A Higgs Boson Composed of Gauge Bosons

It is proposed to replace the Higgs boson of the standard model by a Lorentz- and gauge-invariant combination of SU(2) gauge bosons. A pair of Higgs bosons is identified with pairs of gauge bosons by setting their mass Lagrangians equal to each other. That immediately determines the mass of the composite Higgs boson. It becomes simply half of the vacuum expectation value of the standard Higgs boson, which matches the observed mass with tree-level accuracy (2%). The two parameters of the standard Higgs potential are replaced by five one-loop self-interactions of the SU(2) gauge bosons, derived from the fundamental gauge couplings. The Brout-Englert-Higgs mechanism of spontaneous symmetry breaking is generalized from scalars to vectors. Their transverse components acquire finite vacuum expectation values which generate masses for both gauge bosons and the Higgs boson. This concept leads beyond the standard model by enabling calculations of the Higgs mass and its potential without adjustable parameters. It can be applied to non-abelian gauge theories in general, such as grand unified models and supersymmetry.Comment: 27 pages, 10 figures, added appendix, fixed errors and typos, clarified the text, added explanation of Equation (15), added reference

Structure of Quantum Wires in Au/Si(557)

The structure of the Au/Si(557) surface is determined from three-dimensional x-ray diffraction measurements, which directly mandate a single Au atom per unit cell. We use a “heavy atom” method in which the Au atom images the rest of the structure. Au is found to substitute for a row of first-layer Si atoms in the middle of the terrace, which then reconstructs by step rebonding and adatoms. The structure is consistent with the 1D metallic behavior seen by photoemission

Structure and energetics of Si(111)-(5x2)-Au

We propose a new structural model for the Si(111)-(5x2)-Au reconstruction. The model incorporates a new experimental value of 0.6 monolayer for the coverage of gold atoms, equivalent to six gold atoms per 5x2 cell. Five main theoretical results, obtained from first-principles total-energy calculations, support the model. (1) In the presence of silicon adatoms the periodicity of the gold rows spontaneously doubles, in agreement with experiment. (2) The dependence of the surface energy on the adatom coverage indicates that a uniformly covered phase is unstable and will phase-separate into empty and covered regions, as observed experimentally. (3) Theoretical scanning tunneling microscopy images are in excellent agreement with experiment. (4) The calculated band structure is consistent with angle-resolved photoemission spectra; analysis of their correspondence allows the straightforward assignment of observed surface states to specific atoms. (5) The calculated activation barrier for diffusion of silicon adatoms along the row direction is in excellent agreement with the experimentally measured barrier.Comment: 11 pages, 7 figures, also available with higher-resolution figures from http://cst-www.nrl.navy.mil/users/erwin/ausi111.v5.pd

Surface and Grain Boundary Analysis of High Temperature Superconductors

The purpose of this paper is to survey the methods that are available for probing surfaces and grain boundaries of high temperature superconductors. Various surface-sensitive spectroscopies are applied to the analysis of YBa2Cu3O7-x and Bi2Sr2CaCu2O8+x including photoelectron spectroscopy, spatially-resolved electron energy loss spectroscopy, and scanning electron microscopy (SEM). One of the major sources of contamination at surfaces and grain boundaries is found to be BaCO3. The cleavage surface of single crystal Bi2Sr2CaCu2O8+x is inert and can be used to probe bulk properties of superconductors, even with surface-sensitive techniques. The orbital character of the superconducting oxygen 2p holes is found to be Px,y, with x,y in the a,b plane. Photoemission at the Fermi level indicates a Fermi liquid nature of these states

Plasmon assisted transport through disordered array of quantum wires

Phononless plasmon assisted thermally activated transport through a long disordered array of finite length quantum wires is investigated analytically. Generically strong electron plasmon interaction in quantum wires results in a qualitative change of the temperature dependence of thermally activated resistance in comparison to phonon assisted transport. At high temperatures, the thermally activated resistance is determined by the Luttinger liquid interaction parameter of the wires.Comment: 7 pages, 1 figure, final version as publishe