Alejandro Perez

Multiple-event probability in general-relativistic quantum mechanics: a discrete model (2007)

The problem of background independent quantum gravity is the problem of defining a quantum field theory of matter and gravity in the absence of an underlying background geometry. Loop quantum gravity...

Mondragon, Mauricio, Perez, Alejandro, Rovelli, Carlo

We introduce a simple quantum mechanical model in which time and space are discrete and periodic. These features avoid the complications related to continuous-spectrum operators and infinite-norm...

On the quantum origin of the seeds of cosmic structure (2007)

Perez, Alejandro, Sahlmann, Hanno, Sudarsky, Daniel

The current understanding of the quantum origin of cosmic structure is discussed critically. We point out that in the existing treatments a transition from a symmetric quantum state to an...

On the regularization ambiguities in loop quantum gravity (2007)

Observables in quantum gravity (2007)

One of the main achievements of LQG is the consistent quantization of the Wheeler-DeWitt equation which is free of UV problems. However, ambiguities associated to the intermediate regularization...

Finiteness of a spinfoam model for euclidean quantum general relativity (2007)

We study a family of physical observable quantities in quantum gravity. We denote them W functions, or n-net functions. They represent transition amplitudes between quantum states of the geometry,...

3+1 spinfoam model of quantum gravity with spacelike and timelike components (2007)

We prove that a certain spinfoam model for euclidean quantum general relativity, recently defined, is finite: all its all Feynman diagrams converge. The model is a variant of the Barrett-Crane model,...

Mean field exact solutions showing charge density wave crossover at low fillings in the fractional quantum Hall regime (2007)

We present a spinfoam formulation of Lorentzian quantum General Relativity. The theory is based on a simple generalization of an Euclidean model defined in terms of a field theory over a group. The...

Cabo, Alejandro, Claro, Francisco, Perez, Alejandro, Maze, Jeronimo

A general analytical framework for the determination of the mean field states at arbitrary rational filling factors for the 2DEG in FQHE regime is given. Its use allows to obtain analytic expressions...

Multiple-event probability in general-relativistic quantum mechanics (2006)

Hellmann, Frank, Mondragon, Mauricio, Perez, Alejandro, Rovelli, Carlo

We discuss the definition of quantum probability in the context of "timeless" general--relativistic quantum mechanics. In particular, we study the probability of sequences of events, or multi-event...

Quantization of strings and branes coupled to BF theory (2006)

Baez, John C., Perez, Alejandro

BF theory is a topological theory that can be seen as a natural generalization of 3-dimensional gravity to arbitrary dimensions. Here we show that the coupling to point particles that is natural in...

Physical effects of the Immirzi parameter (2006)

Lorentz Invariance Violation and its Role in Quantum Gravity Phenomenology (2006)

The Immirzi parameter is a constant appearing in the version of the general relativity action utilized as a starting point for the loop quantization of gravity.The parameter is commonly believed not...

Collins, John, Perez, Alejandro, Sudarsky, Daniel

The notion that gravitation might lead to a breakdown of standard space-time structure at small distances, and that this might affect the propagation of ordinary particles has led to a program to...

The spin-foam-representation of loop quantum gravity (2006)

On the regularization ambiguities in loop quantum gravity (2005)

The problem of background independent quantum gravity is the problem of defining a quantum field theory of matter and gravity in the absence of an underlying background geometry. Loop quantum gravity...

On the quantum origin of the seeds of cosmic structure (2005)

One of the main achievements of LQG is the consistent quantization of the Wheeler-DeWitt equation which is free of UV problems. However, ambiguities associated to the intermediate regularization...

Perez, Alejandro, Sahlmann, Hanno, Sudarsky, Daniel

The current understanding of the quantum origin of cosmic structure is discussed critically. We point out that in the existing treatments a transition from a symmetric quantum state to an...

Physical effects of the Immirzi parameter (2005)

Physical effects of the Immirzi parameter (2005)

The Immirzi parameter is a constant appearing in the general relativity action used as a starting point for the loop quantization of gravity. The parameter is commonly believed not to show up in the...

