November 1996 arXiv papers — page 3

Hong-Chen Fu

Polya states of single mode radiation field are proposed and their algebraic characterization and nonclassical properties are investigated. They degenerate to the binomial (atomic coherent) and negative binomial (Perelomov's su(1,1) coherent) states in two different limits and further to the number, the ordinary coherent and Susskind-Glogower phase state

Asher Peres

Errors in quantum computers are of two kinds: sudden perturbations to isolated qubits, and slow random drifts of all the qubits. The latter may be reduced, but not eliminated, by means of symmetrization, namely by using many replicas of the computer, and forcing their joint quantum state to be completely symmetric. On the other hand, isolated errors can be c

Miroslaw Brewczyk, Kazimierz Rzazewski, Charles W. Clark

We solve the hydrodynamic-ballistic equations of motion for a one-dimensional time-dependent Thomas-Fermi model of Cl_2 exposed to an intense subpicosecond laser field, and observe simultaneous multielectron ionization and molecular dissociation. The fragment kinetic energy defect with respect to the simple Coulomb explosion picture is found to originate in

D. Bauer

We show that zero ejection energy of the photoelectrons is classically impossible for hydrogen-like ions, even when field ionization occurs adiabatically. To prove this we transform the basic equations to those describing two 2D anharmonic oscillators. The same method yields an alternative way to derive the anomalous critical field of hydrogen-like ions. The

I. B. Khriplovich, A. I. Milstein, A. S. Yelkhovsky

In the recent paper by Zhang the order $α^4 R_{\infty}$ corrections to the positronium P levels were reconsidered. Those calculations confirm our corresponding results, except for the contribution due to the squared spin-orbit interaction. We present here a new derivation of our previous result for this last correction, this derivation being to our opinion b

Juergen Schaffner-Bielich, Carsten Greiner, Alexander Diener, Horst Stoecker

We discuss the properties of two distinct forms of hypothetical strange matter, small lumps of strange quark matter (strangelets) and of hyperon matter (metastable exotic multihypernuclear objects: MEMOs), with special emphasis on their relevance for present and future heavy ion experiments. The masses of small strangelets up to A = 40 are calculated using t

F. de Jong, U. Mosel

We investigate the effect of the electric formfactor on dilepton production off pp-collisions. In the model we use, the formfactor is separated in a pion-cloud contribution and a Vector Meson Dominance part. We find that the dilepton spectrum is hardly affected by the pion-cloud part, but significantly by the VMD contribution. We point out that data with suf

Heui-Seol Roh, T. Matsui

We study the chiral phase transition at finite temperature in the linear sigma model by employing a self-consistent Hartree approximation. This approximation is introduced by imposing self-consistency conditions on the effective meson mass equations which are derived from the finite temperature one-loop effective potential. It is shown that in the limit of v

J. Cruz, A. Mikovic, J. Navarro-Salas

We construct a one-loop effective metric describing the evaporation phase of a Schwarzschild black hole in a spherically symmetric null-dust model. This is achieved by quantising the Vaidya solution and by chosing a time dependent quantum state. This state describes a black hole which is initially in thermal equilibrium and then the equilibrium is switched o

Noureddine Mohammedi

An explanation of the origin of the hidden eleventh dimension in string theory is given. It is shown that any two sigma models describing the propagation of string backgrounds are related to each other by a Weyl transformation of the world-sheet metric. To avoid this ambiguity in defining two-dimensional sigma models, extra fields are needed. An interesting

A. Kudryavtsev, B. Piette, W. J. Zakrzewski

We study various classical solutions of the baby-Skyrmion model in $(2+1)$ dimensions. We point out the existence of higher energy states interpret them as resonances of Skyrmions and anti-Skyrmions and study their decays. Most of the discussion involves a highly exited Skyrmion-like state with winding number one which decays into an ordinary Skyrmion and a

F. O. Duraes, F. S. Navarra, G. Wilk

We have extended the Interacting Gluon Model (IGM) to calculate diffractive mass spectra generated in hadronic collisions. We show that it is possible to treat both diffractive and non-diffractive events on the same footing, in terms of gluon-gluon collisions. A systematic analysis of available data is performed. The energy dependence of diffractive mass spe

