October 1996 arXiv papers — page 14

Oliver Schnetz

The spectral test of random number generators (R.R. Coveyou and R.D. McPherson, 1967) is generalized. The sequence of random numbers is analyzed explicitly, not just via their n-tupel distributions. We find that the mixed multiplicative generator with power of two modulus does not pass the extended test with an ideal result. Best qualities has a new generato

Oliver Schnetz

The spectral test of random number generators (R.R. Coveyou and R.D. McPherson, 1967) is generalized. The sequence of random numbers is analyzed explicitly not just via their n-tupel distributions. The generalized analysis of many generators becomes possible due to a theorem on the harmonic analysis of multiplicative groups of residue class rings. We find th

E. Perazzi, M. Radici, S. Boffi

Photocouplings for the nucleon resonances most relevant to total photoabsorption are calculated in a constituent quark model including gluon and pion exchange. The sensitivity of the results to the different ingredients of the model is discussed.

Jose Alexandre Nogueira, Adolfo Maia

We investigate a possible difference between the effective potential and zero-point energy. We define the zero-point ambiguity (ZPA) as the difference between these two definitions of vacuum energy. Using the zeta function technique, in order to obtain renormalized quantities, we show that ZPA vanishes, implying that both of the above definitions of vacuum e

Oliver Schnetz

A careful analysis of differential renormalization shows that a distinguished choice of renormalization constants allows for a mathematically more fundamental interpretation of the scheme. With this set of a priori fixed integration constants differential renormalization is most closely related to the theory of generalized functions. The special properties o

Y. Lozano

We present a brief review on the canonical transformation description of some duality symmetries in string and gauge theories. In particular, we consider abelian and non-abelian T-dualities in closed and open string theories as well as S-duality in abelian and non-abelian non-supersymmetric gauge theories.

R. J. Cashmore, E. Elsen, B. A. Kniehl, H. Spiesberger

A high luminosity upgrade of HERA will allow the measurement of standard model parameters and the neutral current couplings of quarks. These results will have to be consistent with other precision measurements or indicate traces of new physics. The analysis of $W$ production will complement future results of LEP 2 and the Tevatron. We summarize the main resu

Subir Sarkar

In effective supergravity theories following from the superstring, a modulus field can quite naturally set the neccessary initial conditions for successful cosmological inflation to be driven by a hidden sector scalar field. The leading term in the scalar potential is {\em cubic} hence the spectrum of scalar density perturbations neccessarily deviates from s

M. E. Shaposhnikov

Lecture Notes, Summer School on Effective Theories and Fundamental Interactions, Erice, July 1996. I describe the construction of effective field theories for equilibrium high-temperature plasma of elementary particles.

Patrik Eden

In an earlier paper, we discuss the ``popcorn'' model for baryon production in quark and gluon jets, and present an improved model (which we call Modified Popcorn Scenarium, MOPS). In this paper we give a manual to the MC program based on MOPS, and also discuss the application of the model to baryon fragmentation, i.e. fragmentation of strings origin

M. F. McDermott, G. Briskin

A review of theoretical models of diffractive structure functions in deep inelastic scattering (DIS) is presented with a view to highlighting distinctive features, that may be distinguished experimentally. In particular, predictions for the behaviour of the diffractive structure functions $F_2^D, F_L^D, F_2^{D(\mbox{\small{charm}})}$ are presented. The measu

A. Pich

Rare K decays are an important testing ground of the electroweak flavour theory. They can provide new signals of CP-violation phenomena and, perhaps, a window into physics beyond the Standard Model. The interplay of long-distance QCD effects in strangeness-changing transitions can be analyzed with Chiral Perturbation Theory techniques. Some theoretical predi

John Swain, Lucas Taylor

We have derived constraints on the tau neutrino mass and fourth generation mixing from an analysis of the partial widths of tau lepton decays, in particular: tau -> e nu nu_tau, tau -> mu nu nu_tau, tau -> pi nu_tau, tau -> K nu_tau. We present predictions for the tau decay widths, allowing for a non-zero tau neutrino mass, m(nu_tau), and for mixing with a n

S. M. Troshin, N. E. Tyurin

We discuss a nonperturbative mechanism for one-spin asymmetries in inclusive hadron production. The main role in generation of this asymmetry belongs to the orbital angular momentum of quark-antiquark cloud in internal structure of constituent quarks.

