Showing papers by "D. P. Benjamin published in 2005"

Measurement of the J/psi meson and b-hadron production cross sections in p(p)over-bar collisions at root s=1960 GeV RID C-1693-2008 RID G-1087-2011 RID E-4473-2011

Abstract: We present a new measurement of the inclusive and differential production cross sections of $J/\ensuremath{\psi}$ mesons and $b$ hadrons in proton-antiproton collisions at $\sqrt{s}=1960\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}$. The data correspond to an integrated luminosity of $39.7\text{ }\text{ }{\mathrm{p}\mathrm{b}}^{\ensuremath{-}1}$ collected by the CDF run II detector. We find the integrated cross section for inclusive $J/\ensuremath{\psi}$ production for all transverse momenta from 0 to $20\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$ in the rapidity range $|y|l0.6$ to be $4.08\ifmmode\pm\else\textpm\fi{}0.02(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}{)}_{\ensuremath{-}0.33}^{+0.36}(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})\text{ }\text{ }\ensuremath{\mu}\mathrm{b}$. We separate the fraction of $J/\ensuremath{\psi}$ events from the decay of the long-lived $b$ hadrons using the lifetime distribution in all events with ${p}_{T}(J/\ensuremath{\psi})g1.25\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$. We find the total cross section for $b$ hadrons, including both hadrons and antihadrons, decaying to $J/\ensuremath{\psi}$ with transverse momenta greater than $1.25\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$ in the rapidity range $|y(J/\ensuremath{\psi})|l0.6$ is $0.330\ifmmode\pm\else\textpm\fi{}0.005(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}{)}_{\ensuremath{-}0.033}^{+0.036}(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})\text{ }\text{ }\ensuremath{\mu}\mathrm{b}$. Using a Monte Carlo simulation of the decay kinematics of $b$ hadrons to all final states containing a $J/\ensuremath{\psi}$, we extract the first measurement of the total single $b$-hadron cross section down to zero transverse momentum at $\sqrt{s}=1960\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}$. We find the total single $b$-hadron cross section integrated over all transverse momenta for $b$ hadrons in the rapidity range $|y|l0.6$ to be $17.6\ifmmode\pm\else\textpm\fi{}0.4(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}{)}_{\ensuremath{-}2.3}^{+2.5}(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})\text{ }\text{ }\ensuremath{\mu}\mathrm{b}$.

Study of jet shapes in inclusive jet production in pp̄ collisions at s=1.96 TeV

Abstract: We report on a study of jet shapes in inclusive jet production in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\mathrm{TeV}$ using the upgraded collider detector at Fermilab in Run II (CDF II) and based on an integrated luminosity of $170\text{ }\mathrm{p}{\mathrm{b}}^{\ensuremath{-}1}$. Measurements are carried out on jets with rapidity $0.1l|{Y}^{\mathrm{jet}}|l0.7$ and transverse momentum $37\text{ }\text{ }\mathrm{GeV}/cl{P}_{T}^{\mathrm{jet}}l380\text{ }\text{ }\mathrm{GeV}/c$. The jets have been corrected to the hadron level. The measured jet shapes are compared to leading-order QCD parton-shower Monte Carlo predictions as implemented in the PYTHIA and HERWIG programs. PYTHIA, tuned to describe the underlying event as measured in CDF Run I, provides a better description of the measured jet shapes than does PYTHIA or HERWIG with their default parameters.

Measurement of the lifetime difference between Bs mass eigenstates

Abstract: We present measurements of the lifetimes and polarization amplitudes for B(0)(s)-->J/psiphi and B(0)(d)-->J/psiK(*0) decays. Lifetimes of the heavy and light mass eigenstates in the B(0)(s) 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. Using 203+/-15 B(0)(s) decays we obtain tau(L) = (1.05(+0.16)(-0.13) +/- 0.02) ps and tau(H) = (2.07(+0.58)(-0.46) +/- 0.03) ps. Expressed in terms of the difference DeltaGamma(s) and average Gamma(s), of the decay rates of the two eigenstates, the results are DeltaGamma(s)/Gamma(s) = (65(+25)(-33) +/- 1)% and DeltaGamma(s) = (0.47(+0.19)(-0.24) +/- 0.01) ps(-1).

