November 1999 arXiv papers

Philip C. Argyres, Sophie Pelland

We discuss the general issues and ambiguities involved in matching the exact results for the low energy effective action of scale invariant N=2 supersymmetric QCD to those obtained by instanton methods. We resolve the reported disagreements and verify agreement between an infinite series of coefficients in the low energy effective actions calculated in the t

J. C. Lopez V., A. Turbiner

Using a variational method we study a sequence of the one-electron atomic and molecular-type systems H, H_2^+, H_3^(2+) and H_4^(3+) in the presence of a homogeneous magnetic field ranging B = 0 - 4.414x10^{13} G. These systems are taken as a linear configuration aligned with the magnetic lines. For H_3^(2+) the potential energy surface has a minimum for B\s

Cristopher Moore, M. E. J. Newman

We study some simple models of disease transmission on small-world networks, in which either the probability of infection by a disease or the probability of its transmission is varied, or both. The resulting models display epidemic behavior when the infection or transmission probability rises above the threshold for site or bond percolation on the network, a

S. J. Puglia, M. J. Ramsey-Musolf

We address the impact of treating the decuplet of spin-3/2 baryons as an explicit degree of freedom in the chiral expansion of the magnetic moments of the octet of spin-1/2 baryons. We carry out a complete calculation of the octet moments to O(1/\lamchic), including decuplet contributions to the chiral loops. In contrast to results of previous analyses, we f

A. Alonso-Herrero, G. H. Rieke, M. J. Rieke, N. Z. Scoville

We present a comprehensive study of the star-formation properties of the infrared luminous galaxy Arp299 (IC694 + NGC3690). The observations include HST/NICMOS imaging and MMT optical and near-infrared spectroscopy together with HST archival data. We correct the galaxy parameters for extinction and use the results as boundary conditions for evolutionary star

W. Coburn, W. A. Heindl, J. Wilms, D. E. Gruber

A failed main-on in the 35d cycle of Her X-1 was observed with the Rossi X-Ray Timing Explorer (RXTE) on 1999 April 26. Exceptions to the normal 35d cycle have been seen only twice before; in 1983 and again 1993. We present timing and spectral results of this latest Anomalous Low State (ALS) along with comparisons to the main-on and normal low states. Pulsat

Shinya Kanemura

The production process of the charged Higgs-boson associated with a $W$ boson at electron-positron colliders is discussed in the two-Higgs-Doublet Model (2HDM) and in the Minimal Supersymmetric Standard Model (MSSM). The process is induced at one-loop level in these models. We examine how much the cross section can be enhanced by quark- and Higgs-loop effect

Eldon G. Emberly, George Kirczenow

In this paper we address the topic of inelastic electron scattering in mesoscopic quantum transport. For systems where only elastic scattering is present, Landauer theory provides an adequate description of transport that relates the electronic current to single-particle transmission and reflection probabilities. A formalism proposed recently by Bonca and Tr

G. Papadopoulos, J. Russo, A. A. Tseytlin

We describe a simple method for generating new string solutions for which the brane worldvolume is a curved space. As a starting point we use solutions with NS-NS charges combined with 2-d CFT's representing different parts of space-time. We illustrate our method with many examples, some of which are associated with conformally invariant sigma models. Us

E. Ivanov, S. Krivonos, F. Toppan

The local Sugawara constructions of the "small" N=4 SCA in terms of supercurrents of N=2 extensions of the affinization of the sl(2|1) and sl(3) algebras are investigated. The associated super mKdV type hierarchies induced by N=4 SKdV ones are defined. In the sl(3) case the existence of two inequivalent Sugawara constructions is found. The long one i

Trinh Xuan Hoang, Marek Cieplak

We consider six different secondary structures of proteins and construct two types of Go-type off-lattice models: with the steric constraints and without. The basic aminoacid-aminoacid potential is Lennard Jones for the native contacts and a soft repulsion for the non-native contacts. The interactions are chosen to make the target secondary structure be the

Supriya Kar

The non-commutative geometry is revisited from the perspective of a generalized D p-brane. In particular, we analyze the open bosonic string world-sheet description and show that an effective non-commutative description on a D p-brane corresponds to a re-normalized world-volume. The world-volume correlators are analyzed to make a note on the non-commutative

John H. Reina, Luis Quiroga, Neil F. Johnson

We show how optically-driven coupled quantum dots can be used to prepare maximally entangled Bell and Greenberger-Horne-Zeilinger states. Manipulation of the strength and duration of the selective light-pulses needed for producing these highly entangled states provides us with crucial elements for the processing of solid-state based quantum information. Theo

Sergio De Filippo

Only craziness I am ashamed about.