B. A. Dobrescu, S. Mrenna

If supersymmetry is dynamically broken in a hidden sector, the gauginos typically have unacceptably small masses. This situation can be corrected if a non-Abelian gauge interaction becomes strong at a scale of order 1 TeV and induces dynamical gaugino masses. We discuss the typical signals of this scenario at present and future colliders.

B. Alles, G. Boyd, M. D'Elia, A. Di Giacomo

We survey recent lattice results on QCD topological properties. The behaviour of the topological susceptibility at the deconfining phase transition has been determined. This advance has been made possible by an i) an improvement of the topological charge operator and ii) a non-perturbative determination of renormalizations.

P. Eerola

The B-physics potential of the ATLAS experiment at LHC is described. Simulation results are shown for the measurement of sin(2beta), with an emphasis on new tagging techniques. Other CP-violation measurements are described briefly. New limits are shown for the reach of the x_s-measurement, resulting from increased statistics and improved fitting methods. Som

Maria Emília X. Guimarães

We consider a local cosmic string described by the Abelian-Higgs model in the framework of scalar-tensor gravities. We find the metric of the cosmic string in the weak-field approximation. The propagation of particles and light is analysed in this background. This analysis shows that the (unperturbed) cosmic string in scalar-tensor theories presents some ana

Yasunori Fujii

We show that regularizing divergent integrals is crucially important when applied to the loop diagrams corresponding to quantum corrections to the coupling of the ``gravitational" scalar field due to the interaction among matter fields. We use the method of continuous spacetime dimensions to demonstrate that WEP is a robust property of the Brans-Dicke th

K. Maiti, N. Y. Vasanthacharya, D. D. Sarma

We report the temperature dependence of transport and magnetic properties of La$_{1-x}$Ca$_x$VO$_3$ for x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5. The system exhibits an insulator-to-metal transition concomitant with an antiferromagnetic-to-paramagnetic transition near x = 0.2 with increasing substitution. Disorder effects are found to influence the low temperatur

Edwin Langmann, Mats Wallin

We present a restricted path integral approach to the 2D and 3D repulsive Hubbard model. In this approach the partition function is approximated by restricting the summation over all states to a (small) subclass which is chosen such as to well represent the important states. This procedure generalizes mean field theory and can be systematically improved by i

Silvio Franz, Luca Peliti

We consider the quasispecies description of a population evolving in both the "master sequence" landscape (where a single sequence is evolutionarily preferred over all others) and the REM landscape (where the fitness of different sequences is an independent, identically distributed, random variable). We show that, in both cases, the error threshold i

G. Zaránd

We construct a generalized multiplicative renormalization group transformation to study the low energy dynamics of a heavy particle tunneling among $M$ different positions and interacting with $N_f$ independent conduction electron channels. Using a $1/N_f$-expansion we show that this M-level scales towards a fixed point equivalent to the $N_f$ channel $SU(M)

Nianzheng Cao, Shiyi Chen, Katepalli R. Sreenivasan

High-resolution direct numerical simulation data for three-dimensional Navier-Stokes turbulence in a periodic box are used to study the scaling behavior of low-order velocity structure functions with positive and negative powers. Similar to high-order statistics, the low-order relative scaling exponents exhibit unambiguous departures from the Kolmogorov 1941

Keith A. Olive, D. N. Schramm, Sean Scully, J. W. Truran

The prediction of standard chemical evolution models of higher abundances of He3 at the solar and present-day epochs than are observed indicates a possible problem with the yield of He3 for stars in the range of 1-3 solar masses. Because He3 is one of the nuclei produced in Big Bang Nucleosynthesis (BBN), it is noted that galactic and stellar evolution uncer

Luca Amendola, Carlo Baccigalupi, Rostislav Konoplich, Franco Occhionero

We calculate analytically the bubble nucleation rate in a model of first order inflation which is able to produce large scale structure. The computation includes the first-order departure from the thin-wall limit, the explicit derivation of the pre-exponential factor, and the gravitational correction. The resulting bubble spectrum is then compared with const

