January 1998 arXiv papers — page 7

T. Barnes, J. Riera, D. A. Tennant

In this paper we present results for the ground state and low-lying excitations of the $S=1/2$ alternating Heisenberg antiferromagnetic chain. Our more conventional techniques include perturbation theory about the dimer limit and numerical diagonalization of systems of up to 28 spins. A novel application of multiple precision numerical diagonalization allows

T. Kottos, A. Politi, F. M. Izrailev

The transfer matrix method is applied to quasi one-dimensional and one-dimensional disordered systems with long-range interactions, described by band random matrices. We investigate the convergence properties of the whole Lyapunov spectra of finite samples as a function of the bandwidth and of the sample length. Two different scaling laws are found at the ma

A. Bill, V. Z. Kresin, S. A. Wolf

We review some aspects of the isotope effect (IE) in superconductors. Our focus is on the influence of factors not related to the pairing mechanism. After summarizing the main results obtained for conventional superconductors, we review the effect of magnetic impurities, the proximity effect and non-adiabaticity on the value of the isotope coefficient (IC).

S. Lubeck, M. Schreckenberg, K. D. Usadel

Within the Nagel-Schreckenberg traffic flow model we consider the transition from the free flow regime to the jammed regime. We introduce a method of analyzing the data which is based on the local density distribution. This analyzes allows us to determine the phase diagram and to examine the separation of the system into a coexisting free flow phase and a ja

K. A. Matsuoka, K. K. Likharev

We have used numerical modeling and a semi-analytical calculation method to find the low frequency value S_{I}(0) of the spectral density of fluctuations of current through 1D arrays of small tunnel junctions, using the ``orthodox theory&#39;&#39; of single-electron tunneling. In all three array types studied, at low temperature (kT << eV), increasing curren

L. Bocquet, E. Charlaix, S. Ciliberto, J. Crassous

We present experiments showing that a granular system of small beads does exhibit ageing properties : its maximum stability angle is measured to increase logarithmically with resting time, i.e. the time elapsed before performing the measure. We show that humidity is the crucial ingredient responsible for this behaviour : while ageing effects are important at

Jacques Magnen, Gilles Poirot, Vincent Rivasseau

Using the particular momentum conservation laws in dimension d=2, we can rewrite the Anderson model in terms of low momentum long range fields, at the price of introducing electron loops. The corresponding loops satisfy a Ward type identity, hence are much smaller than expected. This fact should be useful for a study of the weak-coupling model in the middle

S. N. Artemenko, S. V. Remizov

In the frame of an exactly solvable model we calculate electric and magnetic fields created by uniformly moving lattice of Josephson vortices driven by the transport current in the magnetic field parallel to conducting layers. The distribution of fields and currents is strongly modified at large velocities of the vortex lattice, plasma oscillations of superc

Jürgen König, Herbert Schoeller, Gerd Schön

We study electron transport through a small metallic island in the perturbative regime. Using a diagrammatic real-time technique, we calculate the occupation of the island as well as the conductance through the transistor at arbitrary temperature and bias voltage in forth order in the tunneling matrix elements, a process referred to as cotunneling. Our formu

C. B. Yang, X. Cai

The difficulty is analysed in evaluating fluctuations in phase transition of finite-size system at temperature far below the critical point. Film system is discussed with one-component order parameter $ϕ^4$ model for phase transition. Non-trivial vacuum state corresponding to minimum Hamiltonian is given approximately for various boundary conditions. It is s

Hans C. Fogedby

Levy flights, characterized by the microscopic step index f, are for f<2 (the case of rare events) considered in short range and long range quenched random force fields with arbitrary vector character to first loop order in an expansion about the critical dimension 2f-2 in the short range case and the critical fall-off exponent 2f-2 in the long range case. B

R. Dell&#39;Anna, G. Ruocco, M. Sampoli, G. Viliani

We report a molecular dynamics simulation study of the sound waves in vitreous silica in the mesoscopic exchanged momentum range. The calculated dynamical structure factors are in quantitative agreement with recent experimental inelastic neutron and x-ray scattering data. The analysis of the longitudinal and transverse current spectra allows to discriminate

Stefano Galluccio, Jean-Philippe Bouchaud, Marc Potters

We consider the problem of rational decision making in the presence of nonlinear constraints. By using tools borrowed from spin glass and random matrix theory, we focus on the portfolio optimisation problem. We show that the number of ``optimal&#39;&#39; solutions is generically exponentially large: rationality is thus de facto of limited use. In addition, t

