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Measurement of the Top Quark Mass at CDF Using the Template Method in the Lepton + Jets Channel

Description: A measurement of the top quark mass in p{bar p} collisions at {radical}s = 1.96 TeV is presented. The analysis uses a template method, in which the overconstrained kinematics of the Lepton+Jets channel of the t{bar t} system are used to measure a single quantity, the reconstructed top quark mass, that is strongly correlated with the true top quark mass. in addition, the dijet mass of the hadronically decaying W boson is used to constrain in situ the uncertain jet energy scale in the CDF detector. Two-dimensional probability density functions are derived using a kernel density estimate-based machinery. Using 1.9 fb{sup -1} of data, the top quark mass is measured to be 171.8{sub -1.9}{sup +1.9}(stat.) {+-} 1.0(syst.)GeV/c{sup 2}.
Date: May 1, 2008
Creator: Adelman, Jahred A. & U., /Chicago
Partner: UNT Libraries Government Documents Department

Observation of B0(s) - anti-B0(s) Oscillations

Description: The authors report the observation of B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillations from a time-dependent measurement of the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillation frequency {Delta}m{sub s}. Using a data sample of 1 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron, they find signals of 5600 fully reconstructed hadronic B{sub s} decays, 3100 partially reconstructed hadronic B{sub s} decays, and 61,500 partially reconstructed semileptonic B{sub s} decays. They measure the probability as a function of proper decay time that the B{sub s} decays with the same, or opposite, flavor as the flavor at production, and they find a signal for B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillations. The probability that random fluctuations could produce a comparable signal is 8 x 10{sup -8}, which exceeds 5{sigma} significance. They measure {Delta}m{sub s} = 17.77 {+-} 0.10(stat) {+-} 0.07(syst) ps{sup -1} and extract |V{sub td}/V{sub ts}| = 0.2050 {+-} 0.0007(exp{sub -0.0060}{sup +0.0081})(theor).
Date: September 1, 2006
Creator: Abulencia, A.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D. et al.
Partner: UNT Libraries Government Documents Department

Observation of B0 (s) ---> K+ K- and Measurements of Branching Fractions of Charmless Two-body Decays of B0 and B0(s) Mesons in anti-p p Collisions at s**(1/2) = 1.96-TeV

Description: The authors search for decays of the type B{sub (s)}{sup 0} {yields} h{sup +}h'{sup -} (where h,h' = K or {pi}) in 180 pb{sup -1} of data collected by the CDF II detector at the Fermilab Tevatron. They observe the new mode B{sub s}{sup 0} {yields} K{sup +}K{sup -} with a yield of 236 {+-} 32 events, corresponding to (f{sub s}/f{sub d}) x {Beta}(B{sub s}{sup 0} {yields} K{sup +}K{sup -})/{Beta}(B{sup 0} {yields} K{sup +}{pi}{sup -}) = 0.46 {+-} 0.08(stat.) {+-} 0.07(syst.), where f{sub s}/f{sub d} is the ratio of production fractions of B{sub s}{sup 0} and B{sup 0}. They find results in agreement with world averages for the modes B{sup 0} {yields} {pi}{sup +}{pi}{sup -} and B{sup 0} {yields} K{sup +}{pi}{sup -}, and set the following upper limits at 90% CL: {Beta}(B{sup 0} {yields} K{sup +}K{sup -}) < 1.8 x 10{sup -6}, {Beta}(B{sub s}{sup 0} {yields} K{sup -}{pi}{sup +}) < 5.6 x 10{sup -6}, and {Beta}(B{sub s}{sup 0} {yields} {pi}{sup +}{pi}{sup -}) < 1.7 x 10{sup -6}.
Date: July 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Observation of B0(s) ---> psi(2S)phi and measurement of ratio of branching fractions B(B0(s) ---> psi(2S)phi) / B(B0(s) ---> J/psi phi)

