Slow-roll inflation in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e1295" altimg="si137.svg"><mml:mrow><mml:mi>f</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mi>R</mml:mi><mml:mo>,</mml:mo><mml:mi>T</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math> gravity with a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e1312" altimg="si140.svg"><mml:mrow><mml:mi>R</mml:mi><mml:mi>T</mml:mi></mml:mrow></mml:math> mixing term

Chen, Che-Yu; Reyimuaji, Yakefu; Zhang, Xinyi

doi:10.1016/j.dark.2022.101130

Cited by 11 publications

(1 citation statement)

References 55 publications

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“…On the other hand, Harko and collaborators [57] proposed another extension of standard GR, the f (R, T) modified gravity theories, where the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar R and of the trace of the energy-momentum tensor T. The cosmological consequences [58][59][60][61][62][63][64][65][66][67][68][69] and applications to compact stars [70][71][72][73][74][75][76][77][78][79][80][81][82][83] of such a theory have been addressed by several authors in recent years. See further [84][85][86][87] for a novel scalar-tensor representation of f (R, T) gravity.…”

Section: Introductionmentioning

confidence: 99%

Moment of inertia and compactness of quark stars within the context of f(R, T, L _m) gravity

Pretel

2024

Phys. Scr.

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Within the metric formalism of f(R, T, L m ) gravity theories, we investigate the hydrostatic equilibrium structure of compact stars taking into account both isotropic and anisotropic pressure. For this purpose, we focus on the f(R, T, L m ) = R + α TL m model, where α is a free parameter. We derive the modified TOV equations and the relativistic moment of inertia in the slowly rotating approximation. Using an equation of state (EoS) for color-superconducting quark stars, we examine the effects of the α TL m term on the different macroscopic properties of these stars. Our results reveal that the decrease of the parameter α leads to a noticeable increase in the maximum-mass values. For negative α with sufficiently small ∣α∣, we obtain a qualitative behavior similar to the general relativistic (GR) context, namely, it is possible to obtain a critical stellar configuration such that the mass reaches its maximum. However, for sufficiently large values of ∣α∣ keeping negative α, the critical point cannot be found on the mass-radius diagram. We also find that the inclusion of anisotropic pressure can provide masses and radii quite consistent with the current observational measurements, which opens an outstanding window onto the physics of anisotropic quark stars. By comparing the I − C relations of isotropic quark stars in modified gravity, we show that such a correlation remains almost unchanged as the parameter α varies from GR counterpart. On the other hand, given a fixed α, the I − C relation is insensitive to variations of the anisotropy parameter β to O ( 4 % ) .

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Section: Introductionmentioning

confidence: 99%

Moment of inertia and compactness of quark stars within the context of f(R, T, L _m) gravity

Pretel

2024

Phys. Scr.

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Thermodynamics and Perturbative Analysis of Some Newly Developed F(R,Lm,T)$\mathcal {F}(R,L_m, T)$ Theories Under the Scenario of Conserved Energy‐momentum Tensor

Zubair

Waheed

Muneer

et al. 2023

Fortschritte der Physik

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The present work is devoted to explore some interesting cosmological features of a newly proposed theory of gravity namely theory, where R and T represent the Ricci scalar and trace of energy momentum‐tensor, respectively. First, a non‐equilibrium thermodynamical description is considered on the apparent horizon of the Friedmann's cosmos. The Friedmann equations are demonstrated to be equivalent to the first law of thermodynamics, i.e., , where refers to entropy production term. The constraint for validity of generalized second law of thermodynamics is also formulated and checked it for some simple well‐known forms of generic function . Next, the energy bounds for this framework and constraint the free variables by finding the validity regions for NEC and WEC are developed. Furthermore, some interesting cosmological solutions namely power law, ΛCDM, and de Sitter models in this theory are reconstructed. The reconstructed solutions are then examined by checking the validity of GSLT and energy bounds. Lastly, the stability of all reconstructed solutions by introducing suitable perturbations in the field equations is analyzed. It is concluded that obtained solutions are stable and cosmologically viable.

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Towards a systematic study of non-thermal leptogenesis from inflaton decays

Zhang

2024

J. High Energ. Phys.

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This paper investigates non-thermal leptogenesis from inflaton decays in the minimal extension of the canonical type-I seesaw model, where a complex singlet scalar ϕ is introduced to generate the Majorana masses of right-handed neutrinos (RHNs) and to play the role of inflaton. First, we systematically study non-thermal leptogenesis with the least model dependence. We give a general classification of the parameter space and find four characteristic limits by carefully examining the interplay between inflaton decay into RHNs and the decay of RHNs into the standard-model particles. Three of the four limits are truly non-thermal, with a final efficiency larger than that of thermal leptogenesis. Two analytic estimates for these three limits are provided with working conditions to examine the validity. In particular, we find that the strongly non-thermal RHNs scenario occupies a large parameter space, including the oscillation-preferred K range, and works well for a relatively-low reheating temperature TRH ≥ 103 GeV, extending the lower bound on the RHN mass to 2 × 107 GeV. The lepton flavor effects are discussed. Second, we demonstrate that such a unified picture for inflation, neutrino masses, and baryon number asymmetry can be realized by either a Coleman-Weinberg potential (for the real part of ϕ) or a natural inflation potential (for the imaginary part of ϕ). The allowed parameter ranges for successful inflation and non-thermal leptogenesis are much more constrained than those without inflationary observations. We find that non-thermal leptogenesis from inflaton decay offers a testable framework for the early Universe. It can be further tested with upcoming cosmological and neutrino data. The model-independent investigation of non-thermal leptogenesis should be useful in exploring this direction.

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Slow-roll inflation in f(R,T) gravity with a RT mixing term

Cited by 11 publications

References 55 publications

Moment of inertia and compactness of quark stars within the context of f(R, T, L _m) gravity

Moment of inertia and compactness of quark stars within the context of f(R, T, L _m) gravity

Thermodynamics and Perturbative Analysis of Some Newly Developed F(R,Lm,T)$\mathcal {F}(R,L_m, T)$ Theories Under the Scenario of Conserved Energy‐momentum Tensor

Towards a systematic study of non-thermal leptogenesis from inflaton decays

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Slow-roll inflation in f(R,T) gravity with a RT mixing term

Cited by 11 publications

References 55 publications

Moment of inertia and compactness of quark stars within the context of f(R, T, L m ) gravity

Moment of inertia and compactness of quark stars within the context of f(R, T, L m ) gravity

Thermodynamics and Perturbative Analysis of Some Newly Developed F(R,Lm,T)$\mathcal {F}(R,L_m, T)$ Theories Under the Scenario of Conserved Energy‐momentum Tensor

Towards a systematic study of non-thermal leptogenesis from inflaton decays

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Moment of inertia and compactness of quark stars within the context of f(R, T, L _m) gravity

Moment of inertia and compactness of quark stars within the context of f(R, T, L _m) gravity