May 2000 arXiv papers — page 5

Diego M. Forni, Mirta Iriondo, Carlos N. Kozameh

The Null Surface Formulation of General Relativity is developed for 2+1 dimensional gravity. The geometrical meaning of the metricity condition is analyzed and two approaches to the derivation of the field equations are presented. One method makes explicit use of the conformal factor while the other only uses conformal information. The resulting set of equat

Andrew P. Billyard, Alan A. Coley, James E. Lidsey

We study early universe cosmologies derived from a scalar-tensor action containing cosmological constant terms and massless fields. The governing equations can be written as a dynamical system which contains no past or future asymptotic equilibrium states (i.e. no sources nor sinks). This leads to dynamics with very interesting mathematical behaviour such as

David R. Wolf

The topic of this paper is a novel Bayesian continuous-basis field representation and inference framework. Within this paper several problems are solved: The maximally informative inference of continuous-basis fields, that is where the basis for the field is itself a continuous object and not representable in a finite manner; the tradeoff between accuracy of

Jian-Ming Tang

In two dimensions the microscopic theory, which provides a basis for the naive analogy between a quantized vortex in a superfluid and an electron in an uniform magnetic field, is presented. A one-to-one correspondence between the rotational states of a vortex in a cylinder and the cyclotron states of an electron in the central gauge is found. Like the Landau

J. Heurich, H. Pu, M. G. Moore, P. Meystre

The development of integrated, waveguide-based atom optical devices requires a thorough understanding of nonlinear matter-wave mixing processes in confined geometries. This paper analyzes the stability of counterpropagating two-component Bose-Einstein condensates in such a geometry. The steady state field equations of this system are solved analytically, pre

J. S. Qualls, C. H. Mielke, J. S. Brooks, L. K. Montgomery

We present a unique high magnetic field phase of the quasi-one dimensional organic conductor (TMTSF)$_2$ClO$_4$. This phase, termed "Q-ClO$_4$", is obtained by rapid thermal quenching to avoid ordering of the ClO$_4$ anion. The magnetic field dependent phase of Q-ClO$_4$ is distinctly different from that in the extensively studied annealed material.

Klaus Kassner, Chaouqi Misbah, Judith Mueller, Jens Kappey

A phase-field approach describing the dynamics of a strained solid in contact with its melt is developed. By rigorous asymptotic analysis we show that the sharp-interface limit of this model recovers the continuum model equations for the Grinfeld instability. Moreover, we use our approach to derive hitherto unknown sharp-interface equations for a situation i

A. Villares Ferrer, A. O. Caldeira, A. S. T. Pires

The problem of dissipative motion of solitons in the case of tetramethyl ammonium manganese chloride (TMMC) is studied as a function of the external magnetic field and the temperature. Two specific situations are analyzed separately; the first, above the transition temperature $T_N$, in which the classical motion of the spin degree of freedom is described by

Sanjay Kumar, D. Giri, Sujata Krishna

We study the asymptotic behaviour of resistance scaling and fluctuation of resistance that give rise to flicker noise in an {\em n}-simplex lattice. We propose a simple method to calculate the resistance scaling and give a closed-form formula to calculate the exponent, $β_L$, associated with resistance scaling, for any n. Using current cumulant method we cal

R. J. Radwanski, Z. Ropka

The orbital and spin moment of the Ni2+ ion in NiO has been calculated at 0 K to be 0.54mB and 1.99 mB respectively. Such large orbital moment, more than 20% of the total moment of 2.53 mB, proves the need for the ''unquenching'' of the orbital moment in compounds containing 3d ions. It turns out that the spin-orbit coupling is indispensable

J. Ruostekoski

We consider a weakly interacting coherently coupled Bose-Einstein condensate in a double-well potential. We show by means of stochastic simulations that the system could possibly be driven to an entangled macroscopic superposition state or a Schrödinger cat state by means of a continuous quantum measurement process.