Umberto Cotti, Arnulfo Zepeda

We discuss the case of simultaneous mixing of gauge bosons and mixing of fermions in a model independent way and for a variety of extra-fermion representations. In this context we analyze a class of lepton family violating processes, namely Z --> e tau, Z --> mu tau, Z --> e mu, mu --> e e e, tau --> e e e, tau --> mu mu mu, tau --> e mu mu and tau --> mu e

J. P. Bowes, R. R. Volkas

In the following work we consider the possibility of explaining the observed baryon number asymmetry in the universe from simple baryon number violating modifications, involving massive scalar bosons, to the Standard Model. In these cases baryon number violation is mediated through a combination of Yukawa and scalar self-coupling interactions. Starting with

R. Brandenberger, T. Huang, K. Yang, X. Zhang

We study the classical cosmic string solution in a theory with dynamical $U(1)$ symmetry breaking. We calculate the energy per unit length of the string and compare it to that obtained in a model with a fundamental Higgs. We find that the predictions of the standard Abelian Higgs model are quite stable towards the addition of higher dimension operators expec

K. A. Milton, I. L. Solovtsov

We argue that a technique called analytic perturbation theory leads to a well-defined method for analytically continuing the running coupling constant from the spacelike to the timelike region, which allows us to give a self-consistent definition of the running coupling constant for timelike momentum. The corresponding $\beta$-function is proportional to the

J. Lopez, D. Nanopoulos, A. Zichichi

We study the single-photon signals expected at LEP in models with a very light gravitino. The dominant process is neutralino-gravitino production (e+e- -> chi+ G) with subsequent neutralino decay via chi->gamma+G, giving a gamma+E_miss signal. We first calculate the cross section at arbitrary center-of-mass energies and provide new analytic expressions for t

M. Beuthe, R. Gonzalez Felipe, G. Lopez Castro, J. Pestieau

The absorptive part of the $WWγ$ vertex induced by massive fermion loops is considered for different kinematical configurations. We show that the axial part of this vertex is different from zero not only when massive fermions are involved but also for massless fermion loops, if one of the W bosons is space-like and the other is time-like. We also discuss in

Stefano Moretti

Irreducible background effects due to $e^+e^-\to W^\pm + bbjj$ and $e^+e^-\to W^\pm + jjjj$ events produced via QCD in top-antitop production and heavy Higgs searches in the bremsstrahlung channel are studied at the Next Linear Collider. Various distributions relevant to phenomenological analyses are given and compared to those expected from top and Higgs si

Jose F. Nieves, Palash B. Pal

The structure of the electromagnetic vertex of spin-1 particles are studied in a general way, for the diagonal as well as the off-diagonal couplings. In each case, we consider in detail the consequences of gauge invariance and the space-time discrete symmetries, paying particular attention to the implications for the couplings of the photon to neutral gauge

P. Haberl

Possible CP violating effects in $Z\rightarrow$ 3 jet decays are investigated. The analysis assumes the presence of CP violating $Zq\bar qG$ couplings. The contribution of these couplings to the $Z\rightarrow q\bar qG$ decay width is calculated for different cut algorithms, including nonzero quark masses. Various CP--odd observables are discussed and it is s

D. B. Lichtenberg, R. Roncaglia, E. Predazzi

A diquark model previously formulated to describe exotic mesons is extended to dibaryons. In the model, dibaryons containing only light quarks are unbound. The $H$ dibaryon, consisting of $uuddss$ quarks, is unstable by about 90 MeV or more, and should decay strongly into two $Λ$ baryons. A charmed dibaryon $H_c$, composed of $uuddsc$, is unstable by about 6

D. B. Lichtenberg, R. Roncaglia, E. Predazzi

This is a conference mostly devoted to diquarks. Although an exotic meson can in principle be composed of a diquark and an antidiquark, such an exotic is unlikely to be experimentally observable in the near future. The reason, according to the model, is that diquark-antidiquark exotics have masses well above the threshold for decay into two mesons, and are l

I. L. Grach, I. M. Narodetskii, K. A. Ter-Martirosyan, S. Simula

Exclusive and inclusive, semileptonic and non-leptonic, charmed decays of the B-meson are investigated in the context of a phenomenological quark model. Bound-state effects are taken care of by adopting a single (model-dependent) non-perturbative wave function, describing the motion of the light spectator quark in the B-meson. A nice reproduction of both exc

