeV/c^2 = 171.9 +/- 2.0 GeV/c^2.

We present a measurement of the top quark mass and of the top-antitop ($t\overline{t}$) pair production cross section using $p\overline{p}$ data collected with the CDF II detector at the Tevatron Collider at the Fermi National Accelerator Laboratory and corresponding to an integrated luminosity of $2.9\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. We select events with six or more jets satisfying a number of kinematical requirements imposed by means of a neural-network algorithm. At least one of these jets must originate from a $b$ quark, as identified by the reconstruction of a secondary vertex inside the jet. The mass measurement is based on a likelihood fit incorporating reconstructed mass distributions representative of signal and background, where the absolute jet energy scale (JES) is measured simultaneously with the top quark mass. The measurement yields a value of $174.8\ifmmode\pm\else\textpm\fi{}2.4(\mathrm{stat}+\mathrm{JES}{)}_{\ensuremath{-}1.0}^{+1.2}(\mathrm{syst})\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, where the uncertainty from the absolute jet energy scale is evaluated together with the statistical uncertainty. The procedure also measures the amount of signal from which we derive a cross section, ${\ensuremath{\sigma}}_{t\overline{t}}=7.2\ifmmode\pm\else\textpm\fi{}0.5(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.0(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.4(\mathrm{lum})\text{ }\text{ }\mathrm{pb}$, for the measured values of top quark mass and JES.

We report a set of measurements of particle production in inelastic pbar{p} collisions collected with a minimum-bias trigger at the Tevatron Collider with the CDF II experiment. The inclusive charged particle transverse momentum differential cross section is measured, with improved precision, over a range about ten times wider than in previous measurements. The former modeling of the spectrum appears to be incompatible with the high particle momenta observed. The dependence of the charged particle transverse momentum on the event particle multiplicity is analyzed to study the various components of hadron interactions. This is one of the observable variables most poorly reproduced by the available Monte Carlo generators. A first measurement of the event transverse energy sum differential cross section is also reported. A comparison with a Pythia prediction at the hadron level is performed. The inclusive charged particle differential production cross section is fairly well reproduced only in the transverse momentum range available from previous measurements. At higher momentum the agreement is poor. The transverse energy sum is poorly reproduced over the whole spectrum. The dependence of the charged particle transverse momentum on the particle multiplicity needs the introduction of more sophisticated particle production mechanisms, such as multiple parton interactions, in order to be better explained.

The cross section for photon production in association with at least one jet containing a b quark has been measured in proton antiproton collisions at √s=1.96 TeV. The data sample used corresponds to an integrated luminosity of 340 pb−1 collected with the CDF II detector. Both the differential cross section as a function of photon transverse energy EγT and the total cross section are measured and compared to a next-to-leading order prediction for the process.Received 17 December 2009DOI:https://doi.org/10.1103/PhysRevD.81.052006©2010 American Physical Society

We reconstruct ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}D{K}^{\ifmmode\pm\else\textpm\fi{}}$ decays in a data sample collected by the CDF II detector at the Tevatron collider corresponding to $1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity. We select decay modes where the $D$ meson decays to either ${K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ (flavor eigenstate) or ${K}^{\ensuremath{-}}{K}^{+}$, ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ ($CP$-even eigenstates), and measure the direct $CP$ asymmetry ${A}_{CP+}=0.39\ifmmode\pm\else\textpm\fi{}0.17(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.04(\mathrm{syst})$, and the double ratio of $CP$-even to flavor eigenstate branching fractions ${R}_{CP+}=1.30\ifmmode\pm\else\textpm\fi{}0.24(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.12(\mathrm{syst})$. These measurements will improve the determination of the Cabibbo-Kobayashi-Maskawa angle $\ensuremath{\gamma}$. They are performed here for the first time using data from hadron collisions.

We present measurements of the top quark mass using the \mT2, a variable related to the transverse mass in events with two missing particles. We use the template method applied to t\tbar dilepton events produced in p\pbar collisions at Fermilab's Tevatron and collected by the CDF detector. From a data sample corresponding to an integrated luminosity of 3.4 \invfb, we select 236 t\tbar candidate events. Using the \mT2 distribution, we measure the top quark mass to be M_{Top} = 168.0^{+4.8}_{-4.0} $\pm$ {2.9} GeV/c^{2}. By combining the \mT2 with the reconstructed top mass distributions based on a neutrino weighting method, we measure M_{top}=169.3 $\pm$ 2.7 $\pm$ 3.2 GeV/c^{2}. This is the first application of the \mT2 variable in a mass measurement at a hadron collider.

