July 1995 arXiv papers — page 3

T. D. Palev, N. I. Stoilova

The unitarizable irreps of the deformed para-Bose superalgebra $pB_q$, which is isomorphic to $U_q[osp(1/2)]$, are classified at $q$ being root of 1. New finite-dimensional irreps of $U_q[osp(1/2)]$ are found. Explicit expressions for the matrix elements are written down.

A. Bianconi, S. Jeschonnek, N. N. Nikolaev, J. Speth

Are effects of short range correlations in the ground state of the target nucleus (initial state correlations ISC) observable in experiments on quasielastic $A(e,e'p)$ scattering at large missing momentum $p_{m}$? Will the missing momentum spectrum observed at CEBAF be overwhelmed by final state interactions (FSI) of the struck proton? The recent advance

Daniel Cabra, Eduardo Fradkin, Gerardo L. Rossini, Fidel A. Schaposnik

We discuss the behavior of theories of fermions coupled to Chern-Simons gauge fields with a non-abelian gauge group in three dimensions and at finite temperature. Using non-perturbative arguments and gauge invariance, and in contradiction with perturbative results, we show that the coefficient of the Chern-Simons term of the effective actions for the gauge f

M. Alvarez, F. M. de Carvalho Filho, L. Griguolo

The propagation of a localized wave packet in the conical space-time created by a pointlike massive source in 2+1 dimensional gravity is analyzed. The scattering amplitude is determined and shown to be finite along the classical scattering directions due to interference between the scattered and the transmitted wave functions. The analogy with diffraction th

Bertfried Fauser

We investigate with the help of Clifford algebraic methods the Mandelbrot set over arbitrary two-component number systems. The complex numbers are regarded as operator spinors in D\times spin(2) resp. spin(2). The thereby induced (pseudo) normforms and traces are not the usual ones. A multi quadratic set is obtained in the hyperbolic case contrary to [1]. In

Elso Drigo Filho, Regina Maria Ricotta

The formalism of Supersymmetric Quantum Mechanics provides us the eigenfunctions to be used in the variational mathod to obtain the eigenvalues for the Hulthén Potential.

John W. Lawson, G. S. Guralnik

A new deterministic, numerical method to solve fermion field theories is presented. This approach is based on finding solutions $Z[J]$ to the lattice functional equations for field theories in the presence of an external source $J$. Using Grassmann polynomial expansions for the generating functional $Z$, we calculate propagators for systems of interacting fe

John W. Lawson, G. S. Guralnik

In this paper, we extend previous work on scalar $ϕ^4$ theory using the Source Galerkin method. This approach is based on finding solutions $Z[J]$ to the lattice functional equations for field theories in the presence of an external source $J$. Using polynomial expansions for the generating functional $Z$, we calculate propagators and mass-gaps for a number

Tomasz Brzezinski, Jacob Katriel

Explicit expressions for the Temperley-Lieb-Martin algebras, i.e., the quotients of the Hecke algebra that admit only representations corresponding to Young diagrams with a given maximum number of columns (or rows), are obtained, making explicit use of the Hecke algebra representation theory. Similar techniques are used to construct the algebras whose repres

Thomas G. Rizzo

The rates and corresponding jet distributions for the decay $Z\to b\bar bg$ and the process $e^+e^-\to t\bar tg$ may be sensitive to anomalous dipole-like couplings of heavy quarks to the photon and $Z$. In the $b$-quark case, after updating our previous analysis on the constraints imposed by current experiments on $Zb\bar b$ anomalous couplings, we show tha

D. Boyanovsky, M. D'attanasio, H. J. de Vega, R. Holman

We consider the case of a scalar field, the inflaton, coupled to both lighter scalars and fermions, and the study the relaxation of the inflaton via particle production in both the linear and non-linear regimes. This has an immediate application to the reheating problem in inflationary universe models. The linear regime analysis offers a rationale for the st

Jon J. Thaler

I report on developments in the experimental and phenomenological understanding of the rare decays of mesons containing b and c quarks, especially as they pertain to the understanding of the CKM matrix and the testing of the standard model. Some related measurements are also discussed.