Dima Bardin, Johannes Blümlein, Penka Christova, Lida Kalinovskaya

We describe the state of the art in the field of radiative corrections for deep inelastic scattering. Different methods of calculation of radiative corrections are reviewed. Some new results for QED radiative corrections for polarized deep inelastic scattering at HERA are presented. A comparison of results obtained by the codes POLRAD and HECTOR is given for

L. Covi, E. Roulet

We consider the $CP$ violating asymmetries produced in the decay of heavy particles, studying the effects of heavy particle mixing for arbitrary mass splittings. A considerable enhancement of the asymmetries is achieved when the masses of the mixed states are comparable, and the enhancement is maximal for mass splittings of the order of the widths of the dec

Ulf-G. Meißner

I discuss how dispersion relations can be used to analyse the nucleon electromagnetic form factors, with particular emphasis on the constraints from unitarity and pQCD. Results for nucleon radii, vector-meson couplings, the onset of pQCD and bounds on the strangeness form factors are presented. The em form factors in the time-like region reveal some interest

Maxim Pospelov

We revise the limits on the FCNC higgses in manifestly left-right symmetric theories. It is shown that the combination of the Kobayashi-Maskawa CP-violation with the tree level $ΔS=2$ higgs exchange gives very large contribution to the CP-violating $ε$ parameter. It leads to the new strong constraint on the FCNC higgs mass, M>50- 100 TeV, enhanced by factor

James D. Bjorken

An introduction to some outstanding issues in QCD is presented, with emphasis on work by Diakonov and co-workers on the influence of the instanton vacuum on low-energy QCD observables. This includes the calculation of input valence-parton distributions for deep-inelastic scattering.

H. S. Egawa, T. Hotta, T. Izubuchi, N. Tsuda

Scaling relations in four-dimensional simplicial quantum gravity are proposed using the concept of the geodesic distance. Based on the analogy of a loop length distribution in the two-dimensional case, the scaling relations of the boundary volume distribution in four dimensions are discussed in three regions: the strong-coupling phase, the critical point and

S. P. Spiegel

We calculate the free energy density of the two dimensional O(3) non linear sigma model over a large temperature region. At high temperatures the calculations could be done by perturbation theory whereas in the low temperature regime we used Monte-Carlo simulations. Using the Fixed--Point action the results do not show any remarkable cut-off effects and furt

D0 Collaboration

We report on a search for pair production of a fourth generation charge -1/3 quark (b') in pbar p collisions at sqrt(s) = 1.8 TeV at the Fermilab Tevatron using an integrated luminosity of 93 pb^-1. Both quarks are assumed to decay via flavor changing neutral currents (FCNC). The search uses the signatures gamma + 3 jets + mu-tag and 2 gamma + 2 jets. We

CLEO Collaboration, B. Nemati et al

Using data taken with the CLEO II detector at the Cornell Electron Storage Ring, we have determined the ratio of branching fractions: $R_γ \equiv Γ(Υ(1S) \rightarrow γgg)/Γ(Υ(1S) \rightarrow ggg) = (2.75 \pm 0.04(stat.) \pm 0.15(syst.))%$. From this ratio, we have determined the QCD scale parameter $Λ_{\overline{MS}}$ (defined in the modified minimal subtrac

Roberto Casadio

The independent dynamical variables of a collapsing homogeneous sphere of dust are canonically quantised and coupled equations describing matter (dust) and gravitation are obtained. The conditions for the validity of the adiabatic (Born-Oppenheimer) and semiclassical approximations are derived. On neglecting back-reaction effects, it is also shown that in th

D. Korotkin, H. Samtleben

The conserved nonlocal charges generating the Geroch group with respect to the canonical Poisson structure of the Ernst equation are found. They are shown to build a quadratic Poisson algebra, which suggests to identify the quantum Geroch algebra with Yangian structures.

A. L. Carey, M. G. Eastwood, P. E. Jupp, M. K. Murray

We introduce the spherical phylon group, a subgroup of the group of all formal diffeomorphisms of $\R^d$ that fix the origin. The invariant theory of the spherical phylon group is used to understand the invariants of the Laplace transform.