Ofer Lahav, Tsvi Piran, Marie A. Treyer

The X-Ray Background (XRB) probes structure on scales intermediate between those explored by local galaxy redshift surveys and by the COBE Microwave Background measurements. We predict the large scale angular fluctuations in the XRB, expressed in terms of spherical harmonics for a range of assumed power-spectra and evolution scenarios. The dipole is due to l

Jeremy Heyl, Matthew Colless, Richard S. Ellis, Tom Broadhurst

We determine the evolution of the galaxy luminosity function (LF) as a function of spectral type using the Autofib redshift survey, a compendium of over 1700 galaxy redshifts in various magnitude-limited samples spanning b_J=11.5-24.0. To carry out this analysis we have developed a cross-correlation technique which classifies faint galaxy spectra into one of

S. Savaglio, V. Carbone

We present some statistical features of the large number of \lya absorption lines detected in high redshift quasar spectra, obtained by using the multifractal approach. In the analysed sample of 12 QSO sight--lines, 11 show scaling behaviour with a crossover between two distinct regimes: a non-homogeneous regime at small scales and a homogeneous regime at la

Daniel Koranyi, Michael A. Strauss

We test and reject the claim of Segal et al. (1993) that the correlation of redshifts and flux densities in a complete sample of IRAS galaxies favors a quadratic redshift-distance relation over the linear Hubble law. This is done, in effect, by treating the entire galaxy luminosity function as derived from the 60 micron 1.2 Jy IRAS redshift survey of Fisher

Michael A. Strauss

I review progress in the past few years in studying the large-scale structure of the universe through redshift surveys of galaxies. Of the many statistical methods used to describe the galaxy distribution, I concentrate here on the power spectrum, and go into some detail about the factors which complicate (and make interesting!) its interpretation, such as r

Michael A. Strauss

I summarize both observational and theoretical developments in the last few years in measuring and understanding the large-scale velocity field of galaxies, with special attention to the bulk flow, or average peculiar velocity, within spheres centered on the Local Group.

F. De Paolis, G. Ingrosso, Ph. Jetzer, M. Roncadelli

Reasons supporting the idea that most of the dark matter in galaxies and clusters of galaxies is baryonic is discussed. Moreover it is argued that most of the dark matter in galactic halo should be in the form of MACHOs and cold molecular clouds.

Bob van den Hoek, Martin Groenewegen

We present theoretical yields of H, $^{4}$He, $^{12}$C, $^{13}$C, $^{14}$N, and $^{16}$O for stars with initial masses between 0.8 and 8 M$_{\odot}$ and initial metallicities Z = 0.001, 0.004, 0.008, 0.02, and 0.04. We use the evolutionary tracks of the Geneva group up to the early asymptotic giant branch (AGB) in combination with a synthetic thermal-pulsing

Alessandro Melchiorri, Nicola Vittorio

We present a brief review of the polarization properties of the cosmic microwave background in dark matter models for structure formation. Quite independently of the model parameters, the polarization level is expected to be $\sim 10%$ of the anisotropy signal at angular scales $\le 1^o$. Detections of polarization at larger angular scales would provide a st

Martin Sombra

We present a new effective Nullstellensatz with bounds for the degrees which depend not only on the number of variables and on the degrees of the input polynomials but also on an additional parameter called the {\it geometric degree of the system of equations}. The obtained bound is polynomial in these parameters. It is essentially optimal in the general cas

Alexander V Sardo-Infirri

Let $Γ$ be a finite group acting linearly on $\C^n$, freely outside the origin. In previous work a generalisation of Kronheimer's construction of moduli of Hermitian-Yang-Mills bundles with certain invariance properties was given. This produced varieties $X_ζ$ (parameterised by $ζ\in\Q^N$) which are partial resolutions of $\C^n/Γ$. In this article, it is

Alexander V Sardo Infirri

Let $Γ$ be a finite group acting linearly on $\C^n$, freely outside the origin, and let $N$ be the number of conjugacy classes of $Γ$ minus one. A construction of Kronheimer of moduli spaces $X_ζ$ of translation-invariant $Γ$-equivariant instantons on $\C^2$ is generalised to $\C^n$. The moduli spaces $X_ζ$ depend on a parameter $ζ\in\Q^N$. The following res

Stefano Forte

We review the present status of polarized structure functions measured in deep-inelastic scattering. We discuss the x and Q^2 dependence of the structure function g_1, and how it can be used to test perturbative QCD at next-to-leading order and beyond. We summarize the current knowledge of polarized parton distributions, in particular the determination of th

