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Browsing by Author "Erdem, Recai"
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1/Nc expansion and anomaly cancellation in the presence of electroweak interactions
Erdem, Recai (Institute of Physics Publishing, 199803)We study the question of a consistent formulation of the 1/Nc expansion in the presence of electroweak interactions. We show that in some cases the previous formulation leads to an unrealistic picture. We improve the scheme. ... 
Dark energy mechanisms in the context of extra dimensional models
Yağmurcukardeş, Mehmet (Izmir Institute of Technology, 2011)Dark energy is the simplest and the most standart explanation to account for the observed accelerated expansion of the universe. In this thesis we use the term 'dark energy' in its standart meaning i.e. a field or fluid ... 
Extra dimensional metric reversal symmetry and its prospect for cosmological constant and zeropoint energy problems, automatic paulivillarslike regularization, and an interesting kaluzaklein spectrum
Erdem, Recai (DMFA, 201012)The metric reversal symmetry was introduced in the context of cosmological constant problem. Besides proposing a solution to the cosmological constant problem the metric reversal symmetry has also provided a framework for ... 
Extra timelike dimensions
Ün, Cem Salih (Izmir Institute of Technology, 2006)The current status of extra dimensions in high energy physics with particular emphasis on extra timelike dimensions is briefly reviewed. Some of the phenomenological problems related to the use of extra timelike dimensions ... 
Fermion families and chirality through extra dimensions
Erdem, Recai (Springer, 200211)We give a simple model to explain the origin of fermion families and chirality through the use of a domain wallantidomain wall pair placed in a five dimensional spacetime. Higher dimensional spaces have been revived ... 
Finite number of KaluzaKlein modes, all with zero masses
Erdem, Recai (World Scientific Publishing, 201003)KaluzaKlein modes of fermions in a fivedimensional toy model are considered. The number of KaluzaKlein modes that survive after integration over extra dimensions is finite in this space. Moreover, the extra dimensional ... 
Higgs field as the gauge field corresponding to parity in the usual spacetime
Erdem, Recai (World Scientific Publishing, 199802)We find that the local character of field theory requires the parity degree of freedom of the fields to be considered as an additional discrete fifth dimension which is an artifact emerging due to the local description of ... 
Is it possible to obtain cosmic accelerated expansion through energy transfer between different energy densities?
Erdem, Recai (Elsevier, 201703)The equation of state of an energy density may be significantly modified by coupling it to another energy density. In the light of this observation we check the possibility of producing cosmic accelerated expansion in this ... 
It is sufficient to set the cosmological constant to zero or to a small number at an initial time
Erdem, Recai (TÜBİTAK, 2016)I point out a simple but usually overlooked fact about the cosmological constant problem: to solve the cosmological constant problem it is sufficient to find a symmetry or mechanism that sets the cosmological constant to ... 
A mechanism for formation of BoseEinstein condensation in cosmology
Erdem, Recai; Gultekin, Kemal (Iop Publishing Ltd, 2019)We introduce a toy model of scalar particles with a trilinear scalar coupling in cosmology. The trilinear coupling phi(2)chi causes production of nonrelativistic phi particles through the process chi chi > phi phi where, ... 
Reconsidering extra timelike dimensions
Erdem, Recai; Ün, Cem Salih (Springer, 200609)In this study we reconsider the phenomenological problems related to tachyonic modes in the context of extra timelike dimensions. First we reconsider a lower bound on the size of extra timelike dimensions and improve on ... 
Single scale factor for the universe from the creation of radiation and matter till the present
Erdem, Recai (Springer, 20140923)A scheme for incorporating the creation of radiation and matter into the cosmological evolution is introduced so that it becomes possible to merge the times before and after the creation of radiation and matter in a ... 
Solitonic solutions and particle localization in higher dimensional spaces
Erman, Fatih (Izmir Institute of Technology, 2003)First the basic extra dimensional theory (i.e. KaluzaKlein theory) and the main aspects of solitons are reviewed. Then the current status of extra dimensional models and the application of solitons (especially kinks) in ... 
A symmetry for the vanishing cosmological constant
Erdem, Recai (IOP Publishing, 200706)Two different realizations of a symmetry principle that impose a zero cosmological constant in an extradimensional setup are studied. The symmetry is identified by multiplication of the metric by minus one. In the fist ... 
A symmetry for vanishing cosmological constant in an extradimensional toy model
Erdem, Recai (Elsevier, 200508)We introduce a symmetry principle that forbids a bulk cosmological constant in six and ten dimensions. Then the symmetry is extended in six dimensions so that it insures absence of 4dimensional cosmological constant induced ... 
A symmetry for vanishing cosmological constant: Another realization
Erdem, Recai (Elsevier, 200608)A more conventional realization of a symmetry which had been proposed towards the solution of cosmological constant problem is considered. In this study the multiplication of the coordinates by the imaginary number i in ... 
Towards the solution of cosmological constant and zero point energy problems through metric reversal symmetry
Erdem, Recai (IOP Publishing, 2009)In this talk I review my studies on metric reversal symmetry and their further implications. The talk is mainly concentrated on the relevance of the metric reversal symmetry to the solutions of the cosmological constant ... 
A way to get rid of cosmological constant and zeropoint energy problems of quantum fields through metric reversal symmetry
Erdem, Recai (IOP Publishing, 200806)In this paper, a framework is introduced to remove the huge discrepancy between the empirical value of the cosmological constant and the contribution to the cosmological constant predicted from the vacuum energy of quantum ...