Fredrick I. Olness

Global QCD analysis of parton structure of the nucleon: CTEQ5 parton distributions

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.

Treatment of Heavy Quarks in Deeply Inelastic Scattering

We investigate a simplied version of the ACOT prescription for calculating deeply inelastic scattering from Q 2 values near the squared mass M 2 H of a heavy quark to Q 2

CTEQ6 parton distributions with heavy quark mass effects

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.

When Is a Heavy Quark Not a Parton? Charged Higgs Production and Heavy Quark Mass Effects in the QCD Based Parton Model

Abstract Several issues pertaining to the application of the QCD-based parton model to new physics processes involving heavy partons are described and quantitatively studied using charged Higgs boson production as a prime example. The naive parton model predictions are found to over-estimate the actual cross section by a factor of 2 to 5, depending on the top-quark and Higgs masses. The role of the top quark as a “parton” is examined by a detailed study of the cancellation between the straight parton model contribution and a subtraction term required by QCD corrections. The accuracy of the zero-mass method for evaluating the first-order QCD correction is assessed (in light of the potentially large mass of the top quark) by a quantitative analysis of the cancellation of mass singularities between the correction terms. A pragmatic procedure for calculation based on a renormalization scheme without the heavy quark-parton is formulated and compared with the usual perturbative QCD formalism. The energy ranges over which heavy quarks (or other particles) should or should not be naturally treated as “partons” are delineated. Properly evolved parton distribution functions relevant to the specific renormalization schemes considered are employed for all the numerical studies in order to ensure consistency in the QCD framework.

Nuclear parton distribution functions from neutrino deep inelastic scattering

1 Southern Methodist University, Dallas, TX 75206, USA, Laboratoire de Physique Subatomique et de Cosmologie, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, 53 Avenue des Martyrs, 38026 Grenoble, France, Thomas Jefferson National Accelerator Facility, Newport News, VA 23602, USA, Hampton University, Hampton, VA, 23668, USA, Fermilab, Batavia, IL 60510, USA, Florida State University, Tallahassee, FL 32306-4350, USA Theoretical Physics Division, Physics Department, CERN, CH 1211 Geneva 23, Switzerland (Dated: April 1, 2008)

Neutrino dimuon production and the strangeness asymmetry of the nucleon

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 antistrange parton distributions, s(x) and

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

\bar{s}(x)

Target mass corrections

. To explore the strangeness sector, we adopt a general parametrization of the non-perturbative

Semi-inclusive deeply inelastic scattering at electron-proton colliders

s(x), \bar{s}(x)

Semi-inclusive deeply inelastic scattering at small qT.

functions satisfying basic QCD requirements. We find that the strangeness asymmetry, as represented by the momentum integral