3,360 research outputs found

    Center Vortex Model for the Infrared Sector of SU(3) Yang-Mills Theory - Vortex Free Energy

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    The vortex free energy is studied in the random vortex world-surface model of the infrared sector of SU(3) Yang-Mills theory. The free energy of a center vortex extending into two spatial directions, which is introduced into Yang-Mills configurations when acting with the 't Hooft loop operator, is verified to furnish an order parameter for the deconfinement phase transition. It is shown to exhibit a weak discontinuity at the critical temperature, corresponding to the weak first order character of the transition.Comment: 13 pages, 2 figures containing 3 eps file

    Quantum gauge fixing and vortex dominance

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    We introduce quantum gauge fixing (QGF) as a new class of gauge fixings. While the maximal center gauge might not show vortex dominance, the confining properties of the vortices observed in past lattice calculations are argued to have been obtained in a gauge more akin to QGF than to the strict maximal center gauge.Comment: talk presented at LATTICE99(confinement), Pisa, Italy, 3 pages, 2 figures, LaTeX using espcrc2.st

    Writhe of center vortices and topological charge -- an explicit example

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    The manner in which continuum center vortices generate topological charge density is elucidated using an explicit example. The example vortex world-surface contains one lone self-intersection point, which contributes a quantum 1/2 to the topological charge. On the other hand, the surface in question is orientable and thus must carry global topological charge zero due to general arguments. Therefore, there must be another contribution, coming from vortex writhe. The latter is known for the lattice analogue of the example vortex considered, where it is quite intuitive. For the vortex in the continuum, including the limit of an infinitely thin vortex, a careful analysis is performed and it is shown how the contribution to the topological charge induced by writhe is distributed over the vortex surface.Comment: 33 latex pages, 10 figures incorporating 14 ps files. Furthermore, the time evolution of the vortex line discussed in this work can be viewed as a gif movie, available for download by following the PostScript link below -- watch for the cute feature at the self-intersection poin

    Energy Density of Vortices in the Schroedinger Picture

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    The one-loop energy density of an infinitely thin static magnetic vortex in SU(2) Yang-Mills theory is evaluated using the Schroedinger picture. Both the gluonic fluctuations as well as the quarks in the vortex background are included. The energy density of the magnetic vortex is discussed as a function of the magnetic flux. The center vortices correspond to local minima in the effective potential. These minima are degenerated with the perturbative vacuum if the fermions are ignored. Inclusion of fermions lifts this degeneracy, raising the vortex energy above the energy of the perturbative vacuum.Comment: 25 pages, 2 figure

    Fair Equality of Opportunity Critically Reexamined: The Family and the Sustainability of Health Care Systems

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    A complex interaction of ideological, financial, social, and moral factors makes the financial sustainability of health care systems a challenge across the world. One difficulty is that some of the moral commitments of some health care systems collide with reality. In particular, commitments to equality in access to health care and to fair equality of opportunity undergird an unachievable promise, namely, to provide all with the best of basic health care. In addition, commitments to fair equality of opportunity are in tension with the existence of families, because families are aimed at advantaging their own members in preference to others. Because the social-democratic state is committed to fair equality of opportunity, it offers a web of publicly funded entitlements that make it easier for persons to exit the family and to have children outside of marriage. In the United States, in 2008, 41% of children were born outside of wedlock, whereas, in 1940, the percentage was only 3.8%, and in 1960, 5%, with the further consequence that the social and financial capital generated through families, which aids in supporting health care in families, is diminished. In order to explore the challenge of creating a sustainable health care system that also supports the traditional family, the claims made for fair equality of opportunity in health care are critically reconsidered. This is done by engaging the expository device of John Rawls's original position, but with a thin theory of the good that is substantively different from that of Rawls, one that supports a health care system built around significant copayments, financial counseling, and compulsory savings, with a special focus on enhancing the financial and social capital of the family. This radical recasting of Rawls, which draws inspiration from Singapore, is undertaken as a heuristic to aid in articulating an approach to health care allocation that can lead past the difficulties of social-democratic policy

