February 1997 arXiv papers — page 11

Sergei Gukov

The evidently supersymmetric four-dimensional Wess-Zumino model with quenched disorder is considered at the one-loop level. The infrared fixed points of a beta-function form the moduli space $M = RP^2$ where two types of phases were found: with and without replica symmetry. While the former phase possesses only a trivial fixed point, this point become unstab

Jorge Alfaro

Using the Non-Abelian Batalin-Vilkovisky formalism introduced recently, we present a generalization of the Yang-Mills gauge transformations , to include antisymmetric tensor fields as gauge bosons. The Freedman-Townsend transformation for the two-form gauge field is automatically recovered. New characteristic classes involving this two-form field and the Yan

Peter Cho

Expanding upon earlier work of Pouliot and Strassler, we construct chiral magnetic duals to nonchiral supersymmetric electric theories based upon SO(7), SO(8) and SO(9) gauge groups with various numbers of vector and spinor matter superfields. Anomalies are matched and gauge invariant operators are mapped within each dual pair. Renormalization group flows al

I. V. Lavrinenko, H. Lu, C. N. Pope, T. A. Tran

The plot of allowed p and D values for p-brane solitons in D-dimensional supergravity is the same whether the solitons are extremal or non-extremal. One of the useful tools for relating different points on the plot is vertical dimensional reduction, which is possible if periodic arrays of p-brane solitons can be constructed. This is straightforward for extre

C. Hamzaoui, M. Pospelov, R. Roiban

We study the constraints on the CP-violating soft-breaking phases in the minimal supersymmetric standard model using the limits on the chromoelectric dipole moment of the strange quark extracted from the neutron EDM experiment. Our investigation shows that the phase mediated by the gluino exchange diagram has to be very small, $ϕ\leq 8 10^{-4}$, for the comm

M. T. Ressell, D. J. Dean

We perform nuclear shell model calculations of the neutralino-nucleus cross section for several nuclei in the A = 127 region. Each of the four nuclei considered is a primary target in a direct dark matter detection experiment. The calculations are valid for all relevant values of the momentum transfer. Our calculations are performed in the $3s 2d 1g_{7/2} 1h

M. Heyssler, Z. Kunszt, W. J. Stirling

We use diffractive parton distributions obtained from fits to the diffractive structure function measured at HERA to predict cross sections for single diffractive Higgs production at the LHC. The dominant background processes are also considered. Although some 5% - 15% of Higgs events are predicted to be diffractive in this model, the ratio of signal to back

A. A. Gvozdev, N. V. Mikheev, L. A. Vassilevskaya

High energy neutrino bremsstrahlung $ν\to ν+ γ$ in a strong magnetic field ($B \gg B_s$) is studied in the framework of the Standard Model (SM). A resonance probability and a four-vector of the neutrino energy and momentum loss are presented. A manifestation of the neutrino bremsstrahlung in astrophysical cataclysm of type of a supernova explosion or a merge

Jose F. Nieves, Palash B. Pal

We calculate the rate for the radiative neutrino decay in a thermal background of electrons and photons, taking into account the effect of the stimulated emission of photons in the thermal bath. We show that the rate is enhanced by a large factor relative to the rate for the corresponding process in the vacuum.

P. J. Mulders, J. Rodrigues

The representation of quark distribution functions in terms of nonlocal operators is combined with a simple diquark spectator model. This allows us to estimate these functions for the nucleon ensuring correct crossing and support properties.

B. Ananthanarayan, P. Minkowski

We begin with a brief discussion of the building blocks of supersymmetric grand unified theories. We recall some of the compelling theoretical reasons for viewing supersymmetric grand unification as an attractive avenue for physics beyond the standard model. This is followed by a discussion of some of the circumstantial evidence for these ideas.

Shinji Hioki

Topological charge distributions of SU(3) gauge theory at finite temperature are calculated on the lattice with high statistics in a manner of free from the uncertainty of $β$-function. Clear temperature dependence of the topological charge distribution is obtained. Combining the present result with the recent study about the relation between the masses of $

S. Alam, S. Haider, Aurangzeb

The principles and detection of gravitational waves by resonant antennas are briefly discussed. But the main purpose of this short note is to compare the two geometries of resonant antennas, the well-known cylindrical to the spherical type. Some features of a two sphere observatory are also discussed.

