Results 61 to 70 of about 2,562 (178)
European Physical Journal C: Particles and Fields, 2018 Bouncing cosmologies are obtained by adding to the Einstein–Hilbert action a term of the form $$\sqrt{-\,g}f(\chi )$$ -gf(χ) , with $$\chi $$ χ a scalar depending on the Hubble parameter only, not on its derivatives, and which is here shown to arise from
Jaume de Haro +2 more
doaj +1 more source
Physics Letters B, 2022 Parity violating models based on the symmetric teleparallel gravity have been considered in the literature, but their applications in cosmology and especially the features in cosmological perturbations have not been fully explored.
Mingzhe Li, Dehao Zhao
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Quantum vacuum energy in general relativity [PDF]
, 2017 The paper deals with the scale discrepancy between the observed vacuum energy in cosmology and the theoretical quantum vacuum energy (cosmological constant problem).
C. Henke
semanticscholar +1 more source
Annalen der Physik, EarlyView.The BRST invariant Lagrangian of the gravitationally interacting U(1)$U(1)$ gauge theory, namely the Quantum GraviElectro Dynamics (QGED). The Yan–Mills theory with the Hilbert–Einstein gravitational Lagrangian, namely the Yang–Mills–Utiyama (YMU) theory, is defined and quantised using the standard procedure. The theory is perturbatively renormalisable,
Yoshimasa Kurihara
wiley +1 more source
Logarithmic and Strong Coupling Models in Weyl‐Type f(Q,T)$f(Q,T)$ Gravity
Annalen der Physik, EarlyView.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
wiley +1 more source
The DNA of Calabi–Yau Hypersurfaces
Fortschritte der Physik, EarlyView.Abstract Genetic Algorithms are implemented for triangulations of four‐dimensional reflexive polytopes, which induce Calabi–Yau threefold hypersurfaces via Batyrev's construction. These algorithms are shown to efficiently optimize physical observables such as axion decay constants or axion–photon couplings in string theory compactifications.
Nate MacFadden +2 more
wiley +1 more source
Anomaly-induced effective action and Chern–Simons modification of general relativity
Physics Letters B, 2015 Recently it was shown that the quantum vacuum effects of massless chiral fermion field in curved space–time leads to the parity-violating Pontryagin density term, which appears in the trace anomaly with imaginary coefficient.
Sebastião Mauro, Ilya L. Shapiro
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Phantasmic Encounters in the Arctic: Haunting Materialities Beyond the Ghosts of War
Anthropology of Consciousness, EarlyView.ABSTRACT In the vast north, ghostly experiences are common for locals and outsiders alike. Here, we explore how cultural‐natural attributes, like remoteness and extreme seasonal variation, compound experiences of the haunting in visceral ways. This provides the Arctic region with an unusually pronounced baseline of other‐than‐human agency, which in the
Aki Hakonen, Oula Seitsonen
wiley +1 more source
Classical and quantum cosmology of K-essentially modified $$R^2$$ and pure $$R^p$$ gravity [PDF]
General Relativity and Gravitation, 2018 We present a gravitational action with a modified higher order term of a combination of scalar curvature and Lagrangian density of a scalar field. This type of models has been considered first by Cruz-Dombriz et al.
N. Kan, Kiyoshi Shiraishi, Mai Yashiki
semanticscholar +1 more source