Measurement of B(t --> Wb)/B(t--> Wq) at the collider detector at fermilab.

Abstract: We present a measurement of the ratio of top-quark branching fractions R = B(t --> Wb)/B(t --> Wq), where q can be a b, s, or a d quark, using lepton-plus-jets and dilepton data sets with an integrated luminosity of approximately 162 pb(-1) collected with the Collider Detector at Fermilab during Run II of the Tevatron. The measurement is derived from the relative numbers of tt events with different multiplicity of identified secondary vertices. We set a lower limit of R > 0.61 at 95% confidence level.

Evidence for B-s(0)->phi phi decay and measurements of branching ratio and A(CP) for B+->phi K+

Abstract: We present the first evidence of charmless decays of the B(0)(s) meson, the decay B(0)(s)--> phiphi, and a measurement of the branching ratio BR(B(0)(s)--> phiphi) using 180 pb(-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+-->phiK+ decay are measured. We obtain BR(B(0)(s)--> phiphi)=[14(+6)(-5)(stat)+/-6(syst)] x 10(-6), BR(B+-->phiK+)=[7.6+/-1.3(stat)+/-0.6(syst)] x 10(-6), and A(CP)(B+-->phiK+)= -0.07+/-0.17(stat)+0.03 / -0.02(syst). Both decays are governed in the standard model by second order (penguin) b-->s(-)ss amplitudes.

Measurement of the forward-backward charge asymmetry of electron-positron pairs in (p)over-barp collisions at root s=1.96 TeV

Abstract: We present a measurement of the mass dependence of the forward-backward charge asymmetry (${A}_{FB}$) for ${e}^{+}{e}^{\ensuremath{-}}$ pairs produced via an intermediate $Z/{\ensuremath{\gamma}}^{*}$ with mass ${M}_{ee}g40\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/{c}^{2}$. We study the constraints on the $Z$-quark couplings imposed by our measurement. We analyze an integrated luminosity of $72\text{ }\text{ }{\mathrm{p}\mathrm{b}}^{\ensuremath{-}1}$ collected by the CDF-II detector in $\overline{p}p$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{T}\mathrm{e}\mathrm{V}$ at the Fermilab Tevatron. A comparison of the uncorrected ${A}_{FB}$ between data and standard model Monte Carlo gives good agreement with a ${\ensuremath{\chi}}^{2}/\mathrm{D}\mathrm{O}\mathrm{F}$ of 15.7/15. The couplings measurements are also consistent with standard model predictions.