Kingman Cheung

With the recent discovery of a heavy top quark $(m_t \approx 175 - 200$ GeV), the top quark opens an window to electroweak symmetry breaking. We propose the study of four-top, $t\bar t t\bar t$, production at hadronic supercolliders as a probe to electroweak symmetry breaking.

Tao Han, Ron Sobey

We calculate the three gauge-boson production in the Standard Model at Fermilab Tevatron energies. At $\sqrt s=2$ TeV in $p\bar p$ collisions, the cross sections for the triple gauge-boson production are typically of order 10 femtobarns (fb). For the pure leptonic final states from the gauge-boson decays and with some minimal cuts on final state photons, the

P. M. Stevenson

Recent lattice data for the effective potential of lambda Phi^4 theory fits the massless one-loop formula with amazing precision. Any corrections are at least 100 times smaller than is reasonable, perturbatively. This is strong evidence for the "exactness conjecture" of Consoli and Stevenson.

Frank E. Close, Philip R. Page

We suggest that $ψ$ (4040) and $ψ$ (4160) are strong mixtures of ground state hybrid charmonium at $\sim 4.1$ GeV and the $ψ(3S)$ of conventional charmonium. The $Γ^{e^+e^-}$, masses and total widths of the $ψ(4040)$ and $ψ(4160)$ are in accord with this hypothesis. Their hadronic decays are predicted to be dominated by the $ψ(3S)$ component and hence are co

W. Hollik

The status of the electroweak Standard Model is reviewed in the light of recent precision data and new theoretical results which have contributed to improve the predictions for precision observables, together with the remaining inherent theoretical uncertainties. Consequences for possible new physics are also discussed.

J. Milana, S. Nussinov

The $D_s \rightarrow n π$ measured branching could lead to information on $u, d$ quark masses if it is dominated by the (helicity suppressed) $D_s \rightarrow u \bar d$ annihilation channel. The data would then suggest anomalously high $m_u \approx m_d \approx 30$MeV masses. We find however that $D_s \rightarrow u {\bar d} g$ can explain $\sum Br(D_s \righta

Vadim Zeitlin

A low-temperature expansion of QED one-loop effective Lagrangian valid for a wide range of parameters is presented in a form of finite sums of elementary functions. Starting from the effective action components of the one-loop polarization operator responsible for Hall conductivity and Debye screening are obtained. It is shown that in a strong background mag

Wei Lu, Bo-Qiang Ma

Considering the possible interpretation of the Ellis-Jaffe sum rule violation that the strange quark in the polarized proton is remarkably polarized in the opposite direction of the proton spin, we investigate its implication in the semi-inclusive $Λ$ production in deep inelastic process with the electron beam unpolarized and proton target polarized longitud

J. H. Field, T. Riemann

A new Monte Carlo event generator for wide angle Bhabha scattering and muon pair production in $e^+e^-$ collisions is described. The program includes complete one-loop electroweak corrections, and QED radiative corrections. The O($α$) QED correction uses the exact matrix element. Higher order QED corrections are included in an improved soft photon approximat

Th. Lippert, A. Seyfried, A. Bode, K. Schilling

A new class of parallel algorithms is introduced that can achieve a complexity of O(n^3/2) with respect to the interprocessor communication, in the exact computation of systems with pairwise mutual interactions of all elements. Hitherto, conventional methods exhibit a communicational complexity of O(n^2). The amount of computation operations is not altered f

DO Collaboration, S. Abachi et al

We present a preliminary result from a search for anomalous $WW$ and $WZ$ production in $p\bar{p}$ collisions at $\sqrt{s}=1.8$ TeV using $p\bar{p}\rightarrow eνjj$ events observed during the 1992--1993 run of the Fermilab Tevatron collider. A fit to the $p_T$ spectrum of $W(eν)$ yields direct limits on the CP--conserving anomalous $WWγ$ and $WWZ$ coupling p

Pimentel L O

Exact solutions of N=2 supergravity in five dimensions are found in the metric with cylindrical symmetry, a particular case corresponds to the exterior of a cosmic string.

Pimentel L O

The electromagnetic field is studied in a family of exact solutions of the Einstein equations whose material content is a perfect fluid with stiff equation of state (p = $ε$ ). The field equations are solved exactly for several members of the family.

