27 research outputs found
Amplitudes With Different Helicity Configurations Of Noncommutative QED
The amplitudes of purely photonic and photon{2-fermion processes of non-
commutative QED (NCQED) are derived for different helicity configurations of
photons. The basic ingredient is the NCQED counterpart of Yang-Mills recursion
relations by means of Berends and Giele. The explicit solutions of recursion
relations for NCQED photonic processes with special helicity configurations are
presented.Comment: 23 pages, 2 figure
A Conformally Invariant Holographic Two-Point Function on the Berger Sphere
We apply our previous work on Green's functions for the four-dimensional
quaternionic Taub-NUT manifold to obtain a scalar two-point function on the
homogeneously squashed three-sphere (otherwise known as the Berger sphere),
which lies at its conformal infinity. Using basic notions from conformal
geometry and the theory of boundary value problems, in particular the
Dirichlet-to-Robin operator, we establish that our two-point correlation
function is conformally invariant and corresponds to a boundary operator of
conformal dimension one. It is plausible that the methods we use could have
more general applications in an AdS/CFT context.Comment: 1+49 pages, no figures. v2: Several typos correcte
Holography and Quaternionic Taub-NUT
As a concrete application of the holographic correspondence to manifolds
which are only asymptotically Anti-de Sitter, we take a closer look at the
quaternionic Taub-NUT space. This is a four dimensional, non-compact,
inhomogeneous, riemannian manifold with the interesting property of smoothly
interpolating between two symmetric spaces, AdS_4 itself and the coset
SU(2,1)/U(2). Even more interesting is the fact that the scalar curvature of
the induced conformal structure at the boundary (corresponding to a squashed
three-sphere) changes sign as we interpolate between these two limiting cases.
Using twistor methods, we construct the bulk-to-bulk and bulk-to-boundary
propagators for conformally coupled scalars on quaternionic Taub-NUT. This may
eventually enable us to calculate correlation functions in the dual strongly
coupled CFT on a squashed S^3 using the standard AdS/CFT prescription.Comment: 1+36 pages, no figures. Some minor typos correcte
Monitoramento da variabilidade genética de pacu, Piaractus mesopotamicus, do programa de aumento de estoque do rio Paranapanema
Microsatellite analysis of pacu broodstocks used in the stocking program of Paranapanema River, Brazil
Effective interventions and strategies for improving Early Child Development
This article synthesises evidence about effective interventions and strategies to improve early child development, and call for it to be included in a new global strategy on women's, children's, and adolescents' health.