Thomas Branson, R. P. Lano, V. G. J. Rodgers

In this work we use constructs from the dual space of the semi-direct product of the Virasoro algebra and the affine Lie algebra of a circle to write a theory of gravitation which is a natural analogue of Yang-Mills theory. The theory provides a relation between quadratic differentials in 1+1 dimensions and rank two symmetric tensors in higher dimensions as

Ken Umeno

We present a new systematic method of constructing rational mappings as ergordic transformations with nonuniform invariant measures on the unit interval [0,1]. As a result, we obtain a two-parameter family of rational mappings that have a special property in that their invariant measures can be explicitly written in terms of algebraic functions of parameters

Shmuel Nussinov

We propose a search strategy for the light R0 (glueballino) particle suggested by G.Farrar in connection with the light gluino scenario. The basic idea is to moderate and stop the R0 particles and then observe their decay to almost monochromatic pions - at an appropriate time delay relative to a primary collision event, where a gluino jet, likely to fragment

The MACHO Collaboration, D. L. Welch, C. Alcock, R. A. Allsman

The approximately 1500 Cepheid variables in 22 LMC fields of the MACHO Project survey have been calibrated and analysed. In this paper, we report improved period ratios for a total of 73 beat Cepheids and provide a first look at the Fourier decomposition parameters for both singly- and doubly-periodic Cepheids. We also note an unusual amplitude-changing puls

J. Lopez, D. Nanopoulos, A. Zichichi

We examine the possibility that some anomalous acoplanar diphoton events observed at LEP may be consistent with the predictions of our previously proposed one-parameter no-scale supergravity model with a light gravitino, via the process e^+e^- -> chi chi -> gamma gamma+E_miss. We find that one such event may indeed be consistent with the model predictions fo

M. N. Chernodub, M. I. Polikarpov, A. I. Veselov

We describe numerical calculation results for the probability distribution of the value of the monopole creation operator in the SU(2) lattice gluodynamics. We work in the maximal abelian projection. It occurs that at low temperatures, below the deconfinement phase transition, the maximum of the distribution is shifted from zero, which means that the effecti

J. G. Russo

The supermembrane theory on $R^{10}x S^1$ is investigated, for membranes that wrap once around the compact dimension. The Hamiltonian can be organized as describing $N_s$ interacting strings, the exact supermembrane corresponding to $N_s\to \infty$. The zero-mode part of $N_s-1$ strings turn out to be precisely the modes which are responsible of instabilitie

Daniel Cangemi

I review some recent work that describes the close analogy between self-dual Yang--Mills amplitudes and QCD amplitudes with external gluons of positive helicity. This analogy is carried at tree level for amplitudes with two external quarks and up to one-loop for amplitudes involving only external gluons.

Giampiero Esposito

Maxwell theory can be studied in a gauge which is invariant under conformal rescalings of the metric, and first proposed by Eastwood and Singer. This paper studies the corresponding quantization in flat Euclidean 4-space. The resulting ghost operator is a fourth-order elliptic operator, while the operator P on perturbations of the potential is a sixth-order

F. Bonechi, R. Giachetti, E. Sorace, M. Tarlini

We study the representations of the quantum Galilei group by a suitable generalization of the Kirillov method on spaces of non commutative functions. On these spaces we determine a quasi-invariant measure with respect to the action of the quantum group by which we discuss unitary and irreducible representations. The latter are equivalent to representations o

Marc-Thierry Jaekel, Serge Reynaud

A field state containing photons propagating in different directions has a non vanishing mass which is a quantum observable. We interpret the shift of this mass under transformations to accelerated frames as defining space-time observables canonically conjugated to energy-momentum observables. Shifts of quantum observables differ from the predictions of clas

The New Muon Collaboration

The muon-proton and muon-deuteron inclusive deep inelastic scattering cross sections were measured in the kinematic range 0.002 < x < 0.60 and 0.5 < Q2 < 75 GeV2 at incident muon energies of 90, 120, 200 and 280 GeV. These results are based on the full data set collected by the New Muon Collaboration, including the data taken with a small angle trigger. The