Amos Ori

We propose a simple approach for the radiative evolution of generic orbits around a Kerr black hole. For a scalar-field, we recover the standard results for the evolution of the energy $E$ and the azimuthal angular momentum $L_z$ . In addition, our method provides a closed expression for the evolution of the Carter constant $Q$.

Alfio Bonanno

The structure of the Cauchy horizon of a charged rotating black hole is analyzed under the combined effect of an ingoing and outgoing flux of gravitational waves. In particular, by means of an axisymmetric realization of the Ori model, the growth of the mass parameter near the Cauchy horizon is studied in the slow rotation approximation. It is shown that the

K. Tsemekhman, V. Tsemekhman, C. Wexler, D. J. Thouless

Based on very general arguments we show that for any geometry of the experiment, in the regime when the measurement leads to a quantized Hall conductivity, almost the entire current injected into the sample is carried by the bulk states. The crucial role of the contacts equilibrating different edge channels is emphasized.

M. Kardar, A. Zee

We introduce matrix generalizations of the Navier--Stokes (NS) equation for fluid flow, and the Kardar--Parisi--Zhang (KPZ) equation for interface growth. The underlying field, velocity for the NS equation, or the height in the case of KPZ, is promoted to a matrix that transforms as the adjoint representation of $SU(N)$. Perturbative expansions simplify in t

Anton Bovier, Véronique Gayrard

Standard large deviation estimates or the use of the Hubbard-Stratonovich transformation reduce the analysis of the distribution of the overlap parameters essentially to that of an explicitly known random function $Φ_{N,\b}$ on $\R^M$. In this article we present a rather careful study of the structure of the minima of this random function related to the retr

C. Castellani, C. Di Castro, M. Grilli

We analyze the behavior of the dynamic scattering amplitude between Fermi liquid quasiparticles at the Fermi surface in the proximity of a charge instability, which may occur in the high temperature superconducting cuprates. Within the infinite-U Hubbard-Holstein model in the slave-boson large-N technique we find that, in the absence of long-range Coulomb fo

Michele Fabrizio, Marco Airoldi, Erio Tosatti

We study electron propagation in a molecular lattice model. Each molecular site involves doubly degenerate electronic states coupled to doubly degenerate molecular vibration, leading to a so--called E-e type of Jahn-Teller Hamiltonian. For weak electron-phonon coupling and in the anti-adiabatic limit we find that the orbital degeneracy induces an intersite p

Fausto Borgonovi, Dima Shepelyansky

We study the effect of coherent propagation of two interacting particles in an effective 2-3-d disordered potential. Our numerical data demonstrate that in dimension $d > 2$, interaction can lead to two--particles delocalization below one--particle delocalization border. We also find that the distance between the two delocalized particles (pair size) grows l

Ryusuke Ikeda

A hydrodynamical description for vortex states in type II superconductors is presented based on the time-dependent Ginzburg-Landau equation (TDGL). In contrast to the familiar extension of a single vortex dynamics based on the force balance, our description is consistent with the known hydrodynamics of a rotating neutral superfluid and correctly includes inf

Hyunwoo Lee, L. S. Levitov

We study noise spectra of currents through a tunnel junction in weak tunneling limit. We introduce effective capacitance to take into account the interaction effect and explicitly incorporate the electromagnetic environment of the junction into the formulation. We study the effect of charging energy and macroscopic environment on noise spectra. We calculate

Uwe Reyle

The paper addresses the problem of representing ambiguities in a way that allows for monotonic disambiguation and for direct deductive computation. The paper focuses on an extension of the formalism of underspecified DRSs to ambiguities introduced by plural NPs. It deals with the collective/distributive distinction, and also with generic and cumulative readi

Greg. F. Wellman, Ruth. A. Daly

The radio properties of powerful extended radio sources may be used to estimate the ambient gas density in the vicinity of radio lobes. A sample of 27 radio lobes from 14 radio galaxies and of 14 radio lobes from 8 radio loud quasars was constructed using sources from the published literature with sufficient radio information to allow an estimate of the ambi

Greg F. Wellman, Ruth A. Daly

Measurements of the width of the radio bridge at several locations along the bridge for each of four powerful extended radio sources are presented. Adopting a few simple assumptions, these measurements may be used to predict the radio surface brightness as a function of position across the radio bridge. The predicted and observed surface brightnesses across

