Collective Quartics and Dangerous Singlets in Little Higgs

Any extension of the standard model that aims to describe TeV-scale physics without fine-tuning must have a radiatively-stable Higgs potential. In little Higgs theories, radiative stability is achieved through so-called collective symmetry breaking. In this letter, we focus on the necessary conditions for a little Higgs to have a collective Higgs quartic coupling. In one-Higgs doublet models, a collective quartic requires an electroweak triplet scalar. In two-Higgs doublet models, a collective quartic requires a triplet or singlet scalar. As a corollary of this study, we show that some little Higgs theories have dangerous singlets, a pathology where collective symmetry breaking does not suppress quadratically-divergent corrections to the Higgs mass.Comment: 4 pages; v2: clarified the existing literature; v3: version to appear in JHE

Inversion For Permeability From Stoneley Wave Velocity And Attenuation

The in situ permeability of a formation is obtained by the inversion of Stoneley wave phase velocity and attenuation, which are evaluated by applying the Extended Prony's method to the array sonic logging data. The Maximum Likelihood inversion is used together with logarithmic parameterization of the permeabilities. Formation shear wave velocity is also inverted for. This process is tested on both synthetic and field data. Logarithmic parameterization contributes to rapid convergence of the algorithm. Permeabilities estimated from field data are in good agreement with core measurements.Massachusetts Institute of Technology. Full Waveform Acoustic Logging Consortiu

Fourth-Order Finite Difference Acoustic Logs In A Transversely Isotropic Formation

In this paper we present a finite difference scheme for seismic wave propagation in a fluid-filled borehole in a transversely isotropic formation. The first-order hyperbolic differential equations are approximated explicitly on a staggered grid using an algorithm that is fourth-order accurate in space and second-order accurate in time. The grid dispersion and grid anisotropy are analyzed. Grid dispersion and anisotropy are well suppressed by a grid size of 10 points per wavelength. The stability condition is also obtained from the dispersion analysis. This finite difference scheme is implemented on the nCUBE2 parallel computer with a grid decomposition algorithm. The finite difference synthetic waveforms are compared with those generated using the discrete wavenumber method. They are in good agreement. The damping layers effectively absorbed the boundary reflections. Four vertically heterogeneous borehole models: a horizontal layered formation, a borehole with a radius change, a semi-infinite borehole, and a semi-infinite borehole with a layer, are studied using the finite difference method. Snapshots from the finite difference results provide pictures of the radiating wavefields.Massachusetts Institute of Technology. Borehole Acoustics and Logging Consortiu

Coexistence and competition of multiple charge-density-wave orders in rare-earth tri-telluride RTe3

The occurrences of collective quantum states, such as superconductivity (SC) and charge- or spin-densitywaves (CDWs or SDWs), are among the most fascinating phenomena in solids. To date much effort has been made to explore the interplay between different orders, yet little is known about the relationship of multiple orders of the same type. Here we report optical spectroscopy study on CDWs in the rare-earth tri-telluride compounds RTe3 (R = rare earth elements). Besides the prior reported two CDW orders, the study reveals unexpectedly the presence of a third CDW order in the series which evolves systematically with the size of R element. With increased chemical pressure, the first and third CDW orders are both substantially suppressed and compete with the second one by depleting the low energy spectral weight. A complete phase diagram for the multiple CDW orders in this series is established.Comment: 7 pages, 4 figures, 1 tabl

Borehole Wave Propagation In Isotropic And Anisotropic Media I: Finite Difference Method

In this paper we developed a 3-D finite difference method to simulate wave propagations in an isotropic medium. The wave equation is formulated into the first-order hyperbolic equations by using velocity and stress and then discretizing it on a staggered grid. The 3-D time domain finite difference scheme is second order accurate in time and fourth order accurate in space. The grid dispersion and anisotropy are analyzed and the stable condition of the scheme is obtained. Higdon's absorbing boundary condition is discussed and generalized to the anisotropic medium. The scheme can provide realistic 3-D wave propagation simulation by the use of a parallel computer. The scheme is tested in the homogeneous medium. The finite difference results agree excellently with the analytic solutions of a point explosion source in the acoustic medium and a point force source in the elastic medium. The finite difference method accurately models not only the far field P and S waves, but also the near field term. It demonstrates that the second-order Higdon's absorbing boundary condition works very well in an acoustic and elastic medium.Massachusetts Institute of Technology. Borehole Acoustics and Logging ConsortiumERL/nCUBE Geophysical Center for Parallel Processin