Yeong-Lieh Lin, Franco Nori

We study quantum interference effects due to electron motion on a three-dimensional cubic lattice in a continuously-tunable magnetic field of arbitrary orientation and magnitude. These effects arise from the interference between magnetic phase factors associated with different electron closed paths. The sums of these phase factors, called lattice path-integr

P. H. E. Tiesinga, T. J. Hagenaars, J. E. van Himbergen, Jorge V. José

We have numerically studied the dynamic correlation functions in thermodynamic equilibrium of two-dimensional O(2)-symmetry models with either bond (RSJ) or site (TDGL) dissipation as a function of temperature T. We find that above the critical temperature the frequency dependent flux noise $S_Φ(ω)\sim \vert 1+ {(ω/Ω)}^2\vert^{-α(T)/2}$, with $0.85\leq α(TDG

Artur Sowa

We explore the possibility of using the Kaluza-Klein geometry of Riemannian Submersions to modify the classical Maxwell Theory. We further argue that the resulting modification of Electromagnetism may be interesting in the context of, among other topics, magnetic oscillations in metals.

Frank Julicher, Jacques Prost

We analyze a simple stochastic model to describe motor molecules which cooperate in large groups and present a physical mechanism which can lead to oscillatory motion if the motors are elastically coupled to their environment. Beyond a critical fuel concentration, the non-moving state of the system becomes unstable with respect to a mode with angular frequen

Ugur Tirnakli, Fevzi Buyukkilic, Dogan Demirhan

In this study, recently introduced generalized distribution functions are summarized and by using one of these distribution functions, namely generalized Planck distribution, an alternative approach to the generalized Planck law for the blackbody radiation has been tackled.

F. van Wijland, H. J. Hilhorst

A random walk starts from the origin of a d-dimensional lattice. The occupation number n(x,t) equals unity if after t steps site x has been visited by the walk, and zero otherwise. We study translationally invariant sums M(t) of observables defined locally on the field of occupation numbers. Examples are the number S(t) of visited sites; the area E(t) of the

K. Yaman, P. Pincus, C. M. Marques

We consider a dilute solution of infinitely rigid rods near a curved, perfectly repulsive surface and study the contribution of the rod depletion layer to the bending elastic constants of membranes. We find that a spontaneous curvature state can be induced by exposure of BOTH sides of the membrane to a rod solution. A similar result applies for rigid disks w

R. Kotlyar, S. Das Sarma

We investigate sequential tunneling transport through a semiconductor double quantum dot structure by combining a simple microscopic quantum confinement model with a Mott-Hubbard type correlation model. We calculate nonperturbatively the evolution of the Coulomb blockade oscillations as a function of the interdot barrier conductance, obtaining good qualitati

Jun Zang, Joseph L Birman, A. R. Bishop, L. Wang

We present a microscopic theory for both equilibrium and nonequilibrium transport properties of coupled double quantum dots (DQD). A general formula for current tunneling through the DQD is derived by the nonequilibrium Green's function method. Using a Hartree-Fock approach, effects of multi-level coupling and nonequilibrium electron distributions in res

Yu Zhang, Michael L. Norman, Peter Anninos, Tom Abel

We developed a three-dimensional 2-level hierarchical cosmological code with a realistic and robust treatment of multi-species non-equilibrium ionization and radiative cooling processes, and use it to investigate primordial star forming regions that originate from high-\sigma perturbations in a standard CDM dominated cosmology. We find it is possible to prod

Edward C. Moran, Matthew D. Lehnert

The broadband X-ray spectrum of the prototypical starburst galaxy M82 is very complex. At least three spectral components are required to fit the combined ROSAT and ASCA spectrum in the 0.1--10 keV range. The observed X-ray flux in this band is dominated by a hard Gamma = 1.7, heavily absorbed power law component which originates in the nucleus and near-nucl

John E. Gizis

We present a spectroscopic classification system for M-dwarfs and M-subdwarfs based on quantitative measures of TiO and CaH features in the region 6200 - 7400 Angstroms. Our sample of cool stars covers the range from solar metallicity stars to the most extreme subdwarfs known. Using synthetic spectra computed by Allard and Hauschildt (1995), we derive metall

C. S. Kochanek, E. E. Falco, R. Schild, A. Dobrzycki

The z=1.377, B=17.0 mag quasar SBS 0909+532 A, B is a double with two images separated by 1.107 +/- 0.006 arcsec. Because the faint image has an emission line at the same wavelength as the MgII 2798 A emission line of the quasar, and lacks the broad MgIb absoption feature expected for a star with the same colors (a K star), we conclude that image B is a quas

