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Top physics: measurement of the cross section for ttbar production in ppbar collisions using the kinematics of lepton + jets events

Description: We present a measurement of the top pair production cross section in p{bar p} collisions at {radical}s = 1.96 TeV. We collect a data sample with an integrated luminosity of 194 {+-} 11 pb{sup -1} with the CDF II detector at the Fermilab Tevatron. We use an artificial neural network technique to discriminate between top pair production and background processes in a sample of 519 lepton+jets events, which have one isolated energetic charged lepton, large missing transverse energy and at least three energetic jets. We measure the top pair production cross section to be {sigma}{sub t{bar t}} = 6.6 {+-} 1.1 {+-} 1.5 pb, where the first uncertainty is statistical and the second is systematic.
Date: April 27, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Exotic physics: search for scalar leptoquark pairs decaying to nu nu-bar qq-bar in p anti-p collisions at s**(1/2) = 1.96 tev

Description: We report on a search for the pair production of scalar leptoquarks, LQ, using 191 pb{sup -1} of proton-antiproton collision data recorded by the CDF experiment during Run II of the Tevatron. The leptoquarks are sought via their decay into a neutrino and quark yielding missing transverse energy and several jets of large transverse energy. No evidence for leptoquark production is observed, and limits are set on {sigma}(p{bar p} {yields} LQ{ovr OQ}X {yields} v{bar v}q{bar q}X). Using a next-to-leading order theoretical prediction of the cross section for scalar leptoquark production, we exclude first-generation leptoquarks in the mass interval 78 to 117 GeV/c{sup 2} at the 95% confidence level for BR(LQ {yields} vq) = 100%.
Date: October 25, 2004
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Qcd physics: study of jet shapes in inclusive jet production in ppbar collisions at sqrt s = 1.96 tev

Description: We present a search for excited and exotic electrons (e*) decaying to an electron and a photon, both with high transverse momentum. We use 202 pb{sup -1} of data collected in p{bar p} collisions at {radical}s = 1.96 TeV with the CDF II detector. No signal above standard model expectation is seen for associated ee* production. We discuss the e* sensitivity in the parameter space of the excited electron mass M{sub e*} and the compositeness energy scale {Lambda}. In the contact interaction model, we exclude 132 GeV/c{sup 2} < M{sub e*} < 879 GeV/c{sup 2} for {Lambda} = M{sub e*} at 95% confidence level (C.L.). In the gauge-mediated model, we exclude 126 GeV/c{sup 2} < M{sub e*} < 430 GeV/c{sup 2} at 95% C.L. for the phenomenological coupling f/{Lambda} {approx} 10{sup -2} GeV{sup -1}.
Date: May 8, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Top physics: measurement of the tt-bar production cross section in pp-bar collisions at s**(1/2) = 1.96 tev using dilepton event

Description: We report a measurement of the t{bar t} production cross section using dilepton events with jets and missing transverse energy in p{bar p} collisions at a center-of-mass energy of 1.96 TeV. Using a 197 {+-} 12 pb{sup -1} data sample recorded by the upgraded Collider Detector at Fermilab, we use two complementary techniques to select candidate events. We compare the number of observed events and selected kinematical distributions with the predictions of the standard model and find good agreement. The combined result of the two techniques yields a t{bar t} production cross section of 7.0{sub -2.1}{sup +2.4}(stat){sub -1.1}{sup _1.6}(syst) {+-} 0.4(lum) pb.
Date: October 14, 2004
Creator: Acosta, D.
Partner: UNT Libraries Government Documents Department

Top physics: measurement of the tt-bar production cross section in p anti-p collisions at s**(1/2) = 1.96 tev using lepton + jets events with secondary vertex b-tagging

Description: We 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 1.96TeV. In these events, heavy flavor quarks from top quark decay are identified with a secondary vertex tagging algorithm. From 162 pb{sup -1} of data collected by the Collider Detector at Fermilab, a total of 48 candidate events are selected, where 13.5 {+-} 1.8 events are expected from background contributions. We measure a t{bar t} production cross section of 5.6{sub -1.1}{sup _1.2}(stat.){sub -0.6}{sup +0.9}(syst.)pb.
Date: April 7, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Electroweak physics: search for zz and zw production in p anti-p collisions at s**(1/2) = 1.96 tev

