We analyze the general structure of the fermion mass matrices in effective superstrings. They are generically given at low energy by non-trivial functions of the gauge singlet moduli fields. Interesting structures appear in particular if they are homogeneous functions of zero degree in the moduli. In this case we find Yukawa matrices very similar to the ones obtained by imposing a U(1) family s...

We show through rigorous derivation and experimental support that the dynamic effective mass density of an inhomogeneous mixture, used in the prediction of wave velocities in the long wavelength limit, can differ from the static version--the volume average of the component mass densities. The physical reason for this difference is explained. The dynamic mass density expression, first derived by...

LAMIA KASMI,* MATTEO LUCCHINI, LUCA CASTIGLIONI, PAVEL KLIUIEV, JÜRG OSTERWALDER, MATTHIAS HENGSBERGER, LUKAS GALLMANN, PETER KRÜGER, AND URSULA KELLER Department of Physics, ETH Zurich, 8093 Zürich, Switzerland Department of Physics, University of Zurich, 8057 Zürich, Switzerland Institute of Applied Physics, University of Bern, 3012 Bern, Switzerland Graduate School of Science and Engineering...

The effective mass meff of the nonrelativistic quantum electrodynamics with spin 1/2 is investigated. Let meff/m = 1 + a1(Λ/m)e + a2(Λ/m)e +O(e6), where m denotes the bare mass. a1(Λ/m) ∼ log(Λ/m) as Λ → ∞ is well known. Also a2(Λ/m) ∼ √ Λ/m is established for a spinless case. It is shown that a2(Λ/m) ∼ (Λ/m) in the case including spin 1/2.

– The effective mass of the quasiparticle excitations in quasi two-dimensional systems is calculated analytically. It is shown that the effective mass increases sharply when the density approaches the critical one of metal-insulator transition. This suggests a Mott-type of transition rather than an Anderson-like transition. The experimental measurements can be reproduced in this way without any...

We present a classification of SU(3)C × SU(2)L × U(1)Y gauge invariant ∆L = 2 (L being lepton number) effective operators relevant for generating small Majorana neutrino masses. Operators of dimension up to 11 have been included in our analysis. This approach enables us to systematically identify interesting neutrino mass models. It is shown that many of the well–known models fall into this cla...

We outline a general method of obtaining exact solutions of Schrödinger equations with a position dependent effective mass. Exact solutions of several potentials including the shape invariant potentials have also been obtained.

A three-dimensional full band simulator for nanowire field-effect transistors (FETs) is presented in this thesis. At the nanometer scale the classical drift-diffusion transport theory reaches its limits; quantum transport (QT) phenomena govern the motion of electrons and holes. The development of a QT simulator requires the assembly of several physical models and the choice of appropriate simpl...