V. Antonelli, S. Bertolini, M. Fabbrichesi, E. I. Lashin

We compute the $\widehat B_K$ parameter and the mass difference $ΔM_{LS}$ of the $K^0-\bar K^0$ system by means of the chiral quark model. The chiral coefficients of the relevant $ΔS=2$ and $ΔS=1$ chiral lagrangians are computed via quark-loop integration. We include the relevant effects of one-loop corrections in chiral perturbation theory. The final result

T. Gaffney, S. Kleiman

We establish the principle of specialization of integral dependence for submodules of finite colength of free modules, as part of the general algebraic-geometric theory of the Buchsbaum--Rim multiplicity. Then we apply the principle to the study of equisingularity of ICIS germs, obtaining results for such equisingularity conditions as Whitney&#39;s Condition

Yves Laszlo

We first study the descent theory of line bundles under a morphism which is tors or under a group stack and then use this technical result to determine the exact structure of $\Pic(\M_G)$ where $G=\SL_r/μ_s$ (we include a minor modification to explain the genus 0 case).

R. Foot, R. R. Volkas

Ordinary-sterile neutrino oscillations can generate a significant lepton number asymmetry in the early Universe. We study this phenomenon in detail. We show that the dynamics of ordinary-sterile neutrino oscillations in the early Universe can be approximately described by a single integro-differential equation which we derive from both the density matrix and

J. F. Markham, T. D. Kieu

A method is proposed to handle the sign problem in the simulation of systems having indefinite or complex-valued measures. In general, this new approach, which is based on renormalisation blocking, is shown to yield statistical errors smaller than the crude Monte Carlo method using absolute values of the original measures. The improved method is applied to t

Nicolas J. Cerf, Chris Adami

We present a quantum information theory that allows for the consistent description of quantum entanglement. It parallels classical (Shannon) information theory but is based entirely on density matrices, rather than probability distributions, for the description of quantum ensembles. We find that, unlike in Shannon theory, conditional entropies can be negativ

B. Pasquini

The cross section for the $A(e,e&#39;γ)A$ reaction is calculated, investigating the contribution from the nuclear target with respect to the radiative corrections from the electron. The reaction mechanism is studied for photon emission in the $Δ$-resonance region, varying the scattering geometry and analyzing the most favourable kinematical conditions to ext

D. R. Phillips, M. C. Birse, S. J. Wallace

We consider a composite spin-half particle moving in spatially-varying scalar and vector fields. The vector field is assumed to couple to a conserved charge, but no assumption is made about either the structure of the composite or its coupling to the scalar field. A general form for the piece of the spin-orbit interaction of the composite with the scalar and

K. Langanke, D. J. Dean, S. E. Koonin, P. B. Radha

We perform Shell Model Monte Carlo calculations to study pair correlations in the ground states of $N=Z$ nuclei with masses A=48-60. We find that $T=1$, $J^π=0^+$ proton-neutron correlations play an important, and even dominant role, in the ground states of odd-odd $N=Z$ nuclei, in agreement with experiment. By studying pairing in the ground states of $^{52-

R. Schicker, H. Tsertos

The HADES first level trigger is studied for the system p+Ni at a beam energy of 2 AGeV. The timing properties of the trigger signal are reported. The efficiency loss due to deadtime is specified. A trigger requirement of a time overlap window with the start detector is described. The trigger rates for different overlap windows are given.

R. Schicker, H. Tsertos

The first level trigger of the HADES spectrometer is studied for the heavy-ion collision systems Au+Au and Ne+Ne. The trigger efficiency for central events is given in dependence of the imposed charged particle multiplicity condition. The timing properties of the trigger signal are described. The losses due to deadtime are specified. Finally, the first level

The Orange Collaboration, U. Leinberger, E. Berdermann, F. Heine

We present new results obtained from a series of follow-up e+e- coincidence measurements in heavy-ion collisions, utilizing an improved experimental set-up at the double-Orange beta-spectrometer of GSI. The collision system U+Ta was reinvestigated in three independent runs at beam energies in the range (6.0-6.4)xA MeV and different target thicknesses, with t

Jonathan A. Bagger

In this talk we use nonlinear realizations to study the spontaneous partial breaking of rigid and local supersymmetry.