Inbo Kim, Chil-Min Kim, Won-Ho Kye, Young-Jai Park

We study the phase synchronization (PS) with type-II intermittency showing $\pm 2 π$ irregular phase jumping behavior before the PS transition occurs in a system of two coupled hyperchaotic Rössler oscillators. The behavior is understood as a stochastic hopping of an overdamped particle in a potential which has $2 π$-periodic minima. We characterize it as ty

Stefan Weinzierl, Oleg Yakovlev

The semileptonic decay B -> pi l nu is one of the most important reactions for the determination of the CKM matrix element |V_{ub}|. However, in order to extract |V_{ub}| from data one needs an accurate theoretical calculation of the hadronic matrix element describing the B to pi transition. QCD sum rules, based on operator-product expansion on the light-con

E. Gabrielli

We perform a model independent analysis so as to constrain the leptoquark (LQ) models from negative searches for $μ\to e γ$, $μ\to 3e$ decays (and analogous processes in the $τ$ sector), and coherent $μ-e$ conversion in nuclei. We considerably improve some constraints obtained by analyses known in the literature, analyses which we show have by far underestim

Kimberly C. B. New, Joan M. Centrella, Joel E. Tohline

Compact astrophysical objects that rotate rapidly may encounter the dynamical ``bar instability.'' The bar-like deformation induced by this rotational instability causes the object to become a potentially strong source of gravitational radiation. We have carried out a set of long-duration simulations of the bar instability with two Eulerian hydrodyna

Mario Vietri

The discovery of GRBs' afterglows has allowed us to establish several facts: their distance and energy scales, the fact that they are due to explosions, that the explosions are relativistic, and that the afterglow emission mechanism is synchrotron radiation. On the other hand, recent data have shown that the fireball model is wrong when it comes to the emiss

G. E. Volovik

We discuss two exotic objects, which must be experimentally identified in chiral superfluids and superconductors. These are (i) the vortex with fractional quantum number (N=1/2 in chiral superfluids, and N=1/2 and N=1/4 in chiral superconductors), which plays the part ofthe Alice string in relativistic theories; and (ii) the hedgehog in the l-field, which is

M. Billo', A D'Adda, P. Provero

We quantize pure 2d Yang-Mills theory on an arbitrary Riemann surface in the gauge where the field strength is diagonal. Twisted sectors originate, as in Matrix string theory, from permutations of the eigenvalues around homotopically non-trivial loops. These sectors, that must be discarded in the usual quantization due to divergences occurring when two eigen

Claudia Isola, T. N. Pham

We analyse the $B \to Kπ$ decays using the factorisation model with final state interaction phase shift included. We find that factorisation seems to describe qualitatively the latest CLEO data. For a test of the factorisation model, we derive a relation for the branching ratios independent of the strength of the strong penguin interactions. This relation gi

J. D. Bekenstein, M. Milgrom, R. H. Sanders

In a significant recent paper A. Edery undertakes a new study of light deflection in generalizations of general relativity (GR). He claims to prove that any metric-based gravitational theory that proposes to explain the flat rotation curves of disk galaxies without postulating dark matter halos must conflict with observations of gravitational lensing by gala

A. Gordon, J. E. Avron

We consider the Born-Oppenheimer problem near conical intersection in two dimensions. For energies close to the crossing energy we describe the wave function near an isotropic crossing and show that it is related to generalized hypergeometric functions 0F3. This function is to a conical intersection what the Airy function is to a classical turning point. As

A. T. Doyle

Analyses of event shapes and forward jet production in deep inelastic scattering at the HERA collider are described. The results are compared to QCD predictions.

J. Böckenhauer, D. E. Evans

A braided subfactor determines a coupling matrix Z which commutes with the S- and T-matrices arising from the braiding. Such a coupling matrix is not necessarily of "type I", i.e. in general it does not have a block-diagonal structure which can be reinterpreted as the diagonal coupling matrix with respect to a suitable extension. We show that there a

Shmuel Nussinov, Melissa A. Lampert

We review the subject of QCD inequalities, using both a Hamiltonian variational approach, and a rigorous Euclidean path integral approach.