Description: The authors report the first observation of B{sub s}{sup 0} {yields} {psi}(2S){phi} decay in p{bar p} collisions {radical}s = 1.96 TeV using 360 pb{sup -1} of data collected by the CDF II detector at the Fermilab Tevatron. They observe 20.2 {+-} 5.0 and 12.3 {+-} 4.1 B{sub s}{sup 0} {yields} {psi}(2S){phi} candidates, in {psi}(2S) {yields} {mu}{sup +}{mu}{sup -} and {psi}(2S) {yields} J/{psi}{pi}{sup +}{pi}{sup -} decay modes, respectively. They present a measurement of the relative branching fraction {Beta}(B{sub s}{sup 0} {yields} {psi}(2S){phi})/{Beta}(B{sub s}{sup 0} {yields} J/{psi}{phi}) = 0.52 {+-} 0.13(stat.) {+-} 0.04(syst.) {+-} 0.06(BR) using the {psi}(2S) {yields} {mu}{sup +}{mu}{sup -} decay mode.
Date: February 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Observation of the Omega(b)- Baryon and Measurement of the Properties of the Xi(b)- and Omega(b)- Baryons

Description: The authors report the observation of the bottom, doubly-strange baryon {Omega}{sub b}{sup -} through the decay chain {Omega}{sub b}{sup -} {yields} J/{psi}{Omega}{sup -}, where J/{psi} {yields} {mu}{sup +} {mu}{sup -}, {Omega}{sup -} {yields} {Lambda}K{sup -}, and {Lambda} {yields} p {pi}{sup -}, using 4.2 fb{sup -1} of data from p{bar p} collisions at {radical}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 x 10{sup -8}, or 5.5 Gaussian standard deviations. The {Omega}{sub b}{sup -} mass is measured to be 6054.4 {+-} 6.8(stat.) {+-} 0.9(syst.) MeV/c{sup 2}. The lifetime of the {Omega}{sub b}{sup -} baryon is measured to be 1.13{sub -0.40}{sup +0.53}(stat.) {+-} 0.02(syst.) ps. In addition, for the {Xi}{sub b}{sup -} baryon they measure a mass of 5790.9 {+-} 2.6(stat.) {+-} 0.8(syst.) MeV/c{sup 2} and a lifetime of 1.56{sub -0.25}{sup +0.27}(stat.) {+-} 0.02(syst.) ps.
Date: May 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Evidence for a Narrow Near-Threshold Structure in the $J/\psi\phi$ Mass Spectrum in $B^+\to J/\psi\phi K^+$ Decays

Description: Evidence is reported for a narrow structure near the J/{psi}{phi} threshold in exclusive B{sup +} {yields} J/{psi}{phi}K{sup +} decays produced in {bar p}p collisions at {radical}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{sup -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{sup 2} and 11.7{sub -5.0}{sup +8.3}(stat) {+-} 3.7(syst) MeV/c{sup 2}.
Date: March 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Production of psi(2S) Mesons in p anti-p Collisions at 1.96-TeV

Description: The authors have measured the differential cross section for the inclusive production of {psi}(2S) mesons decaying to {mu}{sup +}{mu}{sup -} that were produced in prompt or B-decay processes from p{bar p} collisions at 1.96 TeV. These measurements have been made using a data set from an integrated luminosity of 1.1 fb{sup -1} collected by the CDF II detector at Fermilab. For events with transverse momentum p{sub T}({psi}(2S)) > 2 GeV/c and rapidity |y({psi}(2S))| < 0.6 we measure the integrated inclusive cross section {sigma}(p{bar p} {yields} {psi}(2S)X) {center_dot} Br({psi}(2S) {yields} {mu}{sup +}{mu}{sup -}) to be 3.29 {+-} 0.04(stat.) {+-} 0.32(syst.) nb.
Date: May 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

First Observation of Vector Boson Pairs in a Hadronic Final State at the Tevatron Collider

Description: 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 fb{sup -1} of integrated luminosity of p{bar p} collisions at {radical}s = 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron. We observe 1516 {+-} 239(stat) {+-} 144(syst) diboson candidate events and measure a cross section {sigma}(p{bar p} {yields} VV + X) of 18.0 {+-} 2.8(stat) {+-} 2.4(syst) {+-} 1.1(lumi) pb, in agreement with the expectations of the standard model.
Date: May 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Measurement of Particle Production and Inclusive Differential Cross Sections in p anti-p Collisions at s**(1/2) = 1.96-TeV

Description: We report a set of measurements of particle production in inelastic p{bar 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.
Date: April 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Measurement of the helicity of W bosons in top-quark decays