Thomas Boutreux, Andrew Gould

Three ongoing microlensing experiments have found more candidate events than expected from the known stars. These experiments measure only one parameter of the massive compact halo objects (machos), the magnification time scale of the events. More information is required to understand the nature of the machos. A satellite experiment has been proposed to meas

G. Tenorio-Tagle, C. Munoz-Tunon, R. Cid Fernandes

The presence of giant shells or loops in giant HII regions are clear witness of the mechanical energy input from massive stars. Here we evaluate the impact that winds may have on the structure of giant nebulae and on their supersonic velocity dispersion. We follow the suggestion from Chu \& Kennicutt (1994) to see if a combination of a large number of unreso

P. G. van Dokkum, M. Franx

The dust properties of all early-type galaxies imaged with the Planetary Camera of the HST in cycles I-III are examined. Dust is detected in 31 out of 64 galaxies, although the sample is biased against the detection of dust. From the distribution of observed axis ratios of the dust features it is inferred that 78 \pm 16% of early-type galaxies contain nuclea

R. Scaramella

We study the gravitational influence of very large scale structures, as traced by clusters of galaxies, on the Local Group [LG] motion and the large scale flows. We derive from the distribution of Abell clusters within $300~$Mpc/h the overdensity field on a 3--D grid of spacing $5~$Mpc/h, then we solve the Poisson equation for the peculiar potential and fina

Mareki Honma, Yoshiaki Sofue, Nobuo Arimoto

We have examined the distribution of HI and H$_2$ gases in four face-on galaxies by using the observed dat a of CO and HI line emissions from the literatures. We demonstrate that the gas phase transition of HI and H$_2$ occurs suddenly within a narrow range of radi us, which we call the molecular front. We have tried to explain such phase transition in galac

Yoshiaki Sofue

We have compiled high-resolution position-velocity diagrams observed along the major axes of nearby spiral galaxies in the CO-line emission, and derived rotation curves for the inner regions of the galaxies. We have combined the inner rotation curves with the outer HI and optical rotation curves to obtain the total rotation curves. The inner rotation curves

Alexei Chekhlov, Victor Yakhot

High-resolution numerical experiments, described in this work, show that velocity fluctuations governed by the one-dimensional Burgers equation driven by a white-in-time random noise with the spectrum $\overline{|f(k)|^2}\propto k^{-1}$ exhibit a biscaling behavior: All moments of velocity differences $S_{n\le 3}(r)=\overline{|u(x+r)-u(x)|^n}\equiv\overline{

T. J. P. Penna, P. M. C. de Oliveira, J. C. Sartorelli, W. M. Gonçalves

We find that intervals between successive drops from a leaky faucet display scale-invariant, long-range anticorrelations characterized by the same exponents of heart beat-to-beat intervals of healthy subjects. This behavior is also confirmed by numerical simulations on lattice and it is faucet-width- and flow-rate-independent. The histogram for the drop inte

T. J. P. Penna, S. Moss de Oliveira, Dietrich Stauffer

The bit-string model of biological aging is used to simulate the catastrophic senescence of Pacific Salmon. We have shown that reproduction occuring only once and at a fixed age is the only ingredient needed to explain the catastrophic senescence according the mutation accumulation theory. Several results are presented, some of them with up to $10^8$ fishes,

E. J. Ferrer, V. de la Incera

The set of Casimir operators associated with the global symmetries of a charged string in a constant magnetic background are found. It is shown that the string rest energy can be expressed as a combination of these invariants. Using this result, the Regge trajectories of the system are derived. The first Regge trajectory is given by a family of infinitely ma

Kingman Cheung, Robert J. Oakes

The production rates and transverse momentum distributions of the strange-beauty mesons $B_s$ and $B_s^*$ at $p\bar p$ colliders are calculated assuming fragmentation is the dominant process. Results are given for the Tevatron in the large transverse momentum region, where fragmentation is expected to be most important.