R. Balasubramanian, S. V. Dhurandhar

The paper presents a statistical model which reproduces the results of Monte Carlo simulations to estimate the parameters of the gravitational wave signal from a coalesing binary system. The model however is quite general and would be useful in other parameter estimation problems.

Ross Niebergall, Gudlaugur Thorbergsson

An immersion of a compact manifold is tight if it admits the minimal total absolute curvature over all immersions of the manifold. A prominent result in the study of minimal total absolute curvature immersions is the theorem of Chern and Lashof, which characterizes minimal total absolute curvature immersions, and tight immersions, of spheres into a Euclidean

Dmitry A. Kalinin

The paper is devoted to the investigation of four-dimensional Kahler manifolds admitting non-affine H-projective mappings. We find all such manifolds which are non-Einstein. In the paper also Kahler manifolds admitting infinitesimal H-projective transformations are determined. It is proved that the class of Kahler manifolds admitting H-projective mappings in

Vicente Munoz

We relate the Donaldson invariants of two four-manifolds $X_i$ with embedded Riemann surfaces of genus 2 and self-intersection zero with the invariants of the manifold X which appears as a connected sum along the surfaces. When the original manifolds are of simple type with $b_1=0$ and $b^+>1$, X is of simple type with $b_1=0$ and $b^+>1$ as well, and the re

Jean-Philippe Bouchaud, Leticia F. Cugliandolo, Jorge Kurchan, Marc Mezard

We review recent theoretical progress on glassy dynamics, with special emphasis on the importance and universality of the ``aging regime'', which is relevant to many experimental situations. The three main subjects which we address are: (i) Phenomenological models of aging (coarsening, trap models), (ii) Analytical results for the low-temperature dyn

Andrea Cavagna, Irene Giardina, Giorgio Parisi

In the context of the p-spin spherical model for generalized spin glasses, we give an estimate of the free energy barriers separating an equilibrium state from the metastable states close to it.

Paolo De Los Rios, Angelo Valleriani, José Luis Vega

We have investigated the essential ingredients allowing a system to show Self Organized Criticality (SOC) in its collective behavior. Using the Bak-Sneppen model of biological evolution as our paradigm, we show that the random microscopic rules of update can be effectively substituted with a chaotic map without changing the universality class. Using periodic

S. A. van Langen, M. Buttiker

Quantum mechanics requires that identical particles are treated as indistinguishable. This requirement leads to correlations in the fluctuating properties of a system. Theoretical predictions are made for an experiment on a multi-lead chaotic quantum dot which can identify exchange effects in electronic current-current correlations. Interestingly, we find th

G. Cristofano, D. Giuliano, G. Maiella

We present a dual two dimensional model for the Quantum Hall Fluid depending on two parameters and show that this model has topologically non-trivial vacua which are infrared stable fixed points of the Renormalization Group. The model has a discrete (modular) symmetry which reproduces the fenomenological law of corresponding states and allows for an unified

Graeme Honner, Miklos Gulacsi

An effective Hamiltonian for the localized spins in the one-dimensional Kondo lattice model is derived via a unitary transformation involving a bosonization of delocalized conduction electrons. The effective Hamiltonian is shown to reproduce all the features of the model as identified in various numerical simulations, and provides much new information on the

David A. Egolf, Ilarion V. Melnikov, Eberhard Bodenschatz

From the striped coats of zebras to the ripples in windblown sand, the natural world abounds with locally banded patterns. Such patterns have been of great interest throughout history, and, in the last twenty years, scientists in a wide variety of fields have been studying the patterns formed in well-controlled experiments that yield enormous quantities of h

Itziar Aretxaga, Brian J. Boyle, Roberto J. Terlevich

We present results of the hosts of four high-redshift ($z \approx 2$) and high luminosity ($M_B \lsim -28$ mag) QSOs, three radio-quiet one radio-loud, imaged in R and K bands. The extensions to the nuclear unresolved source are most likely due to the hosts galaxies of these QSOs, with luminosities at rest-frame 2300Åof at least 3-7% of the QSO luminosity, a

