Black Holes and Abelian Symmetry Breaking
(Submitted on 28 Feb 2016)
Black hole configurations offer insights on the non-linear aspects of gravitational theories, and can suggest testable predictions for modifications of General Relativity. In this work, we examine exact black hole configurations in vector-tensor theories, originally proposed to explain dark energy by breaking the Abelian symmetry with a non-minimal coupling of the vector to gravity. We are able to evade the no-go theorems by Bekenstein on the existence of regular black holes in vector-tensor theories with Proca mass terms, and exhibit regular black hole solutions with a profile for the longitudinal vector polarization, characterised by an additional charge. We analytically find the most general static, spherically symmetric black hole solutions with and without a cosmological constant, and study in some detail their features, such as how the geometry depends on the vector charges. We also include angular momentum, and find solutions describing slowly-rotating black holes. Finally, we extend some of these solutions to higher dimensions.
Observable currents in lattice field theories
(Submitted on 6 Feb 2016)
Observable currents are spacetime local objects that induce physical observables when integrated on an auxiliary codimension one surface. Since the resulting observables are independent of local deformations of the integration surface, the currents themselves carry most of the information about the induced physical observables. I study observable currents in a multisymplectic framework for Lagrangian field theory over discrete spacetime. A weak version of observable currents preserves many of their properties, while inducing a family of observables capable of separating points in the space of physically distinct solutions. A Poisson bracket gives the space of observable currents the structure of a Lie algebra. Peierls bracket for bulk observables gives an algebra homomorphism mapping equivalence classes of bulk observables to weak observable currents. The study covers scalar fields, nonlinear sigma models and gauge theories (including gauge theory formulations of general relativity) on the lattice. Even when this paper is entirely classical, this study is relevant for quantum field theory because a quantization of the framework leads to a spin foam model formulation of lattice field theory.
On the Faddeev-Jackiw Symplectic Framework for Topologically Massive Gravity
(Submitted on 15 Jan 2016)
The dynamical structure of topologically massive gravity in the context of the Faddeev-Jackiw approach is studied. We present a detailed analysis of the constraints and we show that this formalism is equivalent and more economical than Dirac’s method. In particular, we identify the complete set of constraints of the theory, from which the number of physical degrees of freedom is explicitly computed. Furthermore, in order to obtain all the generalized Faddeev-Jackiw brackets an appropriate gauge-fixing procedure is introduced and we prove that the generalized Faddeev-Jackiw brackets and the Dirac ones coincide to each other. Finally, the similarities and advantages between Faddeev-Jackiw method and Dirac’s formalism are discussed.
Llega el primer preprint de la serie Hecho en México 2.0.
(Submitted on 15 Jan 2016)
We develop a new semiclassical approach, which starts with the density matrix given by the Euclidean time path integral with fixed endpoints, and proceed by identifying classical (minimal Euclidean action) path, we name “flucton”, which passes through this point. Fluctuations around flucton path are included, by standard Feynman diagrammatic series, previously developed for instantons. Two classic examples – quartic double-well and sine-Gordon potentials – are discussed in detail. Unlike other semiclassical methods, like WKB, we do not use Schr\”odinger equation, and all the steps generalize to multi-dimensional or quantum fields cases straightforwardly.
El workshop Extreme QCD 2011 se celebrará en San Carlos del 18 al 20 de julio. Mayor información aquí …..
Nuevas cotas para la escala de energía de posibles interacciones de contacto impustas por ATLAS: TeV para interferencia constructiva ( TeV para destructiva) en el modelo de isoscalar left-left compuesto.
Ver referencia aquí …
Acaba de salir el siguiente abstract de una nota interna de ATLAS:
…we studied the γγ invariant mass distribution over the range of 80 to 150 GeV/c2. With 37.5 pb−1 data from 2010 and 26.0 pb−1 from 2011, we observe a γγ resonance around 115 GeV with a significance of 4σ. The event rate for this resonance is about thirty times larger than the expectation from Higgs to γγ in the standard model…
Para mayor info: aquí y aquí