Description: We measure the branching fraction of the top quark to longitudinally and right-handed polarized W bosons, F{sub 0} and F{sub +}, using approximately 200 pb{sup -1} of p{bar p} collisions collected by the CDF II detector. We analyze two quantities sensitive to the W helicity: the invariant mass of the charged lepton and the bottom-quark jet in the decay t {yields} Wb {yields} {ell}{nu}b (where {ell} = e or {mu}), and the transverse momentum of the charged lepton. We find F{sub 0} = 0.74{sub -0.34}{sup +0.22}, and F{sub +} < 0.27 at the 95% confidence level. These measurements are in agreement with the standard model predictions.
Date: November 1, 2005
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the t anti-t Production Cross Section in p anti-p collisions at s**(1/2) = 1.96-TeV using Lepton + Jets Events with Jet Probability b-tagging

Description: The authors present a measurement of the t{bar t} production cross section using events with one charged lepton and jets from p{bar p} collisions at a center-of-mass energy of 1.96 TeV. A b-tagging algorithm based on the probability of displaced tracks coming from the event interaction vertex is applied to identify b quarks from top decay. Using 318 pb{sup -1} of data collected with the CDF II detector, they measure the t{bar t} production cross section in events with at least one restrictive (tight) b-tagged jet and obtain 8.9{sub -1.0}{sup +1.0}(stat.){sub -1.0}{sup +1.1}(syst.) pb. The cross section value assumes a top quark mass of m{sub t} is presented in the paper. This result is consistent with other CDF measurements of the t{bar t} cross section using different samples and analysis techniques, and has similar systematic uncertainties. They have also performed consistency checks by using the b-tagging probability function to vary the signal to background ratio and also using events that have at least two b-tagged jets.
Date: July 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the t anti-t production cross section in p anti-p collisions at s**(1/2) = 1.96-TeV using missing E(T) + jets events with secondary vertex b-tagging

Description: The authors present a measurement of the t{bar t} production cross section in p{bar p} collisions at {radical}s = 1.96 TeV which uses events with an inclusive signature of significant missing transverse energy and jets. This is the first measurement which makes no explicit lepton identification requirements, so that sensitivity to W {yields} {tau}{nu} decays is maintained. Heavy flavor jets from top quark decay are identified with a secondary vertex tagging algorithm. From 311 pb{sup -1} of data collected by the Collider Detector at Fermilab they measure a production cross section of 5.8 {+-} 1.2(stat.){sub -0.7}{sup +0.9}(syst.) pb for a top quark mass of 178 GeV/c{sup 2}, in agreement with previous determinations and standard model predictions.
Date: March 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the tanti-t Production Cross Section in p anti-ptnipbar Collisions at s**(1/2) = 1.96-TeV

Description: The authors present a measurement of the top quark pair production cross section in p{bar p} collisions at {radical}s = 1.96 TeV using 318 pb{sup -1} of data collected with the Collider Detector at Fermilab. They select t{bar t} decays into the final states e{nu} + jets and {mu}{nu} + jets, in which at least one b quark from the t-quark decays is identified using a secondary vertex-finding algorithm. Assuming a top quark mass of 178 GeV/c{sup 2}, they measure a cross section of 8.7 {+-} 0.9(stat.){sub -0.9}{sup +1.1}(syst.) pb. They also report the first observation of t{bar t} with significance greater than 5{sigma} in the subsample in which both b quarks are identified, corresponding to a cross section of 10.1{sub -1.4}{sup +1.6}(stat.){sub -1.3}{sup +2.0}(syst.) pb.
Date: June 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the inclusive jet cross section using the k(T) algorithm in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: The authors report on a measurement of the inclusive jet production cross section in p{bar p} collisions at {radical}s = 1.96 TeV using data collected with the upgraded Collider Detector at Fermilab in Run II (CDF II) corresponding to an integrated luminosity of 385 pb{sup -1}. Jets are reconstructed using the k{sub T} algorithm. The measurement is carried out for jets with rapidity 0.1 < |y{sup jet}| < 0.7 and transverse momentum in the range 54 < p{sub T}{sup jet} < 700 GeV/c. The measured cross section is in good agreement with next-to-leading order perturbative QCD predictions after the necessary non-perturbative parton-to-hadron corrections are included.
Date: December 1, 2005
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the top quark mass using the template method in the lepton plus jets channel with in situ W ---> j j calibration at CDF-II