Jean-Philippe Laval, Pierre-Henri Chavanis, Bérengère Dubrulle, Clément Sire

We use high resolution numerical simulations over several hundred of turnover times to study the influence of small scale dissipation onto vortex statistics in 2D decaying turbulence. A self-similar scaling regime is detected when the scaling laws are expressed in units of mean vorticity and integral scale, as predicted by Carnevale et al., and it is observe

R. Salazar, R. Toral

The fact that mean field theory is appropriate to describe an Ising model with long-range interactions has been already shown by Cannas and Tamarit. Although not explicited in our Letter, we have used periodic boundary conditions in all our simulations, such that the maximum possible distance between two lattice sites is L/2. We make no specific comments abo

Eiji Kaneshita, Masanori Ichioka, Kazushige Machida

Collective excitations both for spin- and charge-channels are investigated in incommensurate spin density wave (or stripe) states on two-dimensional Hubbard model. By random phase approximation, the dynamical susceptibility χ(q,ω) is calculated for full range of (q,ω) with including all higher harmonics components. An intricate landscape of the spectra in χ(

Alessandro Cuccoli, Valerio Tognetti, Tommaso Roscilde, Paola Verrucchi

We study the two dimensional quantum Heisenberg antiferromagnet on the square lattice with easy-axis exchange anisotropy. By the semiclassical method called pure-quantum self-consistent harmonic approximation we analyse several thermodynamic quantities and investigate the existence of a finite temperature transition, possibly describing the low-temperature c

R. Hayn, R. O. Kuzian

The spectral function of one hole in different magnetic states of the one-dimensional t-J model including three-site term and frustration $J^{\prime}$ is studied. In the strong coupling limit $J \to 0$ (corresponding to $U \to \infty$ of the Hubbard-model) a set of eigenoperators of the Liouvillian is found which allows to derive an exact expression for the

X. G. Qiu, V. V. Moshchalkov, J. Karpinski

The vortex correlation along the c-axis in high quality single crystals of YBa$_{2}$Cu$_{4}$O$_{8}$ has been investigated as a function of temperature T in different magnetic fields, using the quasi-flux transformer configuration. A simultaneous sharp drop associated with the vortex lattice melting is observed in both the primary and secondary voltages(V$_{t

S. Ono, Yoichi Ando, T. Murayama, F. F. Balakirev

We measure the normal-state in-plane resistivity of La-doped Bi-2201 single crystals at low temperatures by suppressing superconductivity with 60-T pulsed magnetic fields. With decreasing hole doping, we observe a crossover from a metallic to insulating behavior in the low-temperature normal state. This crossover is estimated to occur near 1/8 doping, well i

Patrick S. Osmer

Quasars continue to be the most luminous objects known in the universe but are now rivaled by galaxies for having the largest redshifts. I review current techniques for finding quasars at z > 5 and the status of current optical surveys. I compare the spectra of known quasars with z \approx 5 with the spectra of some recently discovered galaxies with z > 5 to

M. L. A. Kouwenhoven

I have searched the Westerbork Northern Sky Survey (WENSS) source list for detections of known radio pulsars. A source with a flux density greater than five times the local noise level is found near the positions of 25 pulsars. The probability that one out of these 25 sources is a chance coincidence is about 10%. I have looked at the WENSS maps of the non-de

B. Ricci, F. L. Villante

We provide a determination of the Beryllium neutrino luminosity directly by means of helioseismology, without using additional assumptions. We have constructed solar models where Beryllium neutrino, ($ν_{Be}$) production is artificially changed by varying in an arbitrary way the zero energy astrophysical S-factor $S_{34}$ for the reaction $^3{\rm He}+^4{\rm

Karl Mannheim

Gamma rays trace accelerated particles, and the observed flux of extragalactic gamma rays therefore constrains the global efficiency for particle acceleration. Extragalactic jets in active galactic nuclei can account for the gamma ray background if their particle acceleration efficiency considerably exceeds ~ 18 per cent which would imply that particle accel

M. Ramella, A. Biviano, W. Boschin, S. Bardelli

We measure redshifts for 67 galaxies in the field of six cluster candidates from the ESO Imaging Survey (EIS). The cluster candidates are selected in the EIS patches C and D among those with estimated mean redshifts between 0.5 and 0.7. The observations were made with EFOSC2 at the 3.6m ESO telescope. In the six candidate cluster fields, we identify 19 possi

Peder Norberg, Andre Maeder

(Abriged) At present, there are two scenarios for the formation of massive stars: 1) The accretion scenario and 2) The coalescence scenario, which implies the merging of intermediate mass stars. We examine here some properties of the first one. We calculate three different sets of birthlines, i.e. tracks followed by a continuously accreting star. First, thre

