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 ...
متن کاملMassive Gravity Acausality Redux
Massive gravity (mGR) is a 5(=2s+1) degree of freedom, finite range extension of GR. However, amongst other problems, it is plagued by superluminal propagation, first uncovered via a second order shock analysis. First order mGR shock structures have also been studied, but the existence of superluminal propagation in that context was left open. We present here a concordance of these methods, by ...
متن کاملNo conformal anomaly in unimodular gravity
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...
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...
متن کاملThe Renormalization Group flow of unimodular f(R) gravity
Unimodular gravity is classically equivalent to General Relativity. This equivalence extends to actions which are functions of the curvature scalar. At the quantum level, the dynamics could differ. Most importantly, the cosmological constant is not a coupling in the unimodular action, providing a new vantage point from which to address the cosmological constant fine-tuning problem. Here, a quan...
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ژورنال
عنوان ژورنال: Physical Review D
سال: 2015
ISSN: 1550-7998,1550-2368
DOI: 10.1103/physrevd.92.061502