Description: We present a search for ZZ and ZW vector boson pair production in p{bar p} collisions at {radical}s = 1.96 TeV using the leptonic decay channels ZZ {yields} llvv, ZZ {yields} lll'l' and ZW {yields} lll'v. In a data sample corresponding to an integrated luminosity of 194 pb{sup -1} collected with the Collider Detector at Fermilab, 3 candidate events are found with an expected background of 1.0 {+-} 0.2 events. We set a 95% confidence level upper limit of 15.2 pb on the cross section for ZZ plus ZW production, compared to the standard model prediction of 5.0 {+-} 0.4 pb.
Date: May 18, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

B physics: measurement of partial widths and search for direct cp violation in d0 meson decays

Description: We present a measurement of relative partial widths and decay rate CP asymmetries in K{sup -}K{sup +} and {pi}{sup -}{pi}{sup +} decays of D{sup 0} mesons produced in p{bar p} collisions at {radical}s = 1.96TeV. We use a sample of 2 x 10{sup 5} D*{sup +} {yields} D{sup 0}{pi}{sup +} (and charge conjugate) decays with the D{sup 0} decaying to K{sup -}{pi}{sup +}, K{sup -}K{sup +}, and {pi}{sup -}{pi}{sup +}, corresponding to 123 pb{sup -1} of data collected by the Collider Detector at Fermilab II experiment at the Fermilab Tevatron collider. No significant direct CP violation is observed. We measure {Lambda}(D{sup 0} {yields} K{sup -}K{sup +})/{Lambda}(D{sup 0} {yields} K{sup -}{pi}{sup +}) = 0.0992 {+-} 0.0011 {+-} 0.0012, {Lambda}(D{sup 0} {yields} {pi}{sup -}{pi}{sup +})/{Lambda}(D{sup 0} {yields} K{sup -}{pi}{sup +}) = 0.03594 {+-} 0.00054 {+-} 0.00040, A{sub CP} (K{sup -}K{sup +}) = (2.0 {+-} 1.2 {+-} 0.6)%, and A{sub CP} ({pi}{sup -}{pi}{sup +}) = (1.0 {+-} 1.3 {+-} 0.6) %, where, in all cases, the first uncertainty is statistical and the second is systematic.
Date: April 4, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Measurement of the Moments of the Hadronic Invariant Mass Distribution in Semileptonic Beta Decays

Description: Using 180 pb{sup -1} of data collected with the CDF II detector at the Tevatron, we measure the first two moments of the hadronic invariant mass-squared distribution in charmed semileptonic B decays. From these we determine the non-perturbative Heavy Quark Effective Theory parameters {Lambda} and {lambda}{sub 1} used to relate the B meson semileptonic branching ratio to the CKM matrix element |V{sub cb}|.
Date: March 13, 2005
Creator: Acosta, D. & TITLE=Measuremen, The CDF Collaboration
Partner: UNT Libraries Government Documents Department

B physics: evidence for the exclusive decay b^+/-_c -> j/psi pi^+ and measurement of the mass of the b^+/-_c meson

Description: We report the first evidence of a fully reconstructed decay mode of the B{sub c}{sup {+-}} meson in the channel B{sub c}{sup {+-}} {yields} J/{psi}{sup {+-}}, with J/{psi} {yields} {mu}{sup +}{mu}{sup -}. The analysis is based on an integrated luminosity of 360 pb{sup -1} in p{bar p} collisions collected by the Collider Detector at Fermilab. We observe 18.9 {+-} 5.7 signal events on a background of 10.0 {+-} 1.4 events and the fit to the J/{psi}{pi}{sup {+-}} mass spectrum yields a B{sub c}{sup {+-}} mass of 6287.0 {+-} 4.8(stat) {+-} 1.1(syst) MeV/c{sup 2}.
Date: May 25, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Electroweak physics: measurement of the forward-backward charge asymmetry of electron-positron pairs in p anti-p collisions at s**(1/2) = 1.96 tev