We present a search for supersymmetric neutrino ˜ν production using the Tevatron p¯p collision data collected with the CDF II detector and corresponding to an integrated luminosity of 1 fb−1. We focus on the scenarios predicted by the R-parity violating (RPV) supersymmetric models in which sneutrinos decay to two charged leptons of different flavor. With the data consistent with the standard model expectations, we set upper limits on σ(p¯p→˜ν)×BR(˜ν→eμ,μτ,eτ) and use these results to constrain the RPV couplings as a function of the sneutrino mass.Received 10 May 2010DOI:https://doi.org/10.1103/PhysRevLett.105.191801© 2010 The American Physical Society

We present a measurement of the fractions ${F}_{0}$ and ${F}_{+}$ of longitudinally polarized and right-handed $W$ bosons in top-quark decays using data collected with the CDF II detector. The data set used in the analysis corresponds to an integrated luminosity of approximately $318\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$. We select $t\overline{t}$ candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle ${\ensuremath{\theta}}^{*}$, which is defined as the angle between the momentum of the charged lepton in the $W$ boson rest frame and the $W$ momentum in the top-quark rest frame. The $\mathrm{cos}{\ensuremath{\theta}}^{*}$ distribution in the data is determined by full kinematic reconstruction of the $t\overline{t}$ candidates. We find ${F}_{0}={0.85}_{\ensuremath{-}0.22}^{+0.15}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.06(\mathrm{syst})$ and ${F}_{+}={0.05}_{\ensuremath{-}0.05}^{+0.11}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.03(\mathrm{syst})$, which is consistent with the standard model prediction. We set an upper limit on the fraction of right-handed $W$ bosons of ${F}_{+}&lt;0.26$ at the 95% confidence level.

We report a search for single top quark production with the CDF II detector using 2.1 fb-1 of integrated luminosity of pbar p collisions at sqrt{s}=1.96 TeV. The data selected consist of events characterized by large energy imbalance in the transverse plane and hadronic jets, and no identified electrons and muons, so the sample is enriched in W -> tau nu decays. In order to suppress backgrounds, additional kinematic and topological requirements are imposed through a neural network, and at least one of the jets must be identified as a b-quark jet. We measure an excess of signal-like events in agreement with the standard model prediction, but inconsistent with a model without single top quark production by 2.1 standard deviations (sigma), with a median expected sensitivity of 1.4 sigma. Assuming a top quark mass of 175 GeV/c2 and ascribing the excess to single top quark production, the cross section is measured to be 4.9+2.5-2.2(stat+syst)pb, consistent with measurements performed in independent datasets and with the standard model prediction.

We present the first observation in hadronic collisions of the electroweak production of vector boson pairs ($VV$, $V=W$, $Z$) where one boson decays to a dijet final state. The data correspond to $3.5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity of $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ collected by the CDF II detector at the Fermilab Tevatron. We observe $1516\ifmmode\pm\else\textpm\fi{}239(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}144(\mathrm{syst})$ diboson candidate events and measure a cross section $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}VV+X)$ of $18.0\ifmmode\pm\else\textpm\fi{}2.8(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}2.4(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}1.1(\mathrm{lumi})\text{ }\text{ }\mathrm{pb}$, in agreement with the expectations of the standard model.

We report on a search for direct scalar bottom quark (sbottom) pair production in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$, in events with large missing transverse energy and two jets of hadrons in the final state, where at least one of the jets is required to be identified as originating from a $b$ quark. The study uses a collider detector at Fermilab Run II data sample corresponding to $2.65\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity. The data are in agreement with the standard model. In an $R$-parity conserving minimal supersymmetric scenario, and assuming that the sbottom decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits on the sbottom pair production cross section of 0.1 pb are obtained. For neutralino masses below $70\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, sbottom masses up to $230\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ are excluded at 95% confidence level.

Fully reconstructed tt¯→W+bW−b¯→ℓνqq¯′bb¯ events are used to determine the fractions of right-handed (f+) and longitudinally polarized (f0) W bosons produced in top-quark decays. The helicity fractions are sensitive to the couplings and the Dirac structure of the Wtb vertex. This Letter reports measurements of the W-boson helicity fractions from two different methods using data corresponding to an integrated luminosity of 1.9fb−1 of pp¯ collisions at a center-of-mass energy of 1.96 TeV collected by the CDF II detector operating at the Fermilab Tevatron. Combining the results from the two methods, we find f0=0.62±0.10(stat)±0.05(syst) under the assumption that f+=0, and f+=−0.04±0.04(stat)±0.03(syst) with f0 fixed to the theoretically expected value of 0.70. Model-independent fits are also performed and simultaneously determine f0=0.66±0.16(stat)±0.05(syst) and f+=−0.03±0.06(stat)±0.03(syst). All these results are consistent with standard model expectations.

The analysis uses data from an integrated luminosity of approximately 172 pb-1 of ppbar collisions at sqrt(s)=1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. The Lambda_b and B0 relative branching fractions are measured to be: B(Lambda_b to Lambda_c+ mu nu)/B(Lambda_b to Lambda_c+ pi) = 16.6 +- 3.0 (stat) +- 1.0 (syst) +2.6 -3.4 (PDG) +- 0.3 (EBR), B(B0 to D+ mu nu)/B(B0 to D+ pi) = 9.9 +- 1.0 (stat) +- 0.6 (syst) +- 0.4 (PDG) +- 0.5 (EBR), B(B0 to D*+ mu nu)/B(B0 to D*+ pi) = 16.5 +- 2.3 (stat) +- 0.6 (syst) +- 0.5 (PDG) +- 0.8 (EBR) This article also presents measurements of the branching fractions of four new Lambda_b semileptonic decays: Lambda_b to Lambda_c(2595)+ mu nu, Lambda_b to Lambda_c(2625)+ mu nu, Lambda_b to Sigma_c(2455)0 pi mu nu, Lambda_b to Sigma_c(2455)++ pi mu nu, relative to the branching fraction of the Lambda_b to Lambda_c mu nu decay. Finally, the transverse-momentum distribution of Lambda_b baryons produced in p-pbar collisions is measured and found to be significantly different from that of B0 mesons.

