Irregularity in gamma ray source spectra as a signature of axionlike particles

Oscillations from high energy photons into light pseudoscalar particles in an external magnetic field are expected to occur in some extensions of the standard model. It is usually assumed that those axionlike particles (ALPs) could produce a drop in the energy spectra of gamma ray sources and possibly decrease the opacity of the Universe for TeV gamma rays. We show here that these assumptions are in fact based on an average behavior that cannot happen in real observations of single sources. We propose a new method to search for photon-ALP oscillations, taking advantage of the fact that a single observation would deviate from the average expectation. Our method is based on the search for irregularities in the energy spectra of gamma ray sources. We predict features that are unlikely to be produced by known astrophysical processes and a new signature of ALPs that is easily falsifiable.Comment: 6 pages, 3 figures, matches accepted version, improved discussion on magnetic field models in v

Coherent Virtual Absorption Based on Complex Zero Excitation for Ideal Light Capturing

Absorption of light is directly associated with dissipative processes in a material. In suitably tailored resonators, a specific level of dissipation can support coherent perfect absorption, the time-reversed analogue of lasing, which enables total absorption and zero scattering in open cavities. On the contrary, the scattering zeros of lossless objects strictly occur at complex frequencies. While usually considered non-physical due to their divergent response in time, these zeros play a crucial role in the overall scattering dispersion. Here, we introduce the concept of coherent virtual absorption, accessing these modes by temporally shaping the incident waveform. We show that engaging these complex zeros enables storing and releasing the electromagnetic energy at will within a lossless structure for arbitrary amounts of time, under the control of the impinging field. The effect is robust with respect to inevitable material dissipation and can be realized in systems with any number of input ports. The observed effect may have important implications for flexible control of light propagation and storage, low-energy memory, and optical modulation.Comment: To be published in Optic

Statistical Problems and Solutions in Onomastic Research: Exemplified by a Comparison of Given Name Distributions in Germany throughout the 20th Century

The German Socio Economic Panel Study (SOEP) offers the rare opportunity to look at patterns of given names amongst a representative sample of more than 50,000 people born since 1900. This article develops an exemplary picture of typical frequency distributions for given names and their developments over time. In this paper, we first discuss the advantages and limitations of various data bases which have been widely used to study the distribution of given names. Second, we address the problem that name distributions are typically characterized by a "Large Number of Rare Events" (LNRE) zone. With regard to this, we focus our attention on the difficulties associated with comparing name distributions. Third, we apply some measures of the concentration of distributions from other lines of research (economics and computational linguistics). Finally, we stress the problem of the statistical significance of differences in name distributions based on samples.Given names, large number of rare events (LNRE), concentration of distributions, SOEP

Bifurcating trajectory of non-diffractive electromagnetic Airy pulse

The explicit expression for spatial-temporal Airy pulse is derived from the Maxwell's equations in paraxial approximation. The trajectory of the pulse in the time-space coordinates is analysed. The existence of a bifurcation point that separates regions with qualitatively different features of the pulse propagation is demonstrated. At this point the velocity of the pulse becomes infinite and the orientation of it changes to the opposite