1,721,216 research outputs found
On the decoupling of heavy modes in Kaluza-Klein theories
No full textIn this paper we examine the 4-dimensional effective theory for the light Kaluza-Klein (KK) modes. Our main interest is in the interaction terms. We point out that the contribution of the heavy KK modes is generally needed in order to reproduce the correct predictions for the observable quantities involving the light modes. As an example we study in some detail a 6-dimensional Einstein-Maxwell theory coupled to a charged scalar and fermions. In this case the contribution of the heavy KK modes are geometrically interpreted as the deformation of the internal space. (c) 2006 Elsevier B. V. All rights reserved
One-loop fermionic corrections to the instanton transition in two dimensional chiral Higgs model
No full textBurnier Y, Shaposhnikov M. One-loop fermionic corrections to the instanton transition in two dimensional chiral Higgs model. Phys.Rev. D. 2005;72(6): 65011.The one-loop fermionic contribution to the probability of an instantontransition with fermion number violation is calculated in the chiral AbelianHiggs model in 1+1 dimensions, where the fermions have a Yukawa coupling to thescalar field. The dependence of the determinant on fermionic, scalar and vectormass is determined. We show in detail how to renormalize the fermionicdeterminant in partial wave analysis, which is convenient for computations
Chiral Asymmetry from a 5D Higgs Mechanism
Full text linkAn intriguing feature of the Standard Model is that the representations of the unbroken gauge symmetries are vector-like whereas those of the spontaneously broken gauge symmetries are chiral. Here we provide a toy model which shows that a natural explanation of this property could emerge in higher dimensional field theories and discuss the difficulties that arise in the attempt to construct a realistic theory. An interesting aspect of this type of models is that the 4D low energy effective theory is not generically gauge invariant. However, the non-invariant contributions to the observable quantities are very small, of the order of the square of the ratio between the light particle mass scale and the Kaluza-Klein mass scale. Remarkably, when we take the unbroken limit both the chiral asymmetry and the non-invariant terms disappear. © SISSA 2007.LPP
Baryon and lepton number violation rates across the electroweak crossover
No full textBurnier Y, Laine M, Shaposhnikov M. Baryon and lepton number violation rates across the electroweak crossover. JCAP. 2006;2006(02): 007.We point out that the results from many baryogenesis scenarios operating at or below the TeV scale are rather sensitive to the rate of anomalous fermion number violation across the electroweak crossover. Assuming the validity of the Standard Model of electroweak interactions, and making use of previous theoretical work at small Higgs masses, we estimate this rate for experimentally allowed values of the Higgs mass (m(H) = 100... 300 GeV). We also elaborate on how the rate makes its appearance in (leptogenesis based) baryogenesis computations
Remark on sphaleron erasure of baryon asymmetry
No full textLaine M, Shaposhnikov M. Remark on sphaleron erasure of baryon asymmetry. PHYSICAL REVIEW D. 2000;61(11): 117302.We complete an existing result for how the baryon asymmetry left over after a period of full thermal equilibrium depends on different lepton asymmetries
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
Can an odd number of fermions be created due to chiral anomaly?
Full text linkBezrukov F, Burnier Y, Shaposhnikov M. Can an odd number of fermions be created due to chiral anomaly? Phys .Rev. D. 2006;73(4): 45008.We describe a possibility of creation of an odd number of fractionallycharged fermions in 1+1 dimensional Abelian Higgs model. We point out that for1+1 dimensions this process does not violate any symmetries of the theory, normakes it mathematically inconsistent. We construct the proper definition of thefermionic determinant in this model and underline its non-trivial features thatare of importance for realistic 3+1 dimensional models with fermion numberviolation
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