513 results on '"Tung, W."'
Search Results
2. Proceedings of the workshop: HERA and the LHC workshop series on the implications of HERA for LHC physics
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Jung, H., De Roeck, A., Ajaltouni, Z. J., Albino, S., Altarelli, G., Ambroglini, F., Anderson, J., Antchev, G., Arneodo, M., Aspell, P., Avati, V., Bahr, M., Bacchetta, A., Bagliesi, M. G., Ball, R. D., Banfi, A., Baranov, S., Bartalini, P., Bartels, J., Bechtel, F., Berardi, V., Berretti, M., Beuf, G., Biasini, M., Bierenbaum, I., Blumlein, J., Blair, R. E., Bombonati, C., Boonekamp, M., Bottigli, U., Boutle, S., Bozzo, M., Brucken, E., Bracinik, J., Bruni, A., Bruno, G. E., Buckley, A., Bunyatyan, A., Burkhardt, H., Bussey, P., Buzzo, A., Cacciari, M., Cafagna, F., Calicchio, M., Caola, F., Catanesi, M. G., Catastini, P. L., Cecchi, R., Ceccopieri, F. A., Cerci, S., Chekanov, S., Chierici, R., Ciafaloni, M., Ciocci, M. A., Coco, V., Colferai, D., Cooper-Sarkar, A., Corcella, G., Czakon, M., Dainese, A., Dasgupta, M., Deak, M., Deile, M., Delsart, P. A., Del Debbio, L., de Roeck, A., Diaconu, C., Diehl, M., Dimovasili, E., Dittmar, M., Dremin, I. M., Eggert, K., Engel, R., Eremin, V., Erhan, S., Ewerz, C., Fano, L., Feltesse, J., Ferrera, G., Ferro, F., Field, R., Forte, S., Garcia, F., Geiser, A., Gelis, F., Giani, S., Gieseke, S., Gigg, M. A., Glazov, A., Golec-Biernat, K., Goulianos, K., Grebenyuk, J., Greco, V., Grellscheid, D., Grindhammer, G., Grothe, M., Guffanti, A., Gwenlan, C., Halyo, V., Hamilton, K., Hautmann, F., Heino, J., Heinrich, G., Hilden, T., Hiller, K., Hollar, J., Janssen, X., Joseph, S., Jung, A. W., Juranek, V., Kaspar, J., Kepka, O., Khoze, V. A., Kiesling, Ch., Klasen, M., Klein, S., Kniehl, B. A., Knutsson, A., Kopal, J., Kramer, G., Krauss, F., Kundrat, V., Kurvinen, K., Kutak, K., Lonnblad, L., Lami, S., Latino, G., Latorre, J. I., Latunde-Dada, O., Lauhakangas, R., Lendermann, V., Lenzi, P., Li, G., Likhoded, A., Lipatov, A., Lippmaa, E., Lokajicek, M., Vetere, M. Lo, Rodriguez, F. Lucas, Luisoni, G., Lytken, E., Muller, K., Macri, M., Magazzu, G., Majhi, A., Majhi, S., Marage, P., Marti, L., Martin, A. D., Meucci, M., Milstead, D. A., Minutoli, S., Nischke, A., Moares, A., Moch, S., Motyka, L., Namsoo, T., Newman, P., Niewiadomski, H., Nockles, C., Noschis, E., Notarnicola, G., Nystrand, J., Oliveri, E., Oljemark, F., Osterberg, K., Orava, R., Oriunno, M., Osman, S., Ostapchenko, S., Palazzi, P., Pedreschi, E., Pereira, A. V., Perrey, H., Petajajarvi, J., Petersen, T., Piccione, A., Pierog, T., Pinfold, J. L., Piskounova, O. I., Platzer, S., Quinto, M., Rurikova, Z., Radermacher, E., Radescu, V., Radicioni, E., Ravotti, F., Rella, G., Richardson, P., Robutti, E., Rodrigo, G., Rodrigues, E., Rogal, M., Rogers, T. C., Rojo, J., Roloff, P., Ropelewski, L., Rosemann, C., Royon, Ch., Ruggiero, G., Rummel, A., Ruspa, M., Ryskin, M. G., Salek, D., Slominski, W., Saarikko, H., Vera, A. Sabio, Sako, T., Salam, G. P., Saleev, V. A., Sander, C., Sanguinetti, G., Santroni, A., Schorner-Sadenius, Th., Schicker, R., Schienbein, I., Schmidke, W. B., Schwennsen, F., Scribano, A., Sette, G., Seymour, M. H., Sherstnev, A., Sjostrand, T., Snoeys, W., Somogyi, G., Sonnenschein, L., Soyez, G., Spiesberger, H., Spinella, F., Squillacioti, P., Stasto, A. M., Starodumov, A., Stenzel, H., Stephens, Ph., Ster, A., Stocco, D., Strikman, M., Taylor, C., Teubner, T., Thorne, R. S., Trocsanyi, Z., Treccani, M., Treleani, D., Trentadue, L., Trummal, A., Tully, J., Tung, W. K., Turcato, M., Turini, N., Ubiali, M., Valkarova, A., van Hameren, A., Van Mechelen, P., Vermaseren, J. A. M., Vogt, A., Ward, B. F. L., Watt, G., Webber, B. R., Weiss, Ch., White, Ch., Whitmore, J., Wolf, R., Wu, J., Yagues-Molina, A., Yost, S. A., Zanderighi, G., Zotov, N., and Nedden, M. zur
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High Energy Physics - Phenomenology - Abstract
2nd workshop on the implications of HERA for LHC physics. Working groups: Parton Density Functions Multi-jet final states and energy flows Heavy quarks (charm and beauty) Diffraction Cosmic Rays Monte Carlos and Tools, Comment: 2nd workshop on the implications of HERA for LHC physics 2006 - 2008, Hamburg - Geneva. H. Jung and A. De Roeck Editors
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- 2009
3. 557 Adherence and Factors Related to Completion of SRS22 PROM Scores in Patients Undergoing Surgical Correction for Adolescent Idiopathic Scoliosis
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Bellamy, M, primary, Tung, W S, additional, Courtney, E, additional, Jayasuriya, R, additional, Cole, A, additional, and Bayley, E, additional
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- 2023
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4. Household food waste behaviour in Sarawak, Malaysia: a hierarchical regression analysis
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Rahman, M., primary and Liang Tung, W., additional
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- 2023
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5. PQCD Formulations with Heavy Quark Masses and Global Analysis
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Thorne, R. S. and Tung, W. K.
