1,381 research outputs found
Charged Scalar Perturbations around Garfinkle-Horowitz-Strominger Black Holes
We examine the stability of the Garfinkle-Horowitz-Strominger (GHS) black
hole under charged scalar perturbations. We find that different from the
neutral scalar field perturbations, only two numerical methods, such as the
continued fraction method and the asymptotic iteration method, can keep high
efficiency and accuracy requirements in the frequency domain computations. The
comparisons of the efficiency between these two methods have also been done.
Employing the appropriate numerical method, we show that the GHS black hole is
always stable against charged scalar perturbations. This is different from the
result obtained in the de Sitter and Anti-de Sitter black holes. Furthermore we
argue that in the GHS black hole background there is no amplification of the
incident charged scalar wave to cause the superradiance, so that the
superradiant instability cannot exist in this spacetime.Comment: 24 pages, 5 figure
Superradiant instability of Kerr-de Sitter black holes in scalar-tensor theory
We investigate in detail the mechanism of superradiance to render the
instability of Kerr-de Sitter black holes in scalar-tensor gravity. Our results
provide more clues to examine the scalar-tensor gravity in the astrophysical
black holes in the universe with cosmological constant. We also discuss the
spontaneous scalarization in the de Sitter background and find that this
instability can also happen in the spherical de Sitter configuration in a
special style.Comment: (v2)21 pages, 21 figures; Sec. V revised; This version has been
accepted for publication by JHE
Spin asymmetry and dipole moments in -pair production with ultraperipheral heavy ion collisions
The anomalous magnetic (MDM) and electric (EDM) dipole moments of the
lepton serve as crucial indicators of new physics beyond the Standard Model.
Leveraging azimuthal angular asymmetry as a novel tool in ultraperipheral
collisions (UPCs), we attain unparalleled precision in the study of these key
properties. Driven by the highly linear polarization of coherent photons, this
method uniquely enables both the MDM and EDM to contribute to the
angular distribution in similar magnitudes. Importantly, our approach
substantially narrows the parameter space, excluding more than half of it
compared to expected UPC-based measurements reliant solely on the total
cross-section. This method not only provides improved constraints but also
minimizes the need for additional theoretical assumptions.Comment: 6 pages, 3 figure
- …