Wei-Shu Hou, Kwei-Chou Yang

The newly observed $\bar B^0 \to \bar K^0π^0$ mode is quite sizable while $π^-π^+$ is rather small. Data also hint at $π^-π^0 \gtrsim π^-π^+$. Though consistent with zero, central values of CP violating asymmetries in $K^-π^{+,0}$ and $\bar K^0π^-$ show an interesting pattern. Taking cue from these, we suggest that, besides $γ\equiv {\rm arg} (V_{ub}^*)$ bei

Yutaka Fujita, Tomoka Tosaki, Akika Nakamichi, Nario Kuno

We have searched for molecular gas in the cD galaxy of a poor cluster of galaxies AWM7 using Nobeyama 45 m telescope. We do not detect CO emission in the galaxy. Our limit of molecular gas in the inner 7.5 kpc is M_H_2< 4 x 10^8 M_sun. We estimate the total mass of molecular gas left in the cD galaxy when the gas deposited by a cooling flow once becomes mole

Minxin Huang, Yongde Zhang, Guang Hou

We consider the transmission of classical information over a quantum channel by two senders. The channel capacity region is shown to be a convex hull bound by the Von Neumann entropy and the conditional Von Neumann entropy. We discuss some possible applications of our result. We also show that our scheme allows a reasonable distribution of channel capacity o

Shin&#39;ichirou Yoshida, Yoshiharu Eriguchi

We have investigated an influence of the r-mode instability on hypercritically accreting ($\dot{M}\sim 1M_\odot {y}^{-1}$) neutron stars in close binary systems during their common envelope phases based on the scenario proposed by Bethe et al. \shortcite{bethe-brown-lee}. On the one hand neutron stars are heated by the accreted matter at the stellar surface,

Masaki Mori, S. A. Dazeley, P. G. Edwards, S. Gunji

The CANGAROO-III project,which consists of an array of four 10 m imaging Cherenkov telescopes,has just started being constructed in Woomera, South Australia,in a collaboration between Australia and Japan. The first stereoscopic observation of celestial high-energy gamma-rays in the 100 GeV region with two telescopes will start in 2002,and the four telescope

Seiji Terashima

We derive a BPS-type bound for four-dimensional Born-Infeld action with constant B field background. The supersymmetric configuration saturates this bound and is regarded as an analog of instanton in U(1) gauge theory. Furthermore, we find the explicit solutions of this BPS condition. These solutions have a finite action proportional to the instanton number

A. A. Tseytlin, K. Zarembo

There is a close relation between classical supergravity and quantum SYM descriptions of interactions between separated branes. In the case of D3 branes, the equivalence of leading-order potentials is due to non-renormalization of the F^4 term in N=4 SYM theory. Here we point out the existence of another special non-renormalized term in quantum SYM effective

E. Harikumar, M. Sivakumar

We analyse the equivalence between topologically massive gauge theory (TMGT) and different formulations of non-topologically massive gauge theories (NTMGTs) in the canonical approach. The different NTMGTs studied are Stückelberg formulation of (A) a first order formulation involving one and two form fields, (B) Proca theory, and (C) massive Kalb-Ramond theor

Tsutom Hasuike, Toshihiko Hattori, Seiichi Wakaizumi

CP violation in semileptonic top-quark decay is investigated by exactly using one charged- and three neutral-Higgs bosons obtained by solving the Higgs mass matrix in two-Higgs doublet model. The CP-violating up-down asymmetry of leptons from $W$ boson decays is shown to be $1 \times 10^{-4} - 4 \times 10^{-3}$ for the region of ${\rm tan} β\ll 1$, where ${\

Kei-Ichi Kondo, Yutaro Taira

We derive a new version of the non-Abelian Stokes theorem for the Wilson loop in the SU(N) case by making use of the coherent state representation on the coset space $SU(N)/U(1)^{N-1}=F_{N-1}$, the flag space. We consider the SU(N) Yang-Mills theory in the maximal Abelian gauge in which SU(N) is broken down to $U(1)^{N-1}$. First, we show that the Abelian do