We report a measurement of the top quark mass, ${m}_{t}$, obtained from $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ at the Fermilab Tevatron using the CDF II detector. We analyze a sample corresponding to an integrated luminosity of $1.9\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. We select events with an electron or muon, large missing transverse energy, and exactly four high-energy jets in the central region of the detector, at least one of which is tagged as coming from a $b$ quark. We calculate a signal likelihood using a matrix element integration method, where the matrix element is modified by using effective propagators to take into account assumptions on event kinematics. Our event likelihood is a function of ${m}_{t}$ and a parameter JES (jet energy scale) that determines in situ the calibration of the jet energies. We use a neural network discriminant to distinguish signal from background events. We also apply a cut on the peak value of each event likelihood curve to reduce the contribution of background and badly reconstructed events. Using the 318 events that pass all selection criteria, we find ${m}_{t}=172.7\ifmmode\pm\else\textpm\fi{}1.8(\mathrm{stat}+\mathrm{JES})\ifmmode\pm\else\textpm\fi{}1.2(\mathrm{syst})\text{ }\text{ }\mathrm{GeV}/{c}^{2}$.

We present a measurement of the electric charge of the top quark using p¯p collisions corresponding to an integrated luminosity of 2.7 fb−1 at the CDF II detector. We reconstruct t¯t events in the lepton+jets final state. We use soft lepton taggers to determine the flavor of the b jets, which we use to reconstruct the top quark’s electric charge and exclude an exotic top quark with −4/3 charge at 95% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose.Received 24 June 2010DOI:https://doi.org/10.1103/PhysRevLett.105.101801© 2010 The American Physical Society

We present results of a search for anomalous production of two photons together with an electron, muon, $\ensuremath{\tau}$ lepton, missing transverse energy, or jets using $p\overline{p}$ collision data from $1.1--2.0\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity collected by the Collider Detector at Fermilab (CDF). The event yields and kinematic distributions are examined for signs of new physics without favoring a specific model of new physics. The results are consistent with the standard model expectations. The search employs several new analysis techniques that significantly reduce instrumental backgrounds in channels with an electron and missing transverse energy.

We present the result of a search for a massive color-octet vector particle, (e.g. a massive gluon) decaying to a pair of top quarks in proton-antiproton collisions with a center-of-mass energy of 1.96 TeV. This search is based on 1.9 fb$^{-1}$ of data collected using the CDF detector during Run II of the Tevatron at Fermilab. We study $t\bar{t}$ events in the lepton+jets channel with at least one $b$-tagged jet. A massive gluon is characterized by its mass, decay width, and the strength of its coupling to quarks. These parameters are determined according to the observed invariant mass distribution of top quark pairs. We set limits on the massive gluon coupling strength for masses between 400 and 800 GeV$/c^2$ and width-to-mass ratios between 0.05 and 0.50. The coupling strength of the hypothetical massive gluon to quarks is consistent with zero within the explored parameter space.

We present a measurement of the $\ttbar$ production cross section in $\ppbar$ collisions at $\sqrt{s}=1.96$ TeV using events containing a high transverse momentum electron or muon, three or more jets, and missing transverse energy. Events consistent with $\ttbar$ decay are found by identifying jets containing candidate heavy-flavor semileptonic decays to muons. The measurement uses a CDF Run II data sample corresponding to $2 \mathrm{fb^{-1}}$ of integrated luminosity. Based on 248 candidate events with three or more jets and an expected background of $79.5\pm5.3$ events, we measure a production cross section of $9.1\pm 1.6 \mathrm{pb}$.

This paper reports a measurement of the cross section for the pair production of top quarks in pp¯ collisions at s=1.96 TeV at the Fermilab Tevatron. The data were collected from the CDF run II detector in a set of runs with a total integrated luminosity of 1.1 fb−1. The cross section is measured in the dilepton channel, the subset of tt¯ events in which both top quarks decay through t→Wb→ℓνb, where ℓ=e, μ, or τ. The lepton pair is reconstructed as one identified electron or muon and one isolated track. The use of an isolated track to identify the second lepton increases the tt¯ acceptance, particularly for the case in which one W decays as W→τν. The purity of the sample may be further improved at the cost of a reduction in the number of signal events, by requiring an identified b jet. We present the results of measurements performed with and without the request of an identified b jet. The former is the first published CDF result for which a b-jet requirement is added to the dilepton selection. In the CDF data there are 129 pretag lepton+track candidate events, of which 69 are tagged. With the tagging information, the sample is divided into tagged and untagged subsamples, and a combined cross section is calculated by maximizing a likelihood. The result is σtt¯=9.6±1.2(stat)−0.5+0.6(sys)±0.6(lum) pb, assuming a branching ratio of BR(W→ℓν)=10.8% and a top mass of mt=175 GeV/c2.15 MoreReceived 31 March 2009DOI:https://doi.org/10.1103/PhysRevD.79.112007©2009 American Physical Society

We present a search for associated production of the standard model Higgs boson and a $Z$ boson where the $Z$ boson decays to two leptons and the Higgs decays to a pair of $b$ quarks in $p\overline{p}$ collisions at the Fermilab Tevatron. We use event probabilities based on standard model matrix elements to construct a likelihood function of the Higgs content of the data sample. In a CDF data sample corresponding to an integrated luminosity of $2.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ we see no evidence of a Higgs boson with a mass between $100\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ and $150\text{ }\text{ }\mathrm{GeV}/{c}^{2}$. We set 95% confidence level upper limits on the cross section for $ZH$ production as a function of the Higgs boson mass ${m}_{H}$; the limit is 8.2 times the standard model prediction at ${m}_{H}=115\text{ }\text{ }\mathrm{GeV}/{c}^{2}$.