Description: We report an updated measurement of the top quark mass in the lepton plus jets channel of t{bar t} events from p{bar p} collisions at {radical}s = 1.96 TeV. This measurement uses a dataset with integrated luminosity of 680 pb{sup -1}, containing 360 t{bar t} candidates separated into four subsamples. A top quark mass is reconstructed for each event by using energy and momentum constraints on the top quark pair decay products. We also employ the reconstructed mass of hadronic W boson decays W {yields} jj to constrain in situ the largest systematic uncertainty of the top quark mass measurement: the jet energy scale. Monte Carlo templates of the reconstructed top quark and W boson mass are produced as a function of the true top quark mass and the jet energy scale. The distribution of reconstructed top quark and W boson mass in the data are compared to the Monte Carlo templates using a likelihood fit to obtain: M{sub top} = 173.4 {+-} 2.8 GeV/c{sup 2}.
Date: May 1, 2006
Creator: Adelman, Jahred A.; Arguin, J.F.; Bellettini, G.; Brubaker, E.; Budagov, J.; Chlachidze, G. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the top quark mass with the dynamical likelihood method using lepton plus jets events with b-tags in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: This report describes a measurement of the top quark mass, M{sub top}, with the dynamical likelihood method (DLM) using the CDF II detector at the Fermilab Tevatron. The Tevatron produces top/anti-top (t{bar t}) pairs in p{bar p} collisions at a center-of-mass energy of 1.96 TeV. The data sample used in this analysis was accumulated from March 2002 through August 2004, which corresponds to an integrated luminosity of 318 pb{sup -1}. They use the t{bar t} candidates in the ''lepton+jets'' decay channel, requiring at least one jet identified as a b quark by finding an displaced secondary vertex. The DLM defines a likelihood for each event based on the differential cross section as a function of M{sub top} per unit phase space volume of the final partons, multiplied by the transfer functions from jet to parton energies. The method takes into account all possible jet combinations in an event, and the likelihood is multiplied event by event to derive the top quark mass by the maximum likelihood method. Using 63 t{bar t} candidates observed in the data, with 9.2 events expected from background, they measure the top quark mass to be 173.2{sub -2.4}{sup +2.6}(stat.) {+-} 3.2(syst.) GeV/c{sup 2}, or 173.2{sub -4.0}{sup +4.1} GeV/c{sup 2}.
Date: December 1, 2005
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the B0(s) - anti-B0(s) Oscillation Frequency

Description: The authors present the first measurement of the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillation frequency {Delta}m{sub s}. They use 1 fb{sup -1} of data from p{bar p} collisions at {radical}s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. The sample contains signals of 3600 fully reconstructed hadronic B{sub s} decays and 37,000 partially reconstructed semileptonic B{sub s} decays. They measure the probability as a function of proper decay time that the B{sub s} decays with the same, or opposite, flavor as the flavor at production and they find a signal consistent with B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillations. The probability that random fluctuations could produce a comparable signal is 0.2%. Under the hypothesis that the signal is due to B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillations, they measure {Delta}m{sub s} = 17.31{sub -0.18}{sup +0.33}(stat.) {+-} 0.07(syst.) ps{sup -1} and determine |V{sub td}/V{sub ts}| = 0.208{sub -0.002}{sup +0.001}(exp.){sub -0.006}{sup +0.008}(theo.).
Date: June 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the top quark mass using template methods on dilepton events in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: The authors describe a measurement of the top quark mass from events produced in p{bar p} collisions at a center-of-mass energy of 1.96 TeV, using the Collider Detector at Fermilab. They identify t{bar t} candidates where both W bosons from the top quarks decay into leptons (e{nu}, {mu}{nu}, or {tau}{nu}) from a data sample of 360 pb{sup -1}. The top quark mass is reconstructed in each event separately by three different methods, which draw upon simulated distributions of the neutrino pseudorapidity, t{bar t} longitudinal momentum, or neutrino azimuthal angle in order to extract probability distributions for the top quark mass. For each method, representative mass distributions, or templates, are constructed from simulated samples of signal and background events, and parameterized to form continuous probability density functions. A likelihood fit incorporating these parameterized templates is then performed on the data sample masses in order to derive a final top quark mass. Combining the three template methods, taking into account correlations in their statistical and systematic uncertainties, results in a top quark mass measurement of 170.1 {+-} 6.0(stat.) {+-} 4.1(syst.) GeV/c{sup 2}.
Date: February 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the Top Quark Mass Using the Invariant Mass of Lepton Pairs in Soft Muon b-tagged Events

