105,449 research outputs found
Background effects on reconstructed WIMP couplings
In this talk, I presented effects of small, but non-negligible unrejected
background events on the determinations of WIMP couplings/cross sections.Comment: 4 pages, 5 eps figures, to appear in the proceedings of the 12th
International Conference on Topics in Astroparticle and Underground Physics
(TAUP 2011), September 5-9, 2011, Munich, German
Strong deflection gravitational lensing by a modified Hayward black hole
A modified Hayward black hole is a nonsingular black hole. It is proposed to
form when the pressure generated by quantum gravity can stop matter's collapse
as the matter reaches Planck density. Strong deflection gravitational lensing
happening nearby its event horizon might provide some clues of these quantum
effects in its central core. We investigate observables of the strong
deflection lensing, including angular separations, brightness differences and
time delays between its relativistic images, and estimate their values for the
supermassive black hole in the Galactic center. We find that it is possible to
distinguish the modified Hayward black hole from a Schwarzschild one, but it
demands very high resolution beyond current stage.Comment: 10 pages, 1 figur
Why gravity is not an entropic force
The remarkable connections between gravity and thermodynamics seem to imply that gravity is not
fundamental but emergent, and in particular, as Verlinde suggested, gravity is probably an entropic force. In this
paper, we will argue that the idea of gravity as an entropic force is debatable. It is shown that there is no
convincing analogy between gravity and entropic force in Verlinde’s example. Neither holographic screen nor test
particle satisfies all requirements for the existence of entropic force in a thermodynamics system. As a result, there is no entropic force in the gravity system. Furthermore, we show that the entropy increase of the screen is not caused by its statistical tendency to increase entropy as required by the existence of entropic force, but in fact caused by gravity. Therefore, Verlinde’s argument for the entropic origin of gravity is problematic. In addition, we argue that the existence of a minimum size of spacetime, together with the Heisenberg uncertainty principle in quantum theory, may imply the fundamental existence of gravity as a geometric property of spacetime. This provides a further support for the conclusion that gravity is not an entropic force
- …