We present a measurement of the transverse momentum with respect to the jet axis ($k_{T}$) of particles in jets produced in $p\bar p$ collisions at $\sqrt{s}=1.96$ TeV. Results are obtained for charged particles within a cone of opening angle 0.5 radians around the jet axis in events with dijet invariant masses between 66 and 737 GeV/c$^{2}$. The experimental data are compared to theoretical predictions obtained for fragmentation partons within the framework of resummed perturbative QCD using the modified leading log and next-to-modified leading log approximations. The comparison shows that trends in data are successfully described by the theoretical predictions, indicating that the perturbative QCD stage of jet fragmentation is dominant in shaping basic jet characteristics.

We present a measurement of the top quark mass with tt¯ dilepton events produced in pp¯ collisions at the Fermilab Tevatron (s=1.96 TeV) and collected by the CDF II detector. A sample of 328 events with a charged electron or muon and an isolated track, corresponding to an integrated luminosity of 2.9 fb−1, are selected as tt¯ candidates. To account for the unconstrained event kinematics, we scan over the phase space of the azimuthal angles (ϕν1,ϕν2) of neutrinos and reconstruct the top quark mass for each ϕν1, ϕν2 pair by minimizing a χ2 function in the tt¯ dilepton hypothesis. We assign χ2-dependent weights to the solutions in order to build a preferred mass for each event. Preferred mass distributions (templates) are built from simulated tt¯ and background events, and parametrized in order to provide continuous probability density functions. A likelihood fit to the mass distribution in data as a weighted sum of signal and background probability density functions gives a top quark mass of 165.5−3.3+3.4(stat)±3.1(syst) GeV/c2.3 MoreReceived 4 February 2009DOI:https://doi.org/10.1103/PhysRevD.79.072005©2009 American Physical Society

We present a measurement of the top quark mass in the all-hadronic channel (\tt $\to$ \bb$q_{1}\bar{q_{2}}q_{3}\bar{q_{4}}$) using 943 pb$^{-1}$ of \ppbar collisions at $\sqrt {s} = 1.96$ TeV collected at the CDF II detector at Fermilab (CDF). We apply the standard model production and decay matrix-element (ME) to $\ttbar$ candidate events. We calculate per-event probability densities according to the ME calculation and construct template models of signal and background. The scale of the jet energy is calibrated using additional templates formed with the invariant mass of pairs of jets. These templates form an overall likelihood function that depends on the top quark mass and on the jet energy scale (JES). We estimate both by maximizing this function. Given 72 observed events, we measure a top quark mass of 171.1 $\pm$ 3.7 (stat.+JES) $\pm$ 2.1 (syst.) GeV/$c^{2}$. The combined uncertainty on the top quark mass is 4.3 GeV/$c^{2}$.

We present results of a signature-based search for new physics using a dijet plus missing transverse energy (ET) data sample collected in 2 fb−1 of p¯p collisions at √s=1.96 TeV with the CDF II detector at the Fermilab Tevatron. We observe no significant event excess with respect to the standard model prediction and extract a 95% C.L. upper limit on the cross section times acceptance for a potential contribution from a nonstandard model process. The search is made by using novel, data-driven techniques for estimating backgrounds that are applicable to first searches at the LHC.Received 4 February 2010DOI:https://doi.org/10.1103/PhysRevLett.105.131801© 2010 The American Physical Society

The production rate and kinematics of photons produced in association with $Z$ bosons are studied using $2\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collision data collected at the Collider Detector at Fermilab. The cross section for $p\overline{p}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}\ensuremath{\gamma}+X$ (where the leptons $\ensuremath{\ell}$ are either muons or electrons with dilepton mass ${M}_{\ensuremath{\ell}\ensuremath{\ell}}&gt;40\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, and where the photon has transverse energy ${E}_{T}^{\ensuremath{\gamma}}&gt;7\text{ }\text{ }\mathrm{GeV}$ and is well separated from the leptons) is $4.6\ifmmode\pm\else\textpm\fi{}0.2(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.3(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.3(\mathrm{lum})\text{ }\text{ }\mathrm{pb}$, which is consistent with standard model expectations. We use the photon ${E}_{T}$ distribution from $Z\ensuremath{\gamma}$ events where the $Z$ has decayed to ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, ${e}^{+}{e}^{\ensuremath{-}}$, or $\ensuremath{\nu}\overline{\ensuremath{\nu}}$ to set limits on anomalous (non standard model) trilinear couplings between photons and $Z$ bosons.

