arXiv subjects

Xiang-hua Zhai

Publications and source records attributed to Xiang-hua Zhai.

24 records · Page 2Linked to original sources

arXiv2005

Dynamics of Quintessential Inflation

In this paper, we study a realistic model of quintessential inflation with radiation and matter. By the analysis of the dynamical system and numerical work about the evolution of the equation of state and cosmic density parameter, we show that this model is a good match for the current astronomical observation. The conclusion we obtain is in favor of the model where the modular part of complex field plays the role of the inflaton whereas the argument part is the quintessence field. The numerical calculation shows that a heteroclinic orbit (solution of dynamical system) which interpolates between early-time de Sitter phase (an unstable critical point) and a late-time de Sitter attractor.

astro-ph↗

arXiv2005

A cosmological model with complex scalar field

In this paper, we wish to point out the possibility of using a complex scalar field to account for the inflationary stage and the current acceleration. By the analysis of the dynamical system and numerical work, we show that the amplitude of the complex scalar field plays the role of the inflaton whereas the phase is the quintessence field. The numerical solutions describe heteroclinic orbits, which interpolate between an unstable critical point and a late-time de Sitter attractor. Therefore, this model is more natural to explain the two stages of acceleration.

gr-qc↗

arXiv2003

Features of Motion Around Charged D-Stars

The motion of light and a neutral test particle around the charged D-star has been studied. The difference of the deficit angle of light from the case in asymptotically flat spacetime is in a factor $(1-ε^2)$. The motion of a test particle is affected by the deficit angle and the charge. Through the phase analysis, we prove the existence of the periodic solution to the equation of motion and the effect of the deficit angle and the charge to the critical point and its type. We also give the conditions under which the critical point is a stable center and an unstable saddle point.

gr-qc↗

arXiv2003

On the Quintessence with Abelian and Non-abelian Symmetry

We study the perturbations on both "radial" and "angular" components of the quintessence with an internal abelian and non-abelian symmetry. The properties of the perturbation on the "radial" component depend on the specific potential of the model and is similiar for both abelian and non-abelian case. We show that the consine-type potential is very interesting for the O(\textit{N}) quintessence model and also give a critical condition of instability for the potential. While the properties of perturbations on "angular" components depend on whether the internal symmetry is abelian or non-abelian, which we have discussed respectively. In the non-abelian case, the fluctuation of the "angular" component will increase rapidly with time while in the abelian case it will not.

astro-ph↗

arXiv2003

The Tachyon Inflationary Models with Exact Mode Functions

We show two analytical solutions of the tachyon inflation for which the spectrum of curvature (density) perturbations can be calculated exactly to linear order, ignoring both gravity and the self-interactions of the tachyon field . The main feature of these solutions is that the spectral indices are independent with scale.

hep-ph↗

arXiv2002

Rigorous proof of attractive nature for Casimir force of p-odd hypercube

The Casimir effect giving rise to an attractive force between the configuration boundaries that confine the massless scalar field is rigorously proven for odd dimensional hypercube with the Dirichlet boundary conditions and different spacetime dimensions D by the Epstein zeta function regularization.

hep-th↗