28,087 research outputs found

    Monopole Loop Distribution and Confinement in SU(2) Lattice Gauge Theory

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    The abelian-projected monopole loop distribution is extracted from maximal abelian gauge simulations. The number of loops of a given length falls as a power of the length nearly independent of lattice size. This power increases with β=4/g2\beta=4/g^2, reaching five around β=2.85\beta=2.85, beyond which loops any finite fraction of the lattice size vanish in the infinite lattice limit, suggesting the continuum theory lacks confinement.Comment: 6 pages Latex, 4 eps figures. Minor editing. Final version, to appear in Physics Letters

    Deconfinement from Action Restriction

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    The effect of restricting the plaquette to be greater than a certain cutoff value is studied. The action considered is the standard Wilson action with the addition of a plaquette restriction, which should not affect the continuum limit of the theory. In this investigation, the strong coupling limit is also taken. It is found that a deconfining phase transition occurs as the cutoff is increased, on all lattices studied (up to 20420^4). The critical cutoff on the infinite lattice appears to be around 0.55. For cutoffs above this, a fixed point behavior is observed in the normalized fourth cumulant of the Polyakov loop, suggesting the existence of a line of critical points corresponding to a massless gluon phase, not unlike the situation in compact U(1). The Polyakov loop susceptibility also appears to be diverging with lattice size at these cutoffs. A strong finite volume behavior is observed in the pseudo-specific heat. It is discussed whether these results could still be consistent with the standard crossover picture which precludes the existence of a deconfining phase transition on an infinite symmetric lattice.Comment: 4 pages latex, 6 ps figures, uses espcrc2.sty (included). Poster presented at LATTICE96(topology

    Particle velocity experiments in anorthosite and gabbro

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    Shock wave experiments were conducted in San Gabriel anorthosite and San Marcos gabbra 10 11 GPa using a 40 mm-borne propellant gun. Particle velocities were measured directly at several points in each target by means of electromagnetic gauges. Hugoniot states were calculated by determining shock-transit time from the gauge records. Sound speeds indicate a loss of shear strength upon sock compression for both rocks, with the strength loss persisting upon release to zero stress om the anorthosite. Stress-density release paths in the anorthosite indicate possible transformation of albite to jadeite + (quartz or coesite), with the amount of material transformed increasing as a function of shock stress. Electrical interferene effects in the gabbro precluded the determination of accurate release paths for the rock

    Answering the Calls of "What's Next" and "Library Workers Cannot Live by Love Alone" through Certification and Salary Research

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    Members and staff of the American Library Association (ALA) worked diligently over more than a decade to develop a certification program for public library managers. Spurred by a long-standing trend in many other terminal-degree professions that have post-degree, voluntary certifications, the Certified Public Library Administrator Program was born. Legal authority recommended the establishment of a service organization, a 501(c)(6) to manage the program, which has become one of several programs that will be offered to library employees under the imprimatur of ALA. After the American Library Association???Allied Professional Association (ALA-APA) was instituted, advocacy for salary improvement initiatives was appended to the mission. One means of salary advocacy was to improve available data by expanding the scope and usefulness of the ALA Survey of Librarian Salaries, which resulted in the ALA-APA Salary Survey: Non-MLS???Public and Academic, conducted in 2006 and 2007 to collect salary data from more than sixty positions in the field that do not require a master's degree in Library Science. The experience of establishing two certification programs, the Certified Public Library Administrator Program (CPLA??) and the Library Support Staff Certification Program, has been a study in creating new national models of professional development. This article will also discuss the insights that have emerged from fulfilling elements of ALA strategic plans concerning the needs of support staff through certification and the salary survey.published or submitted for publicatio

    Toward a proof of long range order in 4-d SU(N) lattice gauge theory

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    An extended version of 4-d SU(2) lattice gauge theory is considered in which different inverse coupling parameters are used, βH=4/gH2\beta_H=4/g_{H}^2 for plaquettes which are purely spacelike, and βV\beta_V for those which involve the Euclidean timelike direction. It is shown that when βH=\beta_H = \infty the partition function becomes, in the Coulomb Gauge, exactly that of a set of non-interacting 3-d O(4) classical Heisenberg models. Long range order at low temperatures (weak coupling) has been rigorously proven for this model. It is shown that the correlation function demonstrating spontaneous magnetization in the ferromagnetic phase is a continuous function of gHg_H at gH=0g_H =0 and therefore that the spontaneously broken phase enters the (βH\beta_H, βV\beta_V) phase plane (no step discontinuity at the edge). Once the phase transition line has entered, it can only exit at another identified edge, which requires the SU(2) gauge theory within also to have a phase transition at finite β\beta. A phase exhibiting spontaneous breaking of the remnant symmetry left after Coulomb gauge fixing, the relevant symmetry here, is non-confining. Easy extension to the SU(N) case implies that the continuum limit of zero-temperature 4-d SU(N) lattice gauge theories is not confining, in other words gluons by themselves do not produce a confinement.Comment: 13 pages, LaTex, 3 eps figs. Ver 2 some clarifications added, title modified, one citation fixe

    Exploring Residual Gauge Symmetry Breaking

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    Simulations of pure-gauge SU(2) lattice gauge theory are performed in the minimal Coulomb gauge. This leaves a residual or remnant gauge symmetry still active which is global in three directions but still local in one. Using averaged fourth-dimension pointing links as a spin-like order parameter, the remnant symmetry appears to undergo spontaneous symmetry breaking at around β=2.6\beta = 2.6. Both the Binder cumulant and the magnetization itself exhibit crossings in this region using lattices up to 20420^4, and a susceptibility peak is also observed. Finite size scaling indicates a weak first-order transition. The symmetry breaking is also observed to take place in the fundamental-adjoint plane, and is coincident with the strong first-order transition that exists there at large βadjoint\beta_{\rm{adjoint}}. This provides confirmation that this phase transition is a symmetry-breaking transition. A well-known theorem concerning the instantaneous Coulomb potential has previously proven that a transition where such a Coulomb-gauge remnant symmetry breaks is necessarily deconfining.Comment: 7 pages, 4 figures (6 figure files), PoS style, Lattice 2006 Poster(Topology and Confinement

    An Assessment of the Impact Investing and Social Enterprise Ecosystem in Virginia

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    In a study that spanned more than four months from April through August of 2016, the Virginia Impact Investing Forum surveyed nearly 200 stakeholders and held dozens of personal interviews and focus groups with thought leaders across the state. The goal was to map Virginia’s Impact Investing and Social Enterprise ecosystem and to determine the next steps necessary to the continued growth and prosperity of this emerging field. Results show that there is strong interest in seeing Impact Investing and Social Enterprise development flourish throughout Virginia, as evidenced by concerted efforts from across all three sectors to promote this ecosystem, including bi-partisan government actors, private equity firms, foundations, and entrepreneurs. One general theme that has emerged in conversations and survey responses around Impact Investing is the tension that often exists between prospective Impact Investors and Social Entrepreneurs, and while this research does not seek to solidify answers to some of the most pressing questions that create these tensions, it does make a key point: Impact Investing has the potential to be something entirely different from philanthropy and investing, something that has the power to reshape longstanding economic barriers between one’s wallet and one’s heart, by fueling the creative fire behind social innovation and breaking down the walls between the traditional public, nonprofit, and private sectors - And that is something worth celebrating, and worth continuing to fight for
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