Abstract We report on a CDF measurement of the total cross section and rapidity distribution, d σ / d y , for γ ∗ / Z → e + e − events in the Z boson mass region ( 66 M e e 116 GeV / c 2 ) produced in p p ¯ collisions at s = 1.96 TeV with 2.1 fb − 1 of integrated luminosity. The measured cross section of 257 ± 16 pb and d σ / d y distribution are compared with Next-to-Leading-Order (NLO) and Next-to-Next-to-Leading-Order (NNLO) QCD theory predictions with CTEQ and MRST/MSTW parton distribution functions (PDFs). There is good agreement between the experimental total cross section and d σ / d y measurements with theoretical calculations with the most recent NNLO PDFs.

We report a search for narrow resonances, produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV, that decay into muon pairs with invariant mass between 6.3 and 9.0 GeV/c 2. The data, collected with the CDF II detector at the Fermilab Tevatron collider, correspond to an integrated luminosity of 630 pb−1. We use the dimuon invariant mass distribution to set 90% upper credible limits of about 1% to the ratio of the production cross section times muonic branching fraction of possible narrow resonances to that of the ϒ(1S) meson.

We present a signature-based search for the anomalous production of events containing a photon, two jets, of which at least one is identified as originating from a $b$ quark, and missing transverse energy (${\mathrm{E\ensuremath{\llap{\not\;}}}}_{T}$). The search uses data corresponding to $2.0\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity from $p\overline{p}$ collisions at a center-of-mass energy of $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$, collected with the CDF II detector at the Fermilab Tevatron. From $6.697\text{ }47\ifmmode\times\else\texttimes\fi{}{10}^{6}$ events with a photon candidate with transverse energy ${E}_{T}&gt;25\text{ }\text{ }\mathrm{GeV}$, we find 617 events with ${\mathrm{E\ensuremath{\llap{\not\;}}}}_{T}&gt;25\text{ }\text{ }\mathrm{GeV}$ and two or more jets with ${E}_{T}&gt;15\text{ }\text{ }\mathrm{GeV}$, at least one identified as originating from a $b$ quark, versus an expectation of $607\ifmmode\pm\else\textpm\fi{}113$ events. Increasing the requirement on ${\mathrm{E\ensuremath{\llap{\not\;}}}}_{T}$ to 50 GeV, we find 28 events versus an expectation of $30\ifmmode\pm\else\textpm\fi{}11$ events. We find no indications of non-standard-model phenomena.

A search for new physics using three-lepton (trilepton) data collected with the CDF II detector and corresponding to an integrated luminosity of 976 pb-1 is presented. The standard model predicts a low rate of trilepton events, which makes some supersymmetric processes, such as chargino-neutralino production, measurable in this channel. The mu+mu+l signature is investigated, where l is an electron or a muon, with the additional requirement of large missing transverse energy. In this analysis, the lepton transverse momenta with respect to the beam direction (pT) are as low as 5 GeV/c, a selection that improves the sensitivity to particles which are light as well as to ones which result in leptonically decaying tau leptons. At the same time, this low-p_T selection presents additional challenges due to the non-negligible heavy-quark background at low lepton momenta. This background is measured with an innovative technique using experimental data. Several dimuon and trilepton control regions are investigated, and good agreement between experimental results and standard-model predictions is observed. In the signal region, we observe one three-muon event and expect 0.4+/-0.1 mu+mu+l events

We have used the Collider Detector at Fermilab (CDF II) to search for the flavor-changing neutral-current (FCNC) top quark decay ${t\goes Zc}$ using a technique employing ratios of $W$ and $Z$ production, measured in \ppbar data corresponding to an integrated luminosity of 1.52 $fb^{-1}$. The analysis uses a comparison of two decay chains, ${p\bar{p}\goes t\bar{t}\goes WbWb\goes\ell\nu bjjb}$ and ${p\bar{p}\goes t\bar{t}\goes ZcWb\goes\ell\ell cjjb}$, to cancel systematic uncertainties in acceptance, efficiency, and luminosity. We validate the modeling of acceptance and efficiency for lepton identification over the multi-year dataset using another ratio of $W$ and $Z$ production, in this case the observed ratio of inclusive production of $W$ to $Z$ bosons. To improve the discrimination against standard model backgrounds to top quark decays, we calculate the top quark mass for each event with two leptons and four jets assuming it is a $t\bar{t}$ event with one of the top quarks decaying to $Zc$. For additional background discrimination we require at least one jet to be identified as originating from a $b$-quark. No significant signal is found and we set an upper limit on the FCNC branching ratio $Br({t\goes Zc})$ using a likelihood constructed from the ${\ell\ell cjjb}$ top quark mass distribution and the number of ${\ell\nu bjjb}$ events. Limits are set as a function of the helicity of the $Z$ boson produced in the FCNC decay. For 100% longitudinally polarized $Z$ bosons we find limits of 8.3% and 9.3% (95% C.L.) depending on the assumptions regarding the theoretical top quark pair production cross-section.