Wei Cui, S. N. Zhang, W. Focke, J. Swank

We report the results from our timing analysis of 15 RXTE observations of Cygnus X-1 throughout its 1996 spectral transitions. The entire period can be divided into 3 distinct phases: (1) transition from the hard to soft state, (2) soft state, and (3) transition from the soft state back to the hard state. The observed X-ray properties in phases 1 and 3 are r

Kurt Roettiger, James M. Stone, Richard Mushotzky

Values of the Hubble constant reported to date which are based on measurement of the Sunyaev-Zeldovich (SZ) effect in clusters of galaxies are systematically lower than those derived by other methods (e.g., Cepheid variable stars, or the Tully-Fisher relation). We investigate the possibility that systematic errors may be introduced into the analysis by the g

Winfried Zimdahl

It is shown that two reacting cosmological fluids, each of them perfect on its own, which exchange energy and momentum without preserving particle numbers, give rise to an entropy producing `reactive' bulk stress of the system as a whole, as soon as the detailed balance between decay and inverse decay processes is perturbed. This demonstrates explicitly

J. W. Bos, D. Chang, S. C. Lee, H. H. Shih

We analyze the Okubo SU(3) relation among the hyperon magnetic moments in the usual scheme of chiral perturbation theory (ChPT). We classify the one-loop diagrams, including those with intermediate decuplet baryons, in a simple way according to whether or not they satisfy the Okubo relation. Contrary to the conventional wisdom, we find that one-loop contribu

V. P. Kulkarni, S. M. Fall, J. W. Truran

We present a quantitative analysis of the abundances of heavy elements in damped Ly-alpha galaxies in the sample of Lu et al. (1996). In particular, we compare the observed gas-phase abundances with those expected when the intrinsic (i.e., nucleosynthetic) pattern is the same as that in either the Sun or in Galactic halo stars and when the depletion pattern

Alexander I. Titov, Yongseok Oh, Shin Nan Yang

The contributions of direct knockout processes, in addition to the diffractive production and one-pion-exchange processes associated with the phi-rho-pi and phi-gamma-pi couplings, to the polarization observables of the phi photoproduction from proton are calculated. We make use of Pomeron-photon analogy and a relativistic harmonic oscillator quark model. We

John F. Donoghue, Fabrizio Gabbiani

The decay K_L -> pi0 gamma e+ e- occurs at a it higher rate than the nonradiative process K_L -> pi0 e+ e-, and hence can be a background to CP violation studies using the latter reaction. It also has an interest in its own right in the context of chiral perturbation theory, through its relation to the decay K_L -> pi0 gamma gamma. The leading order chiral l

Ian Balitsky, Xiangdong Ji

We estimate in the QCD sum rule approach the amount of the nucleon spin carried by the gluon angular momentum: the sum of the gluon spin and orbital angular momenta. The result indicates that gluons contribute at least one half of the nucleon spin at scale of 1 GeV^2.

Daniel Ruberman, Ronald J. Stern

We show that the manifold *CP^2 # *RP^4, which is homotopy equivalent but not homeomorphic to CP^2 # RP^4, is in fact smoothable.

J. Adam,, Franz Gross, Cetin Savkli, J. W. Van Orden

The normalization condition for the relativistic three nucleon Bethe-Salpeter and Gross bound state vertex functions is derived, for the first time, directly from the three body wave equations. It is also shown that the relativistic normalization condition for the two body Gross bound state vertex function is identical to the requirement that the bound state

Atish Dabholkar

A five-dimensional dyonic black hole in Type-I theory is considered that is extremal but non-supersymmetric. It is shown that the Bekenstein-Hawking entropy of this black hole counts precisely the microstates of a D-brane configuration with the same charges and mass, even though there is no apparent supersymmetric nonrenormalization theorem for the mass. A s

S. Lübeck, K. D. Usadel

We consider the Bak-Tang-Wiesenfeld sandpile model on a two-dimensional square lattice of lattice sizes up to L=4096. A detailed analysis of the probability distribution of the size, area, duration and radius of the avalanches will be given. To increase the accuracy of the determination of the avalanche exponents we introduce a new method for analyzing the d

D. Anselmi

I define central functions c(g) and c'(g) in quantum field theory, useful to study the flow of the numbers of vector, spinor and scalar degrees of freedom from the UV limit to the IR limit and basic ingredients for a description of quantum field theory as an interpolating theory between pairs of 4D conformal field theories. The key importance of the correlat

