Neutrinos can have naturally small Dirac masses if the Standard Model singlet right-handed neutrinos are light composite fermions. Theories which produce light composite fermions typically generate many of them, three of which can marry the left-handed neutrinos with small Dirac masses. The rest can serve as sterile states which can mix with the Standard Model neutrinos. We present explicit mod...

We construct supersymmetric gauge theories with new mechanisms of dynamical supersymmetry breaking. The models have flat directions at the classical level, and different mechanisms lift these flat directions in different regions of the classical moduli space. In one branch of the moduli space, supersymmetry is broken by confinement in a novel manner. The models contain only dimensionless coupli...

We consider the possibility of creating an adiabatic transition through a narrow neck, or point contact, between two different quantized Hall states that have the same number of edge modes, such as n51 and n 5 1 3. We apply both the composite-fermion and Luttinger-liquid formalism to analyze the transition. We suggest that using such adiabatic junctions one could build a dc step-up transformer,...

This paper characterizes the effect of finite rate channel state feedback on the sum rate of a multi-access multiple-input multiple-output (MIMO) system. We propose to control the users jointly, specifically, we first choose the users jointly and then select the corresponding beamforming vectors jointly. To quantify the sum rate, this paper introduces the composite Grassmann manifold and the co...

Under certain circumstances, the group velocity in a homogenized composite medium (HCM) can exceed the group velocity in its component material phases. We explore this phenomenon for a uniaxial dielectric HCM comprising isotropic component material phases distributed as oriented spheroidal particles. The theoretical approach is based upon the Bruggeman homogenization formalism. Enhancement in g...

New heavy particles in an SU(2)L multiplet, sometimes introduced in extensions of the standard model, have highly degenerate tree-level mass M if their couplings to the Higgs bosons are very small or forbidden. However, loop corrections may generate the gauge-symmetry-breaking mass splitting within the multiplet, which does not vanish in the large M limit due to the threshold singularity. We ca...

By placing fermions only on the even sites of a lattice, one may halve the momentum spectrum and construct a theory without doublers. The interaction is nonlocal. The fermion propagator is not a sparse matrix, but because the unwanted fermionic states are absent from the formalism, it is 256 times smaller than the usual propagator.

Institut für Theoretische Physik, J.W. Goethe-Universität, 60054 Frankfurt am Main, Germany and Institut de Recherches Subatomiques, 23 rue du Loess BP 28, 67037 Strasbourg Cedex, France (Dated: October 27, 2003) Abstract The exact fermion propagator in a classical time-dependent gauge field is derived by solving the equation of motion for the Dirac Green’s functions. From the retarded propagat...

We have studied scalar perturbations as well as fermion perturbations in pure de Sitter space-times. For scalar perturbations we have shown that well-defined quasinormal modes in d-dimensions can exist provided that the mass of scalar field m > d−1 2l . The quasinormal modes of fermion perturbations in three and four dimensional cases have also been investigated. We found that different from ot...

The current of the bc-system of higher rank introduced recently is examined. Its one-point function is described geometrically and some local computations for the operator product expansions are made.