The CMS experiment has to move Petabytes of data among dozens of computing centres with low latency in order to make ecient use of its resources. Transfer operations are well established to achieve the desired level of throughput, but operators lack a system to identify early on transfers that will need manual intervention to reach completion. File transfer latencies are sensitive to the underlying problems in the transfer infrastructure, and their measurement can be used as prompt trigger for preventive actions. For this reason, PhEDEx, the CMS transfer management system, has recently implemented a monitoring system to measure the transfer latencies at the level of individual files. For the first time now, the system can predict the completion time for the transfer of a data set. The operators can detect abnormal patterns in transfer latencies early, and correct the issues while the transfer is still in progress. Statistics are aggregated for blocks of files, recording a historical log to monitor the long-term evolution of transfer latencies, which are used as cumulative metrics to evaluate the performance of the transfer infrastructure, and to plan the global data placement strategy. In this contribution, we present the typical patterns of transfer latencies that may be identified with the latency monitor, and we show how we are able to detect the sources of latency arising from the underlying infrastructure (such as stuck files) which need operator intervention.

We present a search for WW and WZ production in final states that contain a charged lepton (electron or muon) and at least two jets, produced in sqrt(s) = 1.96 TeV ppbar collisions at the Fermilab Tevatron, using data corresponding to 1.2 fb-1 of integrated luminosity collected with the CDF II detector. Diboson production in this decay channel has yet to be observed at hadron colliders due to the large single W plus jets background. An artificial neural network has been developed to increase signal sensitivity, as compared with an event selection based on conventional cuts. We set a 95% confidence level upper limit of sigma_{WW}* BR(W->lnu,W->jets)+ sigma_{WZ}*BR(W->lnu,Z->jets) <2.88 pb, which is consistent with the standard model next to leading order cross section calculation for this decay channel of 2.09+-0.12 pb.

Received 29 January 2009DOI:https://doi.org/10.1103/PhysRevLett.102.059901©2009 American Physical Society

We present a measurement of the fractions F{sub 0} and F{sub +} of longitudinally polarized and right-handed W bosons in top-quark decays using data collected with the CDF II detector. The data set used in the analysis corresponds to an integrated luminosity of approximately 955 pb{sup -1}. We select t{bar t} candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle {theta}*, which is defined as the angle between the momentum of the charged lepton in the W boson rest-frame and the W momentum in the top-quark rest-frame. The cos{theta}* distribution in the data is determined by full kinematic reconstruction of the t{bar t} candidates. We find F{sub 0}= 0.59 {+-} 0.12(stat){sup +0.07}{sub -0.06}(syst) and F{sub +}=-0.03 {+-} 0.06(stat){sup +0.04}{sub -0.03}(syst), which is consistent with the standard model prediction. We set an upper limit on the fraction of right-handed W bosons of F{sub +} {le} 0.10 at the 95% confidence level.

The ttbar is measured in proton-proton collisions at a centre-of-mass energy of 8 TeV. The data, collected with the CMS experiment at the LHC, correspond to an integrated luminosity of 19.7/fb. Selected events contain an electron or a muon and four or more jets, where at least one jet is identified as originating from b-quark hadronization. The ttbar is measured inclusively and differentially as a function of rapidity, transverse momentum, and invariant mass of the ttbar system. For the first time at the LHC, the measurements are also performed in a reduced fiducial phase space of top quark pair production. Presented at TOP2015 8th International Workshop on Top Quark Physics Inclusive and differential measurements of the tt at 8 TeV with the CMS experiment Thorsten Chwalek∗† Karlsruhe Institute of Technology E-mail: chwalek@cern.ch The tt is measured in proton-proton collisions at a centre-of-mass energy of 8 TeV. The data, collected with the CMS experiment at the LHC, correspond to an integrated luminosity of 19.7fb−1. Selected events contain an electron or a muon and four or more jets, where at least one jet is identified as originating from b-quark hadronization. The tt is measured inclusively and differentially as a function of rapidity, transverse momentum, and invariant mass of the tt system. For the first time at the LHC, the measurements are also performed in a reduced fiducial phase space of top quark pair production. 8th International Workshop on Top Quark Physics 14-18 September, 2015 Ischia, Italy ∗Speaker. †for the CMS Collaboration c © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). http://pos.sissa.it/ tt at CMS Thorsten Chwalek Hundreds of thousands of top quark-antiquark pairs (tt) have been produced during the LHC run at a centre-of-mass energy of 8 TeV. The large data samples collected with the ATLAS and CMS [1] detectors enable precision measurements of properties of the heaviest elementary particle known so far. One interesting property of the production of tt pairs is the so-called charge asymmetry a difference in angular distributions between top quark and antiquark. In the Standard Model (SM) this difference is caused by interference effects between the different possibilities to create a tt pair from the annihilation of an initial qq pair. An observable that is commonly used to measure this effect is the difference in the absolute rapidity between top quark and antiquark, ∆|y|= |yt|− |yt|. With this observable the is defined as AC = N∆|y|>0−N∆|y| 0 +N∆|y|<0 . (1) The CMS collaboration has measured the tt based on a data set corresponding to an integrated luminosity of 19.7TeV of proton proton collisions at 8TeV [2]. Events with a lepton+jets signature are selected, requiring the presence of exactly one highly energetic electron or muon, well isolated from other energy deposits in the calorimeter, and at least four jets. One of these jets has to be identified as b jet by the Combined Secondary Vertex tagger [3]. The amounts of remaining background contributions are estimated by fitting the distributions of two discriminating variables, the transverse mass of the W boson (mT ) and the invariant mass of the three-jet combination that yields the largest transverse momentum (m3). While mT distinguishes between events with and without real W bosons, m3 can be used to discriminate between events with and without top quarks. A signal fraction of about 80% is estimated, with the largest background contribution coming from W+jets production. The four-vectors of top quarks and antiquarks are reconstructed from the decay products observed in the detector. The leptonically decaying W boson is reconstructed from the charged lepton and the missing transverse momentum vector, constraining the mass of the reconstructed object to the known mass of the W boson. The assignment of the reconstructed jets to the final-state quarks in the tt decay chain (two b quarks from the two top quark decays and two light quarks from the decay of the second W boson) is done based on the b-tagging information of the jets and the invariant masses of the reconstructed top quarks and of the reconstructed hadronically decaying W boson. The resulting ∆|y| distribution has to be corrected for background contamination and for distorting effects due to the resolution of the reconstruction and the efficiency of the event selection. This is done using a regularized matrix inversion unfolding method as implemented in TUnfold [4]. For the differential measurements not only the ∆|y| distribution but also that of the given kinematic variable (rapidity |ytt|, transverse momentum ptt T, or mass mtt of the tt system) are unfolded. While the correction for background contamination and reconstruction effects operates only on the selected events, the correction for possible non-flatness of the event selection efficiency includes an extrapolation into a phase-space defined based on parton level objects. In this analysis two different approaches are realized. In the first approach the distributions are extrapolated from the phase space representing the selected data sample to the full phase space of tt production. This procedure enables direct comparisons of the corrected results with theory predictions. However, the extrapolation relies solely on information from simulated events; to reduce the dependence on

