Unimodular gravity redux

@article{lvarez2015UnimodularGR,
  title={Unimodular gravity redux},
  author={Enrique {\'A}lvarez and Sergio Gonz'alez-Mart'in and Mario Herrero-Valea and C. P. Mart'in},
  journal={Physical Review D},
  year={2015},
  volume={92},
  pages={061502}
}
It is well known that the problem of the cosmological constant appears in a new light in unimodular gravity. In particular, the zero-momentum piece of the potential does not automatically produce a corresponding cosmological constant. Here we show that quantum corrections do not renormalize the classical value of this observable. 

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References

SHOWING 1-10 OF 14 REFERENCES

Quantum corrections to unimodular gravity

A bstractThe problem of the comological constant appears in a new light in Unimodular Gravity. In particular, the zero momentum piece of the potential (that is, the constant piece independent of the

Quantizing gravity with a cosmological constant

Unimodular gravity with external sources

The only allowed source of the gravitational field in the unimodular theory, invariant under area-preserving (transverse) diffeomorphisms as well as Weyl transformations, is just the traceless piece

The trace-free Einstein equations and inflation

The trace-free version of the Einstein Gravitational equations, essentially equivalent to unimodular gravity, can solve the troubling issue of the huge discrepancy between quantum field theory

Longitudinal diffeomorphisms obstruct the protection of vacuum energy

To guarantee the stability of the cosmological constant sector against radiative corrections coming from quantum matter fields, one of the most natural ingredients to invoke is the symmetry under

Conformal and non conformal dilaton gravity

A bstractThe quantum dynamics of the gravitational field non-minimally coupled to an (also dynamical) scalar field is studied in the broken phase. For a particular value of the coupling the system is

A "Running" Gravitational Constant?

If the gravitational interaction is unified with the electroweak and strong interactions at a mass M=10^15 GeV, the evolution of Newton's constant must differ from its classical (general

Quadratic divergences and quantum gravitational contributions to gauge coupling constants

The calculation of quadratic divergences in Einstein-Maxwell theory with a possible cosmological constant is considered. We describe a method of calculation, using the background-field method, that

Nonperturbative evolution equation for quantum gravity

A scale-dependent effective action for gravity is introduced and an exact nonperturbative evolution equation is derived which governs its renormalization group flow. It is invariant under general