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High Energy Physics - Phenomenology - Abstract
We critically review heavy quark mass effects in DIS and their impact on global analyses. We lay out all elements of a properly defined general mass variable flavor number scheme (GM VFNS) that are shared by all modern formulations of the problem. We then explain the freedom in choosing specific implementations and spell out, in particular, the current formulations of the CTEQ and MSTW groups. We clarify the approximations in the still widely-used zero mass variable flavor scheme (ZM VFNS), mention the inherent flaws in its conventional implementation, and consider the possibility of mending some of these flaws. We discuss practical issues concerning the use of parton distributions in various physical applications, in view of the different schemes. And we comment on the possible presence of intrinsic heavy flavors., Comment: Contribution to the HERA - LHC Workshop Proceedings. 19 pages, 2 figures in the form of .eps files. Slightly modified, responding to comments and suggestions following submission of initial version
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- 2008
6. Implications of CTEQ global analysis for collider observables
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Nadolsky, P. M., Lai, H. -L., Cao, Q. -H., Huston, J., Pumplin, J., Stump, D., Tung, W. -K., and Yuan, C. -P.
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High Energy Physics - Phenomenology - Abstract
The latest CTEQ6.6 parton distributions, obtained by global analysis of hard scattering data in the framework of general-mass perturbative QCD, are employed to study theoretical predictions and their uncertainties for significant processes at the Fermilab Tevatron and CERN Large Hadron Collider. The previously observed increase in predicted cross sections for the standard-candle W and Z boson production processes in the general-mass scheme (compared to those in the zero-mass scheme) is further investigated and quantified. A novel method to constrain PDF uncertainties in LHC observables, by effectively exploiting PDF-induced correlations with benchmark standard model cross sections, is presented. Using this method, we show that the top-antitop pair cross section can potentially serve as a standard candle observable for the LHC processes dominated by initial-state gluon scattering. Among other benefits, precise measurements of $t\bar{t}$ cross sections would reduce PDF uncertainties in predictions for single-top quark and Higgs boson production in the standard model and minimal supersymmetric standard model., Comment: 32 pages, 15 figures; figures with embedded fonts available at http://hep.pa.msu.edu/cteq/public/6.6/pdfs/; extended discussion of small-x strangeness, added references, minor changes in Figs. 2-4 in the revised version
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- 2008
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7. The Strange Parton Distribution of the Nucleon: Global Analysis and Applications
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Lai, H. L., Nadolsky, P., Pumplin, J., Stump, D., Tung, W. K., and Yuan, C. -P.
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High Energy Physics - Phenomenology - Abstract
The strangeness degrees of freedom in the parton structure of the nucleon are explored in the global analysis framework, using the new CTEQ6.5 implementation of the general mass perturbative QCD formalism of Collins. We systematically determine the constraining power of available hard scattering experimental data on the magnitude and shape of the strange quark and anti-quark parton distributions. We find that current data favor a distinct shape of the strange sea compared to the isoscalar non-strange sea. A new reference parton distribution set, CTEQ6.5S0, and representative sets spanning the allowed ranges of magnitude and shape of the strange distributions, are presented. Some applications to physical processes of current interest in hadron collider phenomenology are discussed., Comment: 19 pages; revised version submitted to JHEP
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- 2007
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8. The Charm Parton Content of the Nucleon
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Pumplin, J., Lai, H. L., and Tung, W. K.
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High Energy Physics - Phenomenology - Abstract
We investigate the charm sector of the nucleon structure phenomenologically, using the most up-to-date global QCD analysis. Going beyond the common assumption of purely radiatively generated charm, we explore possible degrees of freedom in the parton parameter space associated with nonperturbative (intrinsic) charm in the nucleon. Specifically, we explore the limits that can be placed on the intrinsic charm (IC) component, using all relevant hard-scattering data, according to scenarios in which the IC has a form predicted by light-cone wave function models; or a form similar to the light sea-quark distributions. We find that the range of IC is constrained to be from zero (no IC) to a level 2--3 times larger than previous model estimates. The behaviors of typical charm distributions within this range are described, and their implications for hadron collider phenomenology are briefly discussed., Comment: 15 pages, LaTeX
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- 2007
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9. Heavy Quark Mass Effects in Deep Inelastic Scattering and Global QCD Analysis
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Tung, W. K., Lai, H. L., Belyaev, A., Pumplin, J., Stump, D., and Yuan, C. -P.
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High Energy Physics - Phenomenology - Abstract
A new implementation of the general PQCD formalism of Collins, including heavy quark mass effects, is described. Important features that contribute to the accuracy and efficiency of the calculation of both neutral current (NC) and charged current (CC) processess are explicitly discussed. This new implementation is applied to the global analysis of the full HERA I data sets on NC and CC cross sections, with correlated systematic errors, in conjunction with the usual fixed-target and hadron collider data sets. By using a variety of parametrizations to explore the parton parameter space, robust new parton distribution function (PDF) sets (CTEQ6.5) are obtained. The new quark distributions are consistently higher in the region x ~ 10^{-3} than previous ones, with important implications on hadron collider phenomenology, especially at the LHC. The uncertainties of the parton distributions are reassessed and are compared to the previous ones. A new set of CTEQ6.5 eigenvector PDFs that encapsulates these uncertainties is also presented., Comment: 32 pages, 12 figures; updated, Publication Version
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- 2006
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10. Tevatron-for-LHC Report of the QCD Working Group
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TeV4LHC QCD Working Group, Albrow, M., Begel, M., Bourilkov, D., Campanelli, M., Chlebana, F., De Roeck, A., Dittmann, J. R., Ellis, S. D., Field, B., Field, R., Gallinaro, M., Giele, W., Goulianos, K., Group, R. C., Hatakeyama, K., Hubacek, Z., Huston, J., Kilgore, W., Kluge, T., Lee, S. W., Moraes, A., Mrenna, S., Olness, F., Proudfoot, J., Rabbertz, K., Royon, C., Sjostrand, T., Skands, P., Smith, J., Tung, W. K., Whalley, M. R., Wobisch, M., and Zielinski, M.