We give an overview over charge asymmetry and spin correlation measurements in top quark pair production.The presented analyses use data collected with the ATLAS and CMS detectors at a center-of-mass energy of 8 TeV.Events with either dileptonic or semileptonic top quark pair decays are analyzed.All results are comparable with the predictions by the standard model.

The t t charge asymmetry is measured in proton-proton collisions at a centre-of-mass energy of 8 TeV.The data, collected with the CMS experiment at the LHC, correspond to an integrated luminosity of 19.7 fb -1 .Selected events contain an electron or a muon and four or more jets, where at least one jet is identified as originating from b-quark hadronization.The t t charge asymmetry is measured inclusively and differentially as a function of rapidity, transverse momentum, and invariant mass of the t t system.For the first time at the LHC, the measurements are also performed in a reduced fiducial phase space of top quark pair production.

We report on results of tcharge asymmetry measurements in the electron+jets and muon+jets channels, based on a dataset corresponding to an integrated luminosity of 5 fb 1 . The data have been collected with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) at CERN at a centre-of-mass energy of 7 TeV. An inclusive measurement of the tcharge asymmetry and three differential measurements as a function of the invariant mass, the transverse momentum, and the rapidity of the tsystem are presented. All measurements are in agreement with the predictions of the standard model.

We report on results of tcharge asymmetry measurements in the electron+jets and muon+jets channels, based on a dataset corresponding to an integrated luminosity of 5 fb 1 . The data have been collected with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) at CERN at a centre-of-mass energy of 7 TeV. An inclusive measurement of the tcharge asymmetry and three differential measurements as a function of the invariant mass, the transverse momentum, and the rapidity of the tsystem are presented. All measurements are in agreement with the predictions of the standard model.

We report on results of tcharge asymmetry measurements in the electron+jets and muon+jets channels, based on a dataset corresponding to an integrated luminosity of 5 fb 1 . The data have been collected with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) at CERN at a centre-of-mass energy of 7 TeV. An inclusive measurement of the tcharge asymmetry and three differential measurements as a function of the invariant mass, the transverse momentum, and the rapidity of the tsystem are presented. All measurements are in agreement with the predictions of the standard model.

Aus was besteht die Welt? Die Frage nach den fundamentalen Bausteinen der Materie beschaftigte Wissenschaftler und Gelehrte zu allen Zeiten. Ausgehend von abstrakten philosophischen Uberlegungen wurde das Konzept von kleinsten, nicht weiter zerteilbaren Grundbausteinen der Materie bereits einige Jahrhunderte vor Christus von indischen und griechischen Philosophieschulen entwickelt. Etwa 450 v. Chr. pragte Demokrit den Begriff ´atomos, das “Unzerschneidbare”, fur die diskreten Grundbausteine der Materie. Doch erst in der jungeren Vergangenheit konnte dieses philosophische Konzept auch experimentell uberpruft werden.

The production of top quark pairs (tt¯) via the quark-antiquark initial state is not symmetric under the exchange of top quark and antiquark. Calculations of this next-to-leading order effect predict asymmetries of about one to a few percent, depending on the centre-of-mass energy and the selected phase space. Experimentally, this charge asymmetry of tt¯ production manifests itself in differences in angular distributions between top quarks and antiquarks. Sensitive observables are the rapidities of the produced top quarks and antiquarks as well as their energies. In dileptonic tt¯ events, the asymmetry of the tt¯ system is reflected in a similar asymmetry in the system of the produced lepton pair, with the crucial advantage of a simpler reconstruction procedure. In this article we review the measurements of this effect in different final states and using different observables by the ATLAS and CMS Collaborations in LHC collisions at three different centre-of-mass energies.