Kirk Korista, Jack Baldwin, Gary Ferland, Dima Verner

We present graphically the results of several thousand photoionization calculations of broad emission line clouds in quasars, spanning seven orders of magnitude in hydrogen ionizing flux and particle density. The equivalent widths of 42 quasar emission lines are presented as contours in the particle density - ionizing flux plane for a typical incident contin

Richard Saunders, Joanne C. Baker, Malcolm N. Bremer, Andrew J. Bunker

In a companion paper (Paper I: Jones et al. 1996) we report the discovery of a cosmic microwave background decrement, indicative of a distant cluster with mass ~10^{15} solar masses, towards the quasar pair PC1643+4631A&B (z=3.79,3.83, separation 198''). To search for the cluster responsible, we have obtained R-, J- and K-band images of the field and

Michael E. Jones, Richard Saunders, Joanne C. Baker, Garret Cotter

In a 15-GHz Ryle-Telescope observation of PC1643+4631 A & B, a pair of quasars at redshifts z = 3.79 and 3.83 separated by 198 arcsec on the sky, we find a decrement in the cosmic microwave background (CMB) of -380 +/- 64 uJy in a 110 arcsec x 175 arcsec beam. Assuming this to be a Sunyaev-Zel'dovich effect due to an intervening cluster, the minimum magn

C. S. Kochanek, C. R. Keeton

Gravitational lenses are a unique new constraint on the structure of galaxies. We review the evidence that most lenses are early-type galaxies, the optical properties of the lens galaxies, the evidence against constant M/L models, recent work on the axis ratios of the mass distribution, and the role stellar dynamics plays in gravitational lensing.

Michael P. Hobson

By proposing a statistic for the detection of secondary (Doppler) peaks in the CMBR power spectrum, the significance level at which such peaks may be detected are computed for a large range of model CMBR experiments. In particular, we investigate experimental design features required to distinguish between competing cosmological theories, such as cosmic stri

A. N. Lasenby

The effects on CMB measurements of foreground contamination due to synchrotron radiation, free-free emission and discrete sources are considered. Estimates of the level and power spectrum of the Galactic fluctuations are made using low frequency maps and recent Tenerife data. New methods for achieving a frequency-based separation of Galactic and CMB componen

Richard Saunders

The Ryle Telescope has been used to provide images at 15 GHz of the Sunyaev-Zel'dovich decrements towards a dozen clusters in an X-ray luminosity-limited sample. So far, X-ray data have allowed H_0 estimates towards two of these, both giving ``low'' values that are self-consistent, though it is essential to obtain many more estimates to reduce th

Michael E. Jones

We have produced an image of the microwave sky with 30' resolution in a 2 degree field using the Cosmic Anisotropy Telescope (CAT). Analysis of data taken at three frequencies near 15 GHz indicates that most of the signal is due to the CMB, with an equivalent broad-band power of Delta T/T = 1.9 +/- 0.5 x 10^{-5} at angular scales corresponding to multipo

Helene Di Nella, W. Couch, G. Paturel, Q. Parker

A significant empty region was found between the southern Pavo- Indus (PI) wall and the northern Perseus-Pisces (PP) chain. This survey tests the reality of this void which may simply reflect previous poor sampling of the galaxies in this region. Redshifts for a magnitude selected sample of 379 galaxies were obtained covering the four UKST/SERC survey fields

Ian Smail, Alan Dressler, Warrick J. Couch, Richard S. Ellis

We present catalogs of objects detected in deep images of 11 fields in 10 distant clusters obtained using WFPC-2 on board the Hubble Space Telescope. The clusters span the redshift range z=0.37-0.56 and are the subject of a detailed ground- and space-based study to investigate the evolution of galaxies as a function of environment and epoch. The data present

B. Fuchs, H. Jahreiss

We rediscuss the question of what fraction of the population of MACHOs in the halo of the Milky Way might be in the form of halo dwarfs, because recent determinations indicate masses of the MACHOs, which are typical for such stars. For this purpose we have analyzed the Third Catalogue of Nearby Stars and identified the subdwarfs and a high velocity white dwa