Crystal Martin, Jennifer Lotz, Henry C. Ferguson

(Abridged) We present deep, narrow-band images of the redshift 0.41 galaxy cluster Abell 851 (Cl 0939+4713) which isolate [OII] 3726,29 line emission. The [OII]-selected galaxies lie within a projected clustercentric distance of 2 Mpc. The sample is complete to magnitude m_{5129}(AB) = 24.0$ for galaxies with emission-line equivalent widths greater than abou

James L. Crooks, James O. Dunn, Paul H. Frampton, Y. Jack Ng

A particular kind of quintessence is considered, with equation of motion $p_Q/ρ_Q = -1$, corresponding to a cosmological term with time-dependence $Λ(t) = Λ(t_0) (R(t_0)/R(t))^{P}$ which we examine initially for $0 \leq P < 3$. Energy conservation is imposed, as is consistency with big-bang nucleosynthesis, and the range of allowed $P$ is thereby much restri

Viktor A. Sverdlov, Alexander N. Korotkov, Konstantin K. Likharev

We have used Monte Carlo simulation to calculate the shot noise intensity $S_I(ω)$ at 2D hopping using two models: a slanted lattice of localized sites with equal energies and a set of localized sites with random positions and energies. For wide samples we have found a similar dependence of the Fano factor $F \equiv S_I(0)/2eI$ on the sample length $L$: $F \

M. G. Stepanov, L. S. Levitov

Conformal mapping models are used to study competition of noise and anisotropy in Laplacian growth. For that, a new family of models is introduced with the noise level and directional anisotropy controlled independently. Fractalization is observed in both anisotropic growth and the growth with varying noise. Fractal dimension is determined from cluster size

Yongge Ma, Yi Ling

We study the properties of $\hat{Q}[ω]$ operator on the kinematical Hilbert space ${\cal H}$ for canonical quantum gravity. Its complete spectrum with respect to the spin network basis is obtained. It turns out that $\hat{Q}[ω]$ is diagonalized in this basis, and it is a well defined self-adjoint operator on ${\cal H}$. The same conclusions are also tenable

Christof Schmidhuber

We compute the 4--dimensional cosmological constant in string compactifications in which the Standard Model fields live on a non-supersymmetric brane inside a supersymmetric bulk. The cosmological constant receives contributions only from the vacuum energy of the bulk supergravity fields, but not from the vacuum energy of the brane fields. The latter is abso

C. Joseph, D. Merritt, R. Olling, M. Valluri

We have obtained optical long-slit spectroscopy of the nucleus of M32 using the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. The stellar rotation velocity and velocity dispersion, as well as the full line-of-sight velocity distribution (LOSVD), were determined as a function of position along the slit using two independent spectral

M. Cvetic, H. Lu, C. N. Pope, J. F. Vazquez-Poritz

We obtain a large class of AdS spacetimes warped with certain internal spaces in eleven-dimensional and type IIA/IIB supergravities. The warp factors depend only on the internal coordinates. These solutions arise as the near-horizon geometries of more general semi-localised multi-intersections of $p$-branes. We achieve this by noting that any sphere (or AdS

R. Roussev, A. J. Millis

We determine the behavior of the critical temperature of magnetically mediated p-wave superconductivity near a ferromagnetic quantum critical point in three dimensions, distinguishing universal and non-universal aspects of the result. We find that the transition temperature is non-zero at the critical point, raising the possibility of superconductivity in th

Chuan-Jie Zhu

We present an exact thick domain wall solution with naked sigularities to five dimensional gravity coupled with a scalar field with exponential potential. In our solution we found exactly the special coefficient of the exponent as coming from compactification of string theory with cosmological constant. We show that this solution is self-tuning when a 3-bran

S. A. Abel, B. C. Allanach, L. Ibanez, M. Klein

We present an analysis of the low-energy implications of an intermediate scale ~10^{11} GeV string theory. We mainly focus on the evolution of the physical parameters under the renormalisation group equations (RGEs) and find several interesting new features that differ from the standard GUT scale or Planck scale scenarios. We give a general discussion of sof

