Claudio Perini
Centre national de la recherche scientifique
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Featured researches published by Claudio Perini.
Nuclear Physics | 2009
Eugenio Bianchi; Elena Magliaro; Claudio Perini
We compute metric correlations in loop quantum gravity with the dynamics defined by the new spin foam models. The analysis is done at the lowest order in a vertex expansion and at the leading order in a large spin expansion. The result is compared to the graviton propagator of perturbative quantum gravity.
Physics Letters B | 2009
Claudio Perini; Carlo Rovelli; Simone Speziale
Abstract We consider the elementary radiative-correction terms in loop quantum gravity. These are a two-vertex “elementary bubble” and a five-vertex “ball”; they correspond to the one-loop self-energy and the one-loop vertex correction of ordinary quantum field theory. We compute their naive degree of (infrared) divergence.
Physical Review D | 2010
Eugenio Bianchi; Elena Magliaro; Claudio Perini
We study a holomorphic representation for spinfoams. The representation is obtained via the Ashtekar-Lewandowski-Marolf-Mourao-Thiemann coherent state transform. We derive the expression of the 4d spinfoam vertex for Euclidean and for Lorentzian gravity in the holomorphic representation. The advantage of this representation rests on the fact that the variables used have a clear interpretation in terms of a classical intrinsic and extrinsic geometry of space. We show how the peakedness on the extrinsic geometry selects a single exponential of the Regge action in the semiclassical large-scale asymptotics of the spinfoam vertex.
International Journal of Modern Physics D | 2013
Elena Magliaro; Claudio Perini
We consider spinfoam quantum gravity in the flipped limit, which is the double scaling limit γ → 0, j → ∞ with γj = const., where γ is the Immirzi parameter, j is the spin and γj gives the physical area in Planck units. In this regime the amplitude for a 2-complex becomes effectively an integral over Regge-like metrics and seems to enforce Einstein equations in the semiclassical regime. The Immirzi parameter must be considered as dynamical in the sense that it runs to zero when the fine structure of the foam is averaged. In addition to quantum corrections which vanish for ℏ → 0, we find new corrections due to the discreteness of geometric spectra.
Classical and Quantum Gravity | 2010
Emanuele Alesci; Eugenio Bianchi; Elena Magliaro; Claudio Perini
The fusion coefficients from SO(3) to SO(4) play a key role in the definition of spin foam models for the dynamics in Loop Quantum Gravity. In this paper we give a simple analytic formula of the EPRL fusion coefficients. We study the large spin asymptotics and show that they map SO(3) semiclassical intertwiners into
Classical and Quantum Gravity | 2009
Emanuele Alesci; Eugenio Bianchi; Elena Magliaro; Claudio Perini
SU(2)_L\times SU(2)_R
Physical Review D | 2007
Elena Magliaro; Claudio Perini; Carlo Rovelli
semiclassical intertwiners. This non-trivial property opens the possibility for an analysis of the semiclassical behavior of the model.The fusion coefficients from SO(3) to SO(4) play a key role in the definition of spin foam models for the dynamics in Loop Quantum Gravity. In this paper we give a simple analytic formula of the EPRL fusion coefficients. We study the large spin asymptotics and show that they map SO(3) semiclassical intertwiners into
Physical Review D | 2011
Elena Magliaro; Antonino Marciano; Claudio Perini
SU(2)_L\times SU(2)_R
International Journal of Modern Physics A | 2008
Elena Magliaro; Claudio Perini
semiclassical intertwiners. This non-trivial property opens the possibility for an analysis of the semiclassical behavior of the model.
arXiv: General Relativity and Quantum Cosmology | 2012
Claudio Perini
We continue the semiclassical analysis, started in a previous paper, of the intertwiner sector of the flipped vertex spinfoam model. We use independently both a semi-analytical and a purely numerical approach, finding the correct behavior of wavepacket propagation and physical expectation values. In the end, we show preliminary results about correlation functions.