Physical effects of the Immirzi parameter (2005)

The Immirzi parameter is a constant appearing in the version of the general relativity action utilized as a starting point for the loop quantization of gravity.The parameter is commonly believed not...

On the Physical Hilbert Space of Loop Quantum Cosmology (2004)

The Immirzi parameter is a constant appearing in the version of the general relativity action utilized as a starting point for the loop quantization of gravity.The parameter is commonly believed not...

Noui, Karim, Perez, Alejandro, Vandersloot, Kevin

In this paper we present a model of Riemannian loop quantum cosmology with a self-adjoint quantum scalar constraint. The physical Hilbert space is constructed using refined algebraic quantization....

Introduction to Loop Quantum Gravity and Spin Foams (2004)

Lorentz invariance and quantum gravity: an additional fine-tuning problem? (2004)

These notes are a didactic overview of the non perturbative and background independent approach to a quantum theory of gravity known as loop quantum gravity. The definition of real connection...

Collins, John, Perez, Alejandro, Sudarsky, Daniel, Urrutia, Luis, Vucetich, Héctor

Trying to combine standard quantum field theories with gravity leads to a breakdown of the usual structure of space-time at around the Planck length, 1.6*10^{-35} m, with possible violations of...

Three dimensional loop quantum gravity: physical scalar product and spin foam models (2004)

Three dimensional loop quantum gravity: coupling to point particles (2004)

In this paper, we address the problem of the dynamics in three dimensional loop quantum gravity with zero cosmological constant. We construct a rigorous definition of Rovelli's generalized projection...

Dynamics of loop quantum gravity and spin foam models in three dimensions (2004)

We consider the coupling between three dimensional gravity with zero cosmological constant and massive spinning point particles. First, we study the classical canonical analysis of the coupled...

Observability and Geometry in Three dimensional quantum gravity (2004)

We present a rigorous regularization of Rovellis's generalized projection operator in canonical 2+1 gravity. This work establishes a clear-cut connection between loop quantum gravity and the spin...

Beneficial effect of retinoic acid on the outcome of experimental acute renal failure (2004)

We consider the coupling between massive and spinning particles and three dimensional gravity. This allows us to construct geometric operators (distances between particles) as Dirac observables. We...

Perez, Alejandro, Ramirez-Ramos, Marisela, Calleja, Consuelo, Martin, Dolores, Namorado, Maria C., Sierra, Gerardo, ...

Background. Retinoic acid (RA) exerts beneficial effects on vascular remodelling and experimental nephritis, and plays a role in kidney development. Pathological changes caused by acute renal failure...

Beneficial effect of retinoic acid on the outcome of experimental acute renal failure (2004)

Perez, Alejandro, Ramirez-Ramos, Marisela, Calleja, Consuelo, Martin, Dolores, Namorado, Maria C., Sierra, Gerardo, ...

Background. Retinoic acid (RA) exerts beneficial effects on vascular remodelling and experimental nephritis, and plays a role in kidney development. Pathological changes caused by acute renal failure...

Comments on Challenges for Quantum Gravity (2003)

Perez, Alejandro, Sudarsky, Daniel

We examine radiative corrections arising from Lorentz violating dimension five operators presumably associated with Planck scale physics as recently considered by Myers and Pospelov. We find that...

Spin Foam Quantization and Anomalies (2003)

Bojowald, Martin, Perez, Alejandro

The most common spin foam models of gravity are widely believed to be discrete path integral quantizations of the Plebanski action. However, their derivation in present formulations is incomplete and...

Spin Foam Models for Quantum Gravity (2003)

Spin Foam Quantization and Anomalies (2003)

In this article we review the present status of the spin foam formulation of non-perturbative (background independent) quantum gravity. The article is divided in two parts. In the first part we...

Martin Bojowald, Alejandro Perez

The most common spin foam models of gravity are widely believed to be discrete path integral quantizations of the Plebanski action. However, their derivation in present formulations is incomplete and...