Andreas Aste, Michael Dütsch, Günter Scharf

A recent construction of the electroweak theory, based on perturbative quantum gauge invariance alone, is extended to the case of more generations of fermions with arbitrary mixing. The conditions implied by second order gauge invariance lead to an isolated solution for the fermionic couplings in agreement with the standard model. Third order gauge invarianc

Andreas Wirzba, Michael Henseler

We investigate the scattering of a point particle from n non-overlapping, disconnected hard disks which are fixed in the two-dimensional plane and study the connection between the spectral properties of the quantum-mechanical scattering matrix and its semiclassical equivalent based on the semiclassical zeta function of Gutzwiller and Voros. We rewrite the de

Markus Simonius

Parity-even time reversal violation (TRV) in the nucleon-nucleon interaction is reconsidered. The TRV $ρ$-exchange interaction on which recent analyses of measurements are based is necessarily also charge-symmetry breaking (CSB). Limits on its strength $\bar{g}_ρ$ relative to regular $ρ$-exchange are extracted from recent CSB experiments in neutron-proton sc

P. Ao

Physical arguments are presented to show that the Hall anomaly is an effect of the vortex many-body correlation rather than that of an individual vortex. Quantitatively, the characteristic energy scale in the problem, the vortex vacancy formation energy, is obtained for thin films. At low temperatures a scaling relation between the Hall and longitudinal resi

Valter Moretti

A problem related to some Green functions found by Guimarães and Linet in the manifold of a straight cosmic string continued in the Rindler space is investigated.

Takeshi Fukuyama, Takashi Okamura

We study the general theorem about gravitational lensing which states the relationship between the numbers of images with different parities. Our formulation allows an extension to the nontransparent and singular model.

H. Reinhardt

An efficient way of resolving Gauss' law in Yang-Mills theory is presented by starting from the projected gauge invariant partition function and integrating out one spatial field variable. In this way one obtains immediately the description in terms of unconstrained gauge invariant variables which was previously obtained by explicitly resolving Gauss&#39

F. Becattini, U. Heinz

It is shown that the hadron production in high energy pp and p{\bar p} collisions, calculated by assuming that particles originate in hadron gas fireballs at thermal and partial chemical equilibrium, agrees very well with the data. The temperature of the hadron gas fireballs, determined by fitting hadron abundances, does not seem to depend on the centre of m

K. Langfeld, H. Reinhardt

An alternative model to the trivial $ϕ^4$-theory of the standard model of weak interactions is suggested, which embodies the Higgs-mechanism, but is free of the conceptual problems of standard $ϕ^4$-theory. We propose a N-component, O(N)-symmetric scalar field theory, which is originally defined on the lattice. The model can be motivated from SU(2) gauge the

Hugo Garcia-Compean, Jerzy F. Plebanski, Maciej Przanowski

A geometric formulation of the Moyal deformation for the Self-dual Yang-Mills theory and the Chiral Model approach to Self-dual gravity is given. We find in Fedosov's geometrical construction of deformation quantization the natural geometrical framework associated to the Moyal deformation of the six-dimensional version of the second heavenly equation and

Ph. Blanchard, A. Jadczyk

The new solution to the problem of time of arrival in quantum theory is presented herein. It allows for computer simulation of particle counters and it implies Born's interpretation. It also suggests new experiments that can answer the question: can a quantum particle detect a detector without being detected?

Ph. Blanchard, A. Jadczyk

Time plays a special role in Standard Quantum Theory. The concept of time observable causes many controversies there. In Event Enhanced Quantum Theory (in short: EEQT) Schroedinger's differential equation is replaced by a em piecewise deterministic algorithm} that describes also the timing of events. This allows us to revisit the problem of time of arriv

Costas Efthimiou, Donald Spector

We show that the Calogero and Calogero-Sutherland models possess an N-body generalization of shape invariance. We obtain the operator representation that gives rise to this result, and discuss the implications of this result, including the possibility of solving these models using algebraic methods based on this shape invariance. Our representation gives us

