Motivated by an earlier study of Sahoo and Singh[Mod.Phys.Lett.A 17(2002)2409],we investigate the time dependence of the Brans–Dicke parameterω(t)for an expanding Universe in the generalized Brans–Dicke Chameleon c...Motivated by an earlier study of Sahoo and Singh[Mod.Phys.Lett.A 17(2002)2409],we investigate the time dependence of the Brans–Dicke parameterω(t)for an expanding Universe in the generalized Brans–Dicke Chameleon cosmology,and obtain an explicit dependence ofω(t)in different expansion phases of the Universe.Also,we discuss how the observed accelerated expansion of the observable Universe can be accommodated in the present formalism.展开更多
The objective of this paper is to discuss the Chameleon Brans–Dicke gravity with non-minimally matter coupling of scalar field. We take modified Holographic Ricci dark energy model in this gravity with its energy den...The objective of this paper is to discuss the Chameleon Brans–Dicke gravity with non-minimally matter coupling of scalar field. We take modified Holographic Ricci dark energy model in this gravity with its energy density in interaction with energy density of cold dark matter. We assume power-law ansatz for scale factor and scalar field to discuss potential as well as coupling functions in the evolving universe. These reconstructed functions are plotted versus scalar field and time for different values of power component of scale factor n. We observe that potential and coupling functions represent increasing behavior, in particular, consistent results for a specific value of n. Finally, we have examined validity of the generalized second law of thermodynamics and we have observed its validity for all values of n.展开更多
In this paper,we give an Euclidean wormhole solution in the Brans-Dicke theory with cosmological constant.We show that this wormhole is unlike all the others,its configuration is non-static.The throat radius of the wo...In this paper,we give an Euclidean wormhole solution in the Brans-Dicke theory with cosmological constant.We show that this wormhole is unlike all the others,its configuration is non-static.The throat radius of the wormhole will increase as Euclidan cosmic time increases.展开更多
In this paper we constructed the formula of the third quantization of a solvable model in quantum cosmology based on the Brans-Dicke theory and got an abnormal distribution.
We generalize Visser’s method to construct traversable Lorentzian wormholes from surgically modified Friedman-Robertson-Walker spacetimes in both Brans-Dicke’s theory and induced theory of Gravity.Our result shows,i...We generalize Visser’s method to construct traversable Lorentzian wormholes from surgically modified Friedman-Robertson-Walker spacetimes in both Brans-Dicke’s theory and induced theory of Gravity.Our result shows,in both cases,the exotic matter is unavoidable to occur at the throats of the wormholes.展开更多
A new set of exact solutions in vacuum Brans-Dicke theory is obtained,which is a two-way traversable wormhole for the coupling parameterω(ω<-2).This new set of exact solutions satisfies not only the general const...A new set of exact solutions in vacuum Brans-Dicke theory is obtained,which is a two-way traversable wormhole for the coupling parameterω(ω<-2).This new set of exact solutions satisfies not only the general constraints on the shape function b(R)and the redshift functionφ(R)given by Morris and Thorne[Am.J.Phys.56(1988)395],but also the constraints on them from a trip through wormhole.It also follows that the scalar field φ plays a role of exotic mat ter violating the weak energy condition.展开更多
文摘Motivated by an earlier study of Sahoo and Singh[Mod.Phys.Lett.A 17(2002)2409],we investigate the time dependence of the Brans–Dicke parameterω(t)for an expanding Universe in the generalized Brans–Dicke Chameleon cosmology,and obtain an explicit dependence ofω(t)in different expansion phases of the Universe.Also,we discuss how the observed accelerated expansion of the observable Universe can be accommodated in the present formalism.
基金The financial Supported from Department of Science and Technology,Govt.of India under Project Grant No.SR/FTP/PS-167/2011 is thankfully acknowledged by SC
文摘The objective of this paper is to discuss the Chameleon Brans–Dicke gravity with non-minimally matter coupling of scalar field. We take modified Holographic Ricci dark energy model in this gravity with its energy density in interaction with energy density of cold dark matter. We assume power-law ansatz for scale factor and scalar field to discuss potential as well as coupling functions in the evolving universe. These reconstructed functions are plotted versus scalar field and time for different values of power component of scale factor n. We observe that potential and coupling functions represent increasing behavior, in particular, consistent results for a specific value of n. Finally, we have examined validity of the generalized second law of thermodynamics and we have observed its validity for all values of n.
文摘In this paper,we give an Euclidean wormhole solution in the Brans-Dicke theory with cosmological constant.We show that this wormhole is unlike all the others,its configuration is non-static.The throat radius of the wormhole will increase as Euclidan cosmic time increases.
文摘In this paper we constructed the formula of the third quantization of a solvable model in quantum cosmology based on the Brans-Dicke theory and got an abnormal distribution.
基金Supported by the National Natural Science Foundation of China.
文摘We generalize Visser’s method to construct traversable Lorentzian wormholes from surgically modified Friedman-Robertson-Walker spacetimes in both Brans-Dicke’s theory and induced theory of Gravity.Our result shows,in both cases,the exotic matter is unavoidable to occur at the throats of the wormholes.
基金Supported by the National Natural Science Foundation of China under Grant No.19473003.
文摘A new set of exact solutions in vacuum Brans-Dicke theory is obtained,which is a two-way traversable wormhole for the coupling parameterω(ω<-2).This new set of exact solutions satisfies not only the general constraints on the shape function b(R)and the redshift functionφ(R)given by Morris and Thorne[Am.J.Phys.56(1988)395],but also the constraints on them from a trip through wormhole.It also follows that the scalar field φ plays a role of exotic mat ter violating the weak energy condition.
