Physics / Fizik
Permanent URI for this collectionhttps://hdl.handle.net/11147/6
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Article S- and T-Self in Dilatonic F(r) Theories(Springer Verlag, 2017) Rador, TonguçWe search for theories, in general spacetime dimensions, that would incorporate a dilaton and higher powers of the scalar Ricci curvature such that they have exact S- or T-self-dualities. The theories we find are free of Ostrogradsky instabilities. We also show that within the framework we are confining ourselves, a theory of the form mentioned above cannot have both T- and S-dualities except for the case where the action is linear in the scalar curvature.Article Citation - WoS: 1Citation - Scopus: 1Extra dimensions, dilaton and dark energy(Elsevier Ltd., 2011) Rador, TonguçIn view of the recent observations showing that the universe is accelerating we discuss dilaton and radion stabilization from a phenomenological perspective using perfect fluid sources. One general conclusion we present is that the pressure coefficient along extra dimensions should be -2 if that of the observed dimensions is -1, the latter mimicking a cosmological constant compatible with experimental data. The conditions on the dilaton coupling are similarly strong: we find that if the coupling of the dilaton Φ to fields other than gravity is of the form -ge(a-2)ΦL where L representing all other fields yielding the mentioned fluid, a must be -2 if space-time dimensionality is 10. Within our approach these conditions result taking constant radion and dilaton at the level of the equations of motion. To ameliorate this we also discuss how dynamical stabilization may be achieved with a simple variant in which a dilaton potential is added in the picture where the mentioned constraints are shown to remain.Article Citation - WoS: 3Citation - Scopus: 3Merger Dynamics in Three-Agent Games(Springer Verlag, 2011) Rador, Tonguç; Derici, R.We present the effect of mergers, a term which we use to mean a temporary alliance, in the dynamics of the three-agent model studied by Ben-Naim, Kahng and Kim and by Rador and Mungan. Mergers are possible in three-agent games because two agents can combine forces against the third player and thus increase their probability to win a competition. We implement mergers in this three-agent model via resolving merger and no-merger units of competition in terms of a two-agent unit. This way one needs only a single parameter which we have called the competitiveness parameter. We have presented an analytical solution in the fully competitive limit. In this limit the score distribution of agents is stratified and self-similar.Article Special Relativity and Kepler's First Law(IOP Publishing Ltd., 2011) Rador, TonguçConsider a two-body system consisting of a very massive sun and a planet in a circular orbit of radius R around it, as seen by an inertial observer S at rest with respect to the sun. Obviously this sun–planet system obeys Kepler’s first law. For concreteness let the planet revolve on the plane z = 0 and the sun be located at x = y = z = 0. Now consider another inertial observer Sl moving with speed v" = cβˆ x, say, on the plane z = zs relative to the sun.