998 research outputs found
Two-loop renormalization of vector, axial-vector and tensor fermion bilinears on the lattice
We compute the two-loop renormalization functions, in the RI' scheme, of
local bilinear quark operators , where
corresponds to the Vector, Axial-Vector and Tensor Dirac operators, in the
lattice formulation of QCD. We consider both the flavor nonsinglet and singlet
operators.
We use the clover action for fermions and the Wilson action for gluons. Our
results are given as a polynomial in , in terms of both the
renormalized and bare coupling constant, in the renormalized Feynman gauge.
Finally, we present our results in the MSbar scheme, for easier comparison
with calculations in the continuum. The corresponding results, for fermions in
an arbitrary representation, together with some special features of
superficially divergent integrals, are included in the Appendices.Comment: 42 pages, 10 figures. Version accepted in PRD. Added comments and
references, provided per diagram numerical values; final results and
conclusions left unchanged. This paper is a sequel to arXiv:0707.2906 (Phys.
Rev. D76 (2007) 094514), which regards the scalar and pseudoscalar cases
One-loop calculations in Supersymmetric Lattice QCD
We study the self energies of all particles which appear in a lattice
regularization of supersymmetric QCD (). We compute, perturbatively
to one-loop, the relevant two-point Green's functions using both the
dimensional and the lattice regularizations. Our lattice formulation employs
the Wilson fermion acrion for the gluino and quark fields. The gauge group that
we consider is while the number of colors, and the number of
flavors, , are kept as generic parameters. We have also searched for
relations among the propagators which are computed from our one-loop results.
We have obtained analytic expressions for the renormalization functions of the
quark field (), gluon field (), gluino field () and
squark field ().
We present here results from dimensional regularization, relegating to a
forthcoming publication our results along with a more complete list of
references. Part of the lattice study regards also the renormalization of quark
bilinear operators which, unlike the non-supersymmetric case, exhibit a rich
pattern of operator mixing at the quantum level.Comment: 6 pages, 5 figure, XII Quark Confinement proceeding
Perturbative Renormalization of Wilson line operators
We present results for the renormalization of gauge invariant nonlocal
fermion operators which contain a Wilson line, to one loop level in lattice
perturbation theory. Our calculations have been performed for Wilson/clover
fermions and a wide class of Symanzik improved gluon actions. The extended
nature of such `long-link' operators results in a nontrivial renormalization,
including contributions which diverge linearly as well as logarithmically with
the lattice spacing, along with additional finite factors. We present
nonperturbative prescriptions to extract the linearly divergent contributions.Comment: 8 pages, 2 figures. Talk presented at the 35th International
Symposium on Lattice Field Theory, 18-24 June 2017, Granada, Spai
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