We present a measurement of the fractions F_0 and F_+ of longitudinally polarized and right-handed W bosons in top-quark decays using data collected with the CDF II detector. The data set used in the analysis corresponds to an integrated luminosity of approximately 955 pb-1. We select top-antitop candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle theta*, which is defined as the angle between the momentum of the charged lepton in the W boson rest-frame and the W momentum in the top-quark rest-frame. The cos(theta*) distribution in the data is determined by full kinematic reconstruction of the top-antotop candidates. We find F_0 = 0.59 +- 0.12 (stat) +0.07 -0.06 (syst) and F_+ = -0.03 +- 0.06 (stat) +0.04 -0.03 (syst), which is consistent with the standard model prediction. We set an upper limit on the fraction of right-handed W-bosons of F_+ < 0.1 at the 95% confidence level.

We present a measurement of the fractions F_0 and F_+ of longitudinally polarized and right-handed W bosons in top-quark decays using data collected with the CDF II detector. The data set used in the analysis corresponds to an integrated luminosity of approximately 955 pb-1. We select top-antitop candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle theta*, which is defined as the angle between the momentum of the charged lepton in the W boson rest-frame and the W momentum in the top-quark rest-frame. The cos(theta*) distribution in the data is determined by full kinematic reconstruction of the top-antotop candidates. We find F_0 = 0.59 +- 0.12 (stat) +0.07 -0.06 (syst) and F_+ = -0.03 +- 0.06 (stat) +0.04 -0.03 (syst), which is consistent with the standard model prediction. We set an upper limit on the fraction of right-handed W-bosons of F_+ &lt; 0.1 at the 95% confidence level.

In 1995 the top quark was discovered at the Tevatron proton-antiproton collider at Fermilab by the CDF and D0 collaborations [1, 2]. It is the most massive known elementary particle and its mass is currently measured with a precision of about 1.3% [3, 4]. However, the measurements of several other top quark properties are still statistically limited, so the question remains whether the Standard Model of elementary particle physics successfully predicts these properties. This thesis addresses one interesting aspect of top quark decay, the helicity of the produced W boson. Until the start of the Large Hadron Collider (LHC) at CERN, the Tevatron with a center-of-mass energy of {radical}s = 1.96 TeV is the only collider, where top quarks can be produced. In the Standard Model the top quark decays predominantly into a W boson and a b quark, with a branching ratio close to 100%. The V-A structure of the weak interaction of the Standard Model predicts that the W{sup +} bosons from the top quark decay t {yields} W{sup +}b are dominantly either longitudinally polarized or left handed, while right handed W bosons are heavily suppressed and even forbidden in the limit of a massless b quark. Under the assumption of a massless b quark, for a top quark mass of 173 GeV/c{sup 2} the Standard Model predicts the fraction F0 of longitudinally polarized W bosons to be 0.7 and 0.3 for the fraction F{_} of left handed W bosons, while the fraction F{sub +} of right handed W bosons is predicted to be zero. Since next-to-leading order corrections change these fractions only slightly, a significant deviation from the predicted value for F{sub 0} or a nonzero value for F{sub +} could indicate new physics. Left-right symmetric models [5], for example, lead to a significant right handed fraction of W bosons in top decays. Such a right handed component (V+A coupling) would lead to a smaller left handed fraction, while F{sub 0} would remain unchanged. Since the decay rate to longitudinal W bosons depends on the Yukawa coupling of the top quarks, the measurement of F{sub 0} is sensitive to the mechanism of electroweak symmetry breaking. Alternative models can lead to an altered F{sub 0} fraction. In this analysis the W helicity fractions are measured in a selected sample rich in t{bar B} events where one lepton, at least four jets, and missing transverse energy are required. All kinematic quantities describing the t{bar t} decay are determined. As a sensitive observable, we use the cosine of the decay angle {theta}*, which is defined as the angle between the momentum of the charged lepton in the W boson rest frame and the W boson momentum in the top quark rest frame. The data used in this analysis were taken with the Collider Detector at Fermilab (CDF II) in the years 2002-2006 and correspond to an integrated luminosity of about 955 pb{sup -1}. Previous CDF measurements of the W boson helicity fractions in top quark decays used either the square of the invariant mass of the charged lepton and the b quark jet, M{sub {ell}b}{sup 2}, or the lepton p{sub T} distribution as a discriminant. The D0 collaboration used a matrix-element method to extract a value of F{sub 0}; in a second analysis the reconstructed distribution of cos {theta}* was utilized to measure F{sub +}. CDF gives the latest value of F{sub 0} = 0.74{sub -0.34}{sup +0.22}, while D measured F{sub 0} = 0.56 {+-} 0.31. The CDF collaboration also gives the current upper limit of F{sub +} < 0.09.

An approach to predicting the characteristics of a meander line structure is presented. Since the structure is periodic, it is considered to be electrically equivalent to a waveguide with a unit cell placed inside. Using the mode matching procedure, the transmitted and the reflected fields are determined in terms of the incident field and the induced current on the unit cell. The unknown induced current is determined setting the boundary condition that the tangential electric field vanished on the conducting unit cell. From the transmitted and the reflected fields, the transmission and reflection coefficients are obtained, from which the equivalent susceptances are determined. This formulation is utilized to predict the inductance and capacitance of a meander line. The formulation for the equivalent susceptances was also used to compute the transmission coefficient and the axial ratio of a four-layered meander line polarizer.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>