On the naturalness of Einstein’s equation

Navarro, José; Sancho, J. B.

doi:10.1016/j.geomphys.2008.03.007

Cited by 16 publications

(23 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If one would consider contributions from loops then their vertices that are suppressed by Λ 5 might lower the scale with which the decay rate is suppressed down to Λ 5 . 7 As mentioned before, the decay rate (5.7) corresponds only to the scattering process that dominates in the UV. The validity of this assumption is not obvious for low cutoff scales.…”

Section: Jhep11(2016)118mentioning

confidence: 84%

A spectre is haunting the cosmos: quantum stability of massive gravity with ghosts

Könnig

Nersisyan

Akrami

et al. 2016

J. High Energ. Phys.

View full text Add to dashboard Cite

Many theories of modified gravity with higher order derivatives are usually ignored because of serious problems that appear due to an additional ghost degree of freedom. Most dangerously, it causes an immediate decay of the vacuum. However, breaking Lorentz invariance can cure such abominable behavior. By analyzing a model that describes a massive graviton together with a remaining Boulware-Deser ghost mode we show that even ghostly theories of modified gravity can yield models that are viable at both classical and quantum levels and, therefore, they should not generally be ruled out. Furthermore, we identify the most dangerous quantum scattering process that has the main impact on the decay time and find differences to simple theories that only describe an ordinary scalar field and a ghost. Additionally, constraints on the parameters of the theory including some upper bounds on the Lorentz-breaking cutoff scale are presented. In particular, for a simple theory of massive gravity we find that a breaking of Lorentz invariance is allowed to happen even at scales above the Planck mass. Finally, we discuss the relevance to other theories of modified gravity.

show abstract

Section: Jhep11(2016)118mentioning

confidence: 84%

A spectre is haunting the cosmos: quantum stability of massive gravity with ghosts

Könnig

Nersisyan

Akrami

et al. 2016

J. High Energ. Phys.

View full text Add to dashboard Cite

show abstract

“…A variation on Lovelock's approach, first described by Aldersley (1977) and elaborated by Navarro and Sancho (2008), drops condition 3 for the following "dimensional analysis" condition: 7.G ab (g) is independent of the unit of scale, i.e., for any λ > 0,G ab (λ 2 g) =G ab (g).…”

Section: Lovelock Variationsmentioning

confidence: 99%

Would two dimensions be world enough for spacetime?

Fletcher

Manchak

Schneider

et al. 2018

Studies in History and Philosophy of Science Part B: Studies in

View full text Add to dashboard Cite

We consider various curious features of general relativity, and relativistic field theory, in two spacetime dimensions. In particular, we discuss: the vanishing of the Einstein tensor; the failure of an initial-value formulation for vacuum spacetimes; the status of singularity theorems; the non-existence of a Newtonian limit; the status of the cosmological constant; and the character of matter fields, including perfect fluids and electromagnetic fields. We conclude with a discussion of what constrains our understanding of physics in different dimensions. (James Owen Weatherall) 1 For background on geometrized Newtonian gravitation, see Trautman (1965) and (especially) Malament (2012, Ch. 4). For projects that aim to use this theory to provide new insight into general relativty, see, for instance,

show abstract

“…Finally, let us observe that, if T ∈ T 2p,w is a (2p)-covariant, universal tensor, homogeneous of degree w, then w has to be an even integer, lesser or equal than p (see, v. gr., [13]), so that we may write, without loss of generality:…”

Section: Dimensional Curvature Identitiesmentioning

confidence: 99%

Dimensional curvature identities on pseudo-Riemannian geometry

Navarro

2014

Journal of Geometry and Physics

Self Cite

View full text Add to dashboard Cite

Publicado en: Journal of Geometry and Physics 86 (2014) 554–563 DOI: 10.1016/j.geomphys.2014.10.001Para un fijo n ∈ N, el tensor de curvatura de una métrica pseudo-Riemanniana, así como sus derivadas covariantes, satisfacen ciertas identidades que mantienen en cualquier colector de dimensión menor o igual que n. En este trabajo, elaboramos los resultados recientes de Gilkey-Park-Sekigawa en relación a estas identidades de curvatura p-covariante, siendo p = 0, 2. Con este fin, utilizamos la teoría clásica de las operaciones naturales, que nos permite simplificar algunos argumentos y generalizar los resultados principales de Gilkey-Park-Sekigawa, tanto por dejar caer una hipótesis de simetría como por incluir las identidades de curvatura p-covariante, incluso para cualquier p. Por lo tanto, para cualquier dimensión n, nuestro resultado principal describe el primer espacio (es decir, la de más alto peso) de las identidades de curvatura dimensional p-covariante, incluso para cualquier p.For a fixed n ∈ N, the curvature tensor of a pseudo-Riemannian metric, as well as its covariant derivatives, satisfy certain identities that hold on any manifold of dimension less or equal than n. In this paper, we re-elaborate recent results by Gilkey-Park-Sekigawa regarding these p-covariant curvature identities, for p = 0, 2. To this end, we use the classical theory of natural operations, that allows us to simplify some arguments and to generalize the main results of Gilkey-Park-Sekigawa, both by dropping a symmetry hypothesis and by including p-covariant curvature identities, for any even p. Thus, for any dimension n, our main result describes the first space (i.e., that of highest weight) of p-covariant dimensional curvature identities, for any even p.El segundo autor ha sido financiado parcialmente por la Junta de Extremadura y fondos FEDE

show abstract

On the naturalness of Einstein’s equation

Cited by 16 publications

References 12 publications

A spectre is haunting the cosmos: quantum stability of massive gravity with ghosts

A spectre is haunting the cosmos: quantum stability of massive gravity with ghosts

Would two dimensions be world enough for spacetime?

Dimensional curvature identities on pseudo-Riemannian geometry

Contact Info

Product

Resources

About