G. L. Fogli, E. Lisi, D. Montanino, A. Palazzo

We discuss in detail solar neutrino oscillations with δm^2/E in the range [10^-10,10^-7] eV^2/MeV. In this range, which interpolates smoothly between the so-called ``just-so&#39;&#39; and ``Mikheyev-Smirnov-Wolfenstein&#39;&#39; oscillation regimes, neutrino flavor transitions are increasingly affected by matter effects as δm^2/E increases. As a consequence,

O. G. Miranda, C. Peã-Garay, T. I. Rashba, V. B. Semikoz

We re-analyse the resonant spin-flavour (RSF) solutions to the solar neutrino problem in the framework of analytic solutions to the solar magneto-hydrodynamics (MHD) equations. By substantially eliminating the arbitrariness associated to the magnetic field profile due to both mathematical consistency and physical requirements we propose the simplest scheme (

Jonathan L. Rosner

Some past, present, and future aspects of CP violation are reviewed. The discrete symmetries C, P, and T are introduced with an example drawn from Maxwell&#39;s Equations. The history of the discovery of CP violation in the kaon system is described briefly, and brought up-to-date with a review of recent results on kaon decays. The candidate theory of CP viol

Philippe Brax, Gautam Mandal, Yaron Oz

We construct supergravity solutions that correspond to N Dp-branes coinciding with \bar{N} \bar{Dp}-branes. We study the physical properties of the solutions and analyse the supergravity description of tachyon condensation. We construct an interpolation between the brane-antibrane solution and the Schwarzschild solution and discuss its possible application t

S. Chakravarty, R. B. Laughlin, D. K. Morr, C. Nayak

We propose that the enigmatic pseudogap phase of cuprate superconductors is characterized by a hidden broken symmetry of d(x^2-y^2)-type. The transition to this state is rounded by disorder, but in the limit that the disorder is made sufficiently small, the pseudogap crossover should reveal itself to be such a transition. The ordered state breaks time-revers

John R. Thorstensen

HS0907+1902 was recently discovered to be one of a handful of deeply eclipsing dwarf novae with periods longward of the 2 -- 3 hr `gap&#39;. This paper presents orbit-resolved spectra and time series photometry of an eclipse. The apparent velocity amplitude of the M-dwarf secondary is K_2 = 297 +- 15 km/s. The phase of the radial velocities of the H-alpha em

Kazuya Koyama, Jiro Soda

The evolution of the cosmological perturbations is studied in the context of the Randall-Sundrum brane world scenario, in which our universe is realized on a three-brane in the five dimensional Anti-de Sitter(AdS) spacetime. We develop a formalism to solve the coupled dynamics of the cosmological perturbations in the brane world and the gravitational wave in

Ulf-G. Meißner, J. A. Oller

We have studied the invariant mass distributions of the ππand K \bar{K} systems for invariant masses up to 1.2 GeV from the J/Ψ\to ϕππ(K\bar{K}) decays. The approach exploits the connection between these processes and the ππand K\bar{K} strange and non-strange scalar form factors by considering the ϕmeson as a spectator. The calculated scalar form factors ar

Gabriel Baditoiu

We classify semi-Riemannian submersions with connected totally geodesic fibres from a real pseudo-hyperbolic space onto a semi-Riemannian manifold under the assumption that the dimension of the fibres is less than or equal to three and the metrics induced on fibres are negative definite. Also, we obtain the classification of semi-Riemannian submersions with

Samuli Hemming, Esko Keski-Vakkuri

We investigate Hawking radiation from black holes in (d+1)-dimensional anti-de Sitter space. We focus on s-waves, make use of the geometrical optics approximation, and follow three approaches to analyze the radiation. First, we compute a Bogoliubov transformation between Kruskal and asymptotic coordinates and compare the different vacua. Second, following a

T. Charitat, J. F. Joanny

We propose a simple friction model for isolated polymer chains on a solid substrate. The chains are pulled at constant velocity by one end, the other end can be trapped on the solid substrate on localised sites. We focus on the energy dissipation due to the traps. This simple model leads to non trivial friction laws, depending on the velocity and the distanc

