1,720,964 research outputs found
New approaches for studying conformal embeddings and collapsing levels for --algebras
Full text linkIn this paper we prove a general result saying that under certain hypothesis an embedding of an affine vertex algebra into an affine --algebra is conformal if and only if their central charges coincide. This result extends our previous result obtained in the case of minimal affine -algebras. We also find a sufficient condition showing that certain conformal levels are collapsing. This new condition enables us to find some levels where collapses to its affine part when is of hook or rectangular type. Our methods can be applied to non-admissible levels. In particular, we prove Creutzig\u27s conjecture on the conformal embedding in the hook type -algebra of its affine vertex subalgebra. Quite surprisingly, the problem of showing that certain conformal levels are not collapsing turns out to be very difficult. In the cases when is admissible and conformal, we prove that is not collapsing. Then, by generalizing the results on semi-simplicity of conformal embeddings from our previous papers, we find many cases in which is semi-simple as a module for its affine subalgebra at conformal level and we provide explicit decompositions.30 pages, Latex file, revised version, to appear in IMR
Finite vs infinite decompositions in conformal embeddings
Full text linkBuilding on work of the first and last author, we prove that an embedding of simple affine vertex algebras , corresponding to an embedding of a maximal equal rank reductive subalgebra into a simple Lie algebra , is conformal if and only if the corresponding central charges are equal. We classify the equal rank conformal embeddings. Furthermore we describe, in almost all cases, when decomposes finitely as a -module
Conformal embeddings and realizations of certain simple W-algebras
No full textWe shall first recall explicit realizations of certain affine and
superconformal vertex algebras from [D. Adamovic, Transform. Groups
(2015)] and study their relations with vertex operator algebras
appearing in LCFT. Then we shall consider a generalization motivated
by the construction of conformal embeddings of affine vertex
algebras in W-algebras. We shall also present a decomposition of a
large family of non-rational affine W-algebras as modules for affine
vertex operator algebras at admissible and negative levels. A
particular emphasis will be put on the application of affine fusion
rules and intertwining operators in the determination of branching
rules.
The second part of this talk is based on a joint paper with V. Kac,
P. Moseneder-Frajria, P. Papi and O. Perse.Non UBCUnreviewedAuthor affiliation: University of ZagrebFacult
Conformal embeddings in affine vertex superalgebras
Full text linkThis paper is a natural continuation of our previous work on conformal embeddings of vertex algebras [6], [7], [8]. Here we consider conformal embeddings in simple affine vertex superalgebra V_k(g) where g=g_0+g_1 is a basic classical simple Lie superalgebra. Let VV_k(g_0) be the subalgebra of V_k(g) generated by g_0. We first classify all levels k for which the embedding VV_k(g_0) in V_k(g) is conformal. Next we prove that, for a large family of such conformal levels, V_k(g) is a completely reducible VV_k(g_0)–module and obtain decomposition rules. Proofs are based on fusion rules arguments and on the representation theory of certain affine vertex algebras. The most interesting case is the decomposition of V_{-2}(sop(2n+8|2n)) as a finite, non simple current extension of V_{-2}(D_{n+4})otimes V_1(C_n). This decomposition uses our previous work [10] on the representation theory of V_{-2}(D_{n+4}). We also study conformal embeddings gl(n|m) ---> sl(n+1|m) and in most cases we obtain decomposition rules
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
Affine, Vertex and W-algebras
No full textThis book focuses on recent developments in the theory of vertex algebras, with particular emphasis on affine vertex algebras, affine W-algebras, and W-algebras appearing in physical theories such as logarithmic conformal field theory. It is widely accepted in the mathematical community that the best way to study the representation theory of affine Kac–Moody algebras is by investigating the representation theory of the associated affine vertex and W-algebras. In this volume, this general idea can be seen at work from several points of view. Most relevant state of the art topics are covered, including fusion, relationships with finite dimensional Lie theory, permutation orbifolds, higher Zhu algebras, connections with combinatorics, and mathematical physics. The volume is based on the INdAM Workshop Affine, Vertex and W-algebras, held in Rome from 11 to 15 December 2017. It will be of interest to all researchers in the field
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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