Description: We report a measurement of the forward-backward charge asymmetry of electrons from W boson decays in p{bar p} collisions at {radical}s = 1.96 TeV using a data sample of 170 pb{sup -1} collected by the Collider Detector at Fermilab. The asymmetry is measured as a function of electron rapidity and transverse energy and provides new input on the momentum fraction dependence of the u and d quark parton distribution functions within the proton.
Date: February 23, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Exotic physics: search for first-generation scalar leptoquarks in ppbar collisions at sqrt = 1.96 tev

Description: We report on a search for pair production of first-generation scalar leptoquarks (LQ) in p{bar p} collisions at {radical}s = 1.96 TeV using an integrated luminosity of 203 pb{sup -1} collected at the Fermilab Tevatron collider by the CDF experiment. We observe no evidence for LQ production in the topologies arising from LQ{ovr LQ} {yields} eqeq and LQ{ovr LQ} {yields} eq{nu}q, and derive 95% C.L. upper limits on the LQ production cross section. The results are combined with those obtained from a separately reported CDF search in the topology arising from LQ{ovr LQ} {yields} {nu}q{nu}q and 95% C.L. lower limits on the LQ mass as a function of {beta} = BR(LQ {yields} eq) are derived. The limits are 236, 205 and 145 GeV/c{sup 2} for {beta} = 1, {beta} = 0.5 and {beta} = 0.1, respectively.
Date: June 29, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

B physics: measurement of the j/psi meson and b-hadron production cross sections in p anti-p collisions at s**(1/2) = 1960 gev

Description: The authors present a new measurement of the inclusive and differential production cross sections of J/{psi} mesons and b-hadrons in proton-antiproton collisions at {radical}s = 1960 GeV. The data correspond to an integrated luminosity of 39.7 pb{sup -1} collected by the CDF Run II detector. They find the integrated cross section for inclusive J/{psi} production for all transverse momenta from 0 to 20 GeV/c in the rapidity range |y| < 0.6 to be 4.08 {+-} 0.02(stat){sub -0.33}{sup +0.36}(syst) {mu}b. They separate the fraction of J/{psi} events from the decay of the long-lived b-hadrons using the lifetime distribution in all events with p{sub T}(J/{psi}) > 1.25 GeV/c. They find the total cross section for b-hadrons, including both hadrons and anti-hadrons, decaying to J/{psi} with transverse momenta greater than 1.25 GeV/c in the rapidity range |y(J/{psi})| < 0.6, is 0.330 {+-} 0.005(stat){sub -0.033}{sup +0.036}(syst) {mu}b. Using a Monte Carlo simulation of the decay kinematics of b-hadrons to all final states containing a J/{psi}, they extract the first measurement of the total single b-hadron cross section down to zero transverse momentum at {radical}s = 1960 GeV. They find the total single b-hadron cross section integrated over all transverse momenta for b-hadrons in the rapidity range |y| < 0.6 to be 17.6 {+-} 0.4(stat){sub -2.3}{sup +2.5}(syst) {mu}b.
Date: December 23, 2004
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Exotic physics: search for long-lived doubly-charged higgs bosons in p anti-p collisions at s**(1/2) = 1.96 tev

Description: We present a search for long-lived doubly-charged Higgs bosons (H{sup {+-}{+-}}), with signatures of high ionization energy loss and muon-like penetration. We use 292 pb{sup -1} of data collected in p{bar p} collisions at {radical}s = 1.96 TeV by the CDF II detector at the Fermilab Tevatron. Observing no evidence of long-lived doubly-charged particle production, we exclude H{sub L}{sup {+-}{+-}} and H{sub R}{sup {+-}{+-}} bosons with masses below 133 GeV/c{sup 2} and 109 GeV/c{sup 2}, respectively. In the degenerate case we exclude H{sup {+-}{+-}} mass below 146 GeV/c{sup 2}. All limits are quoted at the 95% confidence level.
Date: March 2, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Search for b0(s) --> mu+ mu- and b0(d) --> mu+ mu- decays in p anti-p collisions at s**(1/2) = 1.96 tev

