منابع مشابه
Troubles for Unimodular Gravity
We compute the contribution of various gravitational instantons to the path integral in the standard formulation of unimodular gravity, an alternative theory of gravity where the determinant of the metric is not dynamical. Following similar computations in General Relativity, we derive the entropy/area ratio for cosmological and black hole horizons, finding in general disagreement with General ...
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The conformal invariance of unimodular gravity survives quantum corrections, even in the presence of conformal matter. Unimodular gravity can actually be understood as a certain truncation of the full Einstein-Hilbert theory, where in the Einstein frame the metric tensor has unit determinant. Our result is compatible with the idea that the corresponding restriction in the functional integral is...
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Canonical gravity in real Ashtekar–Barbero variables is generalized to allow for fermionic matter. The resulting torsion changes several expressions in Holst's original vacuum analysis, which are explicitly displayed here. This in turn requires adaptations to the known canonical (loop) quantization of gravity coupled to fermions, which is discussed on the basis of the classical analysis.
متن کاملThe quantization of unimodular gravity and the cosmological constant problems
A quantization of unimodular gravity is described, which results in a quantum effective action which is also unimodular, ie a function of a metric with fixed determinant. A consequence is that contributions to the energy momentum tensor of the form of gabC , where C is a spacetime constant, whether classical or quantum, are not sources of curvature in the equations of motion derived from the qu...
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We perform a space-time analysis of the D > 4 quadratic curvature Lanczos-Lovelock (LL) model, exhibiting its dependence on intrinsic/extrinsic curvatures, lapse and shifts. As expected from general covariance, the field equations include D constraints, of zeroth and first time derivative order. In the “linearized” – here necessarily cubic – limit, we give an explicit formulation in terms of th...
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ژورنال
عنوان ژورنال: Physical Review D
سال: 2015
ISSN: 1550-7998,1550-2368
DOI: 10.1103/physrevd.91.064058