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J. Smith

Publications and source records attributed to J. Smith.

122 records · Page 7Linked to original sources
arXiv1996

Determination of the asymptotic behaviour of the heavy flavour coefficient functions in deep inelastic scattering

Using renormalization group techniques we have derived analytic formulae for the next-to-leading order heavy-quark coefficient functions in deep inelastic lepton hadron scattering. These formulae are only valid in the kinematic regime Q^2 >> m^2, where Q^2 and m^2 stand for the masses squared of the virtual photon and heavy quark respectively. Some of the applications of these asymptotic formulae will be discussed.

hep-ph↗
arXiv1996

Bottom quark production cross section at HERA-B

The cross section for bottom quark production is calculated for the HERA-B experiment. We consider both the order $α_s^3$ cross section and the resummation of soft gluon corrections in all orders of QCD perturbation theory.

hep-ph↗
arXiv1996

Heavy quark coefficient functions at asymptotic values $Q^2 \gg m^2$

In this paper we present the analytic form of the heavy-quark coefficient functions for deep-inelastic lepton-hadron scattering in the kinematical regime $Q^2 \gg m^2$ . Here $Q^2$ and $m^2$ stand for the masses squared of the virtual photon and heavy quark respectively. The calculations have been performed up to next-to-leading order in the strong coupling constant $α_s$ using operator product expansion techniques. Apart from a check on earlier calculations, which however are only accessible via large computer programs, the asymptotic forms of the coefficient functions are useful for charm production at HERA when the condition $Q^2 \gg m_c^2$ is satisfied. Furthermore the analytical expressions can also be used when one applies the variable heavy flavour scheme up to next-to-leading order in $α_s$.

hep-ph↗
arXiv1995

Reanalysis of the EMC charm production data with extrinsic and intrinsic charm at NLO

A calculation of the next-to-leading order exclusive extrinsic charm quark differential distributions in deeply inelastic electroproduction has recently been completed. Using these results we compare the NLO extrinsic contributions to the charm structure function $F_2(x,Q^2,m_c^2)$ with the corresponding NLO intrinsic contributions. The results of this analysis are compared with the EMC DIS charm quark data and evidence for an intrinsic charm component in the proton is found.

hep-ph↗
arXiv1995

Bottom quark production cross section at fixed-target $pp$ experiments

The cross section for bottom quark production at fixed-target energies is calculated for a wide range of beam momenta. A detailed analysis is given for the HERA-B experiment. We consider both the order $α_s^3$ cross section and the resummation of soft gluon corrections in all orders of QCD perturbation theory. The inclusive transverse momentum and rapidity distributions, including resummation, for bottom quark production at HERA-B are also presented.

hep-ph↗
arXiv1995

Heavy-quark correlations in deep-inelastic electroproduction

We have completed the next-to-leading order perturbative QCD corrections to the virtual-photon exclusive differential cross sections for heavy quark production in deep-inelastic electron-proton scattering, i.e. $e + P \rightarrow Q + \overline{Q} + X$. Using these results, we have computed distributions which are sensitive to correlations among the heavy quark, the heavy antiquark, and the associated jet. Some predictions for charm and bottom heavy quark production at the electron-proton collider HERA are presented.

hep-ph↗
arXiv1995

Top quark inclusive differential distributions

The inclusive transverse momentum and rapidity distributions for top quark production at the Fermilab Tevatron are presented both in order $α_s^3$ in QCD and using the resummation of the leading soft gluon corrections in all orders of QCD perturbation theory. The resummed results are uniformly larger than the $O(α_s^3)$ results for both distributions.

hep-ph↗
arXiv1994

Rates for Inclusive Deep-Inelastic Electroproduction of Charm Quarks at HERA

The coefficient functions for heavy-flavour production in deeply inelastic electron-hadron scattering have been calculated previously. Analytic expressions are impossible to publish due to their length. Therefore we have tabulated them as two-dimensional arrays as is often done for the scale-dependent parton densities. Using this computer program we present event rates for charm production at HERA in bins of $x$ and $Q^2$. These rates are insensitive to variations in the factorization and renormalization scale $μ$.

hep-ph↗
arXiv1994

Anomalous dimension of the gluon operator in pure Yang-Mills theory

We present new one loop calculations that confirm the theorems of Joglekar and Lee on the renormalization of composite operators. We do this by considering physical matrix elements with the operators inserted at non-zero momentum. The resulting IR singularities are regulated dimensionally. We show that the physical matrix element of the BRST exact gauge variant operator which appears in the energy- momentum tensor is zero. We then show that the physical matrix elements of the classical energy-momentum tensor and the gauge invariant twist two gluon operator are independent of the gauge fixing parameter. A Sudakov factor appears in the latter cases. The universality of this factor and the UV finiteness of the energy-momentum tensor provide another method of finding the anomalous dimension of the gluon operator. We conjecture that this method applies to higher loops and takes full advantage of the triangularity of the mixing matrix.

hep-ph↗
arXiv1993

Top Quark Production Cross Section

The production rate for top quarks at the Fermilab Tevatron is presented using the exact order $α_s^3$ corrected cross section and the resummation of the leading soft gluon corrections in all orders of perturbation theory.

hep-ph↗
arXiv1993

Complete Next to Leading Order QCD Corrections to the Photon Structure Functions $F^γ_2(x,Q^2)$ and $F_L^γ(x,Q^2)$

We present the complete NLO QCD analysis of the photon structure functions $F_2^γ(x,Q^2)$ and $F_L^γ(x,Q^2)$ for a real photon target. In particular we study the heavy flavor content of the structure functions which is due to two different production mechanisms, namely collisions of a virtual photon with a real photon, and with a parton. We observe that the charm contributions are noticeable for $F_2^γ(x,Q^2)$ as well as $F_L^γ(x,Q^2)$ in the x-region studied.

hep-ph↗
arXiv1993

$O(α_S)$ Corrections to the Photon Structure Functions $F^γ_2(x,Q^2)$ and $F_L^γ(x,Q^2)$

We examine the QCD corrections to the structure functions $F_2^γ(x,Q^2)$ and $F_L^γ(x,Q^2)$ for a real photon target. The pointlike photon contributions from light and heavy quarks are computed through $O(αα_S)$. A parameterization of the hadronic (resolved) photon contribution is also included and a comparison is made with the present experimental data. We find that while the pointlike contributions are large for $F_2^γ(x,Q^2)$, they are the dominant part of $F_L^γ(x,Q^2)$. For $Q^2 > 50$ $({\rm GeV}/c)^2$ the charm component is as least as large as the light quark component.

hep-ph↗