Theoretical Modelling on the Magnetization by Electric Field Through Product Property.

Multilayer composites of piezoelectric and magnetostrictive materials can be designed to exhibit the magnetoelectric (ME) effect. This ME effect can be realised as an electric polarisation induced by a magnetic field (called MEH effect) or a magnetization by an electric field (called MEE effect). Theoretical modelling of the MEE effect for 2-2 connectivity composites has been developed for three different boundary conditions for perfect coupling at the interface. The calculated MEE coefficients using material properties of piezoelectric lead zirconate titanate (PZT) and magnetostrictive Terfenol-D are a few orders of magnitude larger than those of single phase ME materials and the calculated values are compared with experimental results in the literature. Keywords: magnetoelectric, multiferroic, piezoelectric, magnetostrictive, piezomagnetic, laminated composites, modelling

Neutrinos with Zee-Mass Matrix in Vacuum and Matter

Neutrino mass matrix generated by the Zee (radiative) mechanism has zero (in general, small) diagonal elements and a natural hierarchy of the nondiagonal elements. It can be considered as an alternative (with strong predictive power) to the matrices generated by the see-saw mechanism. The propagation in medium of the neutrinos with the Zee-mass matrix is studied. The flavor neutrino transitions are described analytically. In the physically interesting cases the probabilities of transitions as functions of neutrino energy can be represented as two-neutrino probabilities modulated by the effect of vacuum oscillations related to the small mass splitting. Possible applications of the results to the solar, supernova, atmospheric and relic neutrinos are discussed. A set of the predictions is found which could allow to identify the Zee-mass matrix and therefore the corresponding mechanism of mass generation.Comment: 25 pages (3 figures available upon request), LaTeX, IC/94/4

Status of Supersymmetric Grand Unified Theories

We begin with a brief discussion of the building blocks of supersymmetric grand unified theories. We recall some of the compelling theoretical reasons for viewing supersymmetric grand unification as an attractive avenue for physics beyond the standard model. This is followed by a discussion of some of the circumstantial evidence for these ideas.Comment: 12 pages plain LaTeX to be run twice. Invited talk at the XII DAE Symposium on High Energy Physics, Guwahati, India, Dec. 26, 1996 - Jan. 1, 199

On the Twisted N=2N=2 Superconformal Structure in 2d2d Gravity Coupled to Matter

It is shown that the two dimensional gravity, described either in the conformal gauge (the Liouville theory) or in the light cone gauge, when coupled to matter possesses an infinite number of twisted $N=2$ superconformal symmetries. The central charges of the $N=2$ algebra for the two gauge choices are in general different. Further, it is argued that the physical states in the light cone gauge theory can be obtained from the Liouville theory by a field redefinition.Comment: Plain Tex, 13 pages, IC/93/81, UG-3/9

Diagrammatic theory for twofold degenerate Anderson impurity model

The twofold degenerate Anderson impurity model [1-4] is investigated and the strong electronic correlations of d-electrons of impurity ion are taken into account by elaborating suitable diagram technique. We discuss the properties of the Slater-Kanamori model [2-4] of d-impurity electrons. After finding the eigenfunctions and eigenvalues of all 16 local states, we determine the local one-particle propagator. Then we construct the perturbation theory around the atomic limit of the impurity ion and obtain the Dyson type equation for the renormalized one-particle propagator. Diagrammatic theory has been developed and correlation function determined. Special diagrammatic approximation was discussed and summation of diagram has been considered.Comment: 14 pages, 4 figure

Out of Equilibrium Phase Transitions and a Toy Model for Disoriented Chiral Condensates

We study the dynamics of a second order phase transition in a situation thatmimics a sudden quench to a temperature below the critical temperature in a model with dynamical symmetry breaking. In particular we show that the domains of correlated values of the condensate grow as $\sqrt{t}$ and that this result seems to be largely model independent.Comment: 17 pages, UR-1315 ER-40685-76

Theoretical Status of Pentaquarks

We review the current status of the theoretical pentaquark search from the direct QCD calculation. The works from the QCD sum rule and the lattice QCD in the literature are carefully examined. The importance of the framework which can distinguish the exotic pentaquark state (if any) from the NK scattering state is emphasized.Comment: Presented at Yukawa International Seminar (YKIS) 2006 on "New Frontiers in QCD", Kyoto, Japan, 20 Nov. - 8 Dec. 2006, 4 page