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BCJ Duality and the Double Copy in the Soft Limit
 Journal of High Energy Physics
"... We examine the structure of infrared singularities in QCD and quantum General Relativity, from the point of view of the recently conjectured double copy property which relates scattering amplitudes in nonAbelian gauge theories with gravitational counterparts. We show that IR divergences in both the ..."
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We examine the structure of infrared singularities in QCD and quantum General Relativity, from the point of view of the recently conjectured double copy property which relates scattering amplitudes in nonAbelian gauge theories with gravitational counterparts. We show that IR divergences in both theories are consistent with the double copy procedure, to all orders in perturbation theory, thus providing all looplevel evidence for the conjecture. We further comment on the relevance, or otherwise, to the socalled dipole formula, a conjecture for the complete structure of IR singularities in QCD. 1
The perturbative Reggecalculus regime of loop quantum gravity
 Nuclear Physics B 796 [FS] (2008) 581–621. BOJAN MOHAR AND IGOR RIVIN
"... The relation between Loop Quantum Gravity and Regge calculus has been pointed out many times in the literature. In particular the large spin asymptotics of the BarrettCrane vertex amplitude is known to be related to the Regge action. In this paper we study a semiclassical regime of Loop Quantum Gra ..."
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The relation between Loop Quantum Gravity and Regge calculus has been pointed out many times in the literature. In particular the large spin asymptotics of the BarrettCrane vertex amplitude is known to be related to the Regge action. In this paper we study a semiclassical regime of Loop Quantum Gravity and show that it admits an effective description in terms of perturbative areaReggecalculus. The regime of interest is identified by a class of states given by superpositions of fourvalent spin networks, peaked on large spins. As a probe of the dynamics in this regime, we compute explicitly two and threearea correlation functions at the vertex amplitude level. We find that they match with the ones computed perturbatively in areaReggecalculus with a single 4simplex, once a specific perturbative action and measure have been chosen in the Reggecalculus path integral. Correlations of other geometric operators and the existence of this regime for other models for the dynamics are briefly discussed. 1
Home Search Collections Journals About Contact us My IOPscience IOP PUBLISHING CLASSICAL AND QUANTUM GRAVITY
, 2010
"... Download details: IP Address: 194.94.224.254 The article was downloaded on 02/04/2013 at 12:27 Please note that terms and conditions apply. View the table of contents for this issue, or go to the journal homepage for more ..."
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Download details: IP Address: 194.94.224.254 The article was downloaded on 02/04/2013 at 12:27 Please note that terms and conditions apply. View the table of contents for this issue, or go to the journal homepage for more
May 2007 Gravitational Wilson Loop and Large Scale Curvature
, 706
"... In a quantum theory of gravity the gravitational Wilson loop, defined as a suitable quantum average of a parallel transport operator around a large nearplanar loop, provides important information about the largescale curvature properties of the geometry. Here we shows that such properties can be s ..."
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In a quantum theory of gravity the gravitational Wilson loop, defined as a suitable quantum average of a parallel transport operator around a large nearplanar loop, provides important information about the largescale curvature properties of the geometry. Here we shows that such properties can be systematically computed in the strong coupling limit of lattice regularized quantum gravity, by performing a local average over rotations, using an assumed nearuniform measure in group space. We then relate the resulting quantum averages to an expected semiclassical form valid for macroscopic observers, which leads to an identification of the gravitational correlation length appearing in the Wilson loop with an observed largescale curvature. Our results suggest that strongly coupled gravity leads to a positively curved (De Sitterlike) quantum ground state, implying a positive effective cosmological constant at large distances. 1
Received Day Month Year Revised Day Month Year Communicated by Managing Editor
, 809
"... A (3+1)evolutionary method in Regge Calculus, essentially a method of approximating manifolds with rigid simplices, makes an excellent tool to probe the evolution of manifolds with nontrivial topology. The “Parallelizable Implicit Evolution Scheme ” in Regge Calculus is one such method, powerful e ..."
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A (3+1)evolutionary method in Regge Calculus, essentially a method of approximating manifolds with rigid simplices, makes an excellent tool to probe the evolution of manifolds with nontrivial topology. The “Parallelizable Implicit Evolution Scheme ” in Regge Calculus is one such method, powerful enough to investigate manifolds devoid of symmetry. Causality however, has not been incorporated in this method properly. In this paper, we show how causality can be accounted for in this evolutionary scheme: we derive three different equations corresponding to the variation of a timelike bone with respect to a timelike edge and a timelike or a spacelike bone with respect to a spacelike edge. In addition, we conclude that in a curved empty space, a spacelike edge which is a side to a spacelike bone must also be a side to at least a timelike bone. Keywords: Causality; Minkowskian Geometry; Regge Calculus. 1.