Alexander V. Gorokhov, Elena V. Rogacheva, Alexander V. Shiryaev

The coherent state representations of the group $G = W_1 \otimes G_0$ (where $G_0 = SU(2), SU(1,1)$) are used in computer simulation of the dynamics of single two-level atom $(G_0 = SU(2))$ interacting with a quantized photon cavity mode - the Jaynes - Cummings model (JCM) without the rotating wave approximation and, in general, nonlinear in photon variables

Robert B. Griffiths, Chi-Sheng Niu

It is shown that the optimum strategy of the eavesdropper, as described in the preceding paper, can be expressed in terms of a quantum circuit in a way which makes it obvious why certain parameters take on particular values, and why obtaining information in one basis gives rise to noise in the conjugate basis.

Dror Bar-Natan, Alexander Stoimenow

The "fundamental theorem of Vassiliev invariants" says that every weight system can be integrated to a knot invariant. We discuss four different approaches to the proof of this theorem: a topological/combinatorial approach following M. Hutchings, a geometrical approach following Kontsevich, an algebraic approach following Drinfel'd's theory o

G. W. Bund, S. S. Mizrahi, M. C. Tijero

The Gaussian Wave-Packet phase-space representation is used to show that the expansion in powers of $\hbar$ of the quantum Liouville propagator leads, in the zeroth order term, to results close to those obtained in the statistical quasiclassical method of Lee and Scully in the Weyl-Wigner picture. It is also verified that propagating the Wigner distribution

A. S. Rinat, M. F. Taragin

We express nuclear structure functions $F_i^A$ as generalized convolutions of the structure function of a nucleon and of a nucleus, composed of point-nucleons. In computations of the latter we include Final State Interactions and results for $F_2^A$ are compared with a few directly measured data on C and Fe. The above $F_i^A$ are primarily used for predictio

Alexander Koldobsky

An old problem of P. Levy is to characterize those Banach spaces which embed isometrically in $L_p.$ We show a new criterion in terms of the second derivative of the norm. As an application, we show that if $M$ is a twice differentiable Orlicz function with $M'(0)=M''(0)=0$ then the $n$-dimensional Orlicz space $\ell_M^n,\ n\ge 3,$ does not embed

Andrew Waldron

Recently we proposed a new Wick rotation for Dirac spinors which resulted in a hermitean action in Euclidean space. Our work was in a path integral context, however, in this note, we provide the canonical formulation of the new Wick rotation along the lines of the proposal of Osterwalder and Schrader.

D. Han, Y. S. Kim, M. E. Noz

The Lorentz group is the fundamental language for space-time symmetries of relativistic particles. This group can these days be derived from the symmetries observed in other branches of physics. It is shown that this group can be derived from optical filters. The group O(2,1) is appropriate for attenuation filters, while the O(3) group describes phase-shift

J. M. F. Labastida, M. Marino

We show that the baryon number of N=2 supersymmetric QCD can be twisted in order to couple the topological field theory of non-abelian monopoles to $Spin^c$-structures. To motivate the construction, we also consider some aspects of the twisting procedure as a gauging of global currents in two and four dimensions, in particular the role played by anomalies.

Tobias Hurth, Peter van Nieuwenhuizen, Andrew Waldron, Christian Preitschopf

We consider a new MacDowell-Mansouri R^2-type of supergravity theory, an extension of conformal supergravity, based on the superalgebra Osp(1|8). Invariance under local symmetries with negative Weyl weight is achieved by imposing chirality-duality and double-duality constraints on curvatures, along with the usual constraint of vanishing supertorsion. An anal

S. Penati, A. Santambrogio, D. Zanon

We study the beta-function of the N=2 sigma-model coupled to N=2 induced supergravity. We compute corrections to first order in the semiclassical limit, $c \to -\infty$, beyond one-loop in the matter fields. As compared to the corresponding bosonic, metric sigma-model calculation, we find new types of contributions arising from the dilaton coupling automatic

C. G. Carvalhaes, L. V. Belvedere, R. L. P. G. Amaral, N. A. Lemos

We propose and canonically quantize a generalization of the two-dimensional massive fermion theory described by a Lagrangian containing third-order derivatives. In our approach the mass term contains a derivative coupling. The quantum solution is expressed in terms of three usual fermions. Employing the standard bosonization scheme, the equivalent boson theo