Search for B0s → μ+ μ- and B0s → μ+μ- decays in p p Collisions with CDF II

Abstract: A. Abulencia, D. Acosta, J. Adelman, T. Affolder, T. Akimoto, M. G. Albrow, D. Ambrose, S. Amerio, D. Amidei, A. Anastassov, K. Anikeev, A. Annovi, J. Antos, M. Aoki, G. Apollinari, J.-F. Arguin, T. Arisawa, A. Artikov, W. Ashmanskas, A. Attal, F. Azfar, P. Azzi-Bacchetta, P. Azzurri, N. Bacchetta, H. Bachacou, W. Badgett, A. Barbaro-Galtieri, V. E. Barnes, B. A. Barnett, S. Baroiant, V. Bartsch, G. Bauer, F. Bedeschi, S. Behari, S. Belforte, G. Bellettini, J. Bellinger, A. Belloni, E. Ben-Haim, D. Benjamin, A. Beretvas, J. Beringer, T. Berry, A. Bhatti, M. Binkley, D. Bisello, M. Bishai, R. E. Blair, C. Blocker, K. Bloom, B. Blumenfeld, A. Bocci, A. Bodek, V. Boisvert, G. Bolla, A. Bolshov, D. Bortoletto, J. Boudreau, S. Bourov, A. Boveia, B. Brau, C. Bromberg, E. Brubaker, J. Budagov, H. S. Budd, S. Budd, K. Burkett, G. Busetto, P. Bussey, K. L. Byrum, S. Cabrera, M. Campanelli, M. Campbell, F. Canelli, A. Canepa, D. Carlsmith, R. Carosi, S. Carron, M. Casarsa, A. Castro, P. Catastini, D. Cauz, M. Cavalli-Sforza, A. Cerri, L. Cerrito, S. H. Chang, J. Chapman, Y. C. Chen, M. Chertok, G. Chiarelli, G. Chlachidze, F. Chlebana, I. Cho, K. Cho, D. Chokheli, J. P. Chou, P. H. Chu, S. H. Chuang, K. Chung, W. H. Chung, Y. S. Chung, M. Ciljak, C. I. Ciobanu, M. A. Ciocci, A. Clark, D. Clark, M. Coca, A. Connolly, M. E. Convery, J. Conway, B. Cooper, K. Copic, M. Cordelli, G. Cortiana, A. Cruz, J. Cuevas, R. Culbertson, D. Cyr, S. DaRonco, S. D’Auria, M. D’onofrio, D. Dagenhart, P. de Barbaro, S. De Cecco, A. Deisher, G. De Lentdecker, M. Dell’Orso, S. Demers, L. Demortier, J. Deng, M. Deninno, D. De Pedis, P. F. Derwent, C. Dionisi, J. Dittmann, P. DiTuro, C. Dörr, A. Dominguez, S. Donati, M. Donega, P. Dong, J. Donini, T. Dorigo, S. Dube, K. Ebina, J. Efron, J. Ehlers, R. Erbacher, D. Errede, S. Errede, R. Eusebi, H. C. Fang, S. Farrington, I. Fedorko, W. T. Fedorko, R. G. Feild, M. Feindt, J. P. Fernandez, R. Field, G. Flanagan, L. R. Flores-Castillo, A. Foland, S. Forrester, G. W. Foster, M. Franklin, J. C. Freeman, Y. Fujii, I. Furic, A. Gajjar, M. Gallinaro, J. Galyardt, J. E. Garcia, M. Garcia Sciverez, A. F. Garfinkel, C. Gay, H. Gerberich, E. Gerchtein, D. Gerdes, S. Giagu, P. Giannetti, A. Gibson, K. Gibson, C. Ginsburg, K. Giolo, M. Giordani, M. Giunta, G. Giurgiu, V. Glagolev, D. Glenzinski, M. Gold, N. Goldschmidt, J. Goldstein, G. Gomez, G. Gomez-Ceballos, M. Goncharov, O. González, I. Gorelov, A. T. Goshaw, Y. Gotra, K. Goulianos, A. Gresele, M. Griffiths, S. Grinstein, C. Grosso-Pilcher, U. Grundler, J. Guimaraes da Costa, C. Haber, S. R. Hahn, K. Hahn, E. Halkiadakis, A. Hamilton, B.-Y. Han, R. Handler, F. Happacher, K. Hara, M. Hare, S. Harper, R. F. Harr, R. M. Harris, K. Hatakeyama, J. Hauser, C. Hays, H. Hayward, A. Heijboer, B. Heinemann, J. Heinrich, M. Hennecke, M. Herndon, J. Heuser, D. Hidas, C. S. Hill, D. Hirschbuehl, A. Hocker, A. Holloway, S. Hou, M. Houlden, S.-C. Hsu, B. T. Huffman, R. E. Hughes, J. Huston, K. Ikado, J. Incandela, G. Introzzi, M. Iori, Y. Ishizawa, A. Ivanov, B. Iyutin, E. James, D. Jang, B. Jayatilaka, D. Jeans, H. Jensen, E. J. Jeon, M. Jones, K. K. Joo, S. Y. Jun, T. R. Junk, T. Kamon, J. Kang, M. Karagoz-Unel, P. E. Karchin, Y. Kato, Y. Kemp, R. Kephart, U. Kerzel, V. Khotilovich, B. Kilminster, D. H. Kim, H. S. Kim, J. E. Kim, M. J. Kim, M. S. Kim, S. B. Kim, S. H. Kim, Y. K. Kim, M. Kirby, L. Kirsch, S. Klimenko, M. Klute, B. Knuteson, B. R. Ko, H. Kobayashi, K. Kondo, D. J. Kong, J. Konigsberg, K. Kordas, A. Korytov, A. V. Kotwal, A. Kovalev, J. Kraus, I. Kravchenko, M. Kreps, A. Kreymer, J. Kroll, N. Krumnack, M. Kruse, V. Krutelyov, S. E. Kuhlmann, Y. Kusakabe, S. Kwang, A. T. Laasanen, S. Lai, S. Lami, S. Lami, S. Lammel, M. Lancaster, R. L. Lander, K. Lannon, A. Lath, G. Latino, I. Lazzizzera, C. Lecci, T. LeCompte, J. Lee, J. Lee, S. W. Lee, R. Lefèvre, N. Leonardo, S. Leone, S. Levy, J. D. Lewis, K. Li, C. Lin, C. S. Lin, M. Lindgren, E. Lipeles, T. M. Liss, A. Lister, D. O. Litvintsev, T. Liu, Y. Liu, N. S. Lockyer, A. Loginov, M. Loreti, P. Loverre, R.-S. Lu, D. Lucchesi, P. Lujan, P. Lukens, G. Lungu, L. Lyons, J. Lys, R. Lysak, E. Lytken, P. Mack, D. MacQueen, R. Madrak, K. Maeshima, P. Maksimovic, G. Manca, F. Margaroli, R. Marginean, C. Marino, A. Martin, M. Martin, V. Martin, M. Martı́nez, T. Maruyama, H. Matsunaga, M. E. Mattson, R. Mazini, P. Mazzanti, K. S. McFarland, D. McGivern, P. McIntyre, P. McNamara, R. McNulty, A. Mehta, S. Menzemer, A. Menzione, P. Merkel, C. Mesropian, A. Messina, M. von der Mey, T. Miao, N. Miladinovic, J. Miles, R. Miller, J. S. Miller, C. Mills, M. Milnik, R. Miquel, S. Miscetti, G. Mitselmakher, A. Miyamoto, N. Moggi, B. Mohr, R. Moore, M. Morello, P. Movilla Fernandez, J. Mülmenstädt, A. Mukherjee, M. Mulhearn, Th. Muller, R. Mumford, P. Murat, J. Nachtman, S. Nahn, I. Nakano,