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High Energy Physics - Phenomenology - Abstract
The experiments at Run 2 of the Tevatron have each accumulated over 1 inverse femtobarn of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focussed on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop., Comment: 156 pages, Tevatron-for-LHC Conference Report of the QCD Working Group
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- 2006
11. Parton Distributions and the Strong Coupling Strength: CTEQ6AB PDFs
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Pumplin, J., Belyaev, A., Huston, J., Stump, D., and Tung, W. K.
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High Energy Physics - Phenomenology - Abstract
We study the global analysis for parton distributions as a function of the QCD strong coupling strength alpha_s, and present a new series of distributions that span the range 0.110 < alpha_s(m_Z) < 0.128. We use these distributions to explore the correlation between alpha_s and the gluon distribution; the viability of global analysis as a method to measure alpha_s; and the dependence on alpha_s of predictions for W, Z, inclusive jet, and Higgs boson production ($b \bar{b} \to H$ and $gg \to H$) cross sections at the Tevatron and the LHC. We find that the uncertainty in alpha_s is the dominant source of uncertainty for inclusive jet production at moderately small p_T and for Higgs production at intermediate masses in the standard model., Comment: 15 pages, 11 figures, revisions and change in title based on JHEP referee's suggestions; reference added
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- 2005
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12. Stability of NLO Global Analysis and Implications for Hadron Collider Physics
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Huston, J., Pumplin, J., Stump, D., and Tung, W. K.
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High Energy Physics - Phenomenology - Abstract
The phenomenology of Standard Model and New Physics at hadron colliders depends critically on results from global QCD analysis for parton distribution functions (PDFs). The accuracy of the standard next-to-leading-order (NLO) global analysis, nominally a few percent, is generally well matched to the expected experimental precision. However, serious questions have been raised recently about the stability of the NLO analysis with respect to certain inputs, including the choice of kinematic cuts on the data sets and the parametrization of the gluon distribution. In this paper, we investigate this stability issue systematically within the CTEQ framework. We find that both the PDFs and their physical predictions are stable, well within the few percent level. Further, we have applied the Lagrange Multiplier method to explore the stability of the predicted cross sections for W production at the Tevatron and the LHC, since W production is often proposed as a standard candle for these colliders. We find the NLO predictions on sigma_W to be stable well within their previously-estimated uncertainty ranges., Comment: 24 pages, 11 figures. Minor changes in response to JHEP referee report
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- 2005
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13. The Parton Structure of the Nucleon and Precision Determination of the Weinberg Angle in Neutrino Scattering
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Kretzer, S., Olness, F., Pumplin, J., Reno, M. H., Stump, D., and Tung, W. K.
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High Energy Physics - Phenomenology - Abstract
A recently completed next-to-leading-order program to calculate neutrino cross sections, including power-suppressed mass correction terms, has been applied to evaluate the Paschos-Wolfenstein relation, in order to quantitatively assess the validity and significance of the NuTeV anomaly. In particular, we study the shift of $\sin^2 \theta_{\mathrm{W}}$ obtained in calculations with a new generation of PDF sets that allow $s(x)\neq \bar{s}(x)$, enabled by recent neutrino dimuon data from CCFR and NuTeV, as compared to the previous $s = \bar{s}$ parton distribution functions like CTEQ6M. The extracted value of $\sin^2 \theta_{\mathrm{W}}$ is closely correlated with the strangeness asymmetry momentum integral $\int_{0}^{1}x[s(x)-\bar{s}(x)] dx$. We also consider isospin violating effects that have recently been explored by the MRST group. The results of our study suggest that the new dimuon data, the Weinberg angle measurement, and other data sets used in global QCD parton structure analysis can all be consistent within the Standard Model., Comment: 4 pages
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- 2003
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14. Neutrino Dimuon Production and the Strangeness Asymmetry of the Nucleon
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Olness, F., Pumplin, J., Stump, D., Huston, J., Nadolsky, P., Lai, H. L., Kretzer, S., Owens, J. F., and Tung, W. K.
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High Energy Physics - Phenomenology - Abstract
We have performed the first global QCD analysis to include the CCFR and NuTeV dimuon data, which provide direct constraints on the strange and anti-strange parton distributions, $s(x)$ and $\bar{s}(x)$. To explore the strangeness sector, we adopt a general parametrization of the non-perturbative $s(x), \bar{s}(x)$ functions satisfying basic QCD requirements. We find that the strangeness asymmetry, as represented by the momentum integral $[S^{-}]\equiv \int_0^1 x [s(x)-\bar{s}(x)] dx$, is sensitive to the dimuon data provided the theoretical QCD constraints are enforced. We use the Lagrange Multiplier method to probe the quality of the global fit as a function of $[S^-]$ and find $-0.001 < [S^-] < 0.004$. Representative parton distribution sets spanning this range are given. Comparisons with previous work are made., Comment: 23 pages, 4 figures; expanded version for publication
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- 2003
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15. CTEQ6 Parton Distributions with Heavy Quark Mass Effects
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Kretzer, S., Lai, H. L., Olness, F. I., and Tung, W. -K.
