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We study the phase diagram of scalar field theory on a three dimensional Euclidean spacetime whose spatial component is a fuzzy sphere. The corresponding model is an ordinary one-dimensional matrix model deformed by terms involving fixed…

High Energy Physics - Theory · Physics 2011-03-22 Matthias Ihl , Christoph Sachse , Christian Saemann

The correspondence of single-field cosmological models based on Einstein gravity to modern observational data is considered. A method is proposed to determine possible types of dynamics based on extreme values of the scalar field. It is…

General Relativity and Quantum Cosmology · Physics 2025-10-10 I. V. Fomin

A simple theoretical model of scalar fields in one spatial dimension with internal symmetry is considered. Assuming the existence of localized classical field configurations, the Schr\"{o}dinger picture is used to describe their quantum…

High Energy Physics - Theory · Physics 2021-01-01 Avtandil Shurgaia

We investigate, in the framework of a recently introduced new class of invariant geometrical scalar-tensor theory of gravity, the possibility that a viscous dark fluid can be described in a unified manner by a single scalar field. Thus we…

General Relativity and Quantum Cosmology · Physics 2020-09-03 José Edgar Madriz Aguilar , A. Gil-Ocaranza , M. Montes , J. Zamarripa

We evaluated the scattering amplitude of neutral scalar particles at one-loop order in the context of effective field theory of quantum gravity in the presence of a cosmological constant. Our study suggests that quantum gravitational…

High Energy Physics - Theory · Physics 2013-12-02 A. C. Lehum

As a toy model for the implementation of the diffeomorphism constraint, the interpretation of the resulting states, and the treatment of ordering ambiguities in loop quantum gravity, we consider the Hilbert space of spatially diffeomorphism…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Hanno Sahlmann

The recent formulation of locally covariant quantum field theory may open the way towards a background independent perturbative formulation of Quantum Gravity.

General Relativity and Quantum Cosmology · Physics 2007-05-23 Romeo Brunetti , Klaus Fredenhagen

We provide a short introduction to the main features of the algebraic approach to quantum field theories.

Mathematical Physics · Physics 2007-05-23 Romeo Brunetti , Klaus Fredenhagen

A self-consistent system of interaction nonlinear spinor and scalar fields within the scope of a BI cosmological model filled with perfect fluid is considered. The role of spinor field in the evolution of the Universe is studied. It is…

General Relativity and Quantum Cosmology · Physics 2015-05-01 Bijan Saha

We describe the construction of quantum gravity, i.e. of a theory of self-interacting massless spin-2 quantum gauge fields, the gravitons, on flat space-time, in the framework of causal perturbation theory.

High Energy Physics - Theory · Physics 2007-05-23 Nicola Grillo

Results of a general study on the dynamics of cosmological scalar fields with arbitrary potentials are presented. Exact and approximate attractor solutions are found, with applications to quintessence, moduli stabilization and inflation.

Astrophysics · Physics 2007-05-23 F. Rosati

Quantum gravity is sometimes considered as a kind of metaphysical speculation. In this review, we show that, although still extremely difficult to reach, observational signatures can in fact be expected. The early universe is an invaluable…

General Relativity and Quantum Cosmology · Physics 2015-06-17 A. Barrau , T. Cailleteau , J. Grain , J. Mielczarek

This lecture reviews aspects of and prospects for progress towards a theory of quantum gravity from a particle physics perspective, also paying attention to recent findings of the LHC experiments at CERN.

General Relativity and Quantum Cosmology · Physics 2015-06-12 Hermann Nicolai

A scalar quantum field theory defined on a discrete spatial coordinate is examined. The renormalization of the lattice propagator is discussed with an emphasis on the periodic nature of the associated momentum coordinate. The analytic…

High Energy Physics - Theory · Physics 2013-03-14 Micheal S. Berger , Naoki Yamatsu

We analyze cosmological perturbations to the linear order in the context of inflation with an arbitrary number of scalar fields. The fields take values on a non-trivial manifold with a positive-definite metric and are non-minimally coupled…

Astrophysics · Physics 2007-05-23 Joydev Lahiri , Gautam Bhattacharya

The new classes of homogeneous cosmological models for the scalar fields are build in the context of Lyra's geometry. The different types of exact solution for the model are obtained by applying two procedures, viz the generating function…

General Relativity and Quantum Cosmology · Physics 2015-11-06 V. K. Shchigolev , E. A. Semenova

After a long technical and consequently philosophical disgression about the necessity of the construction presented in this book, a logically consistent and precise theory of quantum gravity is presented. The construction of this theory…

General Physics · Physics 2013-05-07 Johan Noldus

A nonlinear scalar field theory from which an effective metric can be deduced is considered. This metric is shown to be compatible with requirements of general relativity. It is demonstrated that there is a class of solutions which fulfill…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Andrzej Okninski

Out of several possible extensions of general relativity, the scalar-tensor theory is the most popular for several reasons. Since the quantum description of gravity is yet to be formulated properly, the understanding of a gravitational…

General Relativity and Quantum Cosmology · Physics 2022-10-12 Krishnakanta Bhattacharya , Bibhas Ranjan Majhi

We revisit the classical and quantum cosmology of a universe in which a self interacting scalar field is coupled to gravity with a flat FRW type metric undergoing continuous signature transition. We arrange for quantum cosmologically…

General Relativity and Quantum Cosmology · Physics 2009-11-10 F. Darabi , A. Rastkar