Measurement of partial widths and search for direct CP violation in D 0 meson decays to K-K+ and π -π+

Abstract: We present a measurement of relative partial widths and decay rate CP asymmetries in K- K+ and π-π+ decays of D0 mesons produced in pp collisions at,√s = 1.96 TeV. We use a sample of 2 × 105 D*+ →D0π+ (and charge conjugate) decays with the D0 decaying to K-π+, K-K +, and π-π+, corresponding to 123 pb -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 γ(D0→ K- K +)/γ(D0-→K-π+) = 0.0992 ±0.0992 ±0.0012, γ(D0→K -π+)/γ(D0→K -π+) = 0.03594 ± 0.00054 ±0.00040, A CP(K- K+) = (2.0 ±1.2 ±0.6)%, and ACP(π-π+) = (1.0 ±1.3 ±0.6)%, where, in all cases, the first uncertainty is statistical and the second is systematic. © 2005 The American Physical Society.

KS0 and Λ0 production studies in pp̄ collisions at s=1800 and 630 GeV

Abstract: We present a study of the production of K{sub S}{sup 0} and {lambda}{sup 0} in inelastic pp collisions at {radical}(s)=1800 and 630 GeV using data collected by the CDF experiment at the Fermilab Tevatron. Analyses of K{sub S}{sup 0} and {lambda}{sup 0} multiplicity and transverse momentum distributions, as well as of the dependencies of the average number and of K{sub S}{sup 0} and {lambda}{sup 0} on charged particle multiplicity, are reported. Systematic comparisons are performed for the full sample of inelastic collisions, and for the low and high momentum transfer subsamples, at the two energies. The p{sub T} distributions extend above 8 GeV/c, showing a higher than previous measurements. The dependence of the mean K{sub S}{sup 0}({lambda}{sup 0}) p{sub T} on the charged particle multiplicity for the three samples shows a behavior analogous to that of charged primary tracks.

