Searcharxiv⌕ Search

arXiv subjects

Hongbo Cheng

Publications and source records attributed to Hongbo Cheng.

46 records · Page 3Linked to original sources
arXiv2010

The Casimir force between parallel plates in Randall-Sundrum I model

The Casimir effect for parallel plates within the frame of five-dimensional Randall-Sundrum model with two branes is reexamined. We argue that the nature of Casimir force is repulsive if the distance between the plates is not extremely tiny, which is not consistent with the experimental phenomena. We also point out that the estimation of the separation between the two branes, by means of Casimir effect for two-parallel-plate system, is not feasible, in contrast to another recent study.

hep-th↗
arXiv2008

The circular loop equation of a cosmic string with time-varying tension in de Sitter spacetimes

In this work the equation of circular loops of cosmic string possessing time-dependent tension is studied in the de Sitter spacetime. We find that the cosmic string loops with initial radius $r(t_{0})>0.707L$, L de Sitter radius, should not collapse to form a black holes. It is also found that in the case of $r(t_{0})<0.707L$ a loop of cosmic string whose tension depends on some power of cosmic time can not become a black hole if the power is lower than a critical value which is associated with the initial size of the loop.

hep-th↗
arXiv2008

The Casimir force on a piston in the spacetime with extra compactified dimensions

A one-dimensional Casimir piston for massless scalar fields obeying Dirichlet boundary conditions in high-dimensional spacetimes within the frame of Kaluza-Klein theory is analyzed. We derive and calculate the exact expression for the Casimir force on the piston. We also compute the Casimir force in the limit that one outer plate is moved to the extremely distant place to show that the reduced force is associated with the properties of additional spatial dimensions. The more dimensionality the spacetime has, the stronger the extra-dimension influence is. The Casimir force for the piston in the model excluding one plate under the background with extra compactified dimensions always keeps attractive. Further we find that when the limit is taken the Casimir force between one plate and the piston will change to be the same form as the corresponding force for the standard system consisting of two parallel plates in the four-dimensional spacetimes if the ratio of the plate-piston distance and extra dimensions size is large enough.

hep-th↗
arXiv2008

The circular loop equation of a cosmic string with time-varying tension

The equation of circular loops of cosmic string with time-dependent tension is studied in the Minkowski spacetime and Robertson-Walker universe. We find that, in the case where the tension depends on some power of the cosmic time, cosmic string loops with time-varying tension should not collapse to form a black hole if the power is lower than a critical value.

hep-th↗
arXiv2006

The asymptotic behavior of Casimir force in the presence of compactified universal extra dimensions

The Casimir effect for parallel plates in the presence of compactified universal extra dimensions within the frame of Kaluza-Klein theory is analyzed. Having regularized and discussed the expressions of Casimir force in the limit, we show that the nature of Casimir force is repulsive if the distance between the plates is large enough and the higher-dimensional spacetime is, the greater the value of repulsive Casimir force between plates is. The repulsive nature of the force is not consistent with the experimental phenomena.

hep-th↗
arXiv2004

The special nontopological scalar solitons in anti de Sitter spacetimes

In this letter the nontopological scalar solitons are investigated in an anti de Sitter spacetime. We find analytically that the solitons obeying the necessary conditions $m=\frac{2}{\sqrt{3}}|Λ|^{1/2}$ or $m=\sqrt{\frac{2(n+3)(2n+3)}{3}}|Λ|^{1/2}$ can exist in the background by means of the series expansion.

hep-th↗
arXiv2004

The nontopological scalar solitons in de Sitter spacetimes

In this letter the nontopological scalar solitons with a self-interaction potential are investigated in a static de Sitter spacetime and their field equations are derived. In particular, with series expansion we prove analytically the nonexistence of the solutions under the boundary conditions, which show that some nontopological solitons can not live in the background.

hep-th↗