N. B. Kopnin, G. E. Volovik

We reply to the criticism raised by Ao in his Comment (cond-mat/9801180). Being unable to properly treat the Hall conductivity in a mixed state of superconductors, Ao is looking for possible mistakes in microscopic and phenomenological calculations, as well as in the corresponding experiments. The errors in his treatment of the problem (cond-mat/9704247) are

Takami Tohyama, Sadamichi Maekawa

We examine the effect of spin gap on single-hole spectral function in the one-dimensional t-J-J&#39;model. At J&#39;/J=1/2, where a dimer state is the ground state, an analytic expression is derived for J/t \to 0. At finite values of J/t, the numerical diagonalizations for finite-size clusters are performed. In contrast to the gapless case, we find that (i)

Hidetoshi Nishimori, Jun-ichi Inoue

We prove weak ergodicity of the inhomogeneous Markov process generated by the generalized transition probability of Tsallis and Stariolo under power-law decay of the temperature. We thus have a mathematical foundation to conjecture convergence of simulated annealing processes with the generalized transition probability to the minimum of the cost function. An

Tetsuya Mutou, Naokazu Shibata, Kazuo Ueda

We study the metal-insulator transition accompanied with a charge ordering in the one-dimensional (1D) t-J&#39; model at quarter filling by the density matrix renormalization group method. In this model the nearest-neighbor hopping energy t competes with the next-nearest-neighbor exchange energy J&#39;. We have found that a metal-insulator transition occurs

C. Knigge, N. Drake, K. S. Long, R. A. Wade

[abridged abstract] Low amplitude (~=0.5%) 29-s oscillations have been detected in HST/FOS eclipse observations of the nova-like cataclysmic variable UX UMa. These are the same dwarf nova-type oscillations that were originally discovered in this system by Warner & Nather in 1972. The oscillations are sinusoidal to within the small observational errors and un

C. Knigge, K. S. Long, R. A. Wade, R. Baptista

[abridged abstract] We present and analyze Hubble Space Telescope observations of the eclipsing nova-like cataclysmic variable UX UMa obtained with the Faint Object Spectrograph. Two eclipses each were observed with the G160L grating (covering the ultraviolet waveband) in August of 1994 and with the PRISM (covering the near-ultraviolet to near-infrared) in N

K. W. Weiler, S. D. Van Dyk, M. J. Montes, N. Panagia

Long-term monitoring of the radio emission from supernovae with the Very Large Array (VLA) shows that the radio ``light curves&#39;&#39; evolve in a systematic fashion with a distinct peak flux density (and thus, in combination with a distance, a peak spectral luminosity) at each frequency and a well-defined time from explosion to that peak. Studying these t

Ilana. M. Harrus, John. P. Hughes, Patrick O. Slane

We present the analysis of the X-ray data collected during an observation of the supernova remnant (SNR) MSH 11-62 by the Advanced Satellite for Cosmology and Astrophysics (ASCA). We show that MSH 11-62 is a composite remnant whose X-ray emission comes from two distinct contributions. Nonthermal, synchrotron emission, localized to a region of radius (~~)3&#3

A. C. Ramirez, R. E. de Souza

A kinematical analysis applied to a sample of galaxy clusters indicates that the differences between the velocity distribution of elliptical and spiral galaxies are associated with the shape of their orbit families. The orbital anisotropies present on each morphological population could be measured with the use of a parameter which is the ratio of the radial

L. Vainshtein, R. Sunyaev, E. Churazov

The differential cross section for scattering of the astrophysically important X-ray emission lines by a helium atom is calculated with an accuracy sufficient for astrophysical applications. For a helium atom an energy ``gap&#39;&#39; (due to the structure of the energy levels) is twice larger than for a hydrogen atom and the ``compton profile&#39;&#39; (due

W. E. Harris

Recent developments relevant to the formation of globular cluster systems in galaxies are discussed, including (1) The age distribution of the oldest Milky Way clusters, (2) Subgroups and possible accretion and merger remnants in the Galactic halo, (3) Key features of globular cluster systems in giant elliptical galaxies (metallicity distribution functions,