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High Energy Physics - Phenomenology - Abstract
Previously published CTEQ6 parton distributions adopt the conventional zero-mass parton scheme; these sets are most appropriate for use with massless hard-scattering matrix elements commonly found in most physics applications. For precision observables which are sensitive to charm and bottom quark mass effects, we provide in this paper an additional CTEQ6HQ parton distribution set determined in the more general variable flavor number scheme which incorporates heavy flavor mass effects. The results are obtained by combining these parton distributions with consistently matched DIS structure functions computed in the same scheme. We describe the analysis procedure, examine the predominant features of the new distributions, and compare with previous distributions., Comment: 17 pages, 8 figures
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- 2003
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16. New Generation of Parton Distributions with Uncertainties from Global QCD Analysis
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Pumplin, J., Stump, D. R., Huston, J., Lai, H. L., Nadolsky, P., and Tung, W. K.
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High Energy Physics - Phenomenology ,High Energy Physics - Experiment - Abstract
A new generation of parton distribution functions with increased precision and quantitative estimates of uncertainties is presented. This work significantly extends previous CTEQ and other global analyses on two fronts: (i) a full treatment of available experimental correlated systematic errors for both new and old data sets; (ii) a systematic and pragmatic treatment of uncertainties of the parton distributions and their physical predictions, using a recently developed eigenvector-basis approach to the Hessian method. The new gluon distribution is considerably harder than that of previous standard fits. A number of physics issues, particularly relating to the behavior of the gluon distribution, are addressed in more quantitative terms than before. Extensive results on the uncertainties of parton distributions at various scales, and on parton luminosity functions at the Tevatron RunII and the LHC, are presented. The latter provide the means to quickly estimate the uncertainties of a wide range of physical processes at these high-energy hadron colliders, based on current knowledge of the parton distributions. In particular, the uncertainties on the production cross sections of the $W,Z$ at the Tevatron and the LHC are estimated to be $\pm 4%$ and $\pm 5%$ respectively, and that of a light Higgs at the LHC to be $\pm 5%$., Comment: 44 pages, 25 figures; misprints in tables in Appendix A corrected
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- 2002
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17. Summary: Working Group on QCD and Strong Interactions
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Berger, E. L., Magill, Stephen, Sarcevic, I., Jalilian-Marian, J., Kilgore, W. B., Kulesza, Anna, Vogelsang, W., Harlander, R. V., Kinney, E., Ball, R., Flaugher, B., Giele, W., Mackenzie, P., Sullivan, Z., Balazs, C., Reina, L., Tung, W. -K., Kidonakis, N., Nadolsky, P., Olness, F., Sterman, G., and Ellis, S. D.
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High Energy Physics - Phenomenology - Abstract
In this summary of the considerations of the QCD working group at Snowmass 2001, the roles of quantum chromodynamics in the Standard Model and in the search for new physics are reviewed, with empahsis on frontier areas in the field. We discuss the importance of, and prospects for, precision QCD in perturbative and lattice calculations. We describe new ideas in the analysis of parton distribution functions and jet structure, and review progress in small-$x$ and in polarization., Comment: Snowmass 2001. Revtex4, 34 pages, 4 figures, revised to include additional references on jets and lattice QCD
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- 2002
18. Uncertainties of Predictions from Parton Distribution Functions I: the Lagrange Multiplier Method
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Stump, D., Pumplin, J., Brock, R., Casey, D., Huston, J., Kalk, J., Lai, H. L., and Tung, W. K.
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High Energy Physics - Phenomenology - Abstract
We apply the Lagrange Multiplier method to study the uncertainties of physical predictions due to the uncertainties of parton distribution functions (PDFs), using the cross section for W production at a hadron collider as an archetypal example. An effective chi-squared function based on the CTEQ global QCD analysis is used to generate a series of PDFs, each of which represents the best fit to the global data for some specified value of the cross section. By analyzing the likelihood of these "alterative hypotheses", using available information on errors from the individual experiments, we estimate that the fractional uncertainty of the cross section due to current experimental input to the PDF analysis is approximately 4% at the Tevatron, and 8-10% at the LHC. We give sets of PDFs corresponding to these up and down variations of the cross section. We also present similar results on Z production at the colliders. Our method can be applied to any combination of physical variables in precision QCD phenomenology, and it can be used to generate benchmarks for testing the accuracy of approximate methods based on the error matrix., Comment: 36 pages, 12 figures, LaTeX; CERN preprint number added. Tables in Appendix C have been corrected; the calculation of W production at the LHC has been replaced by one with fixed normalization factors
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- 2001
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19. Uncertainties of predictions from parton distribution functions II: the Hessian method
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Pumplin, J., Stump, D., Brock, R., Casey, D., Huston, J., Kalk, J., Lai, H. L., and Tung, W. K.
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High Energy Physics - Phenomenology - Abstract
We develop a general method to quantify the uncertainties of parton distribution functions and their physical predictions, with emphasis on incorporating all relevant experimental constraints. The method uses the Hessian formalism to study an effective chi-squared function that quantifies the fit between theory and experiment. Key ingredients are a recently developed iterative procedure to calculate the Hessian matrix in the difficult global analysis environment, and the use of parameters defined as components along appropriately normalized eigenvectors. The result is a set of 2d Eigenvector Basis parton distributions (where d=16 is the number of parton parameters) from which the uncertainty on any physical quantity due to the uncertainty in parton distributions can be calculated. We illustrate the method by applying it to calculate uncertainties of gluon and quark distribution functions, W boson rapidity distributions, and the correlation between W and Z production cross sections., Comment: 30 pages, Latex. Reference added. Normalization of Hessian matrix changed to HEP standard
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- 2001
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20. Multivariate Fitting and the Error Matrix in Global Analysis of Data
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Pumplin, J., Stump, D. R., and Tung, W. K.