Search for B-s(0)->mu(+)mu(-) and B-s(0)->mu(+)mu(-) decays in p(p)over-bar collisions with CDF II

Abstract: We report on a search for B⁰s → μ+ μ- and B⁰d → mu+mu- decays in p anti-p collisions at √s = 1.96 TeV using 364.4 pb -1 of data collected by the CDF II dectector at Fermilab Tevatron Collider. After applying all selection requirements, we observe no candidates inside the B⁰s or B⁰d mass windows. The resulting upper limits on the branching fractions are β(B⁰s → μ+μ-) < 1.5 x 10-7 and β(B⁰d → μ+μ-) < 3.9 x 10-8 at 90 % confidence level. (auth)

Measurements of bottom-antibottom azimuthal production correlations in proton-antiproton collisions at s=1.8TeV

Abstract: The authors have measured the azimuthal angular correlation of b{bar b} production, using 86.5 pb{sup -1} of data collected by Collider Detector at Fermilab (CDF) in p{bar p} collisions at {radical}s = 1.8 TeV during 1994-1995. In high-energy p{bar p} collisions, such as at the Tevatron, b{bar b} production can be schematically categorized into three mechanisms. The leading-order (LO) process is ''flavor creation'', where both b and {bar b} quarks substantially participate in the hard scattering and result in a distinct back-to-back signal in final state. The ''flavor excitation'' and the ''gluon splitting'' processes, which appear at next-leading-order (NLO), are known to make a comparable contribution to total b{bar b} cross section, while providing very different opening angle distributions from the LO process. An azimuthal opening angle between bottom and anti-bottom, {Delta}{phi}, has been used for the correlation measurement to probe the interaction creating b{bar b} pairs. The {Delta}{phi} distribution has been obtained from two different methods. one method measures the {Delta}{phi} between bottom hadrons using events with two reconstructed secondary vertex tags. The other method uses b{bar b} {yields} (J/{psi}X)({ell}X') events, where the charged lepton ({ell}) is an electron (e) or a muon ({mu}), to measure {Delta}{phi} between bottommore » quarks. The b{bar b} purity is determined as a function of {Delta}{phi} by fitting the decay length of the J/{psi} and the impact parameter of the {ell}. Both methods quantify the contribution from higher-order production mechanisms by the fraction of the b{bar b} pairs produced in the same azimuthal hemisphere, f{sub toward}. The measured f{sub toward} values are consistent with both parton shower Monte Carlo and NLO QCD predictions.« less

Search for excited and exotic electrons in the eγ decay channel in pp̄ collisions at √s= 1.96 TeV

Abstract: 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(-1) of data collected in pp collisions at sqrt[s] = 1.96 TeV with the Collider Detector at Fermilab 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(e(*)) and the compositeness energy scale Lambda. In the contact interaction model, we exclude 132 GeV/c(2)

Search for first-generation scalar leptoquarks in ( pp̅ collisions at√ s = 1.96 TeV

Abstract: We report on a search for pair production of first-generation scalar leptoquarks (LQ) in p (p) over bar collisions at root s=1.96 TeV using an integrated luminosity of 252 pb(-1) collected at the Fermilab Tevatron collider by the D0 detector. We observe no evidence for LQ production in the topologies arising from LQ(LQ) over bar -> eqeq and LQ(LQ) over bar -> eq nu q, and derive 95% C.L. lower limits on the LQ mass as a function of beta, where beta is the branching fraction for LQ -> eq. The limits are 241 and 218 GeV/c(2) for beta=1 and 0.5, respectively. These results are combined with those obtained by D0 at root s=1.8 TeV, which increases these LQ mass limits to 256 and 234 GeV/c(2).

Search for anomalous production of diphoton events with missing transverse energy at CDF and limits on gauge-mediated supersymmetry-breaking models

Abstract: We present the results of a search for anomalous production of diphoton events with large missing transverse energy using the Collider Detector at Fermilab. In 202 pb(-1) of p (p) over bar collisions at s=1.96 TeV we observe no candidate events, with an expected standard model background of 0.27+/-0.07(stat)+/-0.10(syst) events. The results exclude a lightest chargino of mass less than 167 GeV/c(2), and lightest neutralino of mass less than 93 GeV/c(2) at 95% C.L. in a gauge-mediated supersymmetry-breaking model with a light gravitino.

Search forBs0→μ+μ−andBd0→μ+μ−Decays inpp¯Collisions with CDF II

Abstract: We report on a search for ${B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${B}_{d}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ decays in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ using $364\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected by the CDF II detector at the Fermilab Tevatron Collider. After applying all selection requirements, we observe no candidates inside the ${B}_{s}^{0}$ or ${B}_{d}^{0}$ mass windows. The resulting upper limits on the branching fractions are $\mathcal{B}({B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})l1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ and $\mathcal{B}({B}_{d}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})l3.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ at 90% confidence level.

