1,721,006 research outputs found
BCJ relations in AdS5 × S 3 and the double-trace spectrum of super gluons
No full textWe revisit the four-point function of super gluons in AdS5 ×S 3 in the spirit of the large p formalism and show how the integrand of a generalised Mellin transform satisfies various non-trivial properties such as U(1) decoupling identity, BCJ relations and colour-kinematic duality, in a way that directly mirrors the analogous relations in flat space. We unmix the spectrum of double-trace operators at large N and find all anomalous dimensions at leading order. The anomalous dimensions follow a very simple pattern, resembling those of other theories with hidden conformal symmetries
Adjacency for scattering amplitudes from the Gröbner fan
No full textScattering amplitudes in planar N=4 super Yang-Mills theory exhibit singularities which reflect various aspects of the cluster algebras associated to the Grassmannians Gr(4,n) and their tropical counterparts. Here we investigate the potential origins of such structures and examine the extent to which they can be recovered from the Gröbner structure of the underlying Plücker ideals, focussing on the Grassmannians corresponding to finite cluster algebras.Starting from the Plücker ideal, we describe how the polynomial cluster variables are encoded in non-prime initial ideals associated to certain maximal cones of the positive tropical fan. Following [1] we show that extending the Plücker ideal by such variables leads to a Gröbner fan with a single maximal Gröbner cone spanned by the positive tropical rays. The associated initial ideal encodes the compatibility relations among the full set of cluster variables. Thus we find that the Gröbner structure naturally encodes both the symbol alphabet and the cluster adjacency relations exhibited by scattering amplitudes without invoking the cluster algebra at all.As a potential application of these ideas we then examine the kinematic ideal associated to non-dual conformal massless scattering written in terms of spinor helicity variables. For five-particle scattering we find that the ideal can be identified with the Plücker ideal for Gr(3,6) and the corresponding tropical fan contains a number of non-prime ideals which encode all additional letters of the two-loop pentagon function alphabet present in various calculations of massless five-point finite remainders
One-loop string corrections for AdS Kaluza-Klein amplitudes
No full textWe discuss the string corrections to one-loop amplitudes in AdS5×S5, focussing on their expressions in Mellin space. We present the leading (α′)3 corrections to the family of correlators ⟨O2O2OpOp⟩ at one loop and begin the exploration of the form of correlators with multiple channels. From these correlators we extract some string corrections to one- loop anomalous dimensions of families of operators of low twist
BCJ relations in and the double-trace spectrum of super gluons
Full text linkWe revisit the four-point function of super gluons in in
the spirit of the large formalism and show how the integrand of a
generalised Mellin transform satisfies various non-trivial properties such as
decoupling identity, BCJ relations and colour-kinematic duality, in a
way that directly mirrors the analogous relations in flat space. We unmix the
spectrum of double-trace operators at large and find all anomalous
dimensions at leading order. The anomalous dimensions follow a very simple
pattern, resembling those of other theories with hidden conformal symmetries.Comment: 9 page
One-loop string amplitudes in AdS<sub>5 </sub>X S<sup>5</sup>: Mellin space and sphere splitting
No full textWe study string corrections to one-loop amplitudes of single-particle operators in . The tree-level correlators in supergravity enjoy an accidental 10d conformal symmetry. Consequently, one observes a partial degeneracy in the spectrum of anomalous dimensions of double-trace operators and at the same time equality of many different correlators for different external charges . The one-loop contribution is expected to lift such bonus properties, and its precise form can be predicted from tree-level data and consistency with the operator product expansion. Here we present a closed-form Mellin space formula for at order , valid for arbitrary external charges . Our formula makes explicit the lifting of the bonus degeneracy among different correlators through a feature we refer to as `sphere splitting'. While tree-level Mellin amplitudes come with a single crossing symmetric kernel, which defines the pole structure of the amplitude, our one-loop amplitude naturally splits the part into two separate contributions. The amplitude also exhibits a remarkable consistency with the corresponding flat space IIB amplitude through the large limit
Palm worm (coleoptera, Curculionidae: Rhynchophorus palmarum) Traditional Food. Examples from Alto Orinoco, Venezuela
No full textCurrent knowledge about the so-called palm worms, weevil beetles, and
Curculionidae widely used as food in the Amazon is summarized. The Indians
gather the palm worms from damaged or fallen palm stems and eat them raw or
roasted. We analyzed the nutrient composition of the palm worm and found
that it is an excellent source of protein, fat, vitamins A and E, and minerals.
Development of a local, controlled, small-scale palm worm production system
implemented by the Indians in the Amazonas is described. Larvae are bred using
wild palm materials and traditional Indian plants. Larval survival and density
in each palm substrate were analyzed together with their nutrient composition.
These data were compared with the mother palms cucurito (Maximiliana maripa),
seje (Jessenia bataua), and moriche (Mauritia flexuosa). Finally, the palatability of
the palm worm to non-Amerindian tourists is assessed. The nutrient composition
of the palm worm, the simplicity of a more controlled local production system,
and the acceptability of the palm worm to tourists make this nonconventional resource promising, both as a nutritional food and as a source of cash income for
the Indians
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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