Richard Cleve

We consider the problem where P is an unknown permutation on {0,1,...,2^n - 1}, y is an element of {0,1,...,2^n - 1}, and the goal is to determine the minimum r > 0 such that P^r(y) = y (where P^r is P composed with itself r times). Information about P is available only via queries that yield P^x(y) from any x in {0,1,...,2^m - 1} and y in {0,1,...,2^n - 1}

Klaus Kroy, Isabelle Capron, Madeleine Djabourov

Combining direct computations with invariance arguments, Taylor&#39;s constitutive equation for an emulsion can be extrapolated to high shear rates. We show that the resulting expression is consistent with the rigorous limits of small drop deformation and that it bears a strong similarity to an a priori unrelated rheological quantity, namely the dynamic (fre

J. C. Lemm

Nonparametric Bayesian approaches based on Gaussian processes have recently become popular in the empirical learning community. They encompass many classical methods of statistics, like Radial Basis Functions or various splines, and are technically convenient because Gaussian integrals can be calculated analytically. Restricting to Gaussian processes, howeve

G. Do Dang, A. Klein, N. R. Walet

The goal of the present account is to review our efforts to obtain and apply a ``collective&#39;&#39; Hamiltonian for a few, approximately decoupled, adiabatic degrees of freedom, starting from a Hamiltonian system with more or many more degrees of freedom. The approach is based on an analysis of the classical limit of quantum-mechanical problems. Initially,

Vladimir Dragovic, Borislav Gajic

We present an L-A pair for the Apel&#39;rot case of a heavy rigid 3-dimensional body. Using it we give an algebro-geometric integration procedure. Generalizing this L-A pair, we obtain a new completely integrable case of the Euler-Poisson equations in dimension four. Explicit formulae for integrals which are in involution are given. This system is a countere

Jasbir Chahal, Matthijs Meijer, Jaap Top

Using some theory of (rational) elliptic surfaces plus elementary properties of a Mordell-Weil group regarded as module over the endomorphism ring of a (CM) elliptic curve, we present examples of such surfaces with j-invariant zero. In particular, a K3 example is given with the maximal possible rank 18, plus that many explicit independent sections on it. Sev

A. N. Dranishnikov, T. Januszkiewicz

Coxeter groups admit amenable actions on compact spaces. Moreover, they have finite asymptotic dimension.

Deepak Parashar, Roger J. McDermott

This paper suveys some recent algebraic developments in two parameter Quantum deformations and their Nonstandard (or Jordanian) counterparts. In particular, we discuss the contraction procedure and the quantum group homomorphisms associated to these deformations. The scheme is then set in the wider context of the coloured extensions of these deformations, na

Charles Livingston, Swatee Naik

Let K be a knot in the 3-sphere with 2-fold branched covering space M. If for some prime p congruent to 3 mod 4 the p-torsion in the first homology of M is cyclic with odd exponent, then K is of infinite order in the knot concordance group. As one application, recall that the n-twisted double of an arbitrary knot has order 4 in Levine&#39;s algebraic concord

Alexander Rashkovskii

A notion of indicator for a plurisubharmonic function u of logarithmic growth in C^n is introduced and studied. It is applied to evaluation of the total Monge-Ampère measure (dd^cu)^n({C}^n). Upper bounds for the measure are obtained in terms of growth characteristics of u. When u=log|f| for a polynomial mapping f with isolated zeros, the indicator generates

Alex Iosevich, Nets Hawk Katz, Terence Tao

We prove that no smooth symmetric convex body $Ω$ with at least one point of non-vanishing Gaussian curvature can admit an orthogonal basis of exponentials. (The non-symmetric case was proven by Kolountzakis). This is further evidence of Fuglede&#39;s conjecture, which states that such a basis is possible if and only if $Ω$ can tile $R^d$ by translations.

Apoloniusz Tyszka

Let M denote the ideal of first category subsets of R. We prove that min{card X: X \subseteq R, X \not\in M} is the smallest cardinality of a family S \subseteq {0,1}^ωwith the property that for each f: ω-> \bigcup_{n \in ω}{0,1}^n there exists a sequence {a_n}_{n \in ω} belonging to S such that for infinitely many i \in ωthe infinite sequence {a_{i+n}}_{n \

John Lott

We define and study the signature, A-hat genus and higher signatures of the quotient space of an $S^1$-action on a closed oriented manifold. We give applications to questions of positive scalar curvature and to an Equivariant Novikov Conjecture.