Description: We present the first measurement of the mass of the top quark in a sample of t{bar t} {yields} {ell}{bar {nu}}b{bar b}q{bar q} events (where {ell} = e, {mu}) selected by identifying jets containing a muon candidate from the semileptonic decay of heavy-flavor hadrons (soft muon b-tagging). The p{bar p} collision data used corresponds to an integrated luminosity of 2 fb{sup -1} and was collected by the CDF II detector at the Fermilab Tevatron. The measurement is based on a novel technique exploiting the invariant mass of a subset of the decay particles, specifically the lepton from the W boson of the t {yields} Wb decay, and the muon from a semileptonic b decay. We fit template histograms, derived from simulation of t{bar t} events and a modeling of the background, to the mass distribution observed in the data and measure a top quark mass of 180.5 {+-} 12.0(stat.) {+-} 3.6(syst.) GeV/c{sup 2}, consistent with the current world average.
Date: June 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Search for the Neutral Current Top Quark Decay t-->Zc Using Ratio of Z-Boson + 4 Jets to W-Boson + 4 Jets Production

Description: We have used the Collider Detector at Fermilab (CDF II) to search for the flavor-changing neutral-current (FCNC) top quark decay t {yields} Zc using a technique employing ratios of W and Z production, measured in p{bar p} data corresponding to an integrated luminosity of 1.52 fb{sup -1}. The analysis uses a comparison of two decay chains, p{bar p} {yields} t{bar t} {yields} WbWb {yields} {ell}{nu}bjjb and p{bar p} {yields} t{bar t} {yields} ZcWb {yields} {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 {yields} 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.
Date: May 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Search for narrow resonances lighter than Upsilon mesons

Description: We report a search for narrow resonances, produced in p{bar p} collisions at {radical}s = 1.96 TeV, that decay into muon pairs with invariant mass between 6.3 and 9.0 GeV/c{sup 2}. The data, collected with the CDF II detector at the Fermilab Tevatron collider, correspond to an integrated luminosity of 630 pb{sup -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 {Upsilon}(1S) meson.
Date: March 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Search for Z' ---> e+ e- using dielectron mass and angular distribution

Description: The authors search Z{prime} bosons in dielectron events produced in p{bar p} collisions at {radical}s = 1.96 TeV, using a 0.45 fb{sup -1} dataset accumulated with the CDF II detector at the Fermilab Tevatron. To identify the Z{prime} {yields} e{sup +}e{sup -} signal, both the dielectron invariant mass distribution and the angular distribution of the electron pair are used. No evidence of a signal is found, and 95% confidence level lower limits are set on the Z{prime} mass for several models. Limits are also placed on the mass and gauge coupling of a generic Z{prime}, as well as on the contact interaction mass scales for different helicity structure scenarios.
Date: February 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Top quark mass measurement from dilepton events at CDF II

Description: We report a measurement of the top quark mass using events collected by the CDF II Detector from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron. We calculate a likelihood function for the top mass in events that are consistent with t{bar t} {yields} {bar b}{ell}{sup -}{bar {nu}}{sub {ell}}b{ell}{prime}{sup +}{nu}{sub {ell}}{prime} decays. The likelihood is formed as the convolution of the leading-order matrix element and detector resolution functions. The joint likelihood is the product of likelihoods for each of 33 events collected in 340 pb{sup -1} of integrated luminosity, yielding a top quark mass M{sub t} = 165.2 {+-} 6.1(stat.) {+-} 3.4(syst.) GeV/c{sup 2}. This first application of a matrix-element technique to t{bar t} {yields} b{ell}{sup +}{nu}{sub {ell}}{bar b}{ell}{prime}{sup -}{bar {nu}}{sub {ell}}, decays gives the most precise single measurement of M{sub t} in dilepton events. Combined with other CDF Run II measurements using dilepton events, we measure M{sub t} = 167.9 {+-} 5.2(stat.) {+-} 3.7(syst.) GeV/c{sup 2}.
Date: December 1, 2005
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department