Noriaki Kitazawa

A guiding principle to determine the Kaehler potential in the low energy effective theory of the supersymmetric chiral gauge theory with no flat direction is proposed. The guiding principle is applied to the SU(5) gauge theory with chiral superfields in the 5* and 10 representation, and the low energy effective theory is consistently constructed. The spontan

Matthias Jamin, Antonio Pich

The mass of the bottom quark and the strong coupling constant alpha_s are determined from QCD moment sum rules for the Upsilon system. Two analyses are performed using both the pole mass M_b as well as the mass m_b in the $\MSb$ scheme. In the pole-mass scheme large perturbative corrections resulting from coulombic contributions have to be resummed. In the $

Eduard Masso, Ramon Toldra

We obtain new stringent constraints on a light spinless particle phi coupled only to photons at low energies, considering its effects on the extragalactic photon background, the blackbody spectrum of the CMBR and the cosmological abundance of deuterium.

D. Kharzeev, M. Nardi, H. Satz

In proton-nucleus and nucleus-nucleus collisions up to central $S-U$ interactions, the $P_T$-dependence of $J/ψ$ production is determined by initial state parton scattering and pre-resonance nuclear absorption (``normal" $J/ψ$ suppression). The ``anomalous" $J/ψ$ suppression in $Pb-Pb$ collisions must reduce the normal $P_T$ broadening, since it occu

R. Akhoury, M. G. Sotiropoulos, V. I. Zakharov

We present a covariant formulation of the Kinoshita, Lee, Nauenberg (KLN) theorem for processes involving the radiation of soft particles. The role of the disconnected diagrams is explored and a rearrangement of the perturbation theory is performed such that the purely disconnected diagrams are factored out. The remaining effect of the disconnected diagrams

M. Feurstein, H. Markum, S. Thurner

We analyze the interplay of topological objects in four-dimensional QCD on the lattice. The distributions of color magnetic monopoles in the maximum abelian gauge are computed around instantons in both pure and full QCD. We find an enhanced probability for monopoles inside the core of an instanton on gauge field average. This feature is independent of the to

Rajamani Narayanan, Pavlos Vranas

The overlap formalism of chiral fermions provides a tool to measure the index, Q, of the chiral Dirac operator in a fixed gauge field background on the lattice. This enables a numerical measurement of the probability distribution, p(Q), in Yang-Mills theories. We have obtained an estimate for p(Q) in pure SU(2) gauge theory by measuring Q on 140 independent

J. W. Moffat

A model of the universe as a self-organized critical system is considered. The universe evolves to a state independently of the initial conditions at the edge of chaos. The critical state is an attractor of the dynamics. Random metric fluctuations exhibit noise without any characteristic length scales, and the power spectrum for the fluctuations has a self-s

Vicente Munoz

We solve a conjecture of Morgan and Szabo (Embedded genus 2 surfaces in four-manifolds, Preprint) about the relationship of the basic classes of two four-manifolds $X_i$ of simple type with $b_1=0$, $b^+>1$, such that there are embedded Riemann surfaces of genus $g \geq 2$ and self-intersection zero (and representing odd homology classes) with the basic clas

W. C. Wu, W. A. Atkinson, J. P. Carbotte

We consider the effect of interband transitions on the c-axis conductivity, DC resistivity, and thermal conductivity in a plane-chain bilayer model of a cuprate. The relation between the c-axis resistivity and thermal conductivity is governed by the Wiedemann-Franz law. When the perpendicular hopping matrix element between chain and plane ($t_\perp$) is smal

Normand Mousseau, Laurent J. Lewis

We present a detailed study of the effect of local chemical ordering on the structural, electronic, and dynamical properties of amorphous gallium arsenide. Using the recently-proposed ``activation-relaxation technique'' and empirical potentials, we have constructed two 216-atom tetrahedral continuous random networks with different topological propert

C. Dalitz

For different models of the electron-phonon interaction, the asymptotic behaviour of the moments of the stationary homogeneous solution of the linear Boltzmann equation is determined in the limit of a high external field. For Hilbert-Schmidt kernels of a finite rank, a result recently proven for kernels of rank one is found generally valid; as a consequence

