88 research outputs found
Deep Inelastic Scattering in Improved Lattice QCD. II. The second moment of structure functions
In this paper we present the 1-loop perturbative computation of the
renormalization constants and mixing coefficients of the lattice quark
operators of rank three whose hadronic elements enter in the determination of
the second moment of Deep Inelastic Scattering (DIS) structure functions.
We have employed in our calculations the nearest-neighbor improved
``clover-leaf'' lattice QCD action. The interest of using this action in Monte
Carlo simulations lies in the fact that all terms which in the continuum limit
are effectively of order ( being the lattice spacing) have been
demonstrated to be absent from on-shell hadronic lattice matrix elements. We
have limited our computations to the quenched case, in which quark operators do
not mix with gluon operators.
We have studied the transformation properties under the hypercubic group of
the operators up to the rank five (which are related to moments up to the
fourth of DIS structure functions), and we discuss the choice of the operators
considered in this paper together with the feasibility of lattice computations
for operators of higher ranks.
To perform the huge amount of calculations required for the evaluation of all
the relevant Feynman diagrams, we have extensively used the symbolic
manipulation languages Schoonschip and Form.Comment: 30 pages, latex + elsart + feynman (complete postscript file
available upon request to [email protected]); submitted to
Nuclear Physics
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
DIS Structure Functions in Lattice QCD
In this talk I present the complete 1-loop perturbative computation of the
renormalization constants and mixing coefficients of quark and gluon lattice
operators of rank two and three whose hadronic elements enter in the
determination of the first and second moment of Deep Inelastic Scattering
Structure Functions, making use of the nearest-neighbor improved
``clover-leaf'' lattice QCD action.
To perform the huge amount of calculations required for the evaluation of all
the relevant Feynman diagrams, extensive use of symbolic manipulation languages
like Schoonschip and Form has been made.Comment: Talk presented at LATTICE96(theoretical developments) by S. Capitani;
3 pages, LaTeX and espcrc2.sty (included
Lattice computation of structure functions
Recent lattice calculations of hadron structure functions are described.Comment: Plenary talk presented at LATTICE96, LaTeX, 7 pages, 5 figures,
espcrc2.sty and epsfig.sty include
Moments of parton evolution probabilities on the lattice within the Schroedinger functional scheme
We define, within the Schroedinger functional scheme (SF), the matrix
elements of the twist-2 operators corresponding to the first two moments of
non-singlet parton densities. We perform a lattice one-loop calculation that
fixes the relation between the SF scheme and other common schemes and shows the
main source of lattice artefacts. This calculation sets the basis for a
numerical evaluation of the non-perturbative running of parton densities.Comment: Latex file, 4 figures, 15 page
Non-perturbative Renormalization of Lattice Operators
We briefly review and compare three methods (one perturbative, one based on
Ward Identities and one non-perturbative) for the calculation of the
renormalization constants of lattice operators. The following results are
presented: (a) non perturbative renormalization of the operators with light
quarks; (b) the renormalization constants with a heavy (charm) quark mass and
its KLM improvement; (c) the non perturbative determination of the mixing of
the operator.Comment: 9 pages, uuencoded PS file, 8 figures included, 1 tabl
Recommended from our members
The Contingent Role of Conflict: Deliberative Interaction and Disagreement in Shareholder Engagement
How is the tension between conflict and deliberation resolved in shareholder engagement? We address this question by studying shareholder engagement as a deliberative process with three stages: establishing dialogue, solution development, and solution implementation. We theorize that two interactionist mechanisms, deliberative interaction and the voicing of disagreement, play different roles at different stages of the process. We test our hypotheses with a proprietary database of 169 environmental, social and governance (ESG) engagements with US public companies over 2007–2012. We find that while deliberative interaction does not help advance the engagement process, it positively moderates the effect of disagreement in the solution-development stage. By contrast, in the solution-implementation stage, deliberative interaction amplifies the negative effect of disagreement, thus hindering progress in the engagement. Our paper contributes to shareholder engagement, deliberation theory and interactionist organization theory by establishing that engagement effectiveness is an interactional achievement, shaped by both deliberation and disagreement
Perturbative Renormalization of Lattice Bilinear Quark Operators
Our aim is to compute the lower moments of the unpolarized and polarized
deep-inelastic structure functions of the nucleon on the lattice. The
theoretical basis of the calculation is the operator product expansion. To
construct operators with the appropriate continuum behavior out of the bare
lattice operators one must absorb the effects of momentum scales far greater
than any physical scale into a renormalization of the operators. In this work
we compute the renormalization constants of all bilinear quark operators of
leading twist and spin up to four. The calculation is done for Wilson fermions
and in the quenched approximation where dynamical quark loops are neglected.Comment: 28 pages, uuencoded Z-compressed postscript file. Also available from
http://www.desy.de/pub/preprints/desy/199
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