19 research outputs found
Threshold Resummation and the Total Cross Section for Top Quark Production
We discuss the motivation for resummation of the effects of initial-state
soft-gluon radiation, to all orders in the strong coupling strength, for
processes in which the near-threshold region in the partonic subenergy is
important. We summarize our calculation of the total cross section for top
quark production at hadron colliders. Comments are included on the differences
between our treatment of subleading logarithmic terms and other methods.Comment: 7 pages, 1 figure, uses aipproc.sty; Paper presented by E. L. Berger,
to be published in the Proceedings of DIS'97, Fifth International Workshop on
Deep Inelastic Scattering and QCD, Chicago, IL, April 14 - 18, 199
The Perturbative Resummed Series for Top Production
Our calculation of the total cross section for inclusive production of
pairs in hadron collisions is summarized. The principal ingredient
of this calculation is resummation of the universal leading-logarithm effects
of gluon radiation to all orders in the quantum chromodynamics coupling
strength, restricted to the region of phase space that is manifestly
perturbative. We present predictions of the physical cross section as a
function of top quark mass in proton-antiproton reactions at center-of-mass
energies of 1.8 and 2.0 TeV.Comment: 9 pages. Latex file plus 6 ps files of figures submitted togther in
uuencoded form; invited talk presented by Harry Contopanagos at the XXXI
Rencontres de Moriond on QCD and High Energy Hadronic Interactions, Les Arcs,
France, March, 1996. New version to correct problem with unsuccessful posting
of figures on May
Top Quark Production Dynamics in QCD
A calculation of the total cross section for top quark production in
hadron-hadron collisions is presented based on an all-orders perturbative
resummation of initial-state gluon radiative contributions to the basic quantum
chromodynamics subprocesses. Principal-value resummation is used to evaluate
all relevant large threshold contributions. In this method there are no
arbitrary infrared cutoffs, and the perturbative regime of applicability is
well defined, two attributes that significantly reduce the estimated
uncertainty of the results. For collisions at center-of-mass energy
TeV and a top mass of 175 GeV, we obtain
, in agreement with experiment.
Predicted cross sections are provided as a function of top mass in
collisions at TeV and in collisions at CERN LHC energies.Comment: 12 pages. Latex file plus 8 ps files of figures submitted altogther
in uuencoded form; Invited talk presented by E. L. Berger at the
International Symposium on Heavy Flavor and Electroweak Theory, Beijing,
August 16 - 19, 199
Calculation of the Cross Section for Top Quark Production
We summarize calculations of the cross section for top quark production at
hadron colliders within the context of perturbative quantum chromodynamics,
including resummation of the effects of initial-state soft gluon radiation to
all orders in the strong coupling strength. In our approach we resum the
universal leading-logarithm contributions, and we restrict the calculation to
the region of phase space that is demonstrably perturbative. We compare our
approach with other methods. We present predictions of the physical cross
section as a function of the top quark mass in proton-antiproton reactions at
center-of-mass energies of 1.8 and 2.0 TeV, and we discuss estimated
uncertainties.Comment: 13 pages, LaTeX, including 6 ps files of figures. Invited paper
presented by E. L. Berger at the XIth Topical Workshop on Hadron Collider
Physics, Abano Terme, Padova, Italy, May, 199
Non-leading Logarithms in Principal Value Resummation
We apply the method of principal value resummation of large
momentum-dependent radiative corrections to the calculation of the Drell Yan
cross section. We sum all next-to-leading logarithms and provide numerical
results for the resummed exponent and the corresponding hard scattering
function.Comment: 22 pages (LaTeX), 5 figures not included; available upon request from
[email protected], ANL-HEP-PR-94-25, ITP-SB-94-3
Principal Value Resummation
We present a new resummation formula for the Drell-Yan cross section. The
formal resummation of threshold corrections in Drell-Yan hard-scattering
functions produces an exponent with singularities from the infrared pole of the
QCD running coupling. Our reformulation treats such `infrared renormalons' by a
principal value prescription, analogous to a modified Borel transform. The
resulting expression includes all large threshold corrections to the hard
scattering function as an asymptotic series in , but is a finite
function of . We find that the ambiguities of the resummed perturbation
theory imply the presence of higher twist corrections to quark-antiquark
hard-scattering functions that begin at . This suggests an
important role for higher twist in the phenomonolgy of hadron-hadron inclusive
cross sections. We also discuss the numerical evaluation of the exponent and
its asymptotic perturbation series for representative values of .Comment: 28 pages, ITP-SB-93-6
Perturbative Gluon Resummation of the Top Quark Production Cross Section
We present a calculation of the total cross section for top quark production
based on a new perturbative resummation of gluon radiative corrections to the
basic QCD subprocesses. We use Principal Value Resummation to calculate all
relevant large threshold corrections. Advantages of this method include its
independence from arbitrary infrared cutoffs and specification of the
perturbative regime of applicability. For collisions at
center-of-mass energy TeV and a top mass of 175 GeV, we compute
.Comment: PS file, cover page plus 12 pages, plus 4 figure
Threshold Resummation of the Total Cross Section for Heavy Quark Production in Hadronic Collisions
We discuss calculations of the inclusive total cross section for heavy quark
production at hadron collider energies within the context of perturbative
quantum chromodynamics, including resummation of the effects of initial-state
soft gluon radiation to all orders in the strong coupling strength. We resum
the universal leading-logarithm contributions, and we restrict our integrations
to the region of phase space that is demonstrably perturbative. We include a
detailed comparison of the differences between ours and other methods. We
provide predictions of the physical cross section as a function of the heavy
quark mass in proton-antiproton reactions at center-of-mass energies of 1.8 and
2.0 TeV, and we discuss estimated uncertainties.Comment: 31 pages, RevTeX, 7 figure
Sudakov Factorization and Resummation
We present a unified derivation of the resummation of Sudakov logarithms,
directly from the factorization properties of cross sections in which they
occur. We rederive in this manner the well-known exponentiation of leading and
nonleading logarithmic enhancements near the edge of phase space for cross
sections such as deeply inelastic scattering, which are induced by an
electroweak hard scattering. For QCD hard-scattering processes, such as
heavy-quark production, we show that the resummation of nonleading logarithms
requires in general mixing in the space of the color tensors of the hard
scattering. The exponentiation of Sudakov logarithms implies that many weighted
cross sections obey particular evolution equations in momentum transfer, which
streamline the computation of their Sudakov exponents. We illustrate this
method with the resummation of soft-gluon enhancements of the inclusive
Drell-Yan cross section, in both DIS and factorization
schemes.Comment: 32 pages, phyzzx.tex macropackage, 1 figur