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High Energy Physics - Phenomenology - Abstract
When a large body of data from diverse experiments is analyzed using a theoretical model with many parameters, the standard error matrix method and the general tools for evaluating errors may become inadequate. We present an iterative method that significantly improves the reliability of the error matrix calculation. To obtain even better estimates of the uncertainties on predictions of physical observables, we also present a Lagrange multiplier method that explores the entire parameter space and avoids the linear approximations assumed in conventional error propagation calculations. These methods are illustrated by an example from the global analysis of parton distribution functions., Comment: 13 pages, 5 figures, Latex; minor clarifications, fortran program made available; Normalization of Hessian matrix changed to HEP standard
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- 2000
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21. Large-x Parton Distributions
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Kuhlmann, S., Huston, J., Morfin, J., Olness, F., Pumplin, J., Owens, J. F., Tung, W. K., and Whitmore, J. J.
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High Energy Physics - Phenomenology - Abstract
Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x>0.1. We examine the status of the gluon and quark distributions in light of new questions that have been raised in the past two years about "large-x" parton distributions, as well as recent measurements which have improved the parton uncertainties. Finally, we provide a status report of the data used in the global analysis, and note some of the open issues where future experiments, including those planned for Jefferson Labs, might contribute., Comment: LaTeX, 9 pages, 7 figures. Invited talk presented at the ``Workshop on Nucleon Structure in the High x-Bjorken Region (HiX2000),'' Temple University, Philadelphia, Pennsylvania, March 30-April 1, 2000
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- 2000
22. Parton Densitites at High-x
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Kuhlmann, S., Huston, J., Morfin, J., Olness, F., Pumplin, J., Owens, J. F., Tung, W. K., and Whitmore, J. J.
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High Energy Physics - Phenomenology - Abstract
Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x>0.1. We examine the status of the distributions in light of new questions that have been raised about "large-x" parton distributions, as well as recent measurements which have improved the parton uncertainties., Comment: LaTeX, 5 pages, 2 figures. Invited talk at 8th International Workshop on Deep Inelastic Scattering and QCD (DIS 2000), Liverpool, England, 25-30 Apr 2000
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- 2000
23. Parton Distributions Working Group
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de Barbaro, L., Berger, E. L., Brock, R., Casey, D., Demina, R., Giele, W. T., Hirosky, R., Huston, J., Kalk, J., Keller, S. A., Klasen, M., Kosower, D. A., Kramer, M., Kretzer, S., Kuhlmann, S., Martin, R., Olness, F. I., Plehn, T., Pumplin, J., Scalise, R. J., Schellman, H., Smith, J., Soper, D. E., Sterman, G., Stump, D., Tung, W. -K., Varelas, N., Vogelsang, W., and Yang, U. K.
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High Energy Physics - Phenomenology - Abstract
The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, we introduce a "Manifesto" that describes an optimal method for reporting data., Comment: Report of the Parton Distributions Working Group of the 'QCD and Weak Boson Physics workshop in preparation for Run II at the Fermilab Tevatron'. Co-Conveners: L. de Barbaro, S.A. Keller, S. Kuhlmann, H. Schellman, and W.-K. Tung
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- 2000
24. Uncertainties of Parton Distribution Functions and Their Implications on Physical Predictions
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Brock, R., Casey, D., Huston, J., Kalk, J., Pumplin, J., Stump, D., and Tung, W. K.
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High Energy Physics - Phenomenology - Abstract
We describe preliminary results from an effort to quantify the uncertainties in parton distribution functions and the resulting uncertainties in predicted physical quantities. The production cross section of the $W$ boson is given as a first example. Constraints due to the full data sets of the CTEQ global analysis are used in this study. Two complementary approaches, based on the Hessian and the Lagrange multiplier method respectively, are outlined. We discuss issues on obtaining meaningful uncertainty estimates that include the effect of correlated experimental systematic uncertainties and illustrate them with detailed calculations using one set of precision DIS data., Comment: Contribution to Proceedings of Fermilab Workshop on QCD and Weak Boson Physics at the Tevatron: Run II and Beyond, Fermilab, 1999; 15 pages; 7 figures
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- 2000
25. The QCD and Standard Model Working Group: Summary Report from Les Houches
- Author
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Aurenche, P., Balazs, C., Ball, R. D., Binoth, T., Boos, E., Catani, S., Collins, J., del Duca, V., Dittmar, M., Fontannaz, M., Frixione, S., Guillet, J. P., Heinrich, G., Huston, J., Ilyin, V., Kato, Y., Odagiri, K., Paige, F., Pilon, E., Pukhov, A., Puljak, I., Semenov, A., Skatchkova, A., Soper, D., Tano, V., Tapprogge, S., Tung, W. K., Vogelsang, W., Werlen, M., and Zeppenfeld, D.
- Subjects
High Energy Physics - Phenomenology ,High Energy Physics - Experiment - Abstract
The Les Houches Workshop on Physics at TeV Colliders took place from June 8-18, 1999. One of the three working groups at Les Houches concentrated on QCD issues, both at the Tevatron Collider and at the LHC. Besides the interest in QCD in its own right, QCD dynamics plays an important role in the production mechanisms for any new physics process that might be observed at either collider, as well as any processes that may form backgrounds to the new physics. This writeup serves both as a pedagogical overview of QCD as well as an update on the current status of the field., Comment: 179 pages, 65 figures
- Published
- 2000
26. Heavy Quark Production and PDF's Subgroup Report
- Author
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Demina, R., Keller, S., Krämer, M., Kretzer, S., Martin, R., Olness, F. I., Scalise, R. J., Soper, D. E., Tung, W. -K., Varelas, N., and Yang, U. K.