K. Suzuki, A. Hayashigaki, K. Itakura, J. Alam

We study the diffractive photo- and leptoproductions of $J / \psi$ and $\psi '$ on the proton, and examine the validity of the small-size color dipole approximation to the production of radially excited heavy quarkonium. The dipole model predicts a small ratio of $\psi '$ to $J / \psi$ photoproduction cross sections, which does not agree with experimental da

Tomohiro Harada, Hideo Iguchi, Ken-ichi Nakao

Naked singularity occurs in the gravitational collapse of an inhomogeneous dust ball from an initial density profile which is physically reasonable. We show that explosive radiation is emitted during the formation process of the naked singularity. The energy flux is proportional to $(t_{\rm CH}-t)^{-3/2}$ for a minimally coupled massless scalar field, while

Adrian P. Gentle, Daniel E. Holz, Arkady Kheyfets, Pablo Laguna

We reinvestigate the utility of time-independent constant mean curvature foliations for the numerical simulation of a single spherically-symmetric black hole. Each spacelike hypersurface of such a foliation is endowed with the same constant value of the trace of the extrinsic curvature tensor, $K$. Of the three families of $K$-constant surfaces possible (cla

Jen-Chi Lee

We study the mechanism of enhanced gauge symmetry of bosonic open string compatified on torus by analyzing the zero-norm soliton (nonzero winding of wilson line) gauge states in the spectrum. Unlike the closed string case, we find that the soliton gauge state exists only at massive levels. These soliton gauge states correspond to the existence of enhanced ma

Jen-Chi Lee

We study soliton gauge states in the spectrum of bosonic string compatified on torus. The enhenced Kac-Moody gauge symmetry, and thus T-duality, is shown to be related to the existence of these soliton gauge states in some moduli points.

Fabrizio Tamburini, Sergio Ortolani, Antonio Bianchini

This paper has been withdrawn by the author(s)

Y. Nogami, F. M. Toyama, W. van Dijk

We present a Bohmian description of a decaying quantum system. A particle is initially confined in a region around the origin which is surrounded by a repulsive potential barrier. The particle leaks out in time tunneling through the barrier. We determine Bohm trajectories with which we can visualize various features of the decaying system.

A. K. Popov

The effects of coherence of quantum transitions and the interference of resonant nonlinear optical processes on the spectra of absorption, amplification, and nonlinear-optical generation are considered. The most favorable conditions are discussed for the inversionless amplification, resonant refraction in the absence of absorption and for resonant enhancemen

L. Santos, Z. Idziaszek, J. I. Cirac, M. Lewenstein

We consider collective laser cooling of atomic gas in the Festina lente regime, when the heating effects associated with photon reabsorptions are suppressed. We demonstrate that an appropriate sequence of laser pulses allows to condense a gas of trapped bosonic atoms into the ground level of the trap in the presence of collisions. Such condensation is robust

Ashwin Nayak, Amnon Ta-Shma, David Zuckerman

One of the most intriguing facts about communication using quantum states is that these states cannot be used to transmit more classical bits than the number of qubits used, yet there are ways of conveying information with exponentially fewer qubits than possible classically. Moreover, these methods have a very simple structure---they involve little interact

Holger F. Hofmann, Takayoshi Kobayashi, Akira Furusawa

Backaction evasion measurements of a quadrature component of the light field vacuum necessarily induce quantum jumps in the photon number. The correlation between measurement results and quantum jump events reveals fundamental nonclassical aspects of quantization.

Bo Gao

We show that the highly excited rovibrational spectra of a diatomic molecule and the closely related slow atomic collision processes contain more systematics and require less parameters to characterize than the Rydberg spectrum of an atom. In the case of a single channel, for example, we show that a single short-range parameter gives a complete description o

L. Ya. Kobelev

On the base of the hypothesis about a nature of the time as a dimension of alien Universe relation between alteration of time with coordinates $\frac{\partial t}{\partial x}$ and time {t} offered: $ \frac{\partial t} {\partial x} = H_{t} t$ . This relation is an analogy of the Habble law in the time space. The consequence of it is additional redshift $Z_{DT}

L. Ya. Kobelev

We have shown in the paper that for time with fractional dimensions (multifractal time theory) there are small domain of velocities $v$ near $v=c$ where SR must be replaced by fractal theory of almost inertial system that do not contains an infinity and permits moving with arbitrary velocities.

