Öcal, Sultan Eylül
Infinite Derivative Gravity (IDG) is a modified gravity theory which can avoid the singularities and Ultraviolet problem of gravity. This thesis examines the effects of IDG on these problems. First, the propagators and Newtonian potential will be examined as well as the conditions necessary for avoidance of singularities for perturbations around Minkowski background are found. Second, we study the exact pp-wave and AdS-plane wave solutions of quadratic and Infinite derivative gravity theories. We construct exact gravitational shock and impulsive wave solutions of IDG. We have demonstrated that unlike the Einstein's general relativity, even though these waves are created by linear sources having Dirac delta type singularities, singularities get smeared by the non-local interactions. All the calculations are just a review.


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...
DERELI, TEKİN; Üçoluk, Göktürk (IOP Publishing, 1990-07-01)
The Kaluza-Klein reduction of a generalised theory of gravity in D=5 dimensions is given. The form of the interactions among the gravitational, electromagnetic and massless scalar fields in four dimensional spacetime is exhibited.
Non-Einsteinian black holes in generic 3D gravity theories
Gürses, Metin; Şisman, Tahsin Çağrı; Tekin, Bayram (AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA, 2019-09-21)
The Banados-Teitelboim-Zanelli (BTZ) black hole metric solves the three-dimensional Einstein's theory with a negative cosmological constant as well as all the generic higher derivative gravity theories based on the metric; as such it is a universal solution. Here, we find, in all generic higher derivative gravity theories, new universal non-Einsteinian solutions obtained as Kerr-Schild type deformations of the BTZ black hole. Among these, the deformed nonextremal BTZ black hole loses its event horizon while...
Bachian gravity in three dimensions
Alkaç, Gökhan; Tek, Mustafa; Tekin, Bayram (American Physical Society (APS), 2018-11-16)
In three dimensions, there exist modifications of Einstein's gravity akin to the topologically massive gravity that describe massive gravitons about maximally symmetric backgrounds. These theories are built on the three-dimensional version of the Bach tensor (a curl of the Cotton-York tensor) and its higher derivative generalizations; and they are on-shell consistent without a Lagrangian description based on the metric tensor alone. We give a generic construction of these models, find the spectra and comput...
Exact solutions and the consistency of 3D minimal massive gravity
Altas, Emel; Tekin, Bayram (2015-07-20)
We show that all algebraic type-O, type-N and type-D and some Kundt-type solutions of topologically massive gravity are inherited by its holographically well-defined deformation, that is, the recently found minimal massive gravity. This construction provides a large class of constant scalar curvature solutions to the theory. We also study the consistency of the field equations both in the source-free and matter-coupled cases. Since the field equations of MMG do not come from a Lagrangian that depends on the...
Citation Formats
S. E. Öcal, “EXACT SOLUTIONS OF INFINITE DERIVATIVE GRAVITY,” M.S. - Master of Science, Middle East Technical University, 2021.