Description: The authors report on a search for B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -} and B{sub d}{sup 0} {yields} {mu}{sup +}{mu}{sup -} decays in p{bar p} collisions at {radical}s = 1.96 TeV using 171 pb{sup -1} of data collected by the CDF II experiment at the Fermilab Tevatron Collider. The decay rates of these rare processes are sensitive to contributions from physics beyond the Standard Model. One event survives all the selection requirements, consistent with the background expectation. They derive branching ratio limits of {Beta}(B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 5.8 x 10{sup -7} and {Beta}(B{sub d}{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 1.5 x 10{sup -7} at 90% confidence level.
Date: March 20, 2004
Creator: Acosta, D.
Partner: UNT Libraries Government Documents Department

B physics: first evidence for b_s0 --> phi phi decay and measurements of branching ratio and a_cp for b+ --> phi k+

Description: We present the first evidence of charmless decays of the B{sub s}{sup 0} meson, the decay B{sub s}{sup 0} {yields} {phi}{phi}, and a measurement of the Branching Ratio BR(B{sub s}{sup 0} {yields} {phi}{phi}) using 180 pb{sup -1} of data collected by the CDF II experiment at the Fermilab Tevatron collider. In addition, the BR and direct CP asymmetry for the B{sup +} {yields} {phi}K{sup +} decay are measured.
Date: May 31, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Exotic physics: search for doubly-charged higgs bosons decaying to dileptons in p anti-p collisions at s**(1/2) = 1.96 tev

Description: The authors present the results of a search for doubly-charged Higgs bosons (H{sup {+-}}{sup {+-}}) decaying to dileptons (ll') using {approx} 240 pb{sup -1} of p{bar p} collision data collected by the CDF II experiment at the Fermilab Tevatron. In the search region, given by same-sign ll' mass m{sub ll'} > 80 GeV/c{sup 2} (100 GeV/c{sup 2} for ee channel), they observe no evidence for H{sup {+-}}{sup {+-}} production. They set limits on {sigma}(p{bar p} {yields} H{sup ++}H{sup --} {yields} l{sup +}l'{sup +}l{sup -}l'{sup -}) as a function of the mass of the H{sup {+-}}{sup {+-}} and the chirality of its couplings. Assuming exclusive same-sign dilepton decays, they derive lower mass limits on H{sub L}{sup {+-}}{sup {+-}} of 133 GeV/c{sup 2}, 136 GeV/c{sup 2}, and 115 GeV/c{sup 2} in the ee, {mu}{mu}, and e{mu} channels, respectively, and a lower mass limit of 113 GeV/c{sup 2} on H{sub R}{sup {+-}}{sup {+-}} in the {mu}{mu} channel, all at the 95% confidence level.
Date: November 15, 2004
Creator: Acosta, D.
Partner: UNT Libraries Government Documents Department

B physics: measurement of the lifetime difference between b_s mass eigenstates

Description: We present measurements of the lifetimes and polarization amplitudes for B{sub s}{sup 0} {yields} J/{psi}{phi} and B{sub d}{sup 0} {yields} J/{psi} K*{sup 0} decays. Lifetimes of the heavy (H) and light (L) mass eigenstates in the B{sub s}{sup 0} system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time.
Date: April 28, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Top physics: search for anomalous kinematics in t anti-t dilepton events at cdf ii

Description: We report on a search for anomalous kinematics of t{bar t} dilepton events in p{bar p} collisions at {radical}s = 1.96 TeV using 193 pb{sup -1} of data collected with the CDF II detector. We developed a new a priori technique designed to isolate the subset in a data sample revealing the largest deviation from standard model (SM) expectations and to quantify the significance of this departure. In the four-variable space considered, no particular subset shows a significant discrepancy and we find that the probability of obtaining a data sample less consistent with the SM than what is observed is 1.0-4.5%.
Date: December 14, 2004
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Electroweak physics: measurement of w gamma and z gamma production in pp-bar collisions at s**(1/2) = 1.96 tev