Energy and angular momentum radiated for non head-on binary black hole collisions (2002)

Moreschi, Osvaldo, Perez, Alejandro, Lehner, Luis

We investigate the possible total radiated energy produced by a binary black hole system containing non-vanishing total angular momentum. For the scenearios considered we find that the total radiated...

Spin foam quantization of SO(4) Plebanski's action (2002)

Spin Foam Models for Quantum Gravity (2002)

The goal of this work is two-fold. In the first part of this paper we regard classical Plebanski's action as a BF action supplemented by constraints. We introduce a spin foam model for Riemannian...

The Erwin, Schrödinger International Boltzmanngasse, Alejandro Perez, Alejandro Perez, Erwin Schroedinger International

In this article we review the present status of the spin foam formulation of nonperturbative (background independent) quantum gravity. The article is divided in two parts. In the first part we...

The Hartree-Fock state for the 2DEG at filling factor 1/2 revisited: analytic solution, dynamics and correlation energy (2001)

Cabo, Alejandro, Claro, Francisco, Perez, Alejandro

The CDW Hartree-Fock state at half filling and half electron per unit cell is examined. Firstly, an exact solution in terms of Bloch-like states is presented. Using this solution we discuss the...

Spin Foam Diagrammatics and Topological Invariance (2001)

Girelli, Florian, Oeckl, Robert, Perez, Alejandro

We provide a simple proof of the topological invariance of the Turaev-Viro model (corresponding to simplicial 3d pure Euclidean gravity with cosmological constant) by means of a novel diagrammatic...

A finiteness proof for the Lorentzian state sum spinfoam model for quantum general relativity (2001)

Crane, Louis, Perez, Alejandro, Rovelli, Carlo

We show that the normalized Lorentzian state sum is finite on any triangulation. It thus provides a candidate for a perturbatively finite quantum theory of general relativity in four dimensions with...

Observables in quantum gravity (2001)

Perturbations with angular momentum of Robinson-Trautman spacetimes (2001)

We study a family of physical observable quantities in quantum gravity. We denote them W functions, or n-net functions. They represent transition amplitudes between quantum states of the geometry,...

Moreschi, Osvaldo M., Perez, Alejandro

We study the possible asymptotically flat perturbations of Robinson-Trautman spacetimes. We differentiate between algebraically special perturbations and general perturbations. The equations that...

2d manifold-independent spinfoam theory (2001)

Livine, Etera R., Perez, Alejandro, Rovelli, Carlo

A number of background independent quantizations procedures have recently been employed in 4d nonperturbative quantum gravity. We investigate and illustrate these techniques and their relation in the...

Spin Foam Models for Quantum Gravity (2001)

The Erwin, Schrodinger International Boltzmanngasse, Alejandro Perez, Alejandro Perez, Erwin Schroedinger International

In this article we review the present status of the spin foam formulation of nonperturbative (background independent) quantum gravity. The article is divided in two parts. In the first part we...

Perturbative Finiteness in Spin-Foam Quantum Gravity (2001)

Crane, Louis, Perez, Alejandro, Rovelli, Carlo

Characterizing exact solutions from asymptotic physical concepts (2000)

Perez, Alejandro, Moreschi, Osvaldo M.

We contribute to the subject of the physical interpretation of exact solutions by characterizing them through a systematic study in terms of unambiguous physical concepts coming from systems in...

Finiteness of a spinfoam model for euclidean quantum general relativity (2000)

3+1 spinfoam model of quantum gravity with spacelike and timelike components (2000)

We prove that a certain spinfoam model for euclidean quantum general relativity, recently defined, is finite: all its all Feynman diagrams converge. The model is a variant of the Barrett-Crane model,...

Spin foam model for Lorentzian General Relativity (2000)

We present a spinfoam formulation of Lorentzian quantum General Relativity. The theory is based on a simple generalization of an Euclidean model defined in terms of a field theory over a group. The...

A spin foam model without bubble divergences (2000)

We present a spin foam formulation of Lorentzian quantum General Relativity. The theory is based on a simple generalization of an Euclidean model defined in terms of a field theory over a group. Its...