I. Antoniadis, P. O. Mazur, E. Mottola

The spectrum and statistics of the cosmic microwave background radiation (CMBR) are investigated under the hypothesis that scale invariance of the primordial density fluctuations should be promoted to full conformal invariance. As in the theory of critical phenomena, this hypothesis leads in general to deviations from naive scaling. The spectral index of the

Dennis Zaritsky, Rodney Smith, Carlos S. Frenk, Simon D. M. White

We find that satellites of isolated disk galaxies at projected radii between 300 and 500 kpc are distributed asymmetrically about the parent galaxy and aligned preferentially with the disk minor axis. The dynamical timescale at these radii is sufficiently long that the shape of this distribution must reflect the formation history of the outer halo rather tha

Gang Tian, Geng Xu

In this short note, we study the semi-simplicity of the quantum cohomology algebra H(V, C) of a Fano complete intersection V, and show that the subspace of H(V, C) generated by the hyperplane sections is semi-simple in the sense of Dubrovin when the degree of V satisfies certain conditions.

Andrzej Weber

Suppose M is a complex manifold of dimension $n+1$ and K is a hypersurface in M. By Poincaré duality we define a residue morphism $res:H^{k+1}(M\setminus K)\longrightarrow H_{2n-k}(K)$ which generalizes the classical Leray residue morphism to cohomology for smooth K. We assume that K has isolated quasihomogeneous singularities. Suppose $ω$ is a holomorphic f

O. Debarre, L. Manivel

Let X be a subvariety of $P^n$ defined by equations of degrees $ d =(d_1,...,d_s)$, over an algebraically closed field k of any characteristic. We study properties of the Fano scheme $F_r(X)$ that parametrizes linear subspaces of dimension r contained in X. We prove that $F_r(X)$ is connected and smooth of the expected dimension for n big enough (this was pr

Y. Choie, W. Eholzer

For any non-negative integer v we construct explicitly [v/2]+1 independent covariant bilinear differential operators from J_{k,m} x J_{k',m'} to J_{k+k'+v,m+m'}. As an application we construct a covariant bilinear differential operator mapping S_k^{(2)} x S^{(2)}_{k'} to S^{(2)}_{k+k'+v}. Here J_{k,m} denotes the space of Jacobi forms

Boon Tiong Melvin Leok

This paper will consider the coevolution of species which are symbiotic in their interaction. In particular, we shall analyse the interaction of squirrels and oak trees, and develop a mathematical framework for determining the coevolutionary equilibrium for consumption and production patterns.

Boon Tiong Melvin Leok

The sustainable biodiversity associated with a specific ecological niche as a function of land area is analysed computationally by considering the interaction of ant societies over a collection of islands. A power law relationship between sustainable species and land area is observed. We will further consider the effect a perturbative inflow of ants has upon

J. I. Collar

Recent tritium beta decay experiments yield unphysical negative best-fit values for the square of the neutrino mass. An unidentified bump-like excess of counts few eV below the endpoint in the electron energy spectrum has been tentatively recognized as the source of this anomaly. It is shown that the repulsive potential acting on the emitted antineutrino and

Michael Kleber

We compute the decomposition of representations of Yangians into g-modules for simply-laced Lie algebras g. The decomposition has an interesting combinatorial tree structure. Results depend on a conjecture of Kirillov and Reshetikhin.

Akikazu Hashimoto, Igor Klebanov

We review a number of perturbative calculations describing the interactions of D-branes with massless elementary string states. The form factors for the scattering of closed strings off D-branes are closely related to the Veneziano amplitude. They show that, in interactions with strings, D-branes acquire many of their physical features: the effective size of

John F. Donoghue, Euy Soo Na

We use dispersive techniques to address the behavior of the pion form factor as $Q^2 \to \infty$ and $Q^2 \to 0$. We perform the matching with the constraints of perturbative QCD and chiral perturbation theory in the high energy and low energy limits, leading to four sum rules. We present a version of the dispersive input which is consistent with the data an

G. Dvali, M. Shifman

Supersymmetry breaking and compactification of extra space-time dimensions may have a common dynamical origin if our universe is spontaneously generated in the form of a four-dimensional topological or non-topological defect in higher dimensional space-time. Within such an approach the conventional particles are zero modes trapped in the core of the defect.

