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.


From smooth curves to universal metrics
GÜRSES, METİN; Sisman, Tahsin Cagri; Tekin, Bayram (2016-08-22)
A special class of metrics, called universal metrics, solves all gravity theories defined by covariant field equations purely based on the metric tensor. Since we currently lack the knowledge of what the full quantum-corrected field equations of gravity are at a given microscopic length scale, these metrics are particularly important in understanding quantum fields in curved backgrounds in a consistent way. However, finding explicit universal metrics has been a difficult problem as there does not seem to be...
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...
Effective-mass Klein-Gordon-Yukawa problem for bound and scattering states
Arda, Altug; Sever, Ramazan (2011-09-01)
Bound and scattering state solutions of the effective-mass Klein-Gordon equation are obtained for the Yukawa potential with any angular momentum l. Energy eigenvalues, normalized wave functions, and scattering phase shifts are calculated as well as for the constant mass case. Bound state solutions of the Coulomb potential are also studied as a limiting case. Analytical and numerical results are compared with the ones obtained before. (C) 2011 American Institute of Physics. [doi:10.1063/1.3641246]
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...
Citation Formats
S. E. Öcal, “EXACT SOLUTIONS OF INFINITE DERIVATIVE GRAVITY,” M.S. - Master of Science, Middle East Technical University, 2021.