We study phantom-like effect on the DGP brane embedded in a five-dimensional AdS bulk. We show that this effect can be realized without phantom matter on this warped DGP brahe. We investigate the role played by the bu...We study phantom-like effect on the DGP brane embedded in a five-dimensional AdS bulk. We show that this effect can be realized without phantom matter on this warped DGP brahe. We investigate the role played by the bulk cosmological constant on the phantom-like effect on the brane and we show that it tends to reduce this effect. Also, warped compactification of the bulk manifold increases the values of the effective and total equation of state parameters of the model relative to the case with Minkowski bulk. We extend our study to the ease that induced curvature on the brahe is modified in the spirit of the f（R）-gravity.展开更多
Recently, a new noncommutative geometry inspired solution of the coupled Einstein Maxwell field equations including black holes in 4-dimension is found. In this paper, we generalize some aspects of this model to the R...Recently, a new noncommutative geometry inspired solution of the coupled Einstein Maxwell field equations including black holes in 4-dimension is found. In this paper, we generalize some aspects of this model to the Reissner Nordstrom （RN） like geometries with large extra dimensions. We discuss Hawking radiation process based on noncommutative inspired solutions. In this framework, existence of black hole remnant and possibility of its detection in LHC are investigated.展开更多
We study the energy distribution of a noncommutative Reissner–Nordström black hole.We consider both Ein-stein and Møller prescriptions,and compare our results with the corresponding results obtained recentl...We study the energy distribution of a noncommutative Reissner–Nordström black hole.We consider both Ein-stein and Møller prescriptions,and compare our results with the corresponding results obtained recently for a Schwarzschild black hole.展开更多
We use the smeared, coherent state picture of noncommutativity to study evolution of perturbations in a noncommutative braneworld scenario. Within the stan- dard procedure of studying braneworld cosmological perturbat...We use the smeared, coherent state picture of noncommutativity to study evolution of perturbations in a noncommutative braneworld scenario. Within the stan- dard procedure of studying braneworld cosmological perturbations, we study the evo- lution of the Bardeen metric potential and curvature perturbations in this model. We show that in this setup, the early stage of the universe＇s evolution has a transient phan- tom evolution with imaginary effective sound speed.展开更多
We study a free scalar field theory in the framework of the Magueijo-Smolin model of the 'Doubly Special Relativity'(DSR) which is a non-linear realization of the action of the Lorentz group on momentum space ...We study a free scalar field theory in the framework of the Magueijo-Smolin model of the 'Doubly Special Relativity'(DSR) which is a non-linear realization of the action of the Lorentz group on momentum space admitting an invariant energy cutoff. We show that unlike the standard quantum field theory, the Klein-Gordon equation obtained via Euler-Lagrange field equation and Heisenberg picture equation of motion of the field are not equivalent in this framework,at least up to the first order of the Planck length scale.展开更多
We study gravitational baryogenesis in the context of f(R, T) gravity where the gravitational Lagrangian is given by a generic function of the Ricci scalar R and the trace of the stress-energy tensor T. We explore how...We study gravitational baryogenesis in the context of f(R, T) gravity where the gravitational Lagrangian is given by a generic function of the Ricci scalar R and the trace of the stress-energy tensor T. We explore how this type of modified gravity is capable to shed light on the issue of baryon asymmetry in a successful manner. We consider various forms of baryogenesis interaction and discuss the effect of these interaction terms on the baryon to entropy ratio in this setup. We show that baryon asymmetry during the radiation era of the expanding universe can be non-zero in this framework. Then, we calculate the baryon to entropy ratio for some specific f(R, T) models and by using the observational data, we give some constraints on the parameter spaces of these models.展开更多
文摘We study phantom-like effect on the DGP brane embedded in a five-dimensional AdS bulk. We show that this effect can be realized without phantom matter on this warped DGP brahe. We investigate the role played by the bulk cosmological constant on the phantom-like effect on the brane and we show that it tends to reduce this effect. Also, warped compactification of the bulk manifold increases the values of the effective and total equation of state parameters of the model relative to the case with Minkowski bulk. We extend our study to the ease that induced curvature on the brahe is modified in the spirit of the f（R）-gravity.
基金supported partially by Research Institute for Astronomy and Astrophysics of Maragha,Iran
文摘Recently, a new noncommutative geometry inspired solution of the coupled Einstein Maxwell field equations including black holes in 4-dimension is found. In this paper, we generalize some aspects of this model to the Reissner Nordstrom （RN） like geometries with large extra dimensions. We discuss Hawking radiation process based on noncommutative inspired solutions. In this framework, existence of black hole remnant and possibility of its detection in LHC are investigated.
基金Supported by the Center for Excellence in Astronomy and Astrophysics(CEAAI-RIAAM),Maragha,Iran.
文摘We study the energy distribution of a noncommutative Reissner–Nordström black hole.We consider both Ein-stein and Møller prescriptions,and compare our results with the corresponding results obtained recently for a Schwarzschild black hole.
文摘We use the smeared, coherent state picture of noncommutativity to study evolution of perturbations in a noncommutative braneworld scenario. Within the stan- dard procedure of studying braneworld cosmological perturbations, we study the evo- lution of the Bardeen metric potential and curvature perturbations in this model. We show that in this setup, the early stage of the universe＇s evolution has a transient phan- tom evolution with imaginary effective sound speed.
基金Supported by Research Institute for Astronomy and Astrophysics of Maragha(RIAAM)under Research Project No.1/6025-73
文摘We study a free scalar field theory in the framework of the Magueijo-Smolin model of the 'Doubly Special Relativity'(DSR) which is a non-linear realization of the action of the Lorentz group on momentum space admitting an invariant energy cutoff. We show that unlike the standard quantum field theory, the Klein-Gordon equation obtained via Euler-Lagrange field equation and Heisenberg picture equation of motion of the field are not equivalent in this framework,at least up to the first order of the Planck length scale.
基金Supported financially by Research Institute for Astronomy and Astrophysics of Maragha(RIAAM)under Research Project Number1/5750/16
文摘We study gravitational baryogenesis in the context of f(R, T) gravity where the gravitational Lagrangian is given by a generic function of the Ricci scalar R and the trace of the stress-energy tensor T. We explore how this type of modified gravity is capable to shed light on the issue of baryon asymmetry in a successful manner. We consider various forms of baryogenesis interaction and discuss the effect of these interaction terms on the baryon to entropy ratio in this setup. We show that baryon asymmetry during the radiation era of the expanding universe can be non-zero in this framework. Then, we calculate the baryon to entropy ratio for some specific f(R, T) models and by using the observational data, we give some constraints on the parameter spaces of these models.
