Özet:
The Effects of Different Types of Fields to Cosmology. Alternative cosmological models are proposed as a harbinger of new physics to overcome the perceived short- comings of the standard theory of cosmology (ACDM). We consider a non-minimally coupled massive complex scalar field to the curvature in the Jordan-Brans-Dicke (JBD) framework. We obtain an extra term to the Friedmann equation and it fits to super- nova observations with a slightly lesser chi-squared value compared to the ACDM. We assign the vector field as the photon field in JBD theory, a small photon mass leads to the late time infation. The background electric potential of the photon permeates the universe and explains the weakness of the gravitational interaction by coupling to the curvature, hence the smallness of the Hubble parameter is linked with the smallness of the photon mass. Another feature of our model is that the Planck mass is interpreted as the electric potential of the photon field that fills the universe. The Effects of an Extra Dimension to Some Hadronic Processes of the SM. Although the SM of particle physics is in perfect consistency with all confirmed collider data and the precision tests so far, it has some deficiencies such as scale hierarchy problem, etc. The compactified extra dimensions have been proposed to reduce the difference between the Planck mass scale and the strength of the electro-weak force. We analyze the effects of a single universal extra dimension (UED) on some flavor changing neutral current (FCNC) decays of hadrons such as baryonic ... and the mesonic B - K2 (1430)... transitions. We calculate some physical quantities such as branching ratio, lepton forward-backward asymmetry, double lepton polarization asymmetries and hadron polarizations in terms of the compactification scale of the extra dimension. Using the experimental data provided by the CDF Collaboration on the branching ratio of decay channel and comparing with our theoretical prediction, we put a constraint on the lower limit of the compactification scale of extra dimension to be 250 GeV . The results of UED show overall considerable deviations from those of the SM which can be considered as indications for the existence of extra dimensions which we should look for them at hadron colliders.