Measurement of the W boson polarization in top decay at CDF at √s = 1.8 TeV

Abstract: The polarization of the W boson in t{yields}Wb decay is unambiguously predicted by the standard model of electroweak interactions and is a powerful test of our understanding of the tbW vertex. We measure this polarization from the invariant mass of the b quark from t{yields}Wb and the lepton from W{yields}l{nu} whose momenta measure the W decay angle and direction of motion, respectively. In this paper we present a measurement of the decay rate (f{sub V+A}) of the W produced from the decay of the top quark in the hypothesis of V+A structure of the tWb vertex. We find no evidence for the nonstandard V+A vertex and set a limit on f{sub V+A} < 0.80 at 95% confidence level. By combining this result with a complementary observable in the same data, we assign a limit on f{sub V+A} < 0.61 at 95% CL. This corresponds to a constraint on the right-handed helicity component of the W polarization of f{sub +}<0.18 at 95% CL. This limit is the first significant direct constraint on f{sub V+A} in top decay.

Measurement of Wγ and Zγ production in pp̄ collisions at √s = 1.96 TeV

Abstract: The standard model predictions for W γ and Z γ production are tested using an integrated luminosity of 200 pb -1 of pp 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 T > 7 GeV that are well separated from leptons. The production cross sections and kinematic distributions for the W γ and Z γ data are compared to SM predictions. © 2005 The American Physical Society.

Measurement of the W(+)W(-) production cross section in p(p)over-bar collisions at root s=1.96 TeV using dilepton events

Abstract: We present a measurement of the W{sup +}W{sup -} production cross section using 184 pb{sup -1} of pp collisions at a center-of-mass energy of 1.96 TeV collected with the Collider Detector at Fermilab. Using the dilepton decay channel W{sup +}W{sup -}{yields}l{sup +}{nu}l{sup -}{nu}, where the charged leptons can be either electrons or muons, we find 17 candidate events compared to an expected background of 5.0{sub -0.8}{sup +2.2} events. The resulting W{sup +}W{sup -} production cross-section measurement of {sigma}(pp{yields}W{sup +}W{sup -})=14.6{sub -5.1}{sup +5.8}(stat){sub -3.0}{sup +1.8}(syst){+-}0.9(= lum) pb agrees well with the standard model expectation.

Search for supersymmetric Higgs bosons in the di-tau decay mode in p(p)over-barcollisions at root s=1.8 TeV

Abstract: A search for the direct production of Higgs bosons in the di-tau decay mode is performed with 86.3 +/- 3.5 pb(-1) of data collected with the Collider Detector at Fermilab during the 1994-1995 data taking period of the Tevatron. We search for events where one tau decays to an electron plus neutrinos and the other tau decays hadronically. We perform a counting experiment and set limits on the cross section for supersymmetric Higgs boson production where tan beta is large and m(A) is small. For a benchmark parameter space point where m(A)(0)=100 GeV/c(2) and tan beta=50, we limit the production cross section multiplied by the branching ratio to be less than 77.9 pb at the 95% confidence level compared to the theoretically predicted value of 11.0 pb. This is the first search for Higgs bosons decaying to tau pairs at a hadron collider.

Measurement of charged-particle multiplicities in gluon and quark jets in p(p)over-bar collisions at root s=1.8 TeV

Abstract: We report the first largely model independent measurement of charged particle multiplicities in quark and gluon jets, N-q and N-g, produced at the Fermilab Tevatron in p (p) over bar collisions with a center-of-mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The measurements are made for jets with average energies of 41 and 53 GeV by counting charged particle tracks in cones with opening angles of theta(c)=0.28, 0.36, and 0.47 rad around the jet axis. The corresponding jet hardness Q=E-jet theta(c) varies in the range from 12 to 25 GeV. At Q=19.2 GeV, the ratio of multiplicities r=N-g/N-q is found to be 1.64 +/- 0.17, where statistical and systematic uncertainties are added in quadrature. The results are in agreement with resummed perturbative QCD calculations.

Search for anomalous kinematics in tt dilepton events at CDF II

Abstract: We report on a search for anomalous kinematics of t (t) over bar dilepton events in p (p) over bar collisions at root s = 1: 96 TeV using 193 pb(-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%.