J. T. Lunardi, B. M. Pimentel, R. G. Teixeira, J. S. Valverde

Two problems relative to the electromagnetic coupling of Duffin-Kemmer-Petiau (DKP) theory are discussed: the presence of an anomalous term in the Hamiltonian form of the theory and the apparent difference between the Interaction terms in DKP and Klein-Gordon (KG) Lagrangians. For this, we first discuss the behavior of DKP field and its physical components u

Ian I. Kogan, John F. Wheater

We discuss some possible relationships in gauge theories, string theory and M theory in the light of some recent results obtained in gauge invariant supersymmetric quantum mechanics. In particular this reveals a new relationship between the gauge group E_8 and 11-dimensional space.

L. Hadasz, G. Lambiase, V. V. Nesterenko

The Casimir energy of a non-uniform string built up from two pieces with different speed of sound is calculated. A standard procedure of subtracting the energy of an infinite uniform string is applied, the subtraction being interpreted as the renormalization of the string tension. It is shown that in the case of a homogeneous string this method is completely

I. B. Pestov

The Kähler-Dirac equation is derived on the Weitzenböck space-time, which has a quadruplet of parallel vector fields as the fundamental structure. A consistent system of equations for the Kähler fields and parallel vector fields is obtained. Key words: teleparallelism, fermions, internal symmetry, equations.

Paul Haney, John R. Hiller, Oleg Lunin, Stephen Pinsky

We consider supersymmetric Yang-Mills theory on R x S^1 x S^1. In particular, we choose one of the compact directions to be light-like and another to be space-like. Since the SDLCQ regularization explicitly preserves supersymmetry, this theory is totally finite, and thus we can solve for bound state wave functions and masses numerically without renormalizing

Christian Fronsdal

The first half is a rapid review of 30 years of work on physics in anti-De Sitter space, with heavy emphasis on singletons. Principal topics are the kinematical basis for regarding singletons as the constituents of massless particles, and the effect of (negative) curvature in the infrared domain. Ideas that lead to an alternative to Big Bang cosmology are me

C. I. Lazaroiu

We generalize the recently proposed noncommutative ADHM construction to the case of $Γ$-equivariant instantons over $\R^4$, with $Γ$ a Kleinian group. We show that a certain form of the inhomogeneous ADHM equations describes instantons over a noncommutative deformation of the Kleinian orbifold $\C^2/Γ$ and we discuss the relation of this with Nakajima&#39;s

Abdel Pérez-Lorenzana, William A. Ponce

We look for a connection between string theories and Grand Unified Theories (GUTs), with the aim to look for new insights in the existing four dimensional string-GUT problems. We argue that the construction of consistent string-GUT models could require the use of non canonical affine levels. We list the most common level values related to realistic GUTs.

G. S. Krishnaswami

We present a model for the structure of baryons in which the valence partons interact through a linear potential. This model can be derived from QCD in the approximation where transverse momenta are ignored. We compare the valence quark distribution function predicted by our model with that extracted from global fits to Deep Inelastic Scattering data. The on

F. J. Cao, H. J. de Vega

The dynamics of a dense relativistic quantum fluid out of thermodynamic equilibrium is studied in the framework of the Phi^4 scalar field theory in the large N limit. The time evolution of a particle distribution in momentum space (the tsunami) is computed. The effective mass felt by the particles in such a high density medium equals the tree level mass plus

Gennaro Corcella, Michael H. Seymour

We show vector boson transverse momentum distributions at the Tevatron, obtained by running the HERWIG Monte Carlo event generator with matrix-element corrections. We compare our results with some recent D0 and CDF data.