L. Ya. Kobelev

Field equations in four order derivatives with respect to time and space coordinates based on modified classic relativistic energy of the fractal theory of time and space are received. It is shown appearing of new spin characteristics and new fields with imaginary energies .

Tae-Sun Park, Kuniharu Kubodera, Dong-Pil Min, Mannque Rho

Fundamental issues involving nuclei in the celebrated solar neutrino problem are discussed in terms of an effective field theory adapted to nuclear few-body systems, with a focus on the proton fusion process and the hep process. Our strategy in addressing these questions is to combine chiral perturbation theory -- an effective field theory of QCD -- with an

Laith Abu-Raddad

The subject of this doctoral study is the pseudoscalar meson photoproduction from nuclei. Two types of processes are investigated in this regard: coherent and quasifree processes. In the case of the coherent process, we study it for the photoproduction of pion and eta mesons. We place special emphasis on the various sources that put into question earlier non

M. B. Hecht, C. D. Roberts, S. M. Schmidt

A perspective on the contemporary use of Dyson-Schwinger equations, focusing on some recent phenomenological applications: a description and unification of light-meson observables using a one-parameter model of the effective quark-quark interaction, and studies of leptonic and nonleptonic nucleon form factors.

V. K. B. Kota, R. Sahu, K. Kar, J. M. G. Gomez

For the embedded Gaussian orthogonal ensemble (EGOE) of random matrices, the strength sums generated by a transition operator acting on an eigenstate vary with the excitation energy as the ratio of two Gaussians. This general result is compared to exact shell model calculations, with realistic interactions, of spherical orbit occupancies and Gamow-Teller str

K. Tsushima, A. Sibirtsev, K. Saito, A. W. Thomas

We discuss the effect of changes in meson properties in a nuclear medium on physical observables, notably, $J/\Psi$ dissociation on pion and $\rho$ meson comovers in relativistic heavy ion collisions, and the prediction of the $\omega$-, $\eta$- and $\eta'$-nuclear bound states.

Florin Diacu, Manuele Santoprete

The anisotropic Manev problem, which lies at the intersection of classical, quantum, and relativity physics, describes the motion of two point masses in an anisotropic space under the influence of a Newtonian force-law with a relativistic correction term. Using an extension of the Poincare&#39;-Melnikov method, we first prove that for weak anisotropy, chaos

Allen Knutson

Horn&#39;s problem was the following: given two Hermitian matrices with known spectra, what might be the eigenvalue spectrum of the sum? This linear algebra problem is exactly of the sort to be approached with the methods of modern Hamiltonian geometry (which were unavailable to Horn). The theorem linking symplectic quotients and geometric invariant theory l

Guangcun Lu

In this paper we prove the existence of a periodic motion of a charge on a large class of manifolds under the action of the magnetic fields. Our methods also give a class of closed manifolds whose cotangent bundle contain no the closed exact Lagrangian submanifolds.

Alexander Retakh

Lie conformal algebras appear in the theory of vertex algebras. Their relation is similar to that of Lie algebras and their universal enveloping algebras. Associative conformal algebras play a role in conformal representation theory. We introduce the notions of conformal identity and unital associative conformal algebras and classify finitely generated simpl

C. Ciliberto, R. Pardini, F. Tovena

Let X be a smooth complex surface of general type such that the image of the canonical map $ϕ$ of X is a surface $Σ$ and that $ϕ$ has degree $δ\geq 2$. Let $ε\colon S\to Σ$ be a desingularization of $Σ$ and assume that the geometric genus of S is not zero. Beauville has proved that in this case S is of general type and $ε$ is the canonical map of S. Beauvill

Francois Labourie

We define a fuchsian affine action of a surface group to be such that the linear part factors through a representation of $SL(2,{\mathbb R})$. We prove a fuchsian affine action of a surface group is never proper.

