Results 51 to 60 of about 4,839,190 (320)
Is the Zero-Point Energy Real? [PDF]
, 2002 I consider the arguments to show that the vacuum energy density should receive a large contribution from the zero-point energy. This is the cosmological constant problem, as it was originally framed. I suggest that the matter is interpretation-dependent,
Simon Saunders, Saunders, Simon
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Bootstrapped Newtonian Cosmology and the Cosmological Constant Problem [PDF]
Symmetry, 2021 Bootstrapped Newtonian gravity was developed with the purpose of estimating the impact of quantum physics in the nonlinear regime of the gravitational interaction, akin to corpuscular models of black holes and inflation. In this work, we set the ground for extending the bootstrapped Newtonian picture to cosmological spaces.
Casadio, Roberto, Giusti, Andrea
openaire +2 more sources
Inflation and the cosmological constant
上海师范大学学报. 自然科学版, 2014 By assuming the cosmological “constant” is no longer a constant during the inflation epoch,it is found that the cosmological constant fine-tuning problem is solved.In the meanwhile,inflation models could predict a large tensor-to-scalar ratio,correct ...
FENG Chaojun, LI Xinzhou
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Dark matter from torsion in Friedmann cosmology
European Physical Journal C: Particles and Fields, 2022 A cosmological model in an Einstein–Cartan framework endowed with torsion is studied. For a torsion function assumed to be proportional to Hubble expansion function, namely $$\phi =-\alpha H$$ ϕ = - α H , the contribution of torsion function as a dark ...
S. H. Pereira +3 more
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Loop quantum gravity and cosmological constant
Physics Letters B, 2021 A one-parameter regularization freedom of the Hamiltonian constraint for loop quantum gravity is analyzed. The corresponding spatially flat, homogenous and isotropic model includes the two well-known models of loop quantum cosmology as special cases. The
Xiangdong Zhang, Gaoping Long, Yongge Ma
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Black hole shadow in an expanding universe with a cosmological constant [PDF]
Physical Review D, 2018 We analytically investigate the influence of a cosmic expansion on the shadow of the Schwarzschild black hole. We suppose that the expansion is driven by a cosmological constant only and use the Kottler (or Schwarzschild–de Sitter) spacetime as a model ...
V. Perlick +2 more
semanticscholar +1 more source
Dilatations and the cosmological constant [PDF]
Nuclear Physics B, 1989 Abstract The role of dilatation symmetry in explaining the smallness of the cosmological constant is investigated. Dilatation-invariant theories necessarily lead to a zero cosmological constant, but only if the vacuum is invariant. This is physically unacceptable, and dilatation invariance must be broken (at least) spontaneously, in which case we do ...
Coughlan, G, Kani, I, Ross, G, Segre, G
openaire +2 more sources
The viability of modified gravity theories [PDF]
, 2009 PhDThis thesis studies the viability of classes of modified gravity (MG) theories based on generalisations of the Einstein-Hilbert action. Particular emphasis is given to f(R) theories in both the metric and Palatini formalisms, scalar-tensor theories ...
Uddin, Kotub
core +4 more sources
Mirror QCD and Cosmological Constant
Universe, 2017 An analog of Quantum Chromo Dynamics (QCD) sector known as mirror QCD (mQCD) can affect the cosmological evolution due to a non-trivial contribution to the Cosmological Constant analogous to that induced by the ground state in non-perturbative QCD.
Roman Pasechnik +2 more
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On Exclusion of Positive Cosmological Constant [PDF]
Fortschritte der Physik, 2018 Some time ago we have suggested that positive vacuum energy exhibits a finite quantum break time, which can be a signal that a positive cosmological constant is inconsistent. From the requirement that the Universe never undergoes through quantum breaking,
G. Dvali, César Gómez
semanticscholar +1 more source