A Not So Little Higgs?

Most recent models assuming the Higgs Boson is a pseudo-Nambu-Goldstone Boson (p NGb) are motivated by the indication from Standard Model fits that its mass is < 200GeV.Starting from a modified SM of Forshaw et. al. with a triplet boson added and a heavier Higgs Boson, we consider a pNGb model. This differs in several wa ys from most little Higgs models: apart from using only one loop, the cutoff sca le is reduced to 5 TeV, and consequently a linear sigma model is used to allevia te FCNC effects; no new vector bosons are required, but vector-like isosinglet f ermions are needed, but play no part in determining the mass of the Higgs Boson. The phenomenology of the isosinglet pNGb that arises from the SU(3)xSU(3)->SU(3) model we use is briefly discussed. Some potential theoretical and phenomenolog ical problems arementioned briefly.Comment: 7 pages, some clarifying remarks added and improved discussion of mass estimates give

The APM Galaxy Survey III: An Analysis of Systematic Errors in the Angular Correlation Function and Cosmological Implications

We present measurements of the angular two-point galaxy correlation function, $w(theta)$, from the APM Galaxy Survey. The performance of various estimators of $w$ is assessed using simulated galaxy catalogues and analytic arguments. Several error analyses show that residual plate-to-plate errors do not bias our estimates of $w$ by more than $10^{-3}$. Direct comparison between our photometry and external CCD photometry of over 13,000 galaxies from the Las Campanas Deep Redshift Survey shows that the rms error in the APM plate zero points lies in the range 0.04-0.05 magnitudes, in agreement with our previous estimates. We estimate the effects on $w$ of atmospheric extinction and obscuration by dust in our Galaxy and conclude that these are negligible. We use our best estimates of the systematic errors in the survey to calculate corrected estimates of $w$. Deep redshift surveys are used to determine the selection function of the APM Galaxy Survey, and this is applied in Limber's equation to compute how $w$ scales as a function of limiting magnitude. Our estimates of $w$ are in excellent agreement with the scaling relation, providing further evidence that systematic errors in the APM survey are small. We explicitly remove large-scale structure by applying filters to the APM galaxy maps and conclude that there is still strong evidence for more clustering at large scales than predicted by the standard scale-invariant cold dark matter (CDM) model. We compare the APM $w$ and the three dimensional power spectrum derived by inverting $w$, with the predictions of scale-invariant CDM models. We show that the observations require $Gamma=Omega_0 h$ in the range 0.2-0.3 and are incompatible with the value $Gamma=0.5$ of the standard CDM model.Comment: 102 pages, plain TeX plus 41 postscript figures. Submitted to MNRA

Angular Momentum Distribution Function of the Laughlin Droplet

We have evaluated the angular-momentum distribution functions for finite numbers of electrons in Laughlin states. For very small numbers of electrons the angular-momentum state occupation numbers have been evaluated exactly while for larger numbers of electrons they have been obtained from Monte-Carlo estimates of the one-particle density matrix. An exact relationship, valid for any number of electrons, has been derived for the ratio of the occupation numbers of the two outermost orbitals of the Laughlin droplet and is used to test the accuracy of the MC calculations. We compare the occupation numbers near the outer edges of the droplets with predictions based on the chiral Luttinger liquid picture of Laughlin state edges and discuss the surprisingly large oscillations in occupation numbers which occur for angular momenta far from the edge.Comment: 11 pages of RevTeX, 2 figures available on request. IUCM93-00

The Numerical Simulation of Radiative Shocks I: The elimination of numerical shock instabilities using a localized oscillation filter

We address a numerical instability that arises in the directionally split computation of hydrodynamic flows when shock fronts are parallel to a grid plane. Transverse oscillations in pressure, density and temperature are produced that are exacerbated by thermal instability when cooling is present, forming post--shock `stripes'. These are orthogonal to the classic post--shock 'ringing' fluctuations. The resulting post--shock `striping' substantially modifies the flow. We discuss three different methods to resolve this problem. These include (1) a method based on artificial viscosity; (2) grid--jittering and (3) a new localized oscillation filter that acts on specific grid cells in the shock front. These methods are tested using a radiative wall shock problem with an embedded shear layer. The artificial viscosity method is unsatisfactory since, while it does reduce post--shock ringing, it does not eliminate the stripes and the excessive shock broadening renders the calculation of cooling inaccurate, resulting in an incorrect shock location. Grid--jittering effectively counteracts striping. However, elsewhere on the grid, the shear layer is unphysically diffused and this is highlighted in an extreme case. The oscillation filter method removes stripes and permits other high velocity gradient regions of the flow to evolve in a physically acceptable manner. It also has the advantage of only acting on a small fraction of the cells in a two or three dimensional simulation and does not significantly impair performance.Comment: 20 pages, 6 figures, revised version submitted to ApJ Supplement Serie

The Apm Galaxy Survey IV: Redshifts of Rich Clusters of Galaxies

We present redshifts for a sample of 229 clusters selected from the APM Galaxy Survey, 189 of which are new redshift determinations. Non-cluster galaxy redshifts have been rejected from this sample using a likelihood ratio test based on the projected and apparent magnitude distributions of the cluster fields. We test this technique using cluster fields in which redshifts have been measured for more than 10 galaxies. Our redshift sample is nearly complete and has been used in previous papers to study the three dimensional distribution of rich clusters of galaxies. 157 of the clusters in our sample are listed in the Abell catalogue or supplement, and the remainder are new cluster identifications.Comment: 15 pages UUencoded compressed postscript. Submitted to Monthly Notices of the R.A.

Universal Level dynamics of Complex Systems

. We study the evolution of the distribution of eigenvalues of a $N\times N$ matrix subject to a random perturbation drawn from (i) a generalized Gaussian ensemble (ii) a non-Gaussian ensemble with a measure variable under the change of basis. It turns out that, in the case (i), a redefinition of the parameter governing the evolution leads to a Fokker-Planck equation similar to the one obtained when the perturbation is taken from a standard Gaussian ensemble (with invariant measure). This equivalence can therefore help us to obtain the correlations for various physically-significant cases modeled by generalized Gaussian ensembles by using the already known correlations for standard Gaussian ensembles. For large $N$-values, our results for both cases (i) and (ii) are similar to those obtained for Wigner-Dyson gas as well as for the perturbation taken from a standard Gaussian ensemble. This seems to suggest the independence of evolution, in thermodynamic limit, from the nature of perturbation involved as well as the initial conditions and therefore universality of dynamics of the eigenvalues of complex systems.Comment: 11 Pages, Latex Fil

Atlas 5013 tank corrosion test

The type and cause of corrosion in spot welded joints were determined by X-ray and chemical analysis. Fatigue and static tests showed the degree of degradation of mechanical properties. The corrosion inhibiting effectiveness of WD-40 compound and required renewal period by exposing typical joint specimens were examined

Model study of a folded plate roof

The purpose of this study was to conduct a model study of a folded plate roof in order to determine the feasability [sic] of using model studies as a method of design. Dimensional analysis was used to derive prediction equations for determining the stresses in two prototype structures, when the stresses in the model were known. One model and two prototype folded plate roofs were constructed of plexiglas [sic]. SR-4 strain gages were attached to the structures and strain readings taken as a uniform vertical load was applied in increments. From the strains the stresses at various points in the folded plates were computed. The analytical, predicted, and experimental stresses were compared for the two prototypes. It was found that the predicted and experimental stress values agreed within 13% at the center of the roof, but near the boundaries of the structure the deviation was much more variable --Abstract, page ii