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

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

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

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 $\Delta S = 2$ operator.Comment: 9 pages, uuencoded PS file, 8 figures included, 1 tabl

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

Moments of Structure Functions in Full QCD

Moments of the quark density distribution, moments of the quark helicity distribution, and the tensor charge are calculated in full QCD. Calculations of matrix elements of operators from the operator product expansion have been performed on $16^3 \times 32$ lattices for Wilson fermions at $\beta = 5.6$ using configurations from the SESAM collaboration and at $\beta = 5.5$ using configurations from SCRI. One-loop perturbative renormalization corrections are included. Selected results are compared with corresponding quenched calculations and with calculations using cooled configurations.Comment: Lattice 2000 (Hadronic Matrix Elements), 4 pages, 5 figure

Nonperturbative Renormalisation of Composite Operators in Lattice QCD

We investigate the nonperturbative renormalisation of composite operators in lattice QCD restricting ourselves to operators that are bilinear in the quark fields. These include operators which are relevant to the calculation of moments of hadronic structure functions. The computations are based on Monte Carlo simulations using quenched Wilson fermions.Comment: LaTeX, 41 pages, 24 figure

Polarized and Unpolarized Nucleon Structure Functions from Lattice QCD

We report on a high statistics quenched lattice QCD calculation of the deep-inelastic structure functions $F_1$, $F_2$, $g_1$ and $g_2$ of the proton and neutron. The theoretical basis for the calculation is the operator product expansion. We consider the moments of the leading twist operators up to spin four. Using Wilson fermions the calculation is done for three values of $\kappa$, and we perform the extrapolation to the chiral limit. The renormalization constants, which lead us from lattice to continuum operators, are calculated in perturbation theory to one loop order.Comment: 17 pages, uuencoded postscript file. Renormalization constant of now include

Moments of Nucleon Light Cone Quark Distributions Calculated in Full Lattice QCD

Moments of the quark density, helicity, and transversity distributions are calculated in unquenched lattice QCD. Calculations of proton matrix elements of operators corresponding to these moments through the operator product expansion have been performed on $16^3 \times 32$ lattices for Wilson fermions at $\beta = 5.6$ using configurations from the SESAM collaboration and at $\beta = 5.5$ using configurations from SCRI. One-loop perturbative renormalization corrections are included. At quark masses accessible in present calculations, there is no statistically significant difference between quenched and full QCD results, indicating that the contributions of quark-antiquark excitations from the Dirac Sea are small. Close agreement between calculations with cooled configurations containing essentially only instantons and the full gluon configurations indicates that quark zero modes associated with instantons play a dominant role. Naive linear extrapolation of the full QCD calculation to the physical pion mass yields results inconsistent with experiment. Extrapolation to the chiral limit including the physics of the pion cloud can resolve this discrepancy and the requirements for a definitive chiral extrapolation are described.Comment: 53 Pages Revtex, 26 Figures, 9 Tables. Added additional reference and updated referenced data in Table I