Test of Factorization Hypothesis from Exclusive Non-leptonic B decays

We investigate the possibility of testing factorization hypothesis in non-leptonic exclusive decays of B-meson. In particular, we considered the non factorizable \bar{B^0} -> D^{(*)+} D_s^{(*)-} modes and \bar{B^0} -> D^{(*)+} (\pi^-, \rho^-) known as well-factorizable modes. By taking the ratios BR(\bar{B^0}-> D^{(*)+}D_s^{(*)-})/BR(\bar{B^0}-> D^{(*)+}(\pi^-,\rho^-)), we found that under the present theoretical and experimental uncertainties there's no evidence for the breakdown of factorization description to heavy-heavy decays of the B meson.Comment: 11 pages; submitted to PR

Seiberg-Witten Description of the Deconstructed 6D (0,2) Theory

It has recently been suggested that, in a large N limit, a particular four dimensional gauge theory is indistinguishable from the six dimensional CFT with (0,2) supersymmetry compactified on a torus. We give further evidence for this correspondence by studying the Seiberg-Witten curve for the "deconstructed" theory and demonstrating that along the reduced Coulomb branch of moduli space (on the intersection of the Higgs and Coulomb branches) it describes the low energy physics on a stack of M5-branes on a torus, which is the (0,2) theory on a torus as claimed. The M-theory construction helps to clarify the enhancement of supersymmetry in the deconstructed theory at low energies, and demonstrates its stability to radiative and instanton corrections. We demonstrate the role of the theta vacuum in the deconstructed theory. We point out that by varying the theta parameters and gauge couplings in the deconstructed theory, the complex structure of the torus can be chosen arbitrarily, and the torus is not metrically S^1 x S^1 in general.Comment: 13 pages, 2 figure

Fractional Quantum Hall Effect of Hard-Core Bosons in Topological Flat Bands

Recent proposals of topological flat band (TFB) models have provided a new route to realize the fractional quantum Hall effect (FQHE) without Landau levels. We study hard-core bosons with short-range interactions in two representative TFB models, one of which is the well known Haldane model (but with different parameters). We demonstrate that FQHE states emerge with signatures of even number of quasi-degenerate ground states on a torus and a robust spectrum gap separating these states from higher energy spectrum. We also establish quantum phase diagrams for the filling factor 1/2 and illustrate quantum phase transitions to other competing symmetry-breaking phases.Comment: 4 pages, 6 figure

Finite Difference Modelling Of Acoustic Logs In Vertically Heterogeneous Biot Solids

This paper discusses the results of tests carried out on a finite difference formulation of Biot's equations for wave propagation in saturated porous media which vary in range and depth (Stephen, 1987). A technique for modeling acoustic logs in two dimensionally varying Biot solids will give insight into the behavior of tube waves at permeable fractures and fissures which intersect the borehole. The code agrees well with other finite difference codes and the discrete wavenumber code for small porosity in the elastic limit of Biot's equations. For large porosity (greater than one per cent) in the elastic limit or for the acoustic limit, good agreement is not obtained with the discrete wavenumber method for vertically homogeneous media. The agreement is worst for amplitudes of the pseudo-Rayleigh wave. The amplitude of the Stoneley wave and the phase velocities of both waves could be acceptable for some applications. An example is shown of propagation across a horizontal high porosity stringer in a Berea sandstone. Reflections from the stringer are observed but given the inaccuracies of the pseudo-Rayleigh waves for vertically heterogeneous media the amplitudes for the stringer model are questionable. We propose a three stage approach for further work: 1) Use the Virieux scheme instead of the Bhasavanija scheme for the finite difference template. The Virieux scheme has been shown in other studies to be more accurate for liquid-solid interfaces. 2) Run the present code for lower frequency sources to emphasize Stoneley waves and diminish pseudo-Rayleigh waves. Stoneley waves are most sensitive to permeability variations which are the primary objective of Biot wave studies. 3) Develop a finite difference code for Biot media with the fluid-solid boundary conditions specifically coded. This code would be suitable for studying constant radius boreholes in vertically varying Biot media.Massachusetts Institute of Technology. Full Waveform Acoustic Logging Consortiu