F. Cardarelli, E. Pace, G. Salme', S. Simula

Nucleon and pion electromagnetic form factors are evaluated in the spacelike region within a light-front constituent quark model, where eigenfunctions of a mass operator, reproducing a large set of hadron energy levels, are adopted and quark form factors are considered in the one-body current. The hadron form factors are sharply affected by the high momentum

F. Boudjema, E. Chopin

We study double Higgs production in the $e^+ e^-$ and $\gamma \gamma$ modes of the linear collider. It is also shown how one can probe the scalar potential in these reactions. We discuss the effective longitudinal $W$ approximation in $\gamma \gamma$ processes and the $W_L W_L$ luminosities in the two modes of a high-energy linear collider. A generalised non

Lajos Diosi

Semiclassical (stochastic) wave equations are proposed for the coupled dynamics of atomic quantum states and semiclassical radiation field. All relevant predictions of standard unitary quantum dynamics are exactly reproducible in the framework of stochastic wave equation model. We stress in such a way that the concept of stochastic wave equations is not to b

W. Hildesheim, M. Seidel

The silicon detectors used in the H1-PLUG calorimeter have shown increasing aging effects during the '94 run period of the electron proton storage ring HERA. These effects were particularly manifest as degradation of the signal to noise level and the calibration stability. The reasons for this behaviour have been found to be correlated with radiation dam

Tomoyuki Arakawa, Tomoki Nakanishi, Kazuyuki Oshima, Akihiro Tsuchiya

We give the {\it spectral decomposition} of the path space of the $U_q(\hatsl)$ vertex model with respect to the local energy functions. The result suggests the hidden Yangian module structure on the $\hatsl$ level $l$ integrable modules, which is consistent with the earlier work [1] in the level one case. Also we prove the fermionic character formula of the

A. Ferrando, A. Jaramillo

We analyze the role played by temperature in QCD_3 by means of a dimensional interpolating approach. Pure gauge QCD_3 is defined on a strip of finite width L, which acts as an interpolating parameter between two and three dimensions. A two-dimensional effective theory can be constructed for small enough widths giving the same longitudinal physics as QCD_3. E

Hang Li, Naoki Abe

We address the problem of automatically acquiring case-frame patterns from large corpus data. In particular, we view this problem as the problem of estimating a (conditional) distribution over a partition of words, and propose a new generalization method based on the MDL (Minimum Description Length) principle. In order to assist with the efficiency, our meth

M. Oshikawa, M. Yamanaka, S. Miyashita

We study ground state properties of the $S=2$ quantum antiferromagnetic chain with a uniaxially anisotropic Hamiltonian: $ H = \sum_{j} [S_{j} \cdot S_{j+1} + D (S^{z}_{j})^2 ] $ by a Monte Carlo calculation. While it has been reported that a string order parameter vanishes exponentially at the isotropic Heisenberg point ($D=0$), we found it tends to remain

Naoki Abe, Hang Li, Atsuyoshi Nakamura

We consider the problem of learning a certain type of lexical semantic knowledge that can be expressed as a binary relation between words, such as the so-called sub-categorization of verbs (a verb-noun relation) and the compound noun phrase relation (a noun-noun relation). Specifically, we view this problem as an on-line learning problem in the sense of Litt

J. F. Bell

Some theories of gravity predict the existence of preferred-frame effects and violations of conservation of energy and momentum. General relativity predicts no such effects. In the parameterised post-Newtonian (PPN) formalism, the parameter, \al3 $\equiv 0$ if these effects do not exist. The period derivatives ($\dot{P}$) of millisecond pulsars (MSPs) are us

N. N. Rao

We show that the coupled mode equations for the stationary propagation of upper--hybrid and magnetoacoustic waves in magnetized electron--ion plasmas with negative group dispersion can be exactly derived from the generalized \Henon--Heiles Hamiltonian. The parameter regimes for the integrable cases of the coupled mode equations have been explicitly obtained.

N. Kaiser, P. B. Siegel, W. Weise

The $SU(3)$ chiral effective lagrangian at next-to-leading order is applied to the S-wave meson-baryon interaction in the energy range around the $ηN$ threshold. Potentials are derived from this lagrangian and used in a coupled channel calculation of the $πN$, $ηN$, $K Λ$, $K Σ$ system in the isospin-$1/2$, $l=0$ partial wave. Using the same parameters as ob

Menachem Kojman

A few steps are made towards representation theory of embeddability among uncountable graphs. A monotone class of graphs is defined by forbidding countable subgraphs, related to the graph's end-structure. Using a combinatorial theorem of Shelah it is proved: - The complexity of the class in every regular uncountable $ł>\aleph_1$ is at least $λ^+ + \sup\{

Samuel Vovsi

In this paper we explicitly compute finite bases of disjunctive identities and finite bases of regular representations for a number of interesting finite groups.