Measurement ofWγandZγProduction inpp¯Collisions ats=1.96TeV

Abstract: The standard model predictions for $W\ensuremath{\gamma}$ and $Z\ensuremath{\gamma}$ production are tested using an integrated luminosity of $200\text{ }{\mathrm{p}\mathrm{b}}^{\ensuremath{-}1}$ of $p\overline{p}$ 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 ${E}_{T}g7\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}$ that are well separated from leptons. The production cross sections and kinematic distributions for the $W\ensuremath{\gamma}$ and $Z\ensuremath{\gamma}$ data are compared to SM predictions.

Search for Higgs bosons decaying into bb(-) and produced in association with a Vector boson in pp- collisions at root s=1.8 TeV

Abstract: We present a new search for H0V production, where H0 is a scalar Higgs boson decaying into bb with branching ratio beta, and V is a Z0 boson decaying into e+e-, mu+mu-, or nunu. This search is then combined with previous searches for H0V where V is a W+/- boson or a hadronically decaying Z0. The data sample consists of 106 +/- 4 pb(-1) of pp collisions at square root of s = 1.8 TeV accumulated by the Collider Detector at Fermilab. Observing no evidence of a signal, we set 95% Bayesian credibility level upper limits on sigma(pp --> H0V) x beta. For H0 masses of 90, 110, and 130 GeV/c2, the limits are 7.8, 7.2, and 6.6 pb, respectively.

Search for scalar leptoquark pairs decaying to νν̄qq̄ in pp̄ collisions at s=1.96TeV

Abstract: We report on a search for the pair production of scalar leptoquarks (LQ), using $191\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ 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 LQ production is observed, and limits are set on $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}\mathrm{LQ}\overline{\mathrm{LQ}}X\ensuremath{\rightarrow}\ensuremath{ u}\overline{\ensuremath{ u}}q\overline{q}X)$. Using a next-to-leading order theoretical prediction of the cross section for LQ production, we exclude first-generation LQ in the mass interval 78 to $117\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ at the 95% confidence level for $BR(\mathrm{LQ}\ensuremath{\rightarrow}\ensuremath{ u}q)=100%$.

Acceptance tests and criteria of the ATLAS transition radiation tracker

Abstract: The Transition Radiation Tracker (TRT) sits at the outermost part of the ATLAS Inner Detector, encasing the Pixel Detector and the Semi-Conductor Tracker (SCT). The TRT combines charged particle track reconstruction with electron identification capability. This is achieved by layers of xenon-filled straw tubes with periodic radiator foils or fibers providing TR photon emission. The design and choice of materials have been optimized to cope with the harsh operating conditions at the LHC, which are expected to lead to an accumulated radiation dose of 10 Mrad and a neutron fluence of up to 2middot1014 n/cm2 after ten years of operation. The TRT comprises a barrel containing 52 000 axial straws and two end-cap parts with 320 000 radial straws. The total of 420 000 electronic channels (two channels per barrel straw) allows continuous tracking with many projective measurements (more than 30 straw hits per track). The assembly of the barrel modules in the US has recently been completed, while the end-cap wheel construction in Russia has reached the 50% mark. After testing at the production sites and shipment to CERN, all modules and wheels undergo a series of quality and conformity measurements. These acceptance tests survey dimensions, wire tension, gas-tightness, high-voltage stability and gas-gain uniformity along each individual straw. This paper gives details on the acceptance criteria and measurement methods. An overview of the most important results obtained to-date is also given

Aging effects in the ATLAS transition radiation tracker and gas filtration studies

Abstract: The transition radiation tracker (TRT) is one of three particle tracking detectors now under construction for the ATLAS experiment, whose goal is to exploit the highly exciting new physics potential at CERN's next accelerator, the so called Large Hadron Collider (LHC) The TRT consists of 370000 straw proportional tubes of 4 mm diameter with a 30 micron thick anode wire, which will be operated with a Xe/CO2 /O2 gas mixture at a high voltage of approximately 15 kV While the construction of the TRT is now well under way, a number of interesting and challenging questions need to be solved with regard to wire aging phenomena, which are induced by pollution originating from very small amounts of silicon-based vacuum materials in some components of the gas system Finally a guideline to avoid aging in wire chamber detectors in high luminosity experiments is given