M. Feurstein, E. -M. Ilgenfritz, M. Müller-Preussker, S. Thurner

Renormalization group transformations as discussed recently in deriving fixed point actions are used to analyse the vacuum structure near to the deconfinement temperature. Monte Carlo configurations are generated using the fixed point action. We compare equilibrium configurations with configurations obtained by inverse blocking from a coarser lattice. The ab

Benoit Vanderheyden, Jean-Yves Ollitrault

We compute the damping rates of one-particle excitations in a cold ultrarelativistic plasma to leading order in the coupling constant e for three types of interaction: Yukawa coupling to a massless scalar boson, QED and QCD. Damping rates of charged particles in QED and QCD are of order e^3 mu, while damping rates of other particles are of order e^4 mu or e^

C. Stephen Hellberg, E. Manousakis

We investigate the phase diagram of the two-dimensional t-J model using a recently developed Green's Function Monte Carlo method for lattice fermions. We use the technique to calculate exact ground-state energies of the model on large lattices. In contrast to many previous studies, we find the model phase separates for all values of J/t. In particular, i

Meng Ta-chung, Zhang Yang

The colorless objects(s) in diffractive lepton-nucleon scattering in the small-$x_B$ region can be probed by examing the final state particles in such processes: (A) Perform multiplicity and/or energy factorial moment analyses, and check especially the $x_B$- and $Q^2$-dependence of the intermittency-indices. (B) Examine the diffractive structure function $F

Denis V. Juriev

This note being devoted to some aspects of the inverse problem of representation theory contains a new insight into it illustrated by two topics. The attention is concentrated on the manner of representation of abstract objects by the concrete ones as well as on the abstract objects themselves. The results of researches allow to state that the actual richnes

Margarida Mendes Lopes, Rita Pardini

We study minimal surfaces X of general type with $K^2_X=6p_g-14$ and $q(X)>0$ such that $K_X$ is ample, the image of the canonical map is a canonically embedded surface of general type and the canonical map is not birational. The main result states that if X satisfies the above assumptions and $q(X)\ge 2$, then, apart from a finite number of exceptions, X be

Z. Aouissat, P. Schuck, J. Wambach

We present a non-perturbative method for the study of the O(N+1)-version of the linear sigma-model. Using boson-mapping techniques, in close analogy to those well-known for fermionic systems, we obtain a systematic 1/N-expansion for the Hamiltonian which is symmetry-conserving order by order. The leading order for the Hamiltonian is evaluated explicitly and

Sergei V. Ketov

An elementary introduction into the Seiberg-Witten theory is given. Many efforts are made to get it as pedagogical as possible, within a reasonable size. The selection of the relevant material is heavily oriented towards graduate students. The basic ideas about solitons, monopoles, supersymmetry and duality are reviewed from first principles, and they are il

Angel Ballesteros, Francisco J. Herranz, Javier Negro

A Gelfan'd--Dyson mapping is used to generate a one-boson realization for the non-standard quantum deformation of $sl(2,\R)$ which directly provides its infinite and finite dimensional irreducible representations. Tensor product decompositions are worked out for some examples. Relations between contraction methods and boson realizations are also explored

Doron Cohen

A new model that generalizes the study of quantum Brownian motion (BM) is constructed. We consider disordered environment that may be either static (quenched), noisy or dynamical. The Zwanzig-Caldeira-Leggett BM-model constitutes formally a special case where the disorder auto-correlation length is taken to be infinite. Alternatively, localization problem is

M. Hotta, T. Kato, K. Nagata

It has been recently pointed out that a definition of the geometric entropy using the partition function in a conical space does not in general lead to a positive definite quantity. For a scalar field model with a non-minimal coupling we clarify the origin of the anomalous behavior from the viewpoint of the canonical formulation.

C. Bachas, E. Kiritsis

We discuss $F_{μν}^4$ terms in torroidal compactifications of type-I and heterotic SO(32) string theory. We give a simple argument why only short BPS multiplets contribute to these terms at one loop, and verify heterotic-type-I duality to this order.