M. Maltoni, V. A. Novikov, L. B. Okun, A. N. Rozanov

The existence of extra chiral generations with all fermions heavier than M_Z is strongly disfavoured by the precision electroweak data. However the data are fitted nicely even by a few extra generations, if one allows neutral leptons to have masses close to 50 GeV. The data allow inclusion of one additional generation of heavy fermions in SUSY extension of S

N. N. Achasov, A. A. Kozhevnikov

Based on the Weinberg lagrangian or, in a new language, the lagrangian of hidden local symmetry added with the term induced by the anomalous lagrangian of Wess and Zumino, the dynamics of the decays rho to 4 pi and omega to 5 pi is considered. The excitation curves of rho resonance in its decay to 4 pi are obtained for the first time. The comparison with rec

Stefan Weinzierl

We report on the next-to-leading order QCD calculation for e+ e- --> 4 jets. We explain some modern techniques which have been used to calculate the one-loop amplitudes efficiently. We further report on the general purpose numerical program ``Mercutio&#39;&#39;, which can be used to calculate any infrared safe four-jet quantity in electron-positron annihilat

X. -H. Guo, A. W. Thomas, A. G. Williams

Corrections of order 1/m_Q (Q=b or c) to the Bethe-Salpeter (B-S) equation for \Lambda_Q are analyzed on the assumption that the heavy baryon \Lambda_Q is composed of a heavy quark and a scalar, light diquark. It is found that in addition to the one B-S scalar function in the limit m_Q -> \infty, two more scalar functions are needed at the order 1/m_Q. These

A. Chuvakin, J. Smith

A study is made of charm and bottom flavor matching conditions on parton densities. Starting from an $\bar{\rm MS}$ three-flavor density set, where the scale $μ< m_c$, and using the recently derived two-loop matching conditions, we provide a new set of four-flavor parton densities where $ m_c \le μ< m_b$ and five-flavor densities where $μ\ge m_b$. The effect

M. Consoli, F. Siringo

We propose a description of {\it Newtonian} gravity as a long wavelength excitation of the scalar condensate inducing electroweak symmetry breaking. Indeed, one finds a $-{{G_F}\overη}{{m_im_j}\over{r}}$ long-range potential where $G_F$ is the Fermi constant and $η\equiv {{M^2_h}\over{2m^2}} $ is determined by the ratio between the Higgs mass $M_h$ and the m

Harry J. Lipkin

The role of simple quantum mechanics in understanding neutrino oscillation experiments is pointed out by comparison with two-slit and Bragg scattering experiments. The importance of considering the beam and the detector as a correlated quantum system is emphasized. Quantum mechanics alone shows that the difference observed in the same neutrino detector at Su

M. Anikina, L. Chkhaidze, T. Djobava, V. Garsevanishvili

The light front analysis of pi^{-} mesons in He(Li,C), C-Ne, C-Cu and O-Pb collisions is carried out. The phase space of secondary pions is divided into two parts in one of which the thermal equilibrium assumption seems to be in a good agreement with the data. Corresponding temperatures T are extracted and their dependence on (A_{P}*A_{T})^{1/2} is studied.

Sung Won Lee

We present results for the photoproduction of inclusive prompt photons and for prompt photons accompanied by jets, measured with the ZEUS detector at HERA. Cross sections as a function of pseudorapidity and transverse energy are presented for 5 < E_T^γ< 10 GeV, E_T^{jet} > 5 GeV in the centre of mass energy range 120-270 GeV. Comparisons are made with predic

N. Macdonald

The dijet cross section as a function of both the fraction of the photon momentum participating in the hard process, x_γ^{OBS}, and the photon&#39;s virtuality, Q^2, is compared with the predictions of Herwig 5.9 for various photon parton distribution functions. The ratio of dijet cross sections with x_γ^{OBS} < 0.75 and x_γ^{OBS} > 0.75 is measured as a fun

N. Macdonald

Measurements sensitive to the structure of both real and virtual photons are presented and compared to theoretical models with various photon parton distribution functions (PDFs). Measurements for real photons show a tendency for the available photon PDFs to be too small to describe the data. For virtual photons, the photon PDF is seen to decrease with incre

J. Vaitkus, E. Gaubas, V. Kazukauskas, V. Rinkevicius

Different methods of trap parameter measurement are analysed. Transient photoconductivity and thermally stimulated effects were used to investigate the influence of traps in LEC SI-GaAs and high resistivity epitaxial GaAs. The peculiarities of the TSC were analysed and shown to be related to the influence of crystal micro-inhomogeneities.

N. H. Brook

The parton spectra as predicted by the ARIADNE Monte Carlo generator, for both e+e- annihilation and deep inelastic scattering, are compared to the QCD MLLA calculations.

Klaus Moenig

Collider measurements on electroweak physics are summarised. Although the precision on some observables is very high, no deviation from the Standard Model of electroweak interactions is observed. The data allow to set stringent limits on some models for new physics.