Koji Harada, Atsushi Okazaki

A new two-step renormalization procedure is proposed. In the first step, the effects of high-energy states are considered in the conventional (Feynman) perturbation theory. In the second step, the coupling to many-body states is eliminated by a similarity transformation. The resultant effective Hamiltonian contains only interactions which do not change parti

Andrea Cappelli, Carlo A. Trugenberger, Guillermo R. Zemba

We briefly review these low-energy effective theories for the quantum Hall effect, with emphasis and language familiar to field theorists. Two models have been proposed for describing the most stable Hall plateaus (the Jain series): the multi-component Abelian theories and the minimal W-infinity models. They both lead to a-priori classifications of quantum H

Kazuyuki Furuuchi, Hiroshi Kunitomo, Toshio Nakatsu

We construct the six-dimensional topological field theory appropriate to describe the ground-state configurations of D5-branes. A close examination on the degenerations of D5-branes gives us the physical observables which can be regarded as the Poincaré duals of the cycles of the moduli space. These observables are identified with the creation opeartors of t

Yu-Qi Chen

The production of the B_c and B_c^* mesons was studied in the framework of the factorization formalism and perturbative QCD. Predicted results implied that an observable number of B_c and B_c^* events can be produced at LEP I and at Tevatron. The fragmentation approximation describes the production of the B_c and B_c^* mesons very well in high energy e^+e^-

J. F. Gunion, C. Loomis, K. T. Pitts

Doubly-charged Higgs bosons ($Δ^{--}/Δ^{++}$) appear in several extensions to the Standard Model and can be relatively light. We review the theoretical motivation for these states and present a study of the discovery reach in future runs of the Fermilab Tevatron for pair-produced doubly-charged Higgs bosons decaying to like-sign lepton pairs. We also comment

M. L. Mangano

We review two subjects in the theoretical study of jet production at the Tevatron collider: the uncertainties in the determination of the partonic densities inside the proton and the uncertainties in the calculation of higher-order corrections to the QCD matrix elements.

M. Carena, G. F. Giudice, C. E. M. Wagner

We study the impact of present and future $(g-2)_μ$ measurements on supersymmetric models. The corrections to $(g-2)_μ$ become particularly relevant in the presence of light sleptons, charginos and neutralinos, especially in the large $\tanβ$ regime. For moderate or large values of $\tanβ$, it is possible to rule out scenarios in which charginos and sneutrin

H. Dreiner, H. -U. Martyn, S. Ritz, D. Wyler

We summarize the work done in the ``Beyond the Standard Model&#39;&#39; group of the 1995-96 HERA Workshop. Of the various proposed HERA upgrades, the luminosity improvement is the most important for this physics. With an integrated luminosity of 1 $fb^{-1}$, collected by 2005, HERA will remain a competitive and potentially fruitful facility for new physics

A. B. Arbuzov, V. A. Astakhov, E. A. Kuraev, N. P. Merenkov

A closed expression for the differential cross section of the large-angle Bhabha $e^+ e^-$ scattering which explicitly takes into account the leading and next-to-leading contributions due to the emission of two hard photons is presented. Both collinear and semi-collinear kinematical regions are considered. The results are illustrated by numerical calculation

Tao Huang, Zuo-Hong Li, Chuan-Wang Luo

The double ratio $(f_{B_s}/f_{B_d})/(f_{D_s}/f_{D_d})$ is calculated by QCD sum rules in heavy quark effective theory (HQET), both numerically and analytically. Our expression for the double ratio shows explicitly the dependence on the light quark masses, the heavy quark symmetry breaking and the vacuum condensates. The numerical result favors the double rat

Thibault Damour, Alexander Vilenkin

The existence of a dilaton (or moduli) with gravitational-strength coupling to matter imposes stringent constraints on the allowed energy scale of cosmic strings, $η$. In particular, superheavy gauge strings with $η\sim 10^{16} GeV$ are ruled out unless the dilaton mass $m_ϕ \gsim 100 TeV$, while the currently popular value $m_ϕ \sim 1 TeV$ imposes the bound

A. Carey, M. Farber, V. Mathai

In this paper, we suggest a construction of determinant lines of finitely generated Hilbertian modules over finite von Neumann algebras. Nonzero elements of the determinant lines can be viewed as volume forms on the Hilbertian modules. Using this, we study both $L^2$ combinatorial and $L^2$ analytic torsion invariants associated to flat Hilbertian bundles ov