    Restorative Justice-Informed Moral Acquaintance: Resolving the Dual Role Problem in Correctional and Forensic Practice

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    The issue of dual roles within forensic and correctional fields has typically been conceptualized as dissonance—experienced by practitioners— when attempting to adhere to the conflicting ethical requirements associated with client well-being and community protection. In this paper, we argue that the dual role problem should be conceptualized more broadly; to incorporate the relationship between the offender and their victim. We also propose that Restorative Justice (RJ) is able to provide a preliminary ethical framework to deal with this common ethical oversight. Furthermore, we unite the RJ framework with that of Ward’s (2013) moral acquaintance model to provide a more powerful approach—RJ informed moral acquaintance—aimed at addressing the ethical challenges faced by practitioners within forensic and correctional roles

    Interaction of confining vortices in SU(2) lattice gauge theory

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    Center projection of SU(2) lattice gauge theory allows to isolate magnetic vortices as confining configurations. The vortex density scales according to the renormalization group, implying that the vortices are physical objects rather than lattice artifacts. Here, the binary correlations between points at which vortices pierce a given plane are investigated. We find an attractive interaction between the vortices. The correlations show the correct scaling behavior and are therefore physical. The range of the interaction is found to be (0.4 +/- 0.2) fm, which should be compared with the average planar vortex density of approximately 2 vortices/fm^2. We comment on the implications of these results for recent discussions of the Casimir scaling behavior of higher dimensional representation Wilson loops in the vortex confinement picture.Comment: 9 pages LaTeX, 2 ps figures included via eps

    Center Vortex Model for the Infrared Sector of SU(3) Yang-Mills Theory - Confinement and Deconfinement

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    The center vortex model for the infrared sector of Yang-Mills theory, previously studied for the SU(2) gauge group, is extended to SU(3). This model is based on the assumption that vortex world-surfaces can be viewed as random surfaces in Euclidean space-time. The confining properties are investigated, with a particular emphasis on the finite-temperature deconfining phase transition. The model predicts a very weak first order transition, in agreement with SU(3) lattice Yang-Mills theory, and also reproduces a consistent behavior of the spatial string tension in the deconfined phase. The geometrical structure of the center vortices is studied, including vortex branchings, which are a new property of the SU(3) case.Comment: 22 pages, 12 figures (30 eps-files), uses LaTeX package "psfrag

    Center vortex properties in the Laplace center gauge of SU(2) Yang-Mills theory

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    Resorting to the the Laplace center gauge (LCG) and to the Maximal-center gauge (MCG), respectively, confining vortices are defined by center projection in either case. Vortex properties are investigated in the continuum limit of SU(2) lattice gauge theory. The vortex (area) density and the density of vortex crossing points are investigated. In the case of MCG, both densities are physical quantities in the continuum limit. By contrast, in the LCG the piercing as well as the crossing points lie dense in the continuum limit. In both cases, an approximate treatment by means of a weakly interacting vortex gas is not appropriate.Comment: reference added, submitted to Phys. Lett.

    Topological Susceptibility of Yang-Mills Center Projection Vortices

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    The topological susceptibility induced by center projection vortices extracted from SU(2) lattice Yang-Mills configurations via the maximal center gauge is measured. Two different smoothing procedures, designed to eliminate spurious ultraviolet fluctuations of these vortices before evaluating the topological charge, are explored. They result in consistent estimates of the topological susceptibility carried by the physical thick vortices characterizing the Yang-Mills vacuum in the vortex picture. This susceptibility is comparable to the one obtained from the full lattice Yang-Mills configurations. The topological properties of the SU(2) Yang-Mills vacuum can thus be accounted for in terms of its vortex content.Comment: 12 revtex pages, 6 ps figures included using eps
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