138 research outputs found

    Neutrino deep-inelastic scattering cross sections from 100 GeV to 1000 EeV

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    The CTEQ-TEA Collaboration has calculated neutrino-nucleon cross sections, based on CTEQ18 NNLO parton distribution functions.Comment: 6 pages, 3 figures, presented at conference DIS2023: XXX International Workshop on Deep-Inelastic Scattering and Related Subjects, Michigan State University, USA, 27-31 March 202

    Stability of NLO Global Analysis and Implications for Hadron Collider Physics

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    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 repor

    The Parton Structure of the Nucleon and Precision Determination of the Weinberg Angle in Neutrino Scattering

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    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 sin2θW\sin^2 \theta_{\mathrm{W}} obtained in calculations with a new generation of PDF sets that allow s(x)sˉ(x)s(x)\neq \bar{s}(x), enabled by recent neutrino dimuon data from CCFR and NuTeV, as compared to the previous s=sˉs = \bar{s} parton distribution functions like CTEQ6M. The extracted value of sin2θW\sin^2 \theta_{\mathrm{W}} is closely correlated with the strangeness asymmetry momentum integral 01x[s(x)sˉ(x)]dx\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 page

    The Strange Parton Distribution of the Nucleon: Global Analysis and Applications

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    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 JHE

    Improving the validity of activity of daily living dependency risk assessment

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    OBJECTIVES: Efforts to prevent activity of daily living (ADL) dependency may be improved through models that assess older adults' dependency risk. We evaluated whether cognition and gait speed measures improve the predictive validity of interview-based models. METHOD: Participants were 8,095 self-respondents in the 2006 Health and Retirement Survey who were aged 65 years or over and independent in five ADLs. Incident ADL dependency was determined from the 2008 interview. Models were developed using random 2/3rd cohorts and validated in the remaining 1/3rd. RESULTS: Compared to a c-statistic of 0.79 in the best interview model, the model including cognitive measures had c-statistics of 0.82 and 0.80 while the best fitting gait speed model had c-statistics of 0.83 and 0.79 in the development and validation cohorts, respectively. CONCLUSION: Two relatively brief models, one that requires an in-person assessment and one that does not, had excellent validity for predicting incident ADL dependency but did not significantly improve the predictive validity of the best fitting interview-based models

    CTEQ-TEA parton distribution functions and HERA Run I and II combined data

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    We analyze the impact of the recent HERA run I+II combination of inclusive deep inelastic scattering cross-section data on the CT14 global analysis of PDFs. New PDFs at NLO and NNLO, called CT14HERA2_{\textrm{HERA2}}, are obtained by a refit of the CT14 data ensembles, in which the HERA run I combined measurements are replaced by the new HERA run I+II combination. The CT14 functional parametrization of PDFs is flexible enough to allow good descriptions of different flavor combinations, so we use the same parametrization for CT14HERA2_{\textrm{HERA2}} but with an additional shape parameter for describing the strange quark PDF. We find that the HERA I+II data can be fit reasonably well, and both CT14 and CT14HERA2_{\textrm{HERA2}} PDFs can describe equally well the non-HERA data included in our global analysis. Because the CT14 and CT14HERA2_{\textrm{HERA2}} PDFs agree well within the PDF errors, we continue to recommend CT14 PDFs for the analysis of LHC Run 2 experiments.Comment: 19 pages, 6 figures and 3 table