V. I. Kozub, A. M. Rudin

We study effect of the adiabatic electron renormalization on the parameters of the dynamical defects in the ballistic metallic point contact. The upper energy states of the ``dressed&#39;&#39; defect are shown to give a smaller contribution to a resistance of the contact than the lower energy ones. This holds both for the &#34;classical&#34; renormalization

M. Buttiker, T. Christen

We present a discussion of the admittance (ac-conductance) and nonlinear I-V-characteristic for a number of mesoscopic conductors. Our approach is based on a generalization of the scattering approach which now includes the effects of the (long-range) Coulomb interaction. We discuss the admittance of a wire with an impurity and with a nearby gate. We extend a

O. Gulseren, R. James, D. W. Bullett

A first-principles atomic orbital-based electronic structure method is used to investigate the low index surfaces of rutile Titanium Dioxide. The method is relatively cheap in computational terms, making it attractive for the study of oxide surfaces, many of which undergo large reconstructions, and may be governed by the presence of Oxygen vacancy defects. C

Ken Umeno

How chaos is useful in the brain information processing is greatly unknown. Here, we show that the statistical property of chaos such as invariant measures naturally organized under a great number of iterations of chaotic mappings can be used for some complex computations, while the precise information of initial conditions which vanishes in the course of it

M. J. Sawicki, H. Lin, H. K. C. Yee

Photometric redshifts for galaxies in the Hubble Deep Field are measured. Luminosity functions show steepening of the faint-end slope and mild brightening of M* out to z~3, followed by a decline at higher z; an excess of faint, star-forming galaxies is seen at low z. Our results are consistent with the formation of large galaxies at z=2-3, followed by that o

M. Bottorff, K. T. Korista, I. Shlosman, R. D. Blandford

We analyze the results of long-term observations of broad-line region (BLR) in the Sy1 galaxy NGC 5548 and provide a critical comparison with the predictions of a hydromagnetically-driven outflow model of Emmering, Blandford and Shlosman. This model was used to generate a time series of CIV line profiles that have responded to a time varying continuum. The m

The MACHO Collaboration, D. Minniti, C. Alcock, D. R. Alves

The MACHO Project has catalogued $\sim 8000$ RR Lyrae stars in the Large Magellanic Cloud, $\sim 1800$ in the Galactic bulge, and $\sim$ 50 in the Sgr dwarf galaxy. These variables are excellent distance indicators, and are used as tools to study the structure of the Large Magellanic Cloud and the bulge. The large datasets also probe uncommon pulsation modes

Robert J. Cumming, Peter Lundqvist

All types of supernovae (SNe), except Type Ia, have been observed to interact with their immediate circumstellar medium (CSM). This interaction can reveal their progenitor&#39;s histories, and constrain our ideas about the evolution of massive stars. As examples of the latest progress in this areas, we present some new results on two SNe: a 3D picture of the

Peter Lundqvist, Robert J. Cumming

Searching for the presence of a circumstellar medium is a direct observational way to discriminate between different types of progenitor systems for Type Ia supernovae. We have modeled whether such gas may give rise to detectable emission, especially in H-alpha, and compare the models with observations of SN 1994D. We obtain a mass loss rate less than about

G. Sonneborn, C. Fransson, P. Lundqvist, A. Cassatella

The presence of narrow high-temperature emission lines from nitrogen-rich gas close to SN 1987A has been the principal observational constraint on the evolu- tionary status of the supernova&#39;s progenitor. A new analysis of the complete five-year set of low and high resolution IUE ultraviolet spectra of SN 1987A (1987.2--1992.3) provide fluxes for the N V

R. J. Cumming, P. Lundqvist, L. J. Smith, M. Pettini

Searching for the presence of circumstellar material is currently the only direct way to discriminate between the different types of possible progenitor systems for Type Ia supernovae. We have therefore looked for narrow H-alpha in a high-resolution spectrum of the normal Type Ia supernova 1994D taken 10 days before maximum and only 6.5 days after explosion.

