4,523 research outputs found
(1+1)-Dimensional Yang-Mills Theory Coupled to Adjoint Fermions on the Light Front
We consider SU(2) Yang-Mills theory in 1+1 dimensions coupled to massless
adjoint fermions. With all fields in the adjoint representation the gauge group
is actually SU(2)/Z_2, which possesses nontrivial topology. In particular,
there are two distinct topological sectors and the physical vacuum state has a
structure analogous to a \theta vacuum. We show how this feature is realized in
light-front quantization, with periodicity conditions used to regulate the
infrared and treating the gauge field zero mode as a dynamical quantity. We
find expressions for the degenerate vacuum states and construct the analog of
the \theta vacuum. We then calculate the bilinear condensate in the model. We
argue that the condensate does not affect the spectrum of the theory, although
it is related to the string tension that characterizes the potential between
fundamental test charges when the dynamical fermions are given a mass. We also
argue that this result is fundamentally different from calculations that use
periodicity conditions in x^1 as an infrared regulator.Comment: 20 pages, Revte
Stability and Boundedness of Solutions to Some Non-autonomous Multidimensional Nonlinear Systems
Assessment of degree of boundedness and stability of multidimensional
nonlinear systems with time-dependent and especially nonperiodic coefficients
is an important applied problem which has no adequate resolution yet. Most of
the known techniques mostly provide computationally intensive and conservative
stability criteria in this area which frequently fail to gage the degrees of
stability and especially boundedness of solutions to the corresponding systems.
Recently, we outline a new approach to this task resting on analysis of
solutions to a scalar auxiliary equation bounding from above time-histories of
the norms of solutions to the original systems. This paper develops a new
technique casting the auxiliary equation in a simplified form which, in turn,
amplifies its application domain and reduces the computational hamper of our
prior approach. Consequently, we develop novel boundedness and stability
criteria and estimated the trapping and stability regions for some
multidimensional nonlinear systems with time - dependent coefficients. This let
us to assess in target simulations the degree of boundedness and stability of
multidimensional nonlinear and non-autonomous systems which were intractable to
our prior methodolog
A solution to the fermion doubling problem for supersymmetric theories on the transverse lattice
Species doubling is a problem that infects most numerical methods that use a
spatial lattice. An understanding of species doubling can be found in the
Nielsen-Ninomiya theorem which gives a set of conditions that require species
doubling. The transverse lattice approach to solving field theories, which has
at least one spatial lattice, fails one of the conditions of the
Nielsen-Ninomiya theorem nevertheless one still finds species doubling for the
standard Lagrangian formulation of the transverse lattice. We will show that
the Supersymmetric Discrete Light Cone Quantization (SDLCQ) formulation of the
transverse lattice does not have species doubling.Comment: 4 pages, v2: a reference and comments added, the version to appear in
Phys. Rev.
Effects of a fundamental mass term in two-dimensional super Yang-Mills theory
We show that adding a vacuum expectation value to a gauge field left over
from a dimensional reduction of three-dimensional pure supersymmetric
Yang-Mills theory generates mass terms for the fundamental fields in the
two-dimensional theory while supersymmetry stays intact. This is similar to the
adjoint mass term that is generated by a Chern-Simons term in this theory. We
study the spectrum of the two-dimensional theory as a function of the vacuum
expectation value and of the Chern-Simons coupling. Apart from some symmetry
issues a straightforward picture arises. We show that at least one massless
state exists if the Chern-Simons coupling vanishes. The numerical spectrum
separates into (almost) massless and very heavy states as the Chern-Simons
coupling grows. We present evidence that the gap survives the continuum limit.
We display structure functions and other properties of some of the bound
states.Comment: 17 pp., 10 figs; substantially revised version to be published in
Phys. Rev.
Comparison of automated nucleic acid extraction methods for the detection of cytomegalovirus DNA in fluids and tissues
Testing for cytomegalovirus (CMV) DNA is increasingly being used for specimen types other than plasma or whole blood. However, few studies have investigated the performance of different nucleic acid extraction protocols in such specimens. In this study, CMV extraction using the Cell-free 1000 and Pathogen Complex 400 protocols on the QIAsymphony Sample Processing (SP) system were compared using bronchoalveolar lavage fluid (BAL), tissue samples, and urine. The QIAsymphonyAssay Set-up (AS) system was used to assemble reactions using artus CMV PCR reagents and amplification was carried out on the Rotor-Gene Q. Samples from 93 patients previously tested for CMV DNA and negative samples spiked with CMV AD-169 were used to evaluate assay performance. The Pathogen Complex 400 protocol yielded the following results: BAL, sensitivity 100% (33/33), specificity 87% (20/23); tissue, sensitivity 100% (25/25), specificity 100% (20/20); urine, sensitivity 100% (21/21), specificity 100% (20/20). Cell-free 1000 extraction gave comparable results for BAL and tissue, however, for urine, the sensitivity was 86% (18/21) and specimen quantitation was inaccurate. Comparative studies of different extraction protocols and DNA detection methods in body fluids and tissues are needed, as assays optimized for blood or plasma will not necessarily perform well on other specimen types
Quantum Mechanics of Dynamical Zero Mode in on the Light-Cone
Motivated by the work of Kalloniatis, Pauli and Pinsky, we consider the
theory of light-cone quantized on a spatial circle with periodic
and anti-periodic boundary conditions on the gluon and quark fields
respectively. This approach is based on Discretized Light-Cone Quantization
(DLCQ). We investigate the canonical structures of the theory. We show that the
traditional light-cone gauge is not available and the zero mode (ZM)
is a dynamical field, which might contribute to the vacuum structure
nontrivially. We construct the full ground state of the system and obtain the
Schr\"{o}dinger equation for ZM in a certain approximation. The results
obtained here are compared to those of Kalloniatis et al. in a specific
coupling region.Comment: 19 pages, LaTeX file, no figure
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