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We investigate the possibility of gravitationally generated particle production via the mechanism of nonminimal torsion--matter coupling. An intriguing feature of this theory is that the divergence of the matter energy--momentum tensor does…

General Relativity and Quantum Cosmology · Physics 2021-07-06 Tiberiu Harko , Francisco S. N. Lobo , Emmanuel N. Saridakis

In this work, we explore the formalism of the irreversible thermodynamics of open systems and the possibility of gravitationally generated particle production in modified gravity. More specifically, we consider the scalar-tensor…

General Relativity and Quantum Cosmology · Physics 2023-06-27 Miguel A. S. Pinto , Tiberiu Harko , Francisco S. N. Lobo

We consider the possibility of a gravitationally induced particle production through the mechanism of a nonminimal curvature-matter coupling. An interesting feature of this gravitational theory is that the divergence of the energy-momentum…

General Relativity and Quantum Cosmology · Physics 2015-08-31 Tiberiu Harko , Francisco S. N. Lobo , José P. Mimoso , Diego Pavón

In this work, we analyze the possibility of gravitationally induced matter creation in the so-called Energy-Momentum-Squared gravity (EMSG), i.e. $f(R,T_{\mu\nu}T^{\mu\nu})$ gravity, in its dynamically equivalent scalar-tensor…

General Relativity and Quantum Cosmology · Physics 2024-03-15 Ricardo A. C. Cipriano , Tiberiu Harko , Francisco S. N. Lobo , Miguel A. S. Pinto , João Luís Rosa

Modified gravity theories with geometry - matter coupling, in which the action is an arbitrary function of the Ricci scalar and the matter Lagrangian ($f\left(R,L_m\right)$ gravity), and of the Ricci scalar and of the trace of the matter…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Tiberiu Harko

Recently, the scalar-tensor representation of $f (R,T)$ gravity was used to explore gravitationally induced particle production/annihilation. Using the framework of irreversible thermodynamics of open systems in the presence of matter…

General Relativity and Quantum Cosmology · Physics 2023-10-20 Amine Bouali , Himanshu Chaudhary , Tiberiu Harko , Francisco S. N. Lobo , Taoufik Ouali , Miguel A. S. Pinto

Modified gravity theories with a nonminimal coupling between curvature and matter offer a compelling alternative to dark energy and dark matter by introducing an explicit interaction between matter and curvature invariants. Two of the main…

General Relativity and Quantum Cosmology · Physics 2025-10-29 Francisco S. N. Lobo , Tiberiu Harko , Miguel A. S. Pinto

An interesting cosmological history was proposed by Prigogine {\it et al.} who considered the Universe as a thermodynamically open system. This scenario is characterized by a process of matter creation, which corresponds to an irreversible…

General Relativity and Quantum Cosmology · Physics 2015-08-14 Francisco S. N. Lobo , Tiberiu Harko , José P. Mimoso , Diego Pavón

A relativistic kinetic description for the irreversible thermodynamic process of gravitationally induced particle production is proposed in the context of an expanding Friedmann-Robertson-Walker (FRW) geometry. We show that the covariant…

General Relativity and Quantum Cosmology · Physics 2014-11-25 J. A. S. Lima , I. P. Baranov

The thermodynamical study of the universe allow particle production in modified $f(T)$ ($T$ is the torsion scalar) theory of gravity within a flat FLRW framework for line element. The torsion scalar $T$ plays the same role as the Ricci…

General Relativity and Quantum Cosmology · Physics 2021-01-18 Sanjay Mandal , P. K. Sahoo

The theoretical and observational consequences of thermodynamics of open systems, which allow particle creation are investigated in modified $f(R,T)$ ($R$ is the Ricci scalar and $T$ is the trace of energy-momentum tensor) theory of gravity…

General Relativity and Quantum Cosmology · Physics 2014-08-26 C. P. Singh , Vijay Singh

By using the thermodynamic theory of irreversible processes and Einstein general relativity, a cosmological model is proposed where the early universe is considered as a mixture of a scalar field with a matter field. The scalar field refers…

General Relativity and Quantum Cosmology · Physics 2009-11-07 G. M. Kremer , F. P. Devecchi

In this proceeding, we review modified theories of gravity with a curvature-matter coupling between an arbitrary function of the scalar curvature and the Lagrangian density of matter. This explicit nonminimal coupling induces a…

General Relativity and Quantum Cosmology · Physics 2022-09-20 Francisco S. N. Lobo , Tiberiu Harko

The paper studies the possible interplay between matter and geometry in scalar tensor theories of gravitation where the energy--momentum tensor is directly coupled with the Einstein tensor. After obtaining the scalar tensor representation…

General Relativity and Quantum Cosmology · Physics 2024-10-08 Mihai Marciu

We investigate the creation of dark matter particles as a result of the decay of the scalar field in the framework of warm inflationary models, by using the irreversible thermodynamics of open systems with matter creation/annihilation. We…

General Relativity and Quantum Cosmology · Physics 2023-03-07 Teodora Matei , Tiberiu Harko , Gabriela Mocanu

A scenario for gravitational particle creation in a stiff matter dominated flat Friedmann-Robertson-Walker universe is presented. The primary creation of scalar particles is calculated using quantum field theory in curved spacetime and it…

General Relativity and Quantum Cosmology · Physics 2017-09-27 Juho Lankinen , Iiro Vilja

We study particle production aspect in the flat FRW universe in the framework of $f(T)$ gravity. The matter is minimally coupled with the gravity and an exact power-law solution is obtained by solving the Friedmann equations, and matter is…

General Physics · Physics 2013-03-26 M. R. Setare , M. J. S. Houndjo

We study particle production in infrared-modified gravitational theories in the contemporary universe. It is shown that in astronomical systems with rising mass density, the curvature scalar may oscillate with very high frequency. These…

General Relativity and Quantum Cosmology · Physics 2015-06-16 E. V. Arbuzova , A. D. Dolgov , L. Reverberi

The Hubble tension and the unknown origin of dark energy motivate the exploration of alternative mechanisms for late-time cosmic acceleration. We investigate gravitationally induced particle creation (PC) as a non-equilibrium process that…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-28 Tiziano Schiavone , Mariaveronica De Angelis , Luis A. Escamilla , Giovanni Montani , Eleonora Di Valentino

The effect of gravitational particle production of scalar particles on the total effective cosmic energy density (in the era after photon decoupling till the present) is considered. The effect is significant for heavy particles. It is found…

General Relativity and Quantum Cosmology · Physics 2024-08-27 Recai Erdem
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