Markus Kissler-Patig

Growing evidence for the existence of two classes of ellipticals calls for a comparison of the properties of their globular cluster systems. I compiled information on the properties of over 50 globular cluster systems of faint and bright early-type galaxies, and investigated them in the light of the properties of the parent galaxies. The properties of globul

George Chapline

Attention is drawn to the possibility that self-organizing biological neural networks could spontaneously acquire the capability to carry out sophisticated computations. In particular it is shown that the effective action governing the formation of synaptic connections in models of networks of feature detectors that encorporate Kohonen-like self-organization

Marek Grabowski, R. E. Camley

We study the spatial pattern formation and emerging long range correlations in a model of three species coevolving in space and time according to stochastic contact rules. Analytical results for the pair correlation functions, based on a truncation approximation and supported by computer simulations, reveal emergent strategies of survival for minority agents

Ramesh Narayan, Didier Barret, Jeffrey E. McClintock

We have analyzed archival ASCA data on the soft X-ray transient source V404 Cyg in quiescence. We find that in the energy range 0.7 to 8.5 keV the spectrum is a hard power-law with a photon spectral index between 1.8 and 2.6 (90% confidence limits). We present a model of V404 Cyg in which the accretion flow has two components: (1) an outer thin disk with a s

S. Majid

We obtain new family of quasitriangular Hopf algebras $C^{0|n}_q\lcross \widetilde{U_q(su_n)}\rcross C^{0|n}_q$ via the author&#39;s recent double-bosonisation construction for new quantum groups. They are versions of $U_q(su_{n+1})$ with a fermionic rather than bosonic quantum plane of roots adjoined to $U_q(su_n)$. We give the $n=2$ case in detail. We also

S. Majid

We demonstrate our recent general results on the Casimir construction and moduli space of all bicovariant calculi by means of some detailed examples, including finite-difference and 2-jet cacluli on $\R^n$ and full details of the Casimir construction of the 4D calculus of $SU_q(2)$. We likewise demonstrate our previous general constructions with T. Brzezinsk

Howard Baer, Michal Brhlik

Recent advances in the QCD corrections to $b\to sγ$ decay in the MSSM include i.) evaluation of the relevant operators, Wilson coefficients and anomalous dimension matrix elements for the various MSSM effective theories valid at scales beyond $Q =M_W$, ii.) calculations of most of the needed anomalous dimension matrix elements to next-to-leading order for sc

Jonathan L. Rosner

The influence of the top quark mass on mixing processes and precise electroweak measurements is described. Experimental observation of the top quark in proton-antiproton collisions is discussed, and some brief remarks are made about electron-positron production. Some speculations are noted about the possible significance of the large top quark mass.

Rangan Lahiri, Sriram Ramaswamy

We study the dynamics of small fluctuations about the uniform state of a crystal moving through a dissipative medium, e.g. a sedimenting colloidal crystal or a moving flux lattice, using a set of continuum equations for the displacement fields, and a one-dimensional driven lattice-gas model for the coupled concentration and tilt fields. For the colloidal cry

Tim R. Morris

Approximation only by derivative (or more generally momentum) expansions, combined with reparametrization invariance, turns the continuous renormalization group for quantum field theory into a set of partial differential equations which at fixed points become non-linear eigenvalue equations for the anomalous scaling dimension $η$. We review how these equatio

Lara De Nardo, Dmitri V. Fursaev, Gennaro Miele

The spherical domains $S^d_β$ with conical singularities are a convenient arena for studying the properties of tensor Laplacians on arbitrary manifolds with such a kind of singular points. In this paper the vector Laplacian on $S^d_β$ is considered and its spectrum is calculated exactly for any dimension $d$. This enables one to find the Schwinger-DeWitt coe

Joseph D. Lykken

A broad class of supersymmetric extensions of the standard model predict a Z&#39; vector boson whose mass is naturally in the range 250 GeV < M_Z&#39; < 2 TeV. To avoid unacceptably large mixing with the Z, one requires either a discrete tuning of the U(1)&#39; charges or a leptophobic Z&#39;. Both cases are likely to arise as the low energy limits of hetero

Hyok-Jon Kwon

We study the Kohn-Luttinger effect in a two-dimensional (2D) nested Fermion liquid with a repulsive interaction via the renormalization group method and identify the resulting order parameter symmetry. Using the band structure of the 2D Hubbard model close to half-filling as a prototype, we construct an effective low-energy theory. We use multidimensional bo