Boris Levitan, Eytan Domany

We investigate the long time behavior of the survivors' area in the scaling state of two dimensional soap froth. We relate this problem to the recently studied temporal decay of the fraction of Potts spins that have never been flipped till time t. The results of our topological simulations are consistent with the value $θ=1$ for the scaling exponent of t

J. Zaanen, W. van Saarloos

It is conjectured that the anomalous spin dynamics observed in the normal state of cuprate superconductors might find its origin in a nearly ordered spin system which is kept in motion by thermally meandering charged domain walls. `Temperature sets the scale' finds a natural explanation, while a crossover to a low temperature quantum domain wall fluid is

Antoine Georges, Anirvan Sengupta

This article describes some recently obtained results on the low-energy properties of the "Kondo quartet" model of two spin-1/2 impurities interacting with two channels (flavours) of conduction electrons. We shall particularly emphasize the connections between conformal field-theory methods and bosonisation approaches, which are first illustrated on

T. Domanski, J. Ranninger, J. M. Robin

The Boson-Fermion model, describing a mixture of hybridized localized Bosons and itinerant Fermions on a lattice, is known to exhibit spectral properties for the Fermions which upon lowering the temperature develop into a three pole structure in the vicinity of the Fermi level. These spectral features go hand in hand with the opening of a pseudogap in the de

Q. Daniel Wang, Melville P. Ulmer

Based on ROSAT PSPC pointed observations, we have determined the aggregate X-ray shapes of 10 distant (z = 0.17-0.54) rich clusters: A2397, A222, A520, A1689, A223B, A1758, A2218, A2111, A2125, and CL0016+16. Four of the clusters have global X-ray ellipticities greater than 0.2, as measured on a scale of diameter 3 h_{50}^{-1} Mpc. These strongly elongated c

Andrzej Maciolek-Niedzwiecki, Julian H. Krolik, Andrzej A. Zdziarski

We study the effects of thermal conduction in a hot, active corona above an accretion disk. We assume that all of the dissipative heating takes place in the corona. We find that the importance of conduction decreases with increases in the local dissipative compactness of the corona, l_{diss,loc}, and increases with increasing abundance of electron-positron p

E. Vesperini

In this paper we address the issue of the origin of some observational properties of the galactic globular cluster system. After a preliminary study of some general properties of the main evolutionary processes, we investigate the evolution of systems of globular clusters located in a model of the Milky Way starting from different initial conditions. We stud

Andrei V. Gruzinov, John N. Bahcall

For solar conditions, we numerically integrate the density matrix equation for a thermal electron in the field of a Be-7 ion and other plasma ions and smeared-out electrons. Our results are in agreement with previous calculations that are based on a different physical picture, a picture which postulates the existence of distinct continuum and bound state orb

Andrei V. Gruzinov

We show that there are no dynamic screening corrections to the Salpeter's enhancement factor in the weak-screening limit.

Craig Sosin, Ben Dorman, S. George Djorgovski, Giampaolo Piotto

We present distributions of colors of stars along the horizontal branch of the globular cluster NGC 2808, from Hubble Space Telescope WFPC2 imaging in B, V, and an ultraviolet filter (F218W). This cluster's HB is already known to be strongly bimodal, with approximately equal-sized HB populations widely separated in the color-magnitude diagram. Our images

D. Thompson

The success of the Hubble Deep Field (HDF) data in identifying galaxies at redshifts up to ~3 has been quite spectacular. It is possible to extend this to even higher redshifts using infrared techniques, several of which are briefly described in this paper.

V. M. Lipunov, K. A. Postnov, M. E. Prokhorov

Galactic binary pulsars with different companion types (OB-star, white dwarf (WD), neutron star (NS), black hole (BH), or planet) assuming various phenomenological distributions for kick velocities of newborn NS are studied. The merging rates of relativistic binary stars (NS+NS, NS+BH, BH+BH) dependence on the kick velocity is specially adresed. The BH+BH me

F. A. Aharonian, G. Heinzelmann, :

A report is given on the status and recent results from the HEGRA imaging atmospheric Cherenkov telescopes (IACT) concerning Mrk 501 and GRS 1915+105 and on recent results from the HEGRA arrays concerning galactic and extragalactic gamma-ray sources, counterparts of TeV Gamma-Ray-Bursts, cosmic ray anisotropies, energy spectrum and composition of primary cos

