2,017 research outputs found
Renormalization of lattice gauge theories with massless Ginsparg Wilson fermions
Using functional techniques, we prove, to all orders of perturbation theory,
that lattice vector gauge theories with Ginsparg Wilson fermions are
renormalizable. For two or more massless fermions, they satisfy a flavour
mixing axial vector Ward identity. It involves a lattice specific part that is
quadratic in the vertex functional and classically irrelevant. We show that it
stays irrelevant under renormalization. This means that in the continuum limit
the (standard) chiral symmetry becomes restored. In particular, the flavour
mixing current does not require renormalization.Comment: 13 pages, Latex2
Practical Algebraic Renormalization
A practical approach is presented which allows the use of a non-invariant
regularization scheme for the computation of quantum corrections in
perturbative quantum field theory. The theoretical control of algebraic
renormalization over non-invariant counterterms is translated into a practical
computational method. We provide a detailed introduction into the handling of
the Slavnov-Taylor and Ward-Takahashi identities in the Standard Model both in
the conventional and the background gauge. Explicit examples for their
practical derivation are presented. After a brief introduction into the Quantum
Action Principle the conventional algebraic method which allows for the
restoration of the functional identities is discussed. The main point of our
approach is the optimization of this procedure which results in an enormous
reduction of the calculational effort. The counterterms which have to be
computed are universal in the sense that they are independent of the
regularization scheme. The method is explicitly illustrated for two processes
of phenomenological interest: QCD corrections to the decay of the Higgs boson
into two photons and two-loop electroweak corrections to the process .Comment: version to be published in Annals of Physic
Stability and renormalization of Yang-Mills theory with Background Field Method: a regularization independent proof
In this paper the stability and the renormalizability of Yang-Mills theory in
the Background Field Gauge are studied. By means of Ward Identities of
Background gauge invariance and Slavnov-Taylor Identities the stability of the
classical model is proved and, in a regularization independent way, its
renormalizability is verified. A prescription on how to build the counterterms
is given and the possible anomalies which may appear for Ward Identities and
for Slavnov-Taylor Identities are shown.Comment: 25 pages, Latex 2.09, no figure
On a class of embeddings of massive Yang-Mills theory
A power-counting renormalizable model into which massive Yang-Mills theory is
embedded is analyzed. The model is invariant under a nilpotent BRST
differential s. The physical observables of the embedding theory, defined by
the cohomology classes of s in the Faddeev-Popov neutral sector, are given by
local gauge-invariant quantities constructed only from the field strength and
its covariant derivatives.Comment: LATEX, 34 pages. One reference added. Version published in the
journa
The Abelian Antighost Equation for The Standard Model in the `t Hooft-Background Gauge
In this paper we study the Abelian Anti-ghost equation for the Standard Model
quantized in the 't Hooft-Background gauge. We show that this equation assures
the non-renormalization of the abelian ghost fields and prevents possible
abelian anomalies.Comment: Latex2e, 22 pages, no figures, use package amssym
The Schwinger Mass in the Massive Schwinger Model
We derive a systematic procedure to compute Green functions for the massive
Schwinger model via a perturbation expansion in the fermion mass. The known
exact solution of the massless Schwinger model is used as a starting point. We
compute the corrections to the Schwinger mass up to second order.Comment: Latex, 7 pages, no figure
Why men with a low-risk prostate cancer select and stay on active surveillance: A qualitative study
https://openworks.mdanderson.org/sumexp21/1151/thumbnail.jp
Dynamical Breakdown of Symmetry in a (2+1) Dimensional Model Containing the Chern-Simons Field
We study the vacuum stability of a model of massless scalar and fermionic
fields minimally coupled to a Chern-Simons field. The classical Lagrangian only
involves dimensionless parameters, and the model can be thought as a (2+1)
dimensional analog of the Coleman-Weinberg model. By calculating the effective
potential, we show that dynamical symmetry breakdown occurs in the two-loop
approximation. The vacuum becomes asymmetric and mass generation, for the boson
and fermion fields takes place. Renormalization group arguments are used to
clarify some aspects of the solution.Comment: Minor modifications in the text and figure
The Lattice Schwinger Model: Confinement, Anomalies, Chiral Fermions and All That
In order to better understand what to expect from numerical CORE computations
for two-dimensional massless QED (the Schwinger model) we wish to obtain some
analytic control over the approach to the continuum limit for various choices
of fermion derivative. To this end we study the Hamiltonian formulation of the
lattice Schwinger model (i.e., the theory defined on the spatial lattice with
continuous time) in gauge. We begin with a discussion of the solution
of the Hamilton equations of motion in the continuum, we then parallel the
derivation of the continuum solution within the lattice framework for a range
of fermion derivatives. The equations of motion for the Fourier transform of
the lattice charge density operator show explicitly why it is a regulated
version of this operator which corresponds to the point-split operator of the
continuum theory and the sense in which the regulated lattice operator can be
treated as a Bose field. The same formulas explicitly exhibit operators whose
matrix elements measure the lack of approach to the continuum physics. We show
that both chirality violating Wilson-type and chirality preserving SLAC-type
derivatives correctly reproduce the continuum theory and show that there is a
clear connection between the strong and weak coupling limits of a theory based
upon a generalized SLAC-type derivative.Comment: 27 pages, 3 figures, revte
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