Generalised hyperbolicity in spacetimes with string-like singularities

In this paper we present well-posedness results of the wave equation in $H^{1}$ for spacetimes that contain string-like singularities. These results extend a framework able to characterise gravitational singularities as obstruction to the dynamics of test fields rather than point particles. In particular, we discuss spacetimes with cosmic strings and the relation of our results to the Strong Cosmic Censorship Conjecture.Comment: Accepted for publication in Classical and Quantum Gravit

Hypernuclear Physics at PANDA

Hypernuclear research will be one of the main topics addressed by the PANDA experiment at the planned Facility for Anti-proton and Ion Research FAIR at Darmstadt, Germany. A copious production of Xi-hyperons at a dedicated internal target in the stored anti-proton beam is expected, which will enable the high-precision gamma-spectroscopy of double strange systems for the first time. In addition to the general purpose PANDA setup, the hypernuclear experiments require an active secondary target of silicon layers and absorber material as well as high purity germanium (HPGe) crystals as gamma-detectors. The design of the setup and the development of these detectors is progressing: a first HPGe crystal with a new electromechanical cooling system was prepared and the properties of a silicon strip detector as a prototype to be used in the secondary target were studied. Simultaneously to the hardware projects, detailed Monte Carlo simulations were performed to predict the yield of particle stable hypernuclei. With the help of the Monte Carlo a procedure for Lambda-Lambda-hypernuclei identification by the detection and correlation of the weak decay pions was developed.Comment: prepared for the International Conference on Exotic Atoms and Related Topics (EXA2011), Vienna, Sept. 5-9, 201

Near field and far field scattering of surface plasmon polaritons by one-dimensional surface defects

A rigorous formulation for the scattering of surface plasmon polaritons (SPP) from a one-dimensional surface defect of any shape that yields the electromagnetic field in the vacuum half-space above the vacuum-metal interface is developed by the use of an impedance boundary condition. The electric and magnetic near fields, the angular distribution of the far-field radiation into vacuum due to SPP-photon coupling, and the SPP reflection and transmission coefficients are calculated by numerically solving the k-space integral equation upon which the formulation is based. In particular, we consider Gaussian-shaped defects and study the dependence of the above mentioned physical quantities on their 1/e half-width a and height h. SPP reflection is significant for narrow defects; maximum reflection (plasmon mirrors) is achieved for a~lambda/10. For increasing defect widths, protuberances and indentations behave differently. The former give rise to a monotonic increase of radiation at the expense of SPP transmission for increasing defect half-width. Indentations exhibit a significant increase of radiation (decrease of SPP transmission) for half-widths of the order of or smaller than the wavelength, but tend to total SPP transmission in an oscillatory manner upon further increasing the half-width. Light-emitters might thus be associated with either wide indentations, or protuberances with widths that are of the order of or smaller than the wavelength.Comment: REVTeX 3.1, 10 pages with 9 EPS figures (epsf macro

The geometry of L^p-spaces over atomless measure spaces and the Daugavet property

We show that $L^p$-spaces over atomless measure spaces can be characterized in terms of a $p$-concavity type geometric property that is related with the Daugavet property

On the connections between Skyrme and Yang Mills theories

Skyrme theories on S^3 and S^2, are analyzed using the generalized zero curvature in any dimensions. In the first case, new symmetries and integrable sectors, including the B =1 skyrmions, are unraveled. In S^2 the relation to QCD suggested by Faddeev is discussedComment: Talk at the Workshop on integrable theories, solitons and duality. IFT Sao Paulo July 200