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The gravitino problem is investigated in the framework of Extended Gravity cosmologies. In particular, we consider $f(R)$ gravity, the most natural extension of the Hilbert-Einstein action, and $f(\cal T)$ gravity, the extension of…

General Relativity and Quantum Cosmology · Physics 2020-12-25 Salvatore Capozziello , Gaetano Lambiase

An equilibrium picture of thermodynamics is discussed at the apparent horizon of FRW universe in $f(T,T_G)$ gravity, where $T$ represents the torsion invariant and $T_G$ is the teleparallel equivalent of the Gauss-Bonnet term. It is found…

General Relativity and Quantum Cosmology · Physics 2015-11-04 M. Zubair

We extend the formalism of the Einstein-Hilbert unimodular gravity in the context of modified $F(R)$ gravity. After appropriately modifying the Friedmann-Robertson-Walker metric in a way that it becomes compatible to the unimodular…

General Relativity and Quantum Cosmology · Physics 2016-06-01 S. Nojiri , S. D. Odintsov , V. K. Oikonomou

We develop the general scheme for modified $f(R)$ gravity reconstruction from any realistic FRW cosmology. We formulate several versions of modified gravity compatible with Solar System tests where the following sequence of cosmological…

High Energy Physics - Theory · Physics 2008-11-26 Shin'ichi Nojiri , Sergei D. Odintsov

In the present paper, we study the thermodynamics behavior of the field equations for the generalized f(T) gravity with an arbitrary coupling between matter and the torsion scalar. In this regard, we explore the verification of the first…

General Relativity and Quantum Cosmology · Physics 2017-01-17 Tahereh Azizi , Najibeh Borhani

Some time ago, it has been suggested that gravitons can acquire mass in the process of spontaneous symmetry breaking of diffeomorphisms through the condensation of scalar fields [Chamseddine and Mukhanov, JHEP, 2010]. Taking this…

General Relativity and Quantum Cosmology · Physics 2024-09-02 Kimet Jusufi , Ahmed Farag Ali , Abdelrahman Yasser , Nader Inan , A. Y. Ellithi

We investigate the Friedmann-Robertson-Walker (FRW) universe (containing dark energy) as a non-equilibrium (irreversible) thermodynamical system by considering the power-law correction to the horizon entropy. By taking power-law entropy…

General Physics · Physics 2011-12-14 M. Umar Farooq , Mubasher Jamil

We investigate the thermodynamics at the apparent horizon of the FRW universe in $f(R,T)$ theory under non-equilibrium description. The laws of thermodynamics have been discussed for two particular models of $f(R,T)$ theory. The first law…

General Relativity and Quantum Cosmology · Physics 2014-09-26 M. Sharif , M. Zubair

In this work we derive general quantum phenomenological equations of gravitational dynamics and analyse its features. The derivation uses the formalism developed in thermodynamics of spacetime and introduces low energy quantum gravity…

General Relativity and Quantum Cosmology · Physics 2021-02-03 Ana Alonso-Serrano , Marek Liška

The paper extends basic Einstein--Hilbert action by adding a newly proposed invariant constructed from a specific contraction between the Einstein tensor and the energy momentum tensor, encoding a non--minimal coupling between the…

General Relativity and Quantum Cosmology · Physics 2023-02-09 Mihai Marciu , Dana Maria Ioan

We disclose the deep connection between the thermodynamics and gravity in a general braneworld model with curvature correction terms on the brane and in the bulk, respectively. We show that the Friedmann equations on the 3-brane embedded in…

High Energy Physics - Theory · Physics 2008-11-26 Ahmad Sheykhi , Bin Wang , Rong-Gen Cai

In the framework of entropic cosmology, entropic forces arising at the cosmological horizon have been proposed as an alternative mechanism to explain the Universe's current accelerated phase. However, recent studies have shown that, under…

General Relativity and Quantum Cosmology · Physics 2025-10-02 Giuseppe Gaetano Luciano

We suggest that using the first law of thermodynamics is a convenient method to obtain a correct form of the expansion law of the universe \cite{T. Padmanabhan1}. We will, then, use this idea to obtain the expansion law for a Kodama…

General Relativity and Quantum Cosmology · Physics 2015-07-07 Fatemeh Lalehgani Dezaki , Behrouz Mirza

In this paper we argue that modified Friedmann equations with a bounce solution can be derived from a modified dispersion relation by employing a thermodynamical description of general relativity on the apparent horizon.

General Relativity and Quantum Cosmology · Physics 2010-04-30 Yi Ling , Wei-Jia Li , Jian-Pin Wu

The Gravity from Entropy (GfE) action posits that gravity that is fundamentally given by the information encoded in the interplay between matter and geometry. The GfE Lagrangian is given by the Geometric Quantum Relative Entropy (GQRE)…

General Relativity and Quantum Cosmology · Physics 2026-05-12 Ginestra Bianconi

The entropy functional formalism allows one to recover general relativity, modified gravity theories, as well as the Bekenstein-Hawking entropy formula. In most approaches to quantum gravity, the Bekenstein-Hawking's entropy formula…

General Relativity and Quantum Cosmology · Physics 2016-06-24 Fayçal Hammad , Mir Faizal

We investigate the correspondence between modified gravity theories and general entropic cosmology theory. Such a theory is proposed by an analogy with Jacobson's work, where the Einstein equation was derived from the Bekenstein-Hawking…

General Relativity and Quantum Cosmology · Physics 2025-03-24 Shin'ichi Nojiri , Sergei D. Odintsov

We construct new classes of modified theories in which the matter sector couples with the Einstein tensor, namely we consider direct couplings of the latter to the energy-momentum tensor, and to the derivatives of its trace. We extract the…

General Relativity and Quantum Cosmology · Physics 2023-05-17 Petros Asimakis , Spyros Basilakos , Andreas Lymperis , Maria Petronikolou , Emmanuel N. Saridakis

Considering the Einstein field equations in Lyra manifold, and applying the unified first law of thermodynamics as well as the Clausius relation to the apparent horizon of FRW universe, we find the entropy of apparent horizon in Lyra…

General Relativity and Quantum Cosmology · Physics 2017-09-12 H. Moradpour , N. Sadeghnezhad , S. Ghaffari , A. Jahan

A possible gluon-condensate-induced modified-gravity model with f(R) \propto |R|^{1/2} has been suggested previously. Here, a simplified version is presented using the constant flat-spacetime equilibrium value of the QCD gluon condensate…

Cosmology and Nongalactic Astrophysics · Physics 2011-12-20 F. R. Klinkhamer
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