1,720,959 research outputs found
SOME INTERESTING FEATURES OF NONCOMPACT QED3
No full textWe study the phase diagram of non compact QED_3 using the MFA method and present evidence for a continuous phase transition line at small . We also analyze the chiral structure of the vacuum by means of the computation of the probability distribution function of the order parameter in the exact chiral limit
Testing logarithmic violations to scaling in strongly coupled QED
No full textUsing very precise measurements of the critical couplings for the chiral transition of non-compact QED_4 in 10^4, 12^4
and 14^4 lattices we analyse the behaviour of the order parameter at the critical point using the equation of state of a
logarithmically improved scalar mean field theory, that of the Nambu-Jona Lasinio theory and a pure power law. The first
case is definitively excluded by the numerical data. Contrary to that, very high quality fits can be found for the other two
cases. A more complex analysis including the susceptibility is however able to clearly distinguish between the last two
possibilities. Triviality a la Nambu-Jona Lasinio is also ruled out
CHIRAL SUSCEPTIBILITIES IN NONCOMPACT QED, A NEW DETERMINATION OF THE GAMMA-EXPONENT AND THE CRITICAL COUPLINGS
No full textWe report the results of a measurement of susceptibilities in noncompact QED_4 in 8^4, 1O^4 and 12^4 lattices. Due to the
potentialities of the MFA approach, we have done simulations in the chiral limit which are therefore free from arbitrary
mass extrapolations. Our results in the Coulomb phase show unambiguously that the susceptibility critical exponent
independently of the flavour symmetry group. The critical couplings extracted from these calculations are in perfect agreement
with previous determinations based on the fermion effective action and plaquette energy, and outside the predictions of a
logarithmically improved scalar mean field theory by eight standard deviations
FERMIONIC EFFECTIVE ACTION AND THE PHASE-STRUCTURE OF NONCOMPACT QUANTUM ELECTRODYNAMICS IN 2+1 DIMENSIONS
No full textWe study the phase diagram of noncompact QED_3 using the microcanonical fermionic average method described elsewhere. We present evidence for a continuous phase transition line in the plane, extending down to an arbitrarily small flavour number N
THE GAUGED NAMBU-JONES LASINIO MODEL - A MEAN FILED CALCULATION WITH NONMEAN FIELD EXPONENTS
No full textWe analyse the phase diagram of the lattice gauged Nambu-Jona Lasinio model with the help of a mean field approximation
plus numerical simulations. We find a phase transition line in the coupling parameters space separating the chirally broken
phase from the symmetric phase, which is in good qualitative agreement with results obtained in the quenched-ladder
approximation. The mean field approximation relates the critical exponents along the continuous phase transition line with
the mass dependence of the chiral condensate in the Coulomb phase of standard noncompact QED. Our numerical results
for noncompact QED strongly suggest nonmean field exponents along the critical line
Chiral condensate, susceptibilities, critical coupling and indices in QED(4).
No full textWe measure chiral susceptibilities in the Coulomb phase of noncompact QED_4 in 8^4, 10^4 and 12^4 lattices. The MFA approach allows simulations in the chiral limit which are therefore free from arbitrary mass extrapolations. Using the critical couplings extracted from these calculations, we study the critical behaviour of the chiral condensate, which we find in disagreement with the predictions of logaritmically improved scalar Mean Field theory
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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