57 research outputs found
Approximate Next-to-Leading Order and Next-to-Next-to-Leading Order Corrections
For processes involving structure functions and/or fragmentation functions,
arguments that, over a range of a proper kinematic variable, there is a part
that dominates the next-to-leading order (NLO) corrections are briefly
reviewed. The arguments are tested against more recent NLO and in particular
complete next-to-next-to-leading order (NNLO) calculations. A critical
examination of when these arguments may not be useful is also presented.Comment: 8 pages and 4 figure
Laurent series expansion of a class of massive scalar one-loop integrals up to {\cal O}(\ep^2) in terms of multiple polylogarithms
In a recent paper we have presented results for a set of massive scalar
one-loop master integrals needed in the NNLO parton model description of the
hadroproduction of heavy flavors. The one--loop integrals were evaluated in
n=4-2\ep dimension and the results were presented in terms of a Laurent
series expansion up to {\cal O}(\ep^2). We found that some of the \ep^2
coefficients contain a new class of functions which we termed the
functions. The functions are defined in terms of one--dimensional integrals
involving products of logarithm and dilogarithm functions. In this paper we
derive a complete set of algebraic relations that allow one to convert the
functions of our previous approach to a sum of classical and multiple
polylogarithms. Using these results we are now able to present the \ep^2
coefficients of the one-loop master integrals in terms of classical and
multiple polylogarithms.Comment: 32 pages, Latex, references added, matches published versio
Next-to-next-to-leading order results for heavy quark pair production in quark--antiquark collisions: The one-loop squared contributions
We calculate the next-to-next-to-leading order
one-loop squared corrections to the production of heavy quark pairs in
quark-antiquark annihilations. These are part of the next-to-next-to-leading
order radiative QCD corrections to this process. Our
results, with the full mass dependence retained, are presented in a closed and
very compact form, in the dimensional regularization scheme. We have found very
intriguing factorization properties for the finite part of the amplitudes.Comment: 12 pages, 2 figures, electronic results file, abbreviation NNLO in
Title and Abstract expanded, Summary expanded, reference updated, version to
appear in Phys.Rev.
One-loop amplitudes for four-point functions with two external massive quarks and two external massless partons up to O(epsilon^2)
We present complete analytical results on the
one-loop amplitudes relevant for the NNLO quark-parton model description of the
hadroproduction of heavy quarks as given by the so-called loop-by-loop
contributions. All results of the perturbative calculation are given in the
dimensional regularization scheme. These one-loop amplitudes can also be used
as input in the determination of the corresponding NNLO cross sections for
heavy flavor photoproduction, and in photon-photon reactions.Comment: 25 pages, 6 figures in the text, Revtex, one reference added, minor
improvements in the text, to appear in Phys.Rev.
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