1,720,957 research outputs found
SUSY, inflation and the origin of matter in the universe
No full textWe consider the standard models of particle physics and hot big bang cosmology, and review the theoretical and experimental motivations for extending these models to include supersymmetry and inflation. An obvious extension would be to unite these two models into a single all-encompassing theory. We identify a list of theoretical challenges that such a theory must address, which we illustrate with a simple model—a variant of the next-to-minimal supersymmetric standard model—that addresses these challenges
Supersymmetric Higgs bosons in a 5D orbifold model
No full textWe analyze the phenomenology of the Higgs sector in a 5D model compactified on an S1/Z2 orbifold where the compactification scale MC is around the TeV scale. We show that the conventional MSSM Higgs boson mass bounds in 4D can be violated when we allow the gauge sector, Higgs and third family multiplets to live in the fifth extra dimension. Supersymmetry is broken at an orbifold fixed point which is spatially separated from the Yukawa brane where two chiral families are localized. When the brane-localized supersymmetry breaking term for the stop sector is arbitrarily large, we find that the stop KK-mode mass spectrum is completely independent of the Higgs fields. Hence, the Higgs masses only receive radiative contributions from the top KK-modes. The 1-loop effective potential is insensitive to the cutoff scale of the theory and yields a negative Higgs squared-mass contribution that triggers electroweak symmetry breaking in the range 1.5tan?20, where bottom/sbottom loop effects can be ignored. The recent LEP Higgs bound at mh0>114.1 GeV, in conjunction with naturalness arguments, allows us to bracket the compactification scale 1.5MC4 TeV. Within this parameter space, we find that the lightest Higgs boson mass has an upper bound mh0160 GeV with the magnitude of the ?-parameter restricted to the range 33|?|347 GeV.<br/
Twisted moduli and supersymmetry breaking
No full textWe consider twisted moduli contributions to supersymmetry breaking in effective type I string constructions involving intersecting D5i and D9-branes using Goldstino angles to parametrise the supersymmetry breaking. It is well known that twisted moduli enter at tree-level into the gauge kinetic functions, and can provide new sources of gaugino mass if they develop F-term vacuum expectation values. It is generally assumed that string states which are sequestered from the twisted moduli receive a zero soft mass in the twisted modulus domination limit, however the standard form of Kähler potential does not reproduce this expectation. We therefore propose a new form of the Kähler potential which is consistent at leading order with the sequestered form proposed by Randall and Sundrum, and show that it leads to exponentially suppressed sequestered soft masses. Including the effects of Green-Schwarz mixing, we write down the soft scalar masses and trilinears arising from a type I string construction involving intersecting D5i and D9-branes in the presence of untwisted and twisted moduli. If the squarks and sleptons are identified with sequestered states then in the twisted moduli dominated limit this corresponds to gaugino mediated supersymmetry breaking, and we discuss two different scenarios for this. The general results will be useful for phenomenological studies involving a combination of gravity and gaugino mediated SUSY breaking due to the dilaton, untwisted and twisted moduli contributions, and enable the soft masses to be studied as a function of the different compactification radii
Supersymmetry and electroweak breaking with large and small extra dimensions
No full textWe consider the problem of supersymmetry and electroweak breaking in a 5d theory compactified on an S1/Z2 orbifold, where the extra dimension may be large or small. We consider the case of a supersymmetry breaking 4d brane located at one of the orbifold fixed points with the Standard Model gauge sector, third family and Higgs fields in the 5d bulk, and the first two families on a parallel 4d matter brane located at the other fixed point. We compute the Kaluza–Klein mass spectrum in this theory using a matrix technique which allows us to interpolate between large and small extra dimensions. We also consider the problem of electroweak symmetry breaking in this theory and localize the Yukawa couplings on the 4d matter brane spatially separated from the brane where supersymmetry is broken. We calculate the 1-loop effective potential using a zeta-function regularization technique, and find that the dominant top and stop contributions are separately finite. Using this result we find consistent electroweak symmetry breaking for a compactification scale 1/R?830 GeV and a lightest Higgs boson mass mh?170 GeV
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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