C. Chicone, B. Mashhoon, D. G. Retzloff

The general phenomena associated with sustained resonance are studied in this paper in connection with relativistic binary pulsars. We represent such a system by two point masses in a Keplerian binary system that evolves via gravitational radiation damping as well as an external tidal perturbation. For further simplification, we assume that the external tida

A. Yu. Neronov

We consider cosmological models in which a homogeneous isotropic universe is embedded as a 3+1 dimensional surface into a 4+1 dimensional manifold. The size of the extra dimension depends on time. It is small compared to the size of the universe only if the energy of gravitational self-interaction of the universe through the compact extra dimension dominates

Jerzy Lewandowski, Andrzej Okolow

We introduce a new spinorial, BF-like action for the Einstein gravity. This is a first, up to our knowledge, 2-form action which describes the real, Lorentzian gravity and uses only the self-dual connection. In the generic case, the corresponding classical canonical theory is equivalent to the Einstein-Ashtekar theory plus the reality conditions.

V. Dzhunushaliev, D. Singleton

Several electric/magnetic charged solutions (dyons) to 5D Kaluza-Klein gravity on the principal bundle are reviewed. Here we examine the possibility that these solutions can act as quantum virtual wormholes in spacetime foam models. By applying a sufficently large, external electric and/or magnetic field it may be possible to ``inflate&#39;&#39; these soluti

Zhong Chao Wu

In gravitational thermodynamics, the entropy of a black hole with distinct surface gravities can be evaluated in a microcanonical ensemble. At the $WKB$ level, the entropy becomes the negative of the Euclidean action of the constrained instanton, which is the seed for the black hole creation in the no-boundary universe. Using the Gauss-Bonnet theorem, we pro

D. V. Dmitriev, V. Ya. Krivnov, A. A. Ovchinnikov

The stability of the ferromagnetic phase of the 2D quantum spin-1/2 model with nearest-neighbor ferro- and next-nearest neighbor antiferromagnetic interactions is studied. It turns out that values of exchange integrals at which the ferromagnetic state becomes unstable with respect to a creation of one and two magnon are different. This difference shows that

N. I. Karchev, K. B. Blagoev, K. S. Bedell, P. B. Littlewood

In this paper we address the question of coexistence of superconductivity and ferromagnetism in the high temperature superconductor RuSr$_2$GdCu$_2$O$_{8-δ}$. Using a field theoretical approach we study a one-fermion effective model of a ferromagnetic superconductor in which the quasiparticles responsible for the ferromagnetism form the Cooper pairs as well.

Niurka R. Quintero, Angel Sanchez, Franz G. Mertens

We investigate the non-parametric, pure ac driven dynamics of nonlinear Klein-Gordon solitary waves having an internal mode of frequency $Ω_i$. We show that the strongest resonance arises when the driving frequency $δ=Ω_i/2$, whereas when $δ=Ω_i$ the resonance is weaker, disappearing for nonzero damping. At resonance, the dynamics of the kink center of mass

M. Fornari, N. Marzari, M. Peressi, A. Baldereschi

We investigate the electronic structure of over-coordinated defects in amorphous silicon via density-functional total-energy calculations, with the aim of understanding the relationship between topological and electronic properties on a microscopic scale. Maximally-localized Wannier functions are computed in order to characterize the bonding and the electron

Masanori Kohno, Masatoshi Imada

We investigate the effects of suppression of single-particle dispersion near the Fermi level on the spin gap and the singlet-pairing correlation by using the exact diagonalization method for finite-size systems. We consider strongly correlated one-dimensional models, which have flat band dispersions near wave number k=π/2, if the interactions are switched of

Alessandro Cuccoli, Valerio Tognetti, Paola Verrucchi, Ruggero Vaia

Using the PQSCHA semiclassical method, we evaluate thermodynamic quantities of one-dimensional Heisenberg ferro- and antiferromagnets. Since the PQSCHA reduces their evaluation to classical-like calculations, we take advantage of Fisher&#39;s exact solution to get all results in an almost fully analytical way. Explicitly considered here are the specific heat