Alberto S. Cattaneo, Giovanni Felder

This paper has been withdrawn by the authors, due a crucial mistake in Lemma 2

S. P. Gavrilov, D. M. Gitman

We revise the problem of the quantization of relativistic particle, presenting a modified consistent canonical scheme, which allows one not only to include arbitrary backgrounds in the consideration but to get in course of the quantization a consistent relativistic quantum mechanics, which reproduces literally the behavior of the one-particle sector of the c

Daniel F. Litim

A simple criterion to optimise coarse-grainings for exact renormalisation group equations is given. It is aimed at improving the convergence of approximate solutions of flow equations. The optimisation criterion is generic, as it refers only to the coarse-grained propagator at vanishing field. In physical terms, it is understood as an optimisation condition

A. Alekseev, A. Mironov, A. Morozov

Generalization of the recent Taylor-Polchinski argument is presented, which helps to explain quantization of RR charges in IIA-like theories in the presence of cohomologically trivial H-fields.

Tanmay Vachaspati, Daniele A. Steer

Motivated by the dual standard model, we study the angular momentum spectrum of stable SU(5) dyons that can be transformed into purely electric states by a suitable duality rotation i.e. are dualizable. The problem reduces to solving a Diophantine equation for the holomorphic charges in each topological sector, but the solutions also have to satisfy certain

H. Nikolic

The Unruh effect can be correctly treated only by using the Minkowski quantization and a model of a &#34;particle&#34; detector, not by using the Rindler quantization. The energy produced by a detector accelerated only for a short time can be much larger than the energy needed to change the velocity of the detector. Although the measuring process lasts an in

D. Karczewska, R. Manka

A numerical study of coupled to the dilaton field, static, spherically symmetric monopole solutions inspired by the Kaluza-Klein theory with large extra dimensions are presented. The generalized Prasad-Sommerfield solution is obtained. We show that monopole may have also the dilaton cloud configurations.

T. Thiemann, O. Winkler

In this article we apply the methods outlined in the previous paper of this series to the particular set of states obtained by choosing the complexifier to be a Laplace operator for each edge of a graph. The corresponding coherent state transform was introduced by Hall for one edge and generalized by Ashtekar, Lewandowski, Marolf, Mourão and Thiemann to arbi

Chiang-Mei Chen, T. Harko, M. K. Mak

An anisotropic (Bianchi type I) cosmology is considered in the four-dimensional NS-NS sector of low-energy effective string theory coupled to a dilaton and an axion-like $H$-field within a de Sitter-Einstein frame background. The time evolution of this Universe is discussed in both the Einstein and string frames.

T. Thiemann, O. Winkler

In the canonical approach to Lorentzian Quantum General Relativity in four spacetime dimensions an important step forward has been made by Ashtekar, Isham and Lewandowski some eight years ago through the introduction of an appropriate Hilbert space structure. This Hilbert space, together with its generalization due to Baez and Sawin, is appropriate for semi-

T. Thiemann, O. Winkler

In the preceding paper of this series of articles we established peakedness properties of a family of coherent states that were introduced by Hall for any compact gauge group and were later generalized to gauge field theory by Ashtekar, Lewandowski, Marolf, Mourão and Thiemann. In this paper we establish the ``Ehrenfest Property&#39;&#39; of these states whi

Thomas Thiemann

In this article we outline a rather general construction of diffeomorphism covariant coherent states for quantum gauge theories. By this we mean states $ψ_{(A,E)}$, labelled by a point (A,E) in the classical phase space, consisting of canonically conjugate pairs of connections A and electric fields E respectively, such that (a) they are eigenstates of a corr

T. Thiemann

Interesting non-linear functions on the phase spaces of classical field theories can never be quantized immediately because the basic fields of the theory become operator valued distributions. Therefore, one is usually forced to find a classical substitute for such a function depending on a regulator which is expressed in terms of smeared quantities and whic

Walter Dittrich

We compute the quantum vacuum polarization for a pure neutral scalar field theory within the context of single-particle quantum mechanics. The loop diagram is computed without ever encountering loop-momentum integrals. Our approach is based on standard Feynman path integrals. Contact is made to scalar QED.

D. Dalmazi, J. J. M Verbaarschot

We investigate the replica trick for the microscopic spectral density, $ρ_s(x)$, of the Euclidean QCD Dirac operator. Our starting point is the low-energy limit of the QCD partition function for $n$ fermionic flavors (or replicas) in the sector of topological charge $ν$. In the domain of the smallest eigenvalues, this partition function is simply given by a

Luis M. A. Bettencourt

I consider several Langevin and Fokker-Planck classes of dynamics for scalar field theories in contact with a thermal bath at temperature T. These models have been applied recently in the numerical description of the dynamics of second order phase transitions and associated topological defect formation as well as in other studies of these critical phenomena.