Dongsu Bak, Domenico Seminara

We reformulate two dimensional string-inspired gravity with point particles as a gauge theory of the extended Poincaré group. A non-minimal gauge coupling is necessary for the equivalence of the two descriptions. The classical one-particle problem is analyzed completely. In addition, we obtain the many-particle effective action after eliminating the gravity

Rupak Chatterjee, Leon Takhtajan

We present recent developments in the theory of Nambu mechanics, which include new examples of Nambu-Poisson manifolds with linear Nambu brackets and new representations of Nambu-Heisenberg commutation relations.

J. M. Aroca, M. Baig, H. Fort, R. Siri

We present the extension of the Lagrangian loop gauge invariant representation in such a way to include matter fields. The partition function of lattice compact U(1)-Higgs model is expressed as a sum over closed as much as open surfaces. We have simulated numerically the loop action equivalent to the Villain form of the action and mapped out the beta-gamma p

Kazuhiro Hikami

We give the infinite-dimensional representation for the elliptic $ K $-operator satisfying the boundary Yang-Baxter equation. By restricting the functional space to finite-dimensional space, we construct the elliptic $ K $-matrix associated to Belavin's completely $ \mathbb{Z} $-symmetric $ R $-matrix.

J. L. Hewett

Signals for new, non-supersymmetric physics at hadron colliders are reviewed. We focus on extended gauge sectors and new matter particles. {Presented at the {\it 10th Topical Workshop on Proton-Antiproton Collider Physics}, Batavia, IL, 9-13 May, 1995}}

Eric Braaten, Tzu Chiang Yuan

The leading color-singlet contribution to the fragmentation function for a gluon to split into spin-triplet S-wave quarkonium is presented. In the case of charmonium, we find that this color-singlet term is always negligible compared to the leading color-octet contribution.

Diego J. Castano, Daniel Z. Freedman, Cristina Manuel

The structure of gauged R supergravity Lagrangians is reviewed, and we consider models with a hidden sector plus light fields of the MSSM. A simple potential for the hidden sector is presented which has a global minimum with zero cosmological constant and spontaneously broken SUSY and R-symmetry. The $\rm U(1)_R$ vector multiplet acquires a Planck scale mass

Leonard P. A. Haakman, Alexei Kaidalov, Justus H. Koch

A model based on Reggeon field theory is used for the description of the photo- and electroproduction of vector mesons ($ρ^0, ω, ϕ, J /ψ$) on the proton. Its main feature is the dependence of the Pomeron intercept on the virtuality of the photon. The few parameters of the model were determined by fitting the total cross sections for real and virtual photons

Zurab G. Berezhiani, Anna Rossi

The neutrino long wavelength (just-so) oscillation is reconsidered as a solution to the solar neutrino problem. In the light of the presently updated results of the four solar neutrino experiments, the data fit in the just-so scenario substantially improves and becomes almost as good as in the MSW scenario. Surprising result of our analysis is that best fit

Hoang Ngoc Long, Dang Van Soa, Tuan A. Tran

Photon-to-axion conversions in the static electromagnetic fields are reconsidered in detail by using the Feynman diagram techniques. The differential cross sections are presented for the conversions in the presence of the electric field of the flat condenser as well as in the magnetic field of the solenoid. Based on our results a laboratory experiment for th

Sandra Malvezzi

A review of the charmed meson and baryon lifetimes is presented. Our knowledge of charmed particle lifetimes has greatly improved over the past two years, a crucial rôle having been played by the E687 experiment at Fermilab, which has almost quadrupled the samples of $D$ mesons. The lifetime ratios $τ(D^+)/τ(D^0)$ and $τ(D_s^+)/τ(D^0)$ are now known with an

A. Barducci, L. Caiani, R. Casalbuoni, R. Gatto

We simulate the formation and growth of disoriented chiral condensate (DCC) regions which follow the expansion of a high energy density region into the ``cold'' vacuum. The numerical study is based on the one-loop effective potential for the massive 2+1-dimensional Gross-Neveu model. We pay attention to the setting of the initial conditions and to de

J. J. van der Bij

A connection is made between a model for strongly interacting vector bosons and the spontaneously broken theory of gravity. The theory contains effectively no Higgs particle, but should have strong interactions at the electroweak scale. Some speculations about the nature of these interactions and possible experimental signatures are discussed.

