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THE COSMOLOGICAL CONSTANT [PDF]
String Phenomenology, 2003 Various contributions to the cosmological constant are discussed and confronted with its recent measurement. We briefly review different scenarious -- and their difficulties -- for a solution of the cosmological constant problem.
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Wormholes and the cosmological constant [PDF]
Nuclear Physics B, 1989 We review Coleman's wormhole mechanism for the vanishing of the cosmological constant. We show that in a minisuperspace model wormhole-connected universes dominate the path integral. We also provide evidence that the euclidean path integral over geometries with spherical topology is unstable with respect to formation of infinitely many wormhole ...
Igor KLEBANOV +2 more
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Inflation and cosmological constant [PDF]
Physica Scripta, 2021 Abstract In construction of an inflationary model, one usually assumes that the matter sector of the gravitational action is minimally coupled to the background. It means that the matter (inflaton) part of the action is coupled with the same metric of the gravitational part.
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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
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Cosmological constant: Relaxation vs multiverse
Physics Letters B, 2019 We consider a scalar field with a bottom-less potential, such as g3ϕ, finding that cosmologies unavoidably end up with a crunch, late enough to be compatible with observations if g≲1.2H02/3MPl1/3. If rebounces avoid singularities, the multiverse acquires
Alessandro Strumia, Daniele Teresi
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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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On the cosmological constant problem
Physics Letters B, 2019 An additional variation of the Einstein-Hilbert action with respect to the Planck mass provides a constraint on the average Ricci scalar that prevents vacuum energy from gravitating. Consideration of the evolution of the inhomogeneous matter distribution
Lucas Lombriser
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Cosmology with varying constants [PDF]
Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 2001 14 pages, no figures. Essay to appear in Phil. Trans. Roy. Soc. Lond. A Triennial Series (Christmas 2002 Issue)
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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
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Unified Dark Matter models with fast transition [PDF]
, 2010 We investigate the general properties of Unified Dark Matter (UDM) fluid models where the pressure and the energy density are linked by a barotropic equation of state (EoS) p = p(ρ) and the perturbations are adiabatic.
Davide Pietrobon +12 more
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