- Subjects
High Energy Physics - Phenomenology - Abstract
We present a status report of a variety of projects related to heavy quark production and parton distributions for the Tevatron Run II., Comment: Latex. 8 pages, 7 eps figures. Contribution to the Physics at Run II Workshops: QCD and Weak Boson Physics
- Published
- 2000
27. QCD
- Author
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Catani, S., Dittmar, M., Soper, D., Stirling, W. J., Tapprogge, S., Alekhin, S., Aurenche, P., Balazs, C., Ball, R. D., Battistoni, G., Berger, E. L., Binoth, T., Brock, R., Casey, D., Corcella, G., Del Duca, V., Del Fabbro, A., De Roeck, A., Ewerz, C., de Florian, D., Fontannaz, M., Frixione, S., Giele, W. T., Grazzini, M., Guillet, J. P., Heinrich, G., Huston, J., Kalk, J., Kataev, A. L., Kato, K., Keller, S., Klasen, M., Kosower, D. A., Kulesza, A., Kunszt, Z., Ilyin, A. Kupco V. A., Magnea, L., Mangano, M. L., Martin, A. D., Mazumdar, K., Mine, Ph., Moretti, M., van Neerven, W. L., Parente, G., Perret-Gallix, D., Pilon, E., Pukhov, A. E., Puljak, I., Pumplin, J., Richter-Was, E., Roberts, R. G., Salam, G. P., Seymour, M. H., Skachkov, N., Sidorov, A. V., Stenzel, H., Stump, D., Thorne, R. S., Treleani, D., Tung, W. K., Vogt, A., Webber, B. R., Werlen, M., and Zmouchko, S.
- Subjects
High Energy Physics - Phenomenology ,High Energy Physics - Experiment - Abstract
We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics, double parton scattering, and backgrounds to Higgs production., Comment: 115 pages, Latex, 47 figures, to appear in the Report of the ``1999 CERN Workshop on SM Physics (and more) at the LHC'', S. Catani, M. Dittmar, D. Soper, W.J. Stirling, S. Tapprogge (convenors)
- Published
- 2000
28. Large-x Parton Distributions
- Author
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Kuhlmann, S., Huston, J., Morfin, J., Olness, F., Pumplin, J., Owens, J. F., Tung, W. K., and Whitmore, J. J.
- Subjects
High Energy Physics - Phenomenology - Abstract
Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x > 0.1. We examine the status of the gluon and quark distributions in light of new questions that have been raised in the past two years about large-x parton distributions, as well as recent measurements which have improved the parton uncertainties. We perform several specific global fits to answer the outstanding questions, and to investigate the potential of future experiments, particularly at HERA, which may provide critical constraints on parton distributions at large x., Comment: 11 pages, 4 figures
- Published
- 1999
- Full Text
- View/download PDF
29. Global QCD Analysis of Parton Structure of the Nucleon: CTEQ5 Parton Distributions
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Lai, H. L., Huston, J., Kuhlmann, S., Morfin, J., Olness, F., Owens, J. F., Pumplin, J., and Tung, W. K.
- Subjects
High Energy Physics - Phenomenology - Abstract
An up-to-date global QCD analysis of high energy lepton-hadron and hadron-hadron interactions is performed to better determine the gluon and quark parton distributions in the nucleon. Improved experimental data on inclusive jet production, in conjunction with precise deep inelastic scattering data, place good constraints on the gluon over a wide range of x; while new data on asymmetries in Drell-Yan processes contribute to better determine the d/u ratio. Comparisons with results of other recent global analyses are made, and the differences are described. Open issues and the general problem of determining the uncertainties of parton distributions are discussed., Comment: 18 pages in 2up format, 21 figures; This is the version to appear in publication (to appear in Eur. Phys. J. C): minor text modifications; some figures improved in quality; note added in proof concerning QCD evolution added
- Published
- 1999
- Full Text
- View/download PDF
30. kt Effects in Direct-Photon Production
- Author
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Apanasevich, L., Balazs, C., Bromberg, C., Huston, J., Maul, A., Tung, W. K., Kuhlmann, S., Owens, J., Begel, M., Ferbel, T., Ginther, G., Slattery, P., and Zielinski, M.
- Subjects
High Energy Physics - Phenomenology - Abstract
We discuss the phenomenology of initial-state parton-kt broadening in direct-photon production and related processes in hadron collisions. After a brief summary of the theoretical basis for a Gaussian-smearing approach, we present a systematic study of recent results on fixed-target and collider direct-photon production, using complementary data on diphoton and pion production to provide empirical guidance on the required amount of kt broadening. This approach provides a consistent description of the observed pattern of deviation of next-to-leading order QCD calculations relative to the direct-photon data, and accounts for the shape and normalization difference between fixed-order perturbative calculations and the data. We also discuss the uncertainties in this phenomenological approach, the implications of these results on the extraction of the gluon distribution of the nucleon, and the comparison of our findings to recent related work., Comment: LaTeX, uses revtex and epsf, 37 pages, 15 figures
- Published
- 1998
- Full Text
- View/download PDF
31. Study of the Uncertainty of the Gluon Distribution
- Author
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Huston, J., Kuhlmann, S., Lai, H. L., Olness, F., Owens, J. F., Soper, D. E., and Tung, W. K.
- Subjects
High Energy Physics - Phenomenology - Abstract
The uncertainty in the calculation of many important new processes at the Tevatron and LHC is dominated by that concerning the gluon distribution function. We investigate the uncertainty in the gluon distribution of the proton by systematically varying the gluon parameters in the global QCD analysis of parton distributions. The results depend critically on the parton momentum fraction x and the QCD scale Q^2. The uncertainties are presented for integrated gluon-gluon and gluon-quark luminosities for both the Tevatron and LHC as a function of sqrt(tau)=sqrt(x1x2)=sqrt(shat/s), the most relevant quantity for new particle production. The uncertainties are reasonably small, except for large x., Comment: Modified version for publication
- Published
- 1998
- Full Text
- View/download PDF
32. Structure Function Subgroup Summary
- Author
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Harris, D., Olness, F. I., Ritz, S., Albrow, M., Berger, E., Bolton, T., Caldwell, A., El-Khadra, A., Ermolaev, B., Gary, J. W., Hughes, E., Huston, J., Jansen, D., Kim, Y. -K., Krakauer, D., Kuhlmann, S., Lai, H., Naples, D., Qiu, J., Reeder, D., Reno, M. H., Scalise, R. J., Schumm, B., Spentzouris, P., Taylor, C., Tung, W. -K., Wang, J., Wang, X., Ward, B., Weerts, H., White, A., Whitmore, J., and Yu, W.
