No abstract

The improvement proposed by Shukla and Easa to the variational calculation of the multipole polarizabilities of atoms and ions has been applied to the Kirkwood-Pople-Schofield approach, to derive a general form of this variational techniqes. This form has been applied to calculate the polarizabilities of free atoms and ions and for atoms and ions in crystalline environments. The accuracy of the results in the KPS method depends on the quality of the initial wavefunction of a given system.

Differential cross sections for the elastic scattering of electrons from the ground states of the closed shell atomic systems Ne, Ar and Na+, and the excited states of the open shell systems containing a highly localized core hole obtained by removing a single electron from any one of the occupied shells of these closed shell systems, have been calculated. Local density approximations to the exchange and correlation potentials have been used in these calculations. A comparison of the calculated results with other experimental and theoretical data is shown and discussed.

An IOP and SISSA journal J Ultra-high energy neutrino fluxes as a probe for non-standard physics Abstract. We examine how light neutrinos coming from distant active galactic nuclei (AGN) and similar high energy sources may be used as tools to probe non-standard physics. In particular we discuss how studying the energy spectra of each neutrino flavour coming from such distant sources and their distortion relative to each other may serve as pointers to exotic physics such as neutrino decay, Lorentz symmetry violation, pseudo-Dirac effects, CP and CPT violation and quantum decoherence. This allows us to probe hitherto unexplored ranges of parameters for the above cases, for example lifetimes in the range 10 −3 − 10 4 s/eV for the case of neutrino decay. We show that standard neutrino oscillations ensure that the different flavours arrive at the earth with similar shapes even if their flavour spectra at source may differ strongly in both shape and magnitude. As a result, observed differences between the spectra of various flavours at the detector would be signatures of non-standard physics altering neutrino fluxes during propagation rather than those arising during their production at source. Since detection of ultra-high energy (UHE) neutrinos is perhaps imminent, it is possible that such differences in spectral shapes will be tested in neutrino detectors in the near future. To that end, using the IceCube detector as an example, we show how our results translate to observable shower and muon-track event rates.

Quantum mechanical calculations of a modification of the x-ray scattering form factor of an atom/ion in an electric field using a three parameter wave function have been performed. These calculations are compared with the previous two parameter wave function calculations. The values of the dipole polarisabilities calculated using these wavefunctions are also compared with some previous results.