I. Borukhov, D. Andelman, H. Orland

The behavior of electrolyte solutions close to a charged surface is studied theoretically. A modified Poisson-Boltzmann equation which takes into account the volume excluded by the ions in addition to the electrostatic interactions is presented. In a formal lattice gas formalism the modified Poisson-Boltzmann equation can be obtained from a mean-field approx

K. Doll, N. M. Harrison

We investigate the adsorption of chlorine on the Cu(111) surface with full potential all-electron density functional calculations. Chlorine adsorption at the fcc hollow sites is slightly preferred over that at the hcp hollow. The adsorption geometry is in excellent agreement with electron diffraction and ion scattering data. Adsorption energies and surface d

F. Igloi, R. Juhasz, H. Rieger

We study XY and dimerized XX spin-1/2 chains with random exchange couplings by analytical and numerical methods and scaling considerations. We extend previous investigations to dynamical properties, to surface quantities and operator profiles, and give a detailed analysis of the Griffiths phase. We present a phenomenological scaling theory of average quantit

Tom Busche, Peter Kopietz

We calculate the effect of a quadratic term in the energy dispersion on the low-energy behavior of the Green&#39;s function of the spinless Tomonaga-Luttinger model (TLM). Assuming that for small wave-vectors q = k - k_F the fermionic excitation energy relative to the Fermi energy is v_F q + q^2 / (2m), we explicitly calculate the single-particle Green&#39;s

Matteo Calandra, Sandro Sorella

We have found that the two dimensional t-J model, for the physical parameter range J/t = 0.4 reproduces the main experimental qualitative features of High-Tc copper oxide superconductors: d-wave superconducting correlations are strongly enhanced upon small doping and clear evidence of off diagonal long range order is found at the optimal doping δ~ 0.15. On t

Viktor Dotsenko

In this paper we present the exact solution for the average minimum energy of the random bipartite matching model with an arbitrary finite number of elements where random paired interactions are described by independent exponential distribution. This solution confirms the Parisi conjecture proposed for this model earlier, as well as the result of the replica

C. P. Burgess, Rim Dib, Brian P. Dolan

We show that, for the transition between any two quantum Hall states, the semi-circle law and the existence of a duality symmetry follow solely from the consistency of the law of corresponding states with the two-dimensional scaling flow. This puts these two effects on a sound theoretical footing, implying that both should hold exactly at zero temperature, i

J. Gilchrist

Dielectric permittivity of KH2PO4 single crystals and pressed powders was measured in the presence of dc electric bias fields. Usually if the bias was switched at time t = 0, real and imaginary permittivity jumped to new values then decreased as logt . This well-known &#39;glassy&#39; effect is attributed to switchable microdomains that are present accidenta

Toshiaki Aida

On-line learning of probability distributions is analyzed from the field theoretical point of view. We can obtain an optimal on-line learning algorithm, since renormalization group enables us to control the number of degrees of freedom of a system according to the number of examples. We do not learn parameters of a model, but probability distributions themse

Klaus Voelker

The influence of gapless dissipative degrees of freedom on the superconductor-insulator transition in two dimensions is investigated. We develop a series expansion for the free energy of a (2+1)-dimensional XY model coupled to a bosonic heat bath that can be approximately summed to all orders. The calculation explicitly conserves topological excitations. We

L. Chayes, K. Shtengel

We consider the Ashkin-Teller model with negative four-spin coupling but still in the region where the ground state is ferromagnetic. We establish the standard Lebowitz inequality as well as the extension that is necessary to prove a divergent susceptibility.

Patrick B. Warren

Using a carefully justified development of Debye-Huckel theory for highly asymmetric electrolytes, one finds that a region of expanded phase instability, or miscibility gap, can appear for charge-stabilised colloidal suspensions at high charges and low ionic strengths. It is argued that this is offers a straightforward explanation for the observations of voi

M. Franz, Z. Tesanovic

A novel singular gauge transformation is developed for quasiparticles in the mixed state of a strongly type-II superconductor which permits a full solution of the problem at low and intermediate fields. For a periodic vortex lattice the natural low-energy quasiparticle states are Bloch waves rather than Landau levels discussed in the recent literature. The n

R. Burghaus

The diffusional growth of wetting droplets on the boundary wall of a semi-infinite system is considered in different regions of a first-order wetting phase diagram. In a quasistationary approximation of the concentration field, a general growth equation is established on the basis of a generalized Gibbs-Thomson relation which includes the van der Waals inter