Sreerup Raychaudhuri, D. P. Roy

The opposite states of the $τ$ polarization resulting from the charged Higgs boson and the $W$ boson decays can be exploited to enhance the $H^\pm$ signal in the inclusive 1-prong hadronic decay channel of $τ$. We suggest practical methods of sharpening up the $H^\pm$ signature in the top quark decay at LHC using this idea. As a result one can carry on the c

Chao-Hsi Chang, Yi-Bing Ding, Xue-Qian Li, Jian-Xiong Wang

We study possible observational effects of the two Higgs doublets in the $e^+e^- \to b \bar{b} Z^0$ at the LEP II energy. We have found that the observational values can be obviously different from that predicted by the minimal Standard Model (MSM), but the results depend on the parameters of the extended model. The possibilities of the observation are discu

Giampiero Esposito

The aim of the lectures is to introduce first-year Ph.D. students and research workers to the theory of the Dirac operator, spinor techniques, and their relevance for the theory of eigenvalues in Riemannian geometry. Topics: differential operators on manifolds, index of elliptic operators, Dirac operator, index problem for manifolds with a boundary, index of

Victor Pidstrigach, Andrei Tyurin

This article is a first step in establishing a link between the Donaldson polynomials and Seiberg-Witten invariants of a smooth 4-manifold.

V. I. Anisimov, R. C. Albers, J. M. Wills, M. Alouani

A parameter-free, mean-field, multi-orbital Hubbard model with nonspherical Coulomb and exchange interactions, implemented around all-electron local-density approximation (LDA) calculations, correctly predicts the band-gap energy, the absence of dimerization, and the antiferromagnetic ground state of halogen-bridged linear-chain Ni compounds. This approach a

N. Read, Subir Sachdev

We study finite temperature ($T$) properties of the continuum quantum field theory of systems with a ferromagnetic ground state. A scaling theory of the $T=0$ system is discussed carefully, and its consequences for crossovers between different finite $T$ regimes in dimensions 1, 2, and 3 are described. The results are compared with recent NMR measurements of

T. C. Chan, H. F. Chau, K. S. Cheng

We investigate the statistics of a model of type-I X-ray burst [Phys. Rev. E, {\bf 51}, 3045 (1995)] in its super-critical phase. The time evolution of the burnable clusters, places where fire can pass through, is studied using simple statistical arguments. We offer a simple picture for the time evolution of the percentage of space covered by burnable cluste

A. C. C. Coolen, S. N. Laughton, D. Sherrington

We present a new method to solve the dynamics of disordered spin systems on finite time-scales. It involves a closed driven diffusion equation for the joint spin-field distribution, with time-dependent coefficients described by a dynamical replica theory which, in the case of detailed balance, incorporates equilibrium replica theory as a stationary state. Th

Enrique Macia, Francisco Dominguez-Adame

We report on a new class of critical states in the energy spectrum of general Fibonacci systems. By introducing a transfer matrix renormalization technique, we prove that the charge distribution of these states spreads over the whole system, showing transport properties characteristic of electronic extended states. Our analytical method is a first step to fi

Kurt Broderix, Reiner Kree

We consider the statistical mechanics of a classical particle in a one-dimensional box subjected to a random potential which constitutes a Wiener process on the coordinate axis. The distribution of the free energy and all correlation functions of the Gibbs states may be calculated exactly as a function of the box length and temperature. This allows for a det

Jun Zang, A. R. Bishop, H. Roder

Jahn-Teller (JT) electron-phonon coupling effects in the colossal magnetoresistance perovskite compounds $La_{1-x}A_xMnO_3$ are investigated. Electron-electron correlations between two degenerate Mn $e_g$ orbitals are studied in the Gutzwiller approximation. The static JT distortion and antiadiabatic polaron effects are studied in a modified Lang-Firsov appr

Tore Burheim

Indexed languages are interesting in computational linguistics because they are the least class of languages in the Chomsky hierarchy that has not been shown not to be adequate to describe the string set of natural language sentences. We here define a class of unification grammars that exactly describe the class of indexed languages.

