39,770 research outputs found
No hair theorem for massless scalar fields outside asymptotically flat horizonless reflecting compact stars
In a recent paper, Hod started a study on no scalar hair theorem for
asymptotically flat spherically symmetric neutral horizonless reflecting
compact stars. In fact, Hod's approach only rules out massive scalar fields. In
the present paper, for massless scalar fields outside neutral horizonless
reflecting compact stars, we provide a rigorous mathematical proof on no hair
theorem. We show that asymptotically flat spherically symmetric neutral
horizonless reflecting compact stars cannot support exterior massless scalar
field hairs.Comment: 7 page
Scalar field configurations supported by charged compact reflecting stars in a curved spacetime
We study the system of static scalar fields coupled to charged compact
reflecting stars through both analytical and numerical methods. We enclose the
star in a box and our solutions are related to cases without box boundaries
when putting the box far away from the star. We provide bottom and upper bounds
for the radius of the scalar hairy compact reflecting star. We obtain numerical
scalar hairy star solutions satisfying boundary conditions and find that the
radius of the hairy star in a box is continuous in a range, which is very
different from cases without box boundaries where the radius is discrete in the
range. We also examine effects of the star charge and mass on the largest
radius.Comment: 10 pages, 4 figures. Accepted for publication in PLB. arXiv admin
note: text overlap with arXiv:1711.0697
Scalar condensation behaviors around regular Neuman reflecting stars
We study static massive scalar field condensations in the regular
asymptotically flat reflecting star background. We impose Neumann reflecting
surface boundary conditions for the scalar field. We show that the no hair
theorem holds in the neutral reflecting star background. For charged reflecting
stars, we provide bounds for radii of hairy reflecting stars. Below the lower
bound, there is no regular compact reflecting star and a black hole will form.
Above the upper bound, the scalar field cannot condense around the reflecting
star or no hair theorems exist. And in between the bounds, we obtain scalar
configurations supported by Neumann reflecting stars.Comment: 9 pages, 1 figur
No short hair behaviors of ultra-compact stars
In the black hole spacetime, a no short hair theorem was proved, which states
that the effective radius of black hole hairs must extend beyond the null
circular orbit. In the present paper, in the horizonless gravity, we find a
similar no short hair behavior that the effective radius of matter fields must
also extend beyond the null circular orbit of ultra-compact stars.Comment: 6 page
Holographic entanglement entropy in superconductor phase transition with dark matter sector
In this paper, we investigate the holographic phase transition with dark
matter sector in the AdS black hole background away from the probe limit. We
disclose the properties of phases mostly from the holographic topological
entanglement entropy of the system. We find the entanglement entropy is a good
probe to the critical temperature and the order of the phase transition in the
general model. The behaviors of entanglement entropy at large strip size
suggest that the area law still holds with dark matter sector. We also conclude
that the holographic topological entanglement entropy is useful in detecting
the stability of the phase transitions. Furthermore, we derive the complete
diagram of the effects of coupled parameters on the critical temperature
through the entanglement entropy and analytical methods.Comment: 15 pages, 7 figure
Studies of a general flat space/boson star transition model in a box through a language similar to holographic superconductors
We study a general flat space/boson star transition model in quasi-local
ensemble through approaches familiar from holographic superconductor theories.
We manage to find a parameter , which is proved to be useful in
disclosing properties of phase transitions. In this work, we explore effects of
the scalar mass, scalar charge and Stckelberg mechanism on the
critical phase transition points and the order of transitions mainly from
behaviors of the parameter . We mention that properties of
transitions in quasi-local gravity are strikingly similar to those in
holographic superconductor models. We also obtain an analytical relation
, which also holds for the condensed
scalar operator in the holographic insulator/superconductor system in
accordance with mean field theories.Comment: 11 pages, 6 figure
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