- Subjects
High Energy Physics - Phenomenology - Abstract
We summarize the studies and discussions of the Structure Function subgroup of the QCD working group of the Snowmass 1996 Workshop: New Directions for High Energy Physics., Comment: 14 pages, LaTeX, 23 PostScript figures, uses epsf.sty and snowhack.cls. Contribution to Snowmass 96 Proceedings. Typographical errors corrected and minor changes made to text
- Published
- 1997
33. Hera Events, Tevatron Jets, and the Uncertainty On Quarks At Large X
- Author
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Kuhlmann, S., Lai, H. L., and Tung, W. K.
- Subjects
High Energy Physics - Phenomenology - Abstract
The recently reported excess of events at HERA compared to QCD calculations impels us to examine all possible Standard Model explanations before invoking ``new physics''. We explore the possibility of adding an unusual, but small, component of additional quarks at large x (beyond x>0.75) as a way to increase the predicted SM cross-section in the HERA kinematic region by the QCD evolution feed-down effect. We describe various scenarios under which this can be achieved while maintaining good global fits to all established data sets. This implies a much larger SM uncertainty than commonly assumed. In addition, the modified parton distributions provide another possible mechanism to account for the CDF high-pt jet excess which occurs at similar x and Q^2 values., Comment: 13 page Latex, 8 ps figures, replaced with modifications to the text
- Published
- 1997
- Full Text
- View/download PDF
34. Charm Production and Parton Distributions
- Author
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Lai, H. L. and Tung, W. K.
- Subjects
High Energy Physics - Phenomenology - Abstract
Recent accurate data on F_2(x,Q) and on F_2^c(x,Q) from HERA at small-x require a more precise treatment of charm production in the global QCD analysis of parton distributions. We improve on existing global analyses by implementing the leptoproduction formalism of Aivazis et al. which represents a natural generalization of the conventional zero mass QCD parton framework to include heavy quark mass effects. We also perform analyses based on the fixed-flavor-number scheme, which is widely used in the literature, and demonstrate their uses and limitations. We discuss the implications of the improved treatment of heavy quark mass effect in practical applications of PQCD and compare our results with recent related works., Comment: 11 pages, 4 figures, plain Latex
- Published
- 1997
35. Improved Parton Distributions from Global Analysis of Recent Deep Inelastic Scattering and Inclusive Jet Data
- Author
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Lai, H. L., Huston, J., Kuhlmann, S., Olness, F., Owens, J., Soper, D., Tung, W. K., and Weerts, H.
- Subjects
High Energy Physics - Phenomenology - Abstract
The impact of recent precision measurements of DIS structure functions and inclusive jet production at the Tevatron on the global QCD analysis of parton distribution functions is studied in detail. Particular emphasis is placed on exploring the range of variation of the gluon distribution $G(x,Q)$ allowed by these new data. The strong coupling of $G(x,Q)$ with $\alpha_s$ is fully taken into account. A new generation of CTEQ parton distributions, CTEQ4, is presented. It consists of the three standard sets (\mbox{\small {$\overline {\rm MS}$}}, {\protect \small DIS} and leading order), a series that gives a range of parton distributions with corresponding $\alpha_s$'s, and a set with a low starting value of $Q$. Previously obtained gluon distributions that are consistent with the high $E_t$ jet cross-section are also discussed in the context of this new global analysis., Comment: 39 pages, 21 figures; Web page address corrected; Mislabelled table rows corrected; Table for CTEQ4LQ added; reformatted for pub. in Phys.Rev
- Published
- 1996
- Full Text
- View/download PDF
36. Comparison of CDF and D0 Inclusive Jet Cross-sections
- Author
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Lai, H. L. and Tung, W. K.
- Subjects
High Energy Physics - Phenomenology - Abstract
The recently reported CDF and D0 inclusive jet cross-sections are compared, using a uniform theoretical NLO QCD calculation to account for the different kinematic coverages of the pseudo-rapidity variable in the two experiments. The two data sets are found to be in good agreement. With a 2-3\% relative overall normalization adjustment, the data sets appear to agree over the entire $E_t$ range, even without taking into account the other systematic errors., Comment: 2.5 pages, 4 figures
- Published
- 1996
37. Large Transverse Momentum Jet Production and the Gluon Distribution Inside the Proton
- Author
-
Huston, J., Kovacs, E., Kuhlmann, S., Lai, H. L., Owens, J. F., Soper, D., and Tung, W. K.
- Subjects
High Energy Physics - Phenomenology ,High Energy Physics - Experiment - Abstract
The CDF experiment has reported an excess of high-$p_t$ jets compared to previous next-to-leading order QCD expectations. Before attributing this to new physics effects, we investigate whether these high-$p_t$ jets can be explained by a modified gluon distribution inside the proton. We find enough flexibility in a global QCD analysis including the CDF inclusive jet data to provide a 25-35\% increase in the jet cross sections at the highest $p_t$ of the experiment. Two possible sets of parton distributions are presented, and the effects of these on other existing data sets are presented. Further theoretical and experimental work needed to clarify unresolved issues is outlined., Comment: 6 page Latex file using epsf.sty for 4 ps figures. Revised with more up-to-date gluon distributions
- Published
- 1995
- Full Text
- View/download PDF
38. A GLOBAL QCD STUDY OF DIRECT PHOTON PRODUCTION
- Author
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Huston, J., Kovacs, E., Kuhlmann, S., Lai, H. L., Owens, J. F., and Tung, W. K.
- Subjects
High Energy Physics - Phenomenology - Abstract
A global QCD analysis of the direct photon production process from both fixed target and collider experiments is presented. These data sets now completely cover the parton $x$ range from 0.01 to 0.6, thereby providing a stringent test of perturbative QCD and parton distributions. Previous detailed studies of direct photons emphasized fixed target data. We find most data sets have a steeper $p_t$ distribution than the QCD prediction. Neither global fits with new parton distributions nor improved photon fragmentation functions can resolve this problem since the deviation occurs at different $x$ values for experiments at different energies. A more likely explanation is the need for additional broadening of the $k_t$ of the initial state partons. The magnitude and the possible physical origin of this effect are investigated and discussed., Comment: 8 page Latex file using epsf.sty for figures. 6 eps figures submitted separately in uuencoded file.