Tore Burheim

First we define a unification grammar formalism called the Tree Homomorphic Feature Structure Grammar. It is based on Lexical Functional Grammar (LFG), but has a strong restriction on the syntax of the equations. We then show that this grammar formalism defines a full abstract family of languages, and that it is capable of describing cross-serial dependencie

Yong -Cheol Kim, Pierre Demarque

This paper provides estimates of convective turnover time scales for Sun-like stars in the pre-main sequence and early post-main sequence phases of evolution, based on up-to-date physical input for the stellar models. In this first study, all models have solar abundances, which is typical of the stars in the Galactic disk where most of the available data hav

Tsvi Piran

Following Blumenthal \etl \cite{blu} and Piran \etl \cite{Pi} I discuss a simple model for the gravitational formation of voids. This model enables us to estimate the primordial perturbation required on the scale of voids. A comparison of this condition with the constraints on the spectrum of fluctuations derived from CMBR observations reveals that gravitati

David Langlois, Tsvi Piran

It is generally accepted that the observed CMBR dipole arises from the motion of the local group relative to the CMBR frame. An alternative interpretation is that the dipole results from an ultra-large scale ($λ> 100 c/H_0)$ isocurvature perturbation. Recently it was argued that this alternative possibility is ruled out. We examine the growth of perturbation

Schramm, T

Arclets in clusters of galaxies can be used to determine the lens mapping and not only to constrain the mass density of the cluster. Multiply imaged arclets are therefore easily identified without further modelling.

H. Ebeling, C. Mendes de Oliveira, D. A. White

We present the results of a spectral-imaging analysis of X-ray data obtained with the Position Sensitive Proportional Counter aboard the ROSAT Observatory in a 32 ks pointed observation of Hickson's Compact Group (HCG) #94. Besides HCG94, A2572, a richness class 0 Abell cluster, is also contained in the central region of the field of view. Both systems a

J. Bryn Jones, Gerard Gilmore, Rosemary F. G. Wyse

We have developed techniques to extract true iron abundances and surface gravities from spectra of the type provided by the multiple-object fibre-fed spectroscopic radial-velocity surveys underway with 2dF, HYDRA, NESSIE, and the forthcoming Sloan survey. Our method is optimised for low S/N, intermediate resolution blue spectra of G stars. Spectroscopic indi

J. F. Bell, S. R. Kulkarni, M. Bailes, E. M. Leitch

We report on optical observations of the low-mass binary millisecond pulsar systems J0034-0534 and J2145-0750. A faint (I=23.5) object was found to be coincident with the timing position of PSR J2145-0750. While a galaxy or distant main-sequence star cannot be ruled out, its magnitude is consistent with an ancient white dwarf, as expected from evolutionary m

U. Chattopadhyay, Pran Nath

A quantitative analysis of $\amu\equiv{1\over 2}(g-2)_μ$ within the framework of Supergravity Grand Unification and radiative breaking of the electro-weak symmetry is given. It is found that $a_μ^{SUSY}$ is dominated by the chiral interference term from the light chargino exchange, and that this term carries a signature which correlates strongly with the sig

Jae-weon Lee, In-guy Koh

We investigate the boson star with the self-interacting scalar field as a model of galactic halos. The model has slightly increasing rotation curves and allows wider ranges of the mass($m$) and coupling($λ$) of the halo dark matter particle than the non-interacting model previously suggested(ref.\cite{sin1}). Two quantities are related by $λ^{\frac{1}{2}} (m

Edward Witten

Three subjects are considered here: a self-dual non-critical string that appears in Type IIB superstring theory at points in ${\rm K3}$ moduli space where the Type IIA theory has extended gauge symmetry; a conformal field theory singularity at such points which may signal quantum effects that persist even at weak coupling; and the rich dynamics of the real w

Chao-Hsi Chang, Caidian Lü

The constraints on the two Higgs doublet model from the new experimental bounds of $b\to sγ$ by CLEO and the latest published value of the top quark mass by CDF and D0 are reanalyzed with the effective Lagrangian covering the full QCD corrections from the energy scale of top quark to that of bottom. The reanalysis result shows that the constraints become mor