arXiv subjects

E. Laenen

Publications and source records attributed to E. Laenen.

48 records · Page 3Linked to original sources

arXiv1996

The Heavy-Flavour Contribution to Proton Structure

We present theoretical and experimental considerations pertaining to deeply inelastic heavy-flavour production at HERA. The various theoretical uncertainties in the cross section calculation are discussed. Cuts are imposed to determine the fraction of charm production accessible to the detectors. The production of charm at asymptotic $Q^2$ and bottom production are also covered. Experimental aspects include current charm production data analysis and prospects for future analyses including anticipated high precision and distinguishing photon-gluon fusion charm events from excitation from the charm parton density. The feasibility of measuring $F_2^{b\overline b}(x,Q^2)$ is investigated.

hep-ph↗

arXiv1996

Deep-inelastic production of heavy quarks

Deep-inelastic production of heavy quarks at HERA, especially charm, is an excellent signal to measure the gluon distribution in the proton at small $x$ values. By measuring various differential distributions of the heavy quarks this reaction permits additional more incisive QCD analyses due to the many scales present. Furthermore, the relatively small mass of the charm quark, compared to the typical momentum transfer $Q$, allows one to study whether and when to treat this quark as a parton. This reaction therefore sheds light on some of the most fundamental aspects of perturbative QCD. We discuss the above issues and review the feasibility of their experimental investigation in the light of a large integrated luminosity.

hep-ph↗

arXiv1996

Gamma-Gamma Physics at LEP2

This report is an overview of the gamma-gamma physics capabilities of LEP2, and covers the following topics: structure functions, equivalent photon approximation, tagging conditions etc, soft and semihard physics, large-$p_t$ processes, heavy-quark physics, and exclusive channels.

hep-ph↗

arXiv1995

Radiative corrections to $e γ$ scattering

We investigate the effects of photon radiation on deep-inelastic $\reγ$ scattering. Depending on the set of variables chosen, we find appreciable effects in the kinematic region accessible at LEP2. Convenient analytic results for $O(α)$ corrected differential cross sections are presented.

hep-ph↗

arXiv1995

Charm Production in Deep-Inelastic $eγ$ Scattering To Next-To-Leading Order in QCD

We discuss the calculation of $F_2^γ({\rm charm})$ to next-to-leading order (NLO) in QCD, including contributions from both hadronlike and pointlike photons. We show that the former dominates strongly below $x\simeq 0.01$, and the latter above this value. This fact makes $F_2^γ({\rm charm})$ for $x \geq 0.01$ calculable, whereas for $x \leq 0.01$ it serves to constrain the small-$x$ gluon density in the photon. Both ranges in $x$ are accessible at LEP2. Theoretical uncertainties are well under control. We present rates for single-tag events for the process for $e^+e^- \rightarrow e^+e^- c X$ for LEP2. Although these event rates are small, we believe a measurement of $F_2^γ({\rm charm})$ is feasible.

hep-ph↗

arXiv1995

A new evolution equation

We propose a new evolution equation for the gluon density relevant for the region of small $x_B$. It generalizes the GLR equation and allows deeper penetration in dense parton systems than the GLR equation does. This generalization consists of taking shadowing effects more comprehensively into account by including multigluon correlations, and allowing for an arbitrary initial gluon distribution in a hadron. We solve the new equation for fixed $α_s$. We find that the effects of multigluon correlations on the deep-inelastic structure function are small.

hep-ph↗

arXiv1994

W Plus Heavy Quark Production at the Tevatron

We summarize the motivations for and the status of the calculation of the $W +$ heavy quark production process in $p \bar p$ colliders to Next-to-Leading Order in QCD. This process can be used to constrain the strange quark distribution function at high $Q^2$ at the Tevatron, and also to study the bottom content of $W+1$~jet events. In addition, when crossed, the calculation essentially describes the single top quark production process to Next-to-Leading Order in QCD.

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

Anomalous Dimensions of High Twist Operators in QCD at $N \rightarrow 1$ and large $Q^2

The anomalous dimensions of high-twist operators in deeply inelastic scattering ($γ_{2n}$) are calculated in the limit when the moment variable $N \rightarrow 1$ (or $x_B\rightarrow 0$) and at large $Q^2$ (the double logarithmic approximation) in perturbative QCD. We find that the value of $γ_{2n}(N-1)$ in this approximation behaves as ${N_c α_S \over π(N-1)} n^2(1 + {δ\over 3} (n^2-1))$ where $δ\approx 10^{-2}$. This implies that the contributions of the high-twist operators give rise to an earlier onset of shadowing than was estimated before. The derivation makes use of a Pomeron exchange approximation, with the Pomerons interacting attractively. We find that they behave as a system of fermions.

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

A Note on `Hot Spot' Hunting in Deep-Inelastic Scattering

We consider the inclusive cross section for jet production with large transverse momentum in deep-inelastic scattering. This process has been proposed as a probe of small-x physics, particularly the measurement of `hot spots' inside the proton. We present a numerical calculation of this process, taking into account a larger phase space. The theoretical reliability as well as phenomenological uncertainties of the calculation are discussed.

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↗