72 research outputs found
Quantum Link Models with Many Rishon Flavors and with Many Colors
Quantum link models are a novel formulation of gauge theories in terms of
discrete degrees of freedom. These degrees of freedom are described by quantum
operators acting in a finite-dimensional Hilbert space. We show that for
certain representations of the operator algebra, the usual Yang-Mills action is
recovered in the continuum limit. The quantum operators can be expressed as
bilinears of fermionic creation and annihilation operators called rishons.
Using the rishon representation the quantum link Hamiltonian can be expressed
entirely in terms of color-neutral operators. This allows us to study the large
N_c limit of this model. In the 't Hooft limit we find an area law for the
Wilson loop and a mass gap. Furthermore, the strong coupling expansion is a
topological expansion in which graphs with handles and boundaries are
suppressed.Comment: Lattice2001(theorydevelop), poster by O. Baer and talk by B.
Schlittgen, 6 page
The Color--Flavor Transformation of induced QCD
The Zirnbauer's color-flavor transformation is applied to the
lattice gauge model, in which the gauge theory is induced by a heavy chiral
scalar field sitting on lattice sites. The flavor degrees of freedom can
encompass several `generations' of the auxiliary field, and for each
generation, remaining indices are associated with the elementary plaquettes
touching the lattice site. The effective, color-flavor transformed theory is
expressed in terms of gauge singlet matrix fields carried by lattice links. The
effective action is analyzed for a hypercubic lattice in arbitrary dimension.
We investigate the corresponding d=2 and d=3 dual lattices. The saddle points
equations of the model in the large- limit are discussed.Comment: 24 pages, 6 figures, to appear in Int. J. Mod. Phys.
Lattice gauge theory with baryons at strong coupling
We study the effective Hamiltonian for strong-coupling lattice QCD in the
case of non-zero baryon density. In leading order the effective Hamiltonian is
a generalized antiferromagnet. For naive fermions, the symmetry is U(4N_f) and
the spins belong to a representation that depends on the local baryon number.
Next-nearest-neighbor (nnn) terms in the Hamiltonian break the symmetry to
U(N_f) x U(N_f). We transform the quantum problem to a Euclidean sigma model
which we analyze in a 1/N_c expansion. In the vacuum sector we recover
spontaneous breaking of chiral symmetry for the nearest-neighbor and nnn
theories. For non-zero baryon density we study the nearest-neighbor theory
only, and show that the pattern of spontaneous symmetry breaking depends on the
baryon density.Comment: 31 pages, 5 EPS figures. Corrected Eq. (6.1
D-Theory: Field Quantization by Dimensional Reduction of Discrete Variables
D-theory is an alternative non-perturbative approach to quantum field theory
formulated in terms of discrete quantized variables instead of classical
fields. Classical scalar fields are replaced by generalized quantum spins and
classical gauge fields are replaced by quantum links. The classical fields of a
d-dimensional quantum field theory reappear as low-energy effective degrees of
freedom of the discrete variables, provided the (d+1)-dimensional D-theory is
massless. When the extent of the extra Euclidean dimension becomes small in
units of the correlation length, an ordinary d-dimensional quantum field theory
emerges by dimensional reduction. The D-theory formulation of scalar field
theories with various global symmetries and of gauge theories with various
gauge groups is constructed explicitly and the mechanism of dimensional
reduction is investigated.Comment: 30 pages, no figure
A few remarks on colour-flavour transformations, truncations of random unitary matrices, Berezin reproducing kernels and Selberg-type integrals
The Humboldt Foundation is acknowledged for the financial support of that visit. The research in Nottingham was supported by EPSRC grant EP/C515056/1 'Random Matrices and Polynomials: a tool to understand complexity'
A graphical vector autoregressive modelling approach to the analysis of electronic diary data
<p>Abstract</p> <p>Background</p> <p>In recent years, electronic diaries are increasingly used in medical research and practice to investigate patients' processes and fluctuations in symptoms over time. To model dynamic dependence structures and feedback mechanisms between symptom-relevant variables, a multivariate time series method has to be applied.</p> <p>Methods</p> <p>We propose to analyse the temporal interrelationships among the variables by a structural modelling approach based on graphical vector autoregressive (VAR) models. We give a comprehensive description of the underlying concepts and explain how the dependence structure can be recovered from electronic diary data by a search over suitable constrained (graphical) VAR models.</p> <p>Results</p> <p>The graphical VAR approach is applied to the electronic diary data of 35 obese patients with and without binge eating disorder (BED). The dynamic relationships for the two subgroups between eating behaviour, depression, anxiety and eating control are visualized in two path diagrams. Results show that the two subgroups of obese patients with and without BED are distinguishable by the temporal patterns which influence their respective eating behaviours.</p> <p>Conclusion</p> <p>The use of the graphical VAR approach for the analysis of electronic diary data leads to a deeper insight into patient's dynamics and dependence structures. An increasing use of this modelling approach could lead to a better understanding of complex psychological and physiological mechanisms in different areas of medical care and research.</p
Ethical Awareness, Ethical Judgment and Whistleblowing: A Moderated Mediation Analysis
This study aims to examine the ethical decision-making (EDM) model proposed by Schwartz (J Bus Ethics, doi:10.1007/s10551-015-2886-8,2016), where we consider the factors of non-rationality and aspects that affect ethical judgments of auditors to make the decision to blow the whistle. In this paper, we argue that the intention of whistleblowing depends on ethical awareness (EAW) and ethical judgment (EJW) as well as there is a mediation–moderation due to emotion (EMT) and perceived moral intensity (PMI) of auditors. Data were collected using an online surveywith 162 external auditors who worked on audit firms in Indonesia as well as 173 internal auditors working in the manufacturing and financial services. The result of multigroup analysis shows that emotion (EMT) can mediate the relationship between EAW and EJW. The nature of this relationship is more complex and then tested by adding moderating variables using consistent partial least squares approach. We found that EMT and PMI can improve the relationship between ethical judgments and whistleblowing intentions. These findings indicate that internal auditors are more likely to blow the whistle than external auditors; and reporting wrongdoing internally and anonymously are the preferred way of professional accountants to blow the whistle in Indonesia
PLS path modeling in marketing and genetic algorithm segmentation
This paper presents the PLS genetic algorithm segmentation methodology which uses directed random searches to detect an optimum solution in the complex search space that underlies data partitioning tasks in PLS path modeling. The results of a simulation study allow a primary assessment of this novel approach and reveal its capabilities and effectiveness. Furthermore, applying the approach to the American Customer Satisfaction Index model allows unobserved heterogeneity and different consumer segments to be uncovered
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