1,720,957 research outputs found
A Study of symmetry restoration at finite temperature in the O(4) model using anisotropic lattices
No full textGavai RV, Heller UM, Karsch F, Plache B, Neuhaus T. A Study of symmetry restoration at finite temperature in the O(4) model using anisotropic lattices. Nucl.Phys.Proc.Suppl. 1992;26:539-541
Vacuum tunneling and periodic structure in lattice Higgs models
Full text linkKarsch F, Laursen ML, Neuhaus T, Plache B. Vacuum tunneling and periodic structure in lattice Higgs models. Nuclear Physics, B. 1993;406(3):825-846.Using a geometruc definition for the lattice Chern-Simons term in even dimensions, we have studied the distribution of Chern-Simons numbers for the 2d U(1) and the 4d SU(2) lattice Higgs models. The periodic structure of the distributions is preserved in our lattice formulation and has been examined in detail. In both cases the finite-size effects visible in the distribution of Chern-Simons numbers are well accounted for by the Haar measure. Moreover, we find that (N CS 2) grows with the spatial volume. We also find numerical evidence that tunneling in 4d is increased at high temperature
Chern-Simons term in the 4-dimensional SU(2) Higgs model
Full text linkKarsch F, Laursen ML, Neuhaus T, Plache B. Chern-Simons term in the 4-dimensional SU(2) Higgs model. Nuclear Physics, B: Proceedings Supplements. 1993;30:715-718.Using Seibergs definition for the geometric charge in SU(2) lattice gauge theory, we have managed to apply it also to the Chern-Simons term. We checked the periodic structure and determined the Chern-Simons density on small lattices L 4 and L 3 × 2,4 with L = 4, 6, and 8 near the critcal region in the SU(2) Higgs mode. The data indicate that tunneling is increased at high temperature
Fluctuations of Chern-Simons numbers in the SU(2) Higgs model
Full text linkKarsch F, Laursen ML, Neuhaus T, Plache B. Fluctuations of Chern-Simons numbers in the SU(2) Higgs model. International journal of modern physics, C. 1993;4(06):1195-1204.We investigate vacuum transitions in lattice higgs models at finite temperature. The 2 dimensional U(1) Higgs model is used as a toy model. In the 4 dimensional SU(2) Higgs model the region of the phase transition and temperatures above it are considered. The couplings (beta, kappa, lambda) = (2.25, 0.27, 0.5) and (8.0, 0.12996, 0.0017235) correspond to masses in lattice units (a(sigma) m(H), a(sigma) m(W)) of (0.02, 0.05) and (0.2, 0.2), respectively. The algorithm is described and a parallelized version is proposed. Taking the influence of the finite lattice into account we discuss temperature effects. We compare our results with perturbative estimates and claim that they link low and high temperature approximations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
A lower bound on T SR/m H in the O(4) model on anisotropic lattices
Full text linkGavai RV, Heller UM, Karsch F, Neuhaus T, Plache B. A lower bound on T SR/m H in the O(4) model on anisotropic lattices. Physics Letters, B. 1992;294(1):84-90.Results of an investigation of the O(4) spin model at finite temperature using anisotropic lattices are presented. In both the large N approximation and numerical simulations using the Wolff cluster algorithm we find that the ratio of the symmetry restoration temperature T(SR) to the Higgs mass m(H) is independent of the anisotropy xi. From the numerical simulations we obtain a lower bound of T(SR)/m(H) congruent-to 0.58 +/- 0.02 at a value for the Higgs mass m(H)a(s) congruent-to 0.5, which is lowered further by about 10% at m(H)a(s) congruent-to 1. Requiring certain timelike correlation functions to coincide with their spacelike counterparts, quantum and scaling corrections to the anisotropy are determined and are found to be small i.e., the anisotropy is found to be close to the ratio of spacelike and timelike lattice spacings
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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