Related papers: Absorption Cross Section for S-wave massive Scalar
Metasurfaces formed of arrays of subwavelength resonators are often tuned to 'critically couple' with incident radiation, so that at resonance dissipative and radiative damping are balanced and absorption is maximised. Such design criteria…
We show that low-energy photon scattering from a body with radius R slightly larger than its Schwarzschild radius r_s resembles black-hole absorption. This absorption occurs via capture to one of the many long-lived, densely packed…
The classical cross section for low energy absorption of the RR-scalar by a stack of noncommutative D3-branes in the large NS B-field limit is calculated. In the spirit of AdS/CFT correspondence, this cross section is related to two point…
We discuss absorption of scalars by a distribution of spinning D3-branes. The D3-branes are multi-center solutions of supergravity theory. We solve the wave equation in various cases of supergravity backgrounds in which the equation becomes…
We study the scattering of a graviton on a gravitational atom. By gravitational atom we mean a quantum mechanical system of a gravitational (bound) state of two massive particles, with possibly some boundary conditions (such as bouncing on…
Absorption of elastic waves in complex media is commonly found to increase linearly with frequency, for both longitudinal and shear waves. This ubiquitous property is observed in media such as rocks, unconsolidated sediments, and human…
Total absorption, defined as the net flux of energy out of a bounded region averaged over one cycle for time harmonic motion, must be non-negative when there are no sources of energy within the region. This passivity condition places…
We study light absorption by a dipolar absorber in a given environment, which can be a nanoantenna or any complex inhomogeneous medium. From first-principle calculations, we derive an upper bound for the absorption, which decouples the…
Some quantum-gravity theories suggest that the absorbing horizon of a classical black hole should be replaced by a reflective surface which is located a microscopic distance above the would-be classical horizon. Instead of an absorbing…
We compute generalized absorption and extinction cross-sections of an optical dipole nanoantenna in a structured environment. The expressions explicitly show the influence of radiation reaction and the local density of states on the…
We have investigated the absorption cross section and the Hawking radiation of electromagnetic field with Weyl correction in the background of a four-dimensional Schwarzschild black hole spacetime. Our results show that the properties of…
Consider a spherically symmetric spacelike slice through a spherically symmetric spacetime. One can derive a universal bound for the optical scalars on any such slice. The only requirement is that the matter sources satisfy the dominant…
Accurate and powerful computational methods developed by the author for the wave scattering by black holes allow to obtain the highly non trivial total absorption spectrum of the Black Hole. As well as partial wave phase shifts and cross…
On the supergravity side, we study the propagation of the RR scalar and the dilaton in the D3-branes with NS $B$-field. To obtain the noncommutative effect, we consider the case of $B\to \infty(\theta \to\pi/2)$. We approximate this as the…
We study the absorption probability of minimally-coupled massive scalars by extremal p-branes. In particular, we find that the massive scalar wave equation under the self-dual string background has the same form as the massless scalar wave…
This note tackles the problem of the backscattering of a mass-less scalar field in the case of Schwarzschildean space-time. It shows that the effect depends both on a distance from the horizon and on the wave length. The obtained estimates…
Absorption of surface acoustic waves by a two-dimensional electron gas in a perpendicular magnetic field is considered. The structure of such system at the filling factor $\nu$ close to 1/2 can be understood as a gas of {\em composite…
We consider the absorption of probe photons by electrons in the presence of an intense, pulsed, background field. Our analysis reveals an interplay between regularisation and gauge invariance which distinguishes absorption from its…
The time variation of fundamental mass scales can have profound cosmological implications. We investigate a particular model of crossover quintessence which is compatible with all present cosmological observations. This model can also…
The rate at which cross sections grow with energy is sensitive to the presence of extra dimensions in a rather model-independent fashion. We examine how rates would be expected to grow if there are more spatial dimensions than 3 which…