Breaking diffeomorphism invariance and tests for the emergence of gravity

Anber, Mohamed M.
Aydemir, Ufuk
Donoghue, John F.
If general relativity is an emergent phenomenon, there may be small violations of diffeomorphism invariance. We propose a phenomenology of perturbatively small violations of general relativity by the inclusion of terms which break general covariance. These can be tested by matching to the parameterized post-Newtonian formalism. The most sensitive tests involve pulsar timing and provide an extremely strong bound, with a dimensionless constraint of order 10(-20) relative to gravitational strength.


Spectra, vacua, and the unitarity of Lovelock gravity in D-dimensional AdS spacetimes
Sisman, Tahsin Cagri; Gullu, Ibrahim; Tekin, Bayram (2012-08-24)
We explicitly confirm the expectation that generic Lovelock gravity in D dimensions has a unitary massless spin-2 excitation around any one of its constant curvature vacua just like the cosmological Einstein gravity. The propagator of the theory reduces to that of Einstein's gravity, but scattering amplitudes must be computed with an effective Newton's constant which we provide. Tree-level unitarity imposes a single constraint on the parameters of the theory yielding a wide range of unitary region. As an ex...
Clifford-based spectral action and renormalization group analysis of the gauge couplings
Aydemir, Ufuk (2019-4-01)
The Spectral Action Principle in noncommutative geometry derives the actions of the Standard Model and General Relativity (along with several other gravitational terms) by reconciling them in a geometric setting, and hence offers an explanation for their common origin. However, one of the requirements in the minimal formalism, unification of the gauge coupling constants, is not satisfied, since the basic construction does not introduce anything new that can change the renormalization group (RG) running of t...
On the energy-momentum in closed universes
Salti, M (Springer Science and Business Media LLC, 2006-02-01)
Using the Moller, Einstein, Bergmann-Thomson and Landau-Lifshitz energy-momentum definitions both in general relativity and teleparallel gravity, we find the energy-momentum of the closed universe based on the generalized Bianchi-I type metric.
On the universality of low-energy string model
Dereli, T; Obukhov, YN (IOP Publishing, 2000-01-07)
The low-energy (bosonic 'heterotic') string theory is interpreted as a universal limit of the Kaluza-Klein reduction when the dimension of an internal space goes to infinity. We show that such an approach is helpful in obtaining classical solutions of the string model. As a particular application, we obtain new exact static solutions for the two-dimensional effective string model. They turn out to be in agreement with the generalized no-hair conjecture, in complete analogy with the four- and higher-dimensio...
Bozkurt, M.; Hudaverdi, M.; ERCAN, ENİSE NİHAL (2008-10-05)
Recent observations and numerical simulations show that galaxies are not distributed in the Universe randomly. They are placed like the pearls of a necklace. The matter is spread into the space in the form of cosmic filaments and voids. The intersection regions of these cosmic filaments are what we observe as "clusters of galaxies". In this work we selected 9 clusters of galaxies (A1644, A1736, A3528, A3530, A3532, A3556, A3558, A3560, A3562) from SHAPLEY super cluster region, the largest concentration of g...
Citation Formats
M. M. Anber, U. Aydemir, and J. F. Donoghue, “Breaking diffeomorphism invariance and tests for the emergence of gravity,” PHYSICAL REVIEW D, vol. 81, no. 8, pp. 0–0, 2010, Accessed: 00, 2022. [Online]. Available: