Results 71 to 80 of about 6,154 (134)
Fortschritte der Physik, Volume 74, Issue 4, April 2026.Abstract String theory has strong implications for cosmology, implying the absence of a cosmological constant, ruling out single‐field slow‐roll inflation, and that black holes decay. The origins of these statements are elucidated within the string‐theoretical swampland programme.
Kay Lehnert
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Kaniadakis Holographic Dark Energy Behavior in f(Q) Theory
Fortschritte der Physik, Volume 74, Issue 4, April 2026.ABSTRACT In this study, the cosmological behavior of the Kaniadakis holographic dark energy model is investigated under the f(Q)$f(Q)$ theory within the framework of a flat Friedmann–Robertson–Walker (FRW) universe. The generalized holographic energy density based on Kaniadakis entropy is modeled using the Hubble horizon infrared cutoff scale, and the ...
Sinem Kalkan, Can Aktaş
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A Re‐Examination of Foundational Elements of Cosmology
Fortschritte der Physik, Volume 74, Issue 3, March 2026.ABSTRACT This paper undertakes a conceptual re‐examination of several foundational elements of cosmology through the lens of spacetime symmetries. A new derivation of the Friedmann–Lemaître–Robertson–Walker metric is obtained by a careful conceptual examination of rotations and translations on generic manifolds, followed by solving the rotational and ...
Lavinia Heisenberg
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Corrected entropy of Friedmann-Robertson-Walker universe in tunneling method [PDF]
, 2009 In this paper, we study the thermodynamic quantities of Friedmann-Robertson-Walker (FRW) universe by using the tunneling formalism beyond semiclassical approximation developed by Banerjee and Majhi [25].
Tao Zhu, Ji-rong Ren, Ming-fan Li
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Logarithmic and Strong Coupling Models in Weyl‐Type f(Q,T)$f(Q,T)$ Gravity
Annalen der Physik, Volume 538, Issue 1, January 2026.This work explores Weyl‐type f(Q,T) gravity using recent observational datasets — CC, Pantheon+, Union 3.0, and DESI DR2. Through MCMC analysis of logarithmic and strong coupling models, the study reveals a transition from deceleration to acceleration, quintessence‐to‐phantom dynamics, and late‐time consistency with LCDM, offering a geometry‐driven ...
Rahul Bhagat, S. K. Tripathy, B. Mishra
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Fermionic decay of a massive scalar in the early universe
European Physical Journal C: Particles and Fields, 2020 We derive a curved space generalization of a scalar to fermion decay rate with a Yukawa coupling in expanding Friedmann–Robertson–Walker universes. This is done using the full theory of quantum fields in curved spacetime and the added-up transition ...
Juho Lankinen, Joonas Malmi, Iiro Vilja
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Exact solutions to Elko spinors in spatially flat Friedmann-Robertson-Walker spacetimes
Journal of Cosmology and Astroparticle Physics, 2014 In this paper we present exact solutions to the so-called Elko spinors for three models of expanding universe, namely the de Sitter, linear and the radiation type evolution. The study was restrict to flat, homogeneous and isotropic Friedmann-Robertson-Walker backgrounds. Starting with an Elko spinor we present the solutions for these cases and compared
J. M. Hoff da Silva, S. H. Pereira
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The Dirac equation and the normalization of its solutions in a closed Friedmann– Robertson–Walker universe [PDF]
, 2009 We set up the Dirac equation in a Friedmann–Robertson–Walker geometry and separate the spatial and time variables. In the case of a closed universe, the spatial dependence is solved explicitly, giving rise to a discrete set of solutions.
F. Finster, Moritz Reintjes
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Novel Theorems on Spacetime Admitting Pseudo‐W2 Curvature Tensor
Journal of Mathematics, Volume 2026, Issue 1, 2026.This paper investigates spacetime manifolds admitting a pseudo‐W2 curvature tensor. We show that a pseudo‐W2 flat spacetime is an Einstein manifold and therefore has constant curvature. Moreover, when the manifold satisfies the Einstein field equations (EFE), with a cosmological constant, the associated energy–momentum tensor is covariantly constant ...
B. B. Chaturvedi +3 more
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Cosmological Dynamics of Interacting Dark Energy and Dark Matter in f(Q)$f(Q)$ Gravity
Fortschritte der Physik, Volume 73, Issue 5, May 2025.Abstract In this work, the behavior of interacting dark energy (DE) and dark matter (DM) within a model of f(Q)$f(Q)$ gravity is explored, employing the standard framework of dynamical system analysis. The power‐law f(Q)$f(Q)$ model is considered, incorporating two different forms of interacting DE and DM: 3αHρm$3\alpha H\rho _m$ and α3HρmρDE$\frac ...
Gaurav N. Gadbail +3 more
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