Graciela B. Gelmini

Relic neutrinos with mass in the range indicated by Super-Kamiokande results if neutrino masses are hierarchial (about 0.07 eV) are many times deemed too light to be cosmologically relevant. Here we remark that these neutrinos may significantly contribute to the dark matter of the Universe (with a large lepton asymmetry $L$) and that their existence might be

Kiwoon Choi, Eung Jin Chun, Kyuwan Hwang

We examine some flavor changing processes such as rare leptonic decays of the long-lived neutral kaon, muon-electron conversion in nuclei and radiative muon decay which are induced by the combined effects of bilinear and trilinear R-parity violations. These processes are used to put strong constraints on certain products of the bilinear and trilinear couplin

A. Martin

I try to describe the extremely fruitful interaction I had with Harry Lehmann and the results which came out of the analyticity unitarity programme, especially the proof of the Froissart bound, which, with recent and future measurements of total cross-sections and real parts, remains topical.

Subir Sarkar

The possibility that the Fermi scale is the only fundamental energy scale of Nature is under serious consideration at present, yet cosmic rays may already have provided direct evidence of new physics at a much higher scale. The recent detection of very high energy particles with no plausible astrophysical sources suggests that these originate from the slow d

E. A. Paschos, L. Pasquali, J. Y. Yu

We calculate single pion production by neutrinos in the resonance region. We consider both charged and neutral current reactions on free protons and neutrons. We present differential and total cross sections which can be compared with experiments. Then we use these results to calculate the spectra of the emerging pions including the Pauli suppression factor

Jungil Lee

The polarization of prompt J/psi at the Tevatron is calculated within the nonrelativistic QCD (NRQCD) factorization framework. The contribution from radiative decays of P-wave charmonium states decreases, but does not eliminate, the transverse polarization at large transverse momentum. The prediction agrees with measurements from the CDF collaboration at int

Y. Sumino

We investigate gauge dependence of a nonrelativistic boundstate formalism used in contemporary calculations. It is known that the effective Hamiltonian of the boundstate system depends on the choice of gauge. We obtain the gauge transformation charge of the Hamiltonian, by which gauge independence of the mass spectrum and gauge dependences of the boundstate

Muneyuki Ishida, Toshihiko Komada, Shin Ishida, Taku Ishida

The pi0 pi0 mass spectra and angular distributions around KKbar -threshold and at 1.5 GeV in ppbar (at rest) --> 3 pi0 in the Crystal Barrel experiment are reanalyzed by applying the new method, which is consistent with unitarity of S-matrix and expressed directly by resonance parameters. The effects of light sigma-meson production are clearly seen to improv

J. W. Moffat

A quantum field theory formalism is reviewed that leads to a self-consistent, finite quantum gravity, Yang-Mills and Higgs theory, which is unitary and gauge invariant to all orders of perturbation theory. The gauge hierarchy problem is solved due to the exponential damping of the Higgs self-energy loop graph for energies greater than a scale $Λ_H\leq 1$ TeV

B. Schlittgen, U. -J. Wiese

We formulate the two-dimensional principal chiral model as a quantum spin model, replacing the classical fields by quantum operators acting in a Hilbert space, and introducing an additional, Euclidean time dimension. Using coherent state path integral techniques, we show that in the limit in which a large representation is chosen for the operators, the low e

Thorsten Wengler

The structure of the photon is studied in photon-photon collisions at LEP. New measurements have become available exploring the structure function F2g of the photon to the lowest values of x yet, where the hadronic component of the photon is most important. Inclusive cross sections for charged D* have been measured as a function of their transverse momenta a

The FOCUS collaboration

A high statistics sample of photoproduced charm particles from the FOCUS (E831) experiment at Fermilab has been used to search for CP violation in the Cabibbo suppressed decay modes D+ to K-K+pi+, D0 to K-K+ and D0 to pi-pi+. We have measured the following CP asymmetry parameters: A_CP(K-K+pi+) = +0.006 +/- 0.011 +/- 0.005, A_CP(K-K+) = -0.001 +/- 0.022 +/-