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Determination of the cabibbo-kobayashi-maskawa matrix element |Vcb|
No full textIn this review we present and discuss the determination of the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameter Vcb. The CKM matrix parametrizes the weak charged current interactions of quarks in the standard model (SM), and a precise determination of its elements has always been one of the most important targets of particle physics. The precise knowledge of the |Vcb| value plays a pivotal role in testing the flavour sector of the SM and in the analyses of the unitarity of the CKM matrix. The SM does not predict the values of the CKM matrix elements, which have to be extracted by experimental data. Given the variety of channels that allow the extraction of |Vcb|, different theoretical and experimental techniques are mustered for the |Vcb| determination. The exertion towards precision represents not only a significant test of our theoretical procedures but a stimulus towards better detection performances. The most precise measurements of |Vcb| come from semileptonic decays, that being tree level at the lowest order in the SM are generally considered unaffected by physics beyond the SM. After summarizing the characteristics of the SM that set the frame for the determination of |Vcb|, we discuss inclusive and exclusive semileptonic B decays. We analyse the |Vcb| extraction methods and recent results, detailing both the theoretical and experimental techniques, and, finally, outline future prospects. We also comment on exclusive decays into heavy leptons, on the observables R(D) and R(D∗), on decays to excited D meson states and on baryon decays
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
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