Description: The Standard Model predictions for W{gamma} and Z{gamma} production are tested using an integrated luminosity of 200 pb{sup -1} of p{bar p} collision data collected at the Collider Detector at Fermilab. The cross sections are measured by selecting leptonic decays of the W and Z bosons, and photons with transverse energy E{sub T} > 7 GeV that are well separated from leptons. The production cross sections and kinematic distributions for the W{gamma} and Z{gamma} data are compared to SM predictions.
Date: February 2, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Exotic physics: search for excited and exotic electrons in the e gamma decay channel in p anti-p collisions at s**(1/2) = 1.96 tev

Description: We present a search for excited and exotic electrons (e*) decaying to an electron and a photon, both with high transverse momentum. We use 202 pb{sup -1} of data collected in p{bar p} collisions at {radical}s = 1.96 TeV with the CDF II detector. No signal above standard model expectation is seen for associated ee* production. We discuss the e* sensitivity in the parameter space of the excited electron mass M{sub e*} and the compositeness energy scale {Lambda}. In the contact interaction model, we exclude 132 GeV/c{sup 2} < M{sub e*} < 879 GeV/c{sup 2} for {Lambda} = M{sub e*} at 95% confidence level (C.L.). In the gauge-mediated model, we exclude 126 GeV/c{sup 2} < M{sub e*} < 430 GeV/c{sup 2} at 95% C.L. for the phenomenological coupling f/{Lambda} {approx} 10{sup -2} GeV{sup -1}.
Date: February 21, 2005
Creator: Acosta, D.
Partner: UNT Libraries Government Documents Department

# top physics: measurement of the ttbar production cross section in pp-bar collisions at sqrt s = 1.96 tev using lepton plus jets events with semileptonic b decays to muons

Description: We present a measurement of the t{bar t} production cross section using 194 pb{sup -1} of CDF II data using events with a high transverse momentum electron or muon, three or more jets, and missing transverse energy. The measurement assumes 100% t {yields} Wb branching fraction. Events consistent with t{bar t} decay are found by identifying jets containing heavy flavor semileptonic decays to muons. The dominant backgrounds are evaluated directly from the data. Based on 20 candidate events and an expected background of 9.5 {+-} 1.1 events, we measure a production cross section of 5.3 {+-} 3.3{sub -1.0}{sup +1.3} pb, in agreement with the standard model.
Date: June 1, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Top physics: search for electroweak single top quark production in p anti-p collisions at s**(1/2) = 1.96 tev

Description: We report on a search for Standard Model t-channel and s-channel single top quark production in p{bar p} collisions at a center of mass energy of 1.96 TeV. We use a data sample corresponding to 162 pb{sup -1} recorded by the upgraded Collider Detector at Fermilab. We find no significant evidence for electroweak top quark production and set upper limits at the 95% confidence level on the production cross section, consistent with the Standard Model: 10.1 pb for the t-channel, 13.6 pb for the s-channel and 17.8 pb for the combined cross section of t- and s-channel.
Date: January 12, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Qcd physics: measurement of the cross section for prompt diphoton production in p anti-p collisions at s**(1/2) = 1.96 tev

Description: We report a measurement of the rate of prompt diphoton production in p{bar p} collisions at {radical}s = 1.96 TeV using a data sample of 207 pb{sup -1} collected with the upgraded Collider Detector at Fermilab (CDF II). The background from non-prompt sources is determined using a statistical method based on differences in the electromagnetic showers. The cross section is measured as a function of the diphoton mass, the transverse momentum of the diphoton system, and the azimuthal angle between the two photons and is found to be consistent with perturbative QCD predictions.
Date: June 13, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Observation of the narrow state x (3872) --> j/psi pi+ pi- in pbar p collisions at s**(1/2) = 1.96 tev

Description: The authors report the observation of a narrow state decaying into J/{psi}{pi}{sup +}{pi}{sup -} and produced in 220 pb{sup -1} of {bar p}p collisions at {radical}s = 1.96 TeV in the CDF II experiment. They observe 730 {+-} 90 decays. The mass is measured to be 3871.3 {+-} 0.7(stat) {+-} 0.4(syst) MeV/c{sup 2}, with an observed width consistent with the detector resolution. This is in agreement with the recent observation by the Belle Collaboration of the X(3872) meson.
Date: February 27, 2004
Creator: Acosta, D.
Partner: UNT Libraries Government Documents Department