J. R. Anglin, J. P. Paz, W. H. Zurek

The study of environmentally induced superselection and of the process of decoherence was originally motivated by the search for the emergence of classical behavior out of the quantum substrate, in the macroscopic limit. This limit, and other simplifying assumptions, have allowed the derivation of several simple results characterizing the onset of environmen

M. Rigo, G. Alber, F. Mota-Furtado, P. F. O'Mahony

We consider a driven damped anharmonic oscillator which classically leads to a bistable steady state and to hysteresis. The quantum counterpart for this system has an exact analytical solution in the steady state which does not display any bistability or hysteresis. We use quantum state diffusion theory to describe this system and to provide a new perspectiv

C. W. Gardiner, P. Zoller

A Quantum Kinetic Master Equation (QKME) for bosonic atoms is formulated. It is a quantum stochastic equation for the kinetics of a dilute quantum Bose gas, and describes the behavior and formation of Bose condensation. The key assumption in deriving the QKME is a Markov approximation for the atomic collision terms. In the present paper the basic structure o

A. Muller, T. Herzog, B. Huttner, W. Tittel

We present a time-multiplexed interferometer based on Faraday mirrors, and apply it to quantum key distribution. The interfering pulses follow exactly the same spatial path, ensuring very high stability and self balancing. Use of Faraday mirrors compensates automatically any birefringence effects and polarization dependent losses in the transmitting fiber. F

N. Gisin, B. Huttner

We analyze various eavesdropping strategies on a quantum cryptographic channel. We present the optimal strategy for an eavesdropper restricted to a two-dimensional probe, interacting on-line with each transmitted signal. The link between safety of the transmission and the violation of Bell's inequality is discussed. We also use a quantum copying machine

B. D. Keister, W. N. Polyzou

A set of exactly computable orthonormal basis functions that are useful in computations involving constituent quarks is presented. These basis functions are distinguished by the property that they fall off algebraically in momentum space and can be exactly Fourier-Bessel transformed. The configuration space functions are associated Laguerre polynomials multi

Ofer Aharony, Micha Berkooz

We analyze some of the kinematical and dynamical properties of flat infinite membrane solutions in the conjectured M theory proposed by Banks, Fischler, Shenker and Susskind. In particular, we compute the long range potential between membranes and anti-membranes, and between membranes and gravitons, and compare it with the supergravity results. We also discu

Vladimir O. Soloviev

It is shown that the Regge-Teitelboim criterion for fixing the unique boundary contribution to the Hamiltonian compatible with free boundary conditions should be modified if the Poisson structure is noncanonical. The new criterion requires cancellation of boundary contributions to the Hamiltonian equations of motion. In the same time, boundary contributions

Franco Ferrari, Ignazio Lazzizzera

In this letter the Chern-Simons field theories are studied in the Coulomb gauge using the Dirac's canonical formalism for constrained systems. As a strategy, we first work out the constraints and then quantize, replacing the Dirac brackets with quantum commutators. We find that the Chern-Simons field theories become two dimensional models with no propaga

W. A. Sabra

We discuss the entropy and the transformation properties of classical extremal N=2 black hole solutions in supergravity theories associated with the minimal coupling models CP(n-1,1). The entropy is given by a manifestly invariant quantity under the embedding of the duality group SU(1,n) into Sp(2n+2) which is a symmetry of the classical BPS mass formula.

I. I Kogan, A. Lewis, O. A. Soloviev

Correlation functions of gauged WZNW models are shown to satisfy a differential equation, which is a gauge generalization of the Knizhnik-Zamolodchikov equation.

Tsunehide Kuroki, Yuji Okawa, Fumihiko Sugino, Tamiaki Yoneya

We present a new class of matrix models which are manifestly symmetric under the T-duality transformation of the target space. The models may serve as a nonperturbative regularization for the T-duality symmetry in continuum string theory. In particular, it now becomes possible to extract winding modes explicitly in terms of extended matrix variables.

Pawel O. Mazur

Quantum mechanics of a test particle interacting with a spinning string (torsion vortex) is the quantum mechanics of the celebrated Aharonov-Bohm effect. The angular momentum per unit length $J$ characterizing the spinning string corresponds to the magnetic flux $Φ$ of the Aharonov-Bom fluxon and the gravitational mass-energy $E$ of an incoming particle corr

A. Yu. Smirnov

Results of solar neutrino spectroscopy based on data from four experiments are presented. Perspectives related to forthcoming experiments are discussed. Implications of the results for neutrino properties are considered.

John F. Donoghue

I discuss the progress in the use of analytic techniques for low energy QCD, in particular as applied to kaon physics. These methods are becoming increasingly powerful and we have gained a good deal of control over the difficult hadronic interactions. There are continuing developments, and I speculate on the ways that these techniques may become yet more sop