- Published
- 1995
- Full Text
- View/download PDF
39. Global QCD Analysis and the CTEQ Parton Distributions
- Author
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Lai, H. L., Botts, J., Huston, J., Morfin, J. G., Owen, J. F., Qiu, J. W., Tung, W. K., and Weerts, H.
- Subjects
High Energy Physics - Phenomenology - Abstract
The CTEQ program for the determination of parton distributions through a global QCD analysis of data for various hard scattering processes is fully described. A new set of distributions, CTEQ3, incorporating several new types of data is reported and compared to the two previous sets of CTEQ distributions. Comparison with current data is discussed in some detail. The remaining uncertainties in the parton distributions and methods to further reduce them are assessed. Comparisons with the results of other global analyses are also presented., Comment: (Change in Latex style only: 2up style removed since many don't have it.) 35 pages, 23 figures separately submitted as uuencoded compressed ps-file; Michigan State Report # MSU-HEP/41024 and CTEQ 404
- Published
- 1994
- Full Text
- View/download PDF
40. Effect of nanofiller shape on viscoelasticity of rubber nanocomposite investigated by FEA
- Author
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Yang, Haibo, Li, Fanzhu, Chan, Tung W., Liu, Li, and Zhang, Liqun
- Published
- 2016
- Full Text
- View/download PDF
41. Aligned carbon nanotubes stabilized liquid phase exfoliated graphene hybrid and their polyurethane dielectric elastomers
- Author
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Liu, Suting, Sun, Haibin, Ning, Nanying, Zhang, Liqun, Tian, Ming, Zhu, Wenjun, and Chan, Tung W.
- Published
- 2016
- Full Text
- View/download PDF
42. Crack precursor size for natural rubber inferred from relaxing and non-relaxing fatigue experiments
- Author
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Li, Fanzhu, Liu, Jinpeng, Mars, W.V., Chan, Tung W., Lu, Yonglai, Yang, Haibo, and Zhang, Liqun
- Published
- 2015
- Full Text
- View/download PDF
43. High elasticity and conductivity of elastomer composites with arrayed carbon nanotubes as nanosprings
- Author
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Ning, Nanying, Ji, Lianjie, Zhang, Liqun, Liu, Jun, Lu, Yonglai, Wu, Shemao, Zou, Hua, Tian, Ming, and Chan, Tung W.
- Published
- 2015
- Full Text
- View/download PDF
44. A combined experimental and molecular dynamics simulation study on the structures and properties of three types of styrene butadiene rubber
- Author
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Li, Yi, Wu, Youping, Luo, Yanlong, Chan, Tung W., Zhang, Liqun, and Wu, Sizhu
- Published
- 2015
- Full Text
- View/download PDF
45. A simulation study on the effect of spring-shaped fillers on the viscoelasticity of rubber nanocomposite
- Author
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Yang, Haibo, Li, Fanzhu, Chan, Tung W., Liu, Li, and Zhang, Liqun
- Published
- 2015
- Full Text
- View/download PDF
46. PP508 [Other]: PEDSQL™ PRESENT FUNCTIONING VISUAL ANALOGUE SCALES: A NOVEL MEASURE OF HEALTH-RELATED FUNCTIONING AMONG CHINESE CHILDREN IN CRITICAL CARE UNIT
- Author
-
Chan, W., primary, Pak, C., additional, Lam, J., additional, Chan, M., additional, Tung, W., additional, Hui, W., additional, Ho, Y., additional, and Chan, N., additional
- Published
- 2022
- Full Text
- View/download PDF
47. Data for effects of lanthanum complex on the thermo-oxidative aging of natural rubber
- Author
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Wei Zheng, Li Liu, Xiuying Zhao, Jingwei He, Ao Wang, Tung W. Chan, and Sizhu Wu
- Subjects
Computer applications to medicine. Medical informatics ,R858-859.7 ,Science (General) ,Q1-390 - Abstract
Novel mixed antioxidants composed of antioxidant IPPD and lanthanum (La) complex were added as a filler to form natural rubber (NR) composites. By mechanical testing, Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and thermogravimetric analysis (TGA), a string of data, including the mechanical properties, the variation of internal groups and the thermal and thermo-oxidative decompositions of NR, was presented in this data article. The data accompanying its research article [1] studied the thermo-oxidative aging properties of NR in detail. The density function theoretical (DFT) calculations were also used as an assistant to study the thermo-oxidative aging mechanism of NR. The data revealed that this new rare-earth antioxidant could indeed enhance the thermo-oxidative aging resistance of NR, which is associated with its different function mechanism from that of the pure antioxidant IPPD.
- Published
- 2015
- Full Text
- View/download PDF
48. Fibrillar Attapulgite–Rubber Nanocomposites
- Author
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Ning, Nanying, primary, Chu, Guangyu, additional, Feng, Yuxing, additional, Zhen, Xiuchun, additional, Tian, Ming, additional, and Chan, Tung W., additional
- Published
- 2016
- Full Text
- View/download PDF
49. A NeuroCognitive Approach to Decision-Making in Chance Discovery
- Author
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Tung, W. L., Quek, C., Kacprzyk, Janusz, editor, Ohsawa, Yukio, editor, and Tsumoto, Shusaku, editor
- Published
- 2006
- Full Text
- View/download PDF
50. In situ self-polymerization of unsaturated metal methacrylate and its dispersion mechanism in rubber-based composites
- Author
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Wen, Shipeng, Zhou, Yao, Yao, Lu, Zhang, Liqun, Chan, Tung W., Liang, Yongri, and Liu, Li
- Published
- 2013
- Full Text
- View/download PDF
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