Martin H. Rugers, Craig J. Hogan

Lyman series absorption features and corresponding metal lines in three high-resolution quasar spectra are fitted in the standard way with thermally broadened discrete redshift components. A candidate sample is assembled, of 10 velocity components in 7 separate complexes, which display features attributable to deuterium. Three of these components in 2 comple

John Bahcall

This talk compares standard model predictions for solar neutrino experiments with the results of actual observations. Here `standard model' means the combined standard model of minimal electroweak theory plus a standard solar model. I emphasize the importance of recent analyses in which the neutrino fluxes are treated as free parameters, independent of a

Eleny-Nicoleta Ionel, Thomas H. Parker

Taubes has recently defined Gromov invariants for symplectic four-manifolds and related them to the Seiberg-Witten invariants. Independently, Ruan and Tian defined symplectic invariants based on ideas of Witten. In this note, we show that Taubes' Gromov invariants are equal to certain combinations of Ruan-Tian invariants. This link allows us to generaliz

V. Gritsenko, K. Hulek

We investigate the existence and non-existence of modular forms of low weight with a character with respect to the paramodular group $Γ_t$ and discuss the resulting geometric consequences. Using an advanced version of Maaß lifting one can construct many examples of such modular forms and in particular examples of weight 3 cusp forms. Consequently we find man

Ricardo Garcia Lopez

Let f be a polinomial with coefficients in a finite field F. Let $Ψ: F \to C^{\ast}$ be a non-trivial additive character. In this paper we give bounds for the exponential sums $\sum_{x\in F^n} Ψ(Tr_{F/F_p} (f(x)))$ in some cases where the highest degree form of f defines a singular projective hypersurface X (e.g. when X is an arrangement of lines in P^2). Th

B. R. Schlei, D. Strottman, N. Xu

We investigate the nature of the new cross term for Gaussian parameterizations of Bose-Einstein correlations of identical particles emitted from purely chaotic hadron sources formed by relativistic heavy ion collisions. We find that this additional parameter in the so-called Bertsch parameterization can be expressed in terms of a linear ``out-longitudinal&#3

Stefan Boettcher, Maya Paczuski

Temporal autocorrelation functions for avalanches in the Bak-Sneppen model display aging behavior similar to glassy systems. Numerical simulations show that they decay as power laws with two distinct regimes separated by a time scale which is the waiting time, or age, of the avalanche. Thus, time-translational invariance is dynamically broken. The critical e

Jonathan W. Keohane, R. Petre, E. V. Gotthelf, M. Ozaki

We present evidence for shock acceleration of cosmic rays to high energies (about 10 TeV) in the supernova remnant IC 443. X-ray imaging spectroscopy with ASCA reveals two regions of particularly hard emission: an unresolved source embedded in an extended emission region, and a ridge of emission coincident with the southeastern rim. Both features are located

A. Ghinculov, Y. -P. Yao

We propose a framework for calculating two-loop Feynman diagrams which appear within a renormalizable theory in the general mass case and at finite external momenta. Our approach is a combination of analytical results and of high accuracy numerical integration, similar to a method proposed previously for treating diagrams without numerators. We reduce all po

Gustavo Burdman, Dimitris Kominis

We identify and compute the main corrections to $R_b$ in Topcolor theories. They are due to the top-pions, the pseudo-Goldstone bosons associated with the chiral symmetry breaking responsible for the top quark mass, and amount to -(1-4)%, independent of the details of the Topcolor model. We show that the cancellation of this effect against the contributions

M. Feurstein, H. Markum, S. Thurner

We compute instanton sizes and study correlation functions between instantons and monopoles in maximum abelian projection within SU(2) lattice QCD at finite temperature. We compare several definitions of the topological charge, different lattice actions and methods of reducing quantum fluctuations. The average instanton size turns out to be $σ\approx 0.2$ fm

A. B. Arbuzov, G. V. Fedotovich, E. A. Kuraev, N. P. Merenkov

QED processes at electron-positron colliders are considerd. We present differential cross-sections for large-angle Bhabha scattering, annihilation into muons and photons. Radiative corrections in the first order are taken into account exactly. Leading logarithmic contributions are calculated in all orders by means of the structure-function method. An accurac