In recent years there has been a lot of interest in discussing frame depeudences/independences of the cosmological perturbations under the conforlnal transformations. This problem has previously been investigated in L...In recent years there has been a lot of interest in discussing frame depeudences/independences of the cosmological perturbations under the conforlnal transformations. This problem has previously been investigated in Lerlns of the cow^riant approach for a single component universe, and it was found that tile covariant approach is very powerful to pick out the perturbative variables which are both gauge and conformal invariant. In this work, we extend the covariant approach to a universe with multicomponent fluids. We find that similar results can be derived, as e, xpected. In addition, some other interesting perturbations are also identified to be conformal invariant, such as entropy perturbation between two different components.展开更多
In this study,we investigate the possibilities of generating baryon number asymmetry under thermal equilibrium within the frameworks of teleparallel and symmetric teleparallel gravities.Through the derivative coupling...In this study,we investigate the possibilities of generating baryon number asymmetry under thermal equilibrium within the frameworks of teleparallel and symmetric teleparallel gravities.Through the derivative couplings of the torsion scalar and the non-metricity scalar to baryons,baryon number asymmetry is produced in the radiation dominated epoch.For gravitational baryogenesis mechanisms in these two frameworks,the produced baryon-to-entropy ratio is too small to be consistent with observations.However,the gravitational leptogenesis models within both frameworks have the potential to explain the observed baryon-antibaryon asymmetry.展开更多
The original mimetic model was proposed to take the role of dark matter. In this paper we consider possible direct interactions of mimetic dark matter with other matter in the universe, especially standard model parti...The original mimetic model was proposed to take the role of dark matter. In this paper we consider possible direct interactions of mimetic dark matter with other matter in the universe, especially standard model particles such as baryons and photons. By imposing shift symmetry, the mimetic dark matter field can only have derivative couplings. We discuss the possibilities of generating baryon number asymmetry and cosmic birefringence in the universe based on the derivative couplings of mimetic dark matter to baryons and photons.展开更多
文摘In recent years there has been a lot of interest in discussing frame depeudences/independences of the cosmological perturbations under the conforlnal transformations. This problem has previously been investigated in Lerlns of the cow^riant approach for a single component universe, and it was found that tile covariant approach is very powerful to pick out the perturbative variables which are both gauge and conformal invariant. In this work, we extend the covariant approach to a universe with multicomponent fluids. We find that similar results can be derived, as e, xpected. In addition, some other interesting perturbations are also identified to be conformal invariant, such as entropy perturbation between two different components.
基金Supported by NSFC(12075231,11653002,12047502,11947301)。
文摘In this study,we investigate the possibilities of generating baryon number asymmetry under thermal equilibrium within the frameworks of teleparallel and symmetric teleparallel gravities.Through the derivative couplings of the torsion scalar and the non-metricity scalar to baryons,baryon number asymmetry is produced in the radiation dominated epoch.For gravitational baryogenesis mechanisms in these two frameworks,the produced baryon-to-entropy ratio is too small to be consistent with observations.However,the gravitational leptogenesis models within both frameworks have the potential to explain the observed baryon-antibaryon asymmetry.
文摘The original mimetic model was proposed to take the role of dark matter. In this paper we consider possible direct interactions of mimetic dark matter with other matter in the universe, especially standard model particles such as baryons and photons. By imposing shift symmetry, the mimetic dark matter field can only have derivative couplings. We discuss the possibilities of generating baryon number asymmetry and cosmic birefringence in the universe based on the derivative couplings of mimetic dark matter to baryons and photons.
