183 citations · 2.1k across the 65 of their papers we have counts for
48 papers · 1 filter
Reconstruction methods and the amplification of the inflationary spectrum
Leonardo Chataignier, Alexander Yu. Kamenshchik, Alessandro Tronconi +1
We analyze the consequences of different evolutions of the Hubble parameter on the spectrum of scalar inflationary perturbations. The analysis is restricted to inflationary phases…
Reflected Waves and Quantum Gravity
Leonardo Chataignier, Alexander Yu. Kamenshchik, Alessandro Tronconi +1
In the context of canonical quantum gravity, we consider the effects of a non-standard expression for the gravitational wave function on the evolution of inflationary perturbations…
Regular black holes, universes without singularities, and phantom-scalar field transitions
Leonardo Chataignier, Alexander Yu. Kamenshchik, Alessandro Tronconi +1
We consider a procedure of elimination of cosmological singularities similar to that suggested in the recent paper by Simpson and Visser for the construction of regular black holes…
DBI Inflation and Warped Black Holes
Alexander Y. Kamenshchik, Alessandro Tronconi, Giovanni Venturi
We study a possible amplification mechanism for the curvature perturbations generated during inflation by a Dirac-Born-Infeld (DBI) inflaton in the presence of a sharp feature in t…
Born-Oppenheimer meets Wigner-Weyl in Quantum Gravity
A. Y. Kamenshchik, A. Tronconi, G. Venturi
Starting from a Born-Oppenheimer decomposition of the Wheeler-DeWitt equation for the quantum cosmology of the matter-gravity system, we have performed a Wigner-Weyl transformation…
The Born-Oppenheimer approach to Quantum Cosmology
A. Y. Kamenshchik, A. Tronconi, G. Venturi
The scope of this paper is to compare two different approaches for solving the Wheeler-DeWitt (WDW) equation in the presence of homogeneous matter (inflaton) and perturbations arou…
Generalized unimodular gravity in Friedmann and Kantowski-Sachs universes
A. Yu. Kamenshchik, A. Tronconi, G. Venturi
We illustrate the recently proposed generalized unimodular gravity using simple examples of the Friedmann, Kantowski-Sachs and Schwarzschild geometries and show that it can be furt…
Quantum Cosmology and the Inflationary Spectra from a Non-Minimally Coupled Inflaton
A. Y. Kamenshchik, A. Tronconi, G. Venturi
We calculate the quantum gravitational corrections to the Mukhanov-Sasaki equation obtained by the canonical quantization of the inflaton-gravity system. Our approach, which is bas…
Induced Gravity and Quantum Cosmology
A. Y. Kamenshchik, A. Tronconi, G. Venturi
We study the Wheeler-DeWitt equation for a class of induced gravity models in the minisuperspace approximation. In such models a scalar field nonminimally coupled to gravity determ…
Duality between static spherically or hyperbolically symmetric solutions and cosmological solutions in scalar-tensor gravity
Alexander Yu. Kamenshchik, Ekaterina O. Pozdeeva, Alexei A. Starobinsky +4
We study static spherically and hyperbolically symmetric solutions of the Einstein equations in the presence of a conformally coupled scalar field and compare them with those in th…
Non-Canonical Inflation and Primordial Black Holes Production
Alexander Y. Kamenshchik, Alessandro Tronconi, Tereza Vardanyan +1
We study a mechanism for the amplification of the inflationary scalar perturbation when the inflaton field action is non-canonical, i.e. the inflaton kinetic term has a non-standar…
Time in quantum theory, the Wheeler-DeWitt equation and the Born-Oppenheimer approximation
Alexander Yu. Kamenshchik, Alessandro Tronconi, Tereza Vardanyan +1
We compare two different approaches to the treatment of the Wheeler-DeWitt equation and the introduction of time in quantum cosmology. One approach is based on the gauge-fixing pro…
Quantum Gravity, Time, Bounces and Matter
A. Y. Kamenshchik, A. Tronconi, T. Vardanyan +1
In the context of Quantum Cosmology and the Wheeler-DeWitt equation we investigate the possible effects of a non semiclassical wave-function of the universe on the evolution of the…
Induced gravity, and minimally and conformally coupled scalar fields in Bianchi-I cosmological models
A. Yu. Kamenshchik, E. O. Pozdeeva, A. A. Starobinsky +3
We study the cosmological evolution and singularity crossing in the Bianchi-I universe filled with a conformally coupled scalar field and compare them with those of the Bianchi-I u…
The Born-Oppenheimer Method, Quantum Gravity and Matter
Alexander Yu Kamenshchik, Alessandro Tronconi, Giovanni Venturi
We illustrate and examine diverse approaches to the quantum matter-gravity system which refer to the Born-Oppenheimer (BO) method. In particular we first examine a quantum geometro…
Bianchi-I cosmological model and crossing singularities
Alexander Yu. Kamenshchik, Ekaterina O. Pozdeeva, Sergey Yu. Vernov +2
We consider a rather simple method for the description of the Big Bang - Big Crunch cosmological singularity crossing. For the flat Friedmann universe this method gives the same re…
Quantum Cosmology and the Evolution of Inflationary Spectra
Alexander Y. Kamenshchik, Alessandro Tronconi, Giovanni Venturi
We illustrate how it is possible to calculate the quantum gravitational effects on the spectra of primordial scalar/tensor perturbations starting from the canonical, Wheeler-De Wit…
Integrable cosmological models in the Einstein and in the Jordan frames and Bianchi-I cosmology
A. Yu. Kamenshchik, E. O. Pozdeeva, A. Tronconi +2
We study integrable models in the Bianchi I metric case with scalar fields minimally and non-minimally coupled with gravity and the correspondence between their general solutions.…
General solutions of integrable cosmological models with non-minimal coupling
A. Yu. Kamenshchik, E. O. Pozdeeva, A. Tronconi +2
We study the integrable model with minimally and non-minimally coupled scalar fields and the correspondence of their general solutions. Using the model with a minimally coupled sca…
Transformations between Jordan and Einstein frames: Bounces, antigravity, and crossing singularities
Alexander Yu. Kamenshchik, Ekaterina O. Pozdeeva, Sergey Yu. Vernov +2
We study the relation between the Jordan-Einstein frame transition and the possible description of the crossing of singularities in flat Friedmann universes, using the fact that th…
Interdependence between integrable cosmological models with minimal and non-minimal coupling
A. Yu. Kamenshchik, E. O. Pozdeeva, A. Tronconi +2
We consider the relation between exact solutions of cosmological models having minimally and non-minimally coupled scalar fields. This is done for a particular class of solvable mo…
Quantum Gravity and the Large Scale Anomaly
Alexander Y. Kamenshchik, Alessandro Tronconi, Giovanni Venturi
The spectrum of primordial perturbations obtained by calculating the quantum gravitational corrections to the dynamics of scalar perturbations is compared with Planck 2013 and BICE…
Signatures of Quantum Gravity in a Born-Oppenheimer Context
Alexander Y. Kamenshchik, Alessandro Tronconi, Giovanni Venturi
We solve a general equation describing the lowest order corrections arising from quantum gravitational effects to the spectrum of cosmological fluctuations. The spectra of scalar a…
Inflation and Quantum Gravity in a Born-Oppenheimer Context
Alexander Y. Kamenshchik, Alessandro Tronconi, Giovanni Venturi
A general equation, describing the lowest order corrections coming from quantum gravitational effects to the spectrum of cosmological scalar fluctuations is obtained. These correct…