5,328 research outputs found
Perturbative and Non-perturbative Lattice Calculations for the Study of Parton Distributions
We discuss how lattice calculations can be a useful tool for the study of
structure functions. Particular emphasis is given to the perturbative
renormalization of the operators.Comment: 6 pages. Talk presented at the 6th International Symposium on
Radiative Corrections "RADCOR 2002" and 6th Zeuthen Workshop on Elementary
Particle Theory "Loops and Legs 2002", Kloster Banz (Germany), September 8 to
13, 200
Perturbative renormalization of the first moment of structure functions for domain-wall QCD
Using the domain-wall formulation of lattice fermions, we have computed the
one-loop renormalization factors of one-link operators which measure the first
nontrivial moment of the unpolarized, polarized and transversity structure
functions, in the flavor nonsinglet sector. The knowledge of these factors is
necessary in order to extract physical numbers from domain-wall Monte Carlo
simulations of parton distributions.
We have automated the perturbative calculations by developing suitable FORM
codes. The results show that in many instances the total renormalization
factors are almost equal to one, and that hence the corresponding operators
are, for the appropriate values of the Dirac mass and the coupling ,
practically unrenormalized.Comment: REVTeX 4, 12 pages, 1 figure; changes in the final paragraphs of
sections 1 and 5 concerning comparisons with previous results, plus
correction of minor typos; final version, accepted for publication in
Physical Review
Perturbative renormalization of the first two moments of non-singlet quark distributions with overlap fermions
Using the overlap-Dirac operator proposed by Neuberger, we have computed in
lattice QCD the one-loop renormalization factors of ten operators which measure
the lowest two moments of unpolarized and polarized non-singlet quark
distributions. These factors are necessary to extract physical numbers from
Monte Carlo simulations made with overlap fermions.
An exact chiral symmetry is maintained in all our results, and the
renormalization constants of corresponding unpolarized and polarized operators
which differ by a matrix have the same value. We have considered two
lattice representations for each continuum operator. The computations have been
carried out using the symbolic language FORM, in a general covariant gauge. In
some simple cases they have also been checked by hand.Comment: 23 pages, 1 Postscript figure, uses elsevier style. Small corrections
made in eqs. (6), (7), (13), (15), (17), (19), (20), (21) and (A.8), with no
influence on the result
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