Sartaş, Enfal
A growing body of experimental and observational evidence shows that Standard Model calculations account for only 5% of the mass and energy of the universe. The remainder consists of dark matter and dark energy, which have yet to be observed. The existence of dark matter, first discovered by Fritz Zwicky, suggests the presence of a hidden sector that is almost neutral under any of the forces predicted by the Standard Model. Within the framework of the portal concept, the vector portal, which brings its own additional dark gauge symmetry, is one of the proposed portals connecting the hidden sector with the Standard Model sector. Holding an additional gauge symmetry also means having an extra gauge field, hence a gauge boson. The traces of this gauge boson, namely the dark photon, are intended to be separated from the SM background in the context of this thesis. Research on the mono-photon channel is carried out within the framework of a B-L model, which is established to explore the decay and production processes of a light-dark photon (in the order of MeV-GeV), and corresponding results are obtained. First, the Lagrangian of the B-L model is created with the assistance of the FeynRules program, and therefore the models mass matrices and interaction vertices are obtained through this program. Then, a model interface is constructed employing the FeynRules program once more for the Madgraph package program that will be used to examine the production and decay channels. In addition to neutrinos, one of the possible undercover decay channels of the dark photon is the decay channel to a dark matter pair. Therefore, the missing energy in the signal of the mono-photon channel (photon + missing energy) needs to contain not only SM particles but also dark matter particles, depending on the model structure. At the final stage of the analysis, the interaction between dark matter and SM particles via the dark photon is also taken into account.


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...
Energy in Reboucas-Tiomno-Korotkii-Obukhov and Godel-type space-times in Bergmann-Thomson's formulations
Aydogdu, O; Salti, M; Korunur, M (2005-12-01)
We calculate the total energy (the matter plus fields) of the universe considering Bergmann-Thomson's energy-momentum formulation in both Einstein's theory of general relativity and tele-parallel gravity on two different space-times; namely Reboucas-Tiomno-Korotkii-Obukhov and the Godel-type metrics. We also compute some kinematical quantities for these space-times and find that these space-times have shear-free expansion and non-vanishing four-acceleration and vorticity. Different approximations of the Ber...
On the relative energy associated with space-times of diagonal metrics
Korunur, Murat; Salt, Mustafa; Havare, Ali (Springer Science and Business Media LLC, 2007-05-01)
In order to evaluate the energy distribution (due to matter and fields including gravitation) associated with a space-time model of generalized diagonal metric, we consider the Einstein, Bergmann-Thomson and Landau-Lifshitz energy and/or momentum definitions both in Einstein's theory of general relativity and the teleparallel gravity (the tetrad theory of gravitation). We find same energy distribution using Einstein and Bergmann-Thomson formulations, but we also find that the energy-momentum prescription of...
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.
Topologically massive gravity as a Pais-Uhlenbeck oscillator
Sarıoğlu, Bahtiyar Özgür; Tekin, Bayram (IOP Publishing, 2006-12-21)
We give a detailed account of the free- field spectrum and the Newtonian limit of the linearized ` massive' ( Pauli -Fierz), 'topologically massive' ( Einstein Hilbert - Chern - Simons) gravity in 2 + 1 dimensions about a Minkowski spacetime. For a certain ratio of the parameters, the linearized free theory is Jordan diagonalizable and reduces to a degenerate ` Pais - Uhlenbeck' oscillator which, despite being a higher derivative theory, is ghost free.
Citation Formats
E. Sartaş, “IN SEARCH OF HIDDEN SECTOR THROUGH THE MONO-PHOTON CHANNEL,” M.S. - Master of Science, Middle East Technical University, 2022.