K. Schertler, C. Greiner, M. H. Thoma

One of the most intriguing consequence of the extreme conditions inside neutron stars is the possibility of the natural existence of a deconfined strange quark matter phase in the high density interior of the star. The equation of state (EOS) of strange quark matter (SQM) was recently improved in the framework of the MIT bag model by including medium effects

L. Berge, I. Berkes, B. Chambon, M. Chapellier

The status of the EDELWEISS experiment (underground dark matter search with heat-ionisation bolometers) is reviewed. Auspicious results achieved with a prototype 70 g Ge heat-ionisation detector under a 2 V reverse bias tension are discussed. Based on gamma and neutron calibrations, a best-case rejection factor, over the 15-45 keV range, of 99.7 % for gammas

F. De Paolis, G. Ingrosso, Ph. Jetzer, M. Roncadelli

Microlensing events towards the Large Magellanic Cloud entail that a sizable fraction of dark matter is in the form of MACHOs (Massive Astrophysical Compact Halo Objects), presumably located in the halo of the Galaxy. Within the present uncertainties, brown dwarfs are a viable candidate for MACHOs. Various reasons strongly suggest that a large amount of MACH

D. S. Krivitsky, V. M. Kontorovich

Connection between the quasar luminosity function and galaxy mass function is investigated in the framework of a phenomenological approach which relates AGN formation to galaxy mergers. Quasars are assumed to be short-lived, the luminosity of a quasar is controlled by the masses and angular momenta of the merged galaxies which have formed the quasar, and the

Pervez Hoodbhoy, Xiangdong Ji

We identify quark and gluon helicity-flip distributions defined between nucleon states of unequal momenta. The evolution of these distributions with change of renormalization scale is calculated in the leading-logarithmic approximation. The helicity-flip gluon distributions do not mix with any quark distribution and are thus a unique signature of gluons in t

J. Anthony Tyson, Greg P. Kochanski, Ian P. Dell&#39;Antonio

We construct a high resolution mass map of the z=0.39 cluster 0024+1654, based on parametric inversion of the associated gravitational lens. The lens creates eight well-resolved sub-images of a background galaxy, seen in deep imaging with HST. Excluding mass concentrations centered on visible galaxies, more than 98% of the remaining mass is represented by a

J. A. Casas, J. R. Espinosa, H. E. Haber

In the infrared fixed point (IFP) scenario of the minimal supersymmetric model (MSSM), the top-quark mass and other physical quantities of the low-energy theory are insensitive to the values of the parameters of the theory at some high energy scale. In this framework we evaluate the light CP-even Higgs mass, $m_h$, taking into account some important effects

Cristina Manuel

Thermal effects in the broken phase of the electroweak theory are studied in the strongly interacting Higgs boson limit. In that limit and at tree level the bosonic sector of the theory is a gauged non-linear sigma model. The associated one-loop thermal effective action for soft fields is then computed by using the background field method together with the S

Manuela Campanelli, William Krivan, Carlos O. Lousto

We revisit the question of the imposition of initial data representing astrophysical gravitational perturbations of black holes. We study their dynamics for the case of nonrotating black holes by numerically evolving the Teukolsky equation in the time domain. In order to express the Teukolsky function Psi explicitly in terms of hypersurface quantities, we re

J. Charles, A. Le Yaouanc, L. Oliver, O. Pène

We study CP-violation in resonant three-body B -> DPP decays, where PP stands for either Dpi, DK_S, pipi or piK_S. Analogously to the B -> 3pi channel and the extraction of 2alpha, the first three channels are shown to measure cos(2beta) in addition to sin(2beta), thus allowing to resolve the beta -> pi/2 -beta ambiguity, while the DpiK_S final state leads t

S. A. Kulagin

We study nuclear effects in the structure function F_3 which describes the parity violating part of the charged-current neuitrino nucleon deep inelastic scattering. Starting from a covariant approach we derive a factorized expression for the nuclear structure function in terms of nuclear spectral function and off-shell nucleon structure functions valid for a

P. Khandelwal, N. N. Kuzma, S. E. Barrett, L. N. Pfeiffer

The Knight shift of Ga-71 nuclei is measured in two different electron-doped multiple quantum well samples using optically pumped NMR. These data are the first direct measurements of the electron spin polarization, P(nu,T)=<Sz(nu,T)>/max<Sz>, near nu=1/3. The P(T) data at nu=1/3 probe the neutral spin-flip excitations of a fractional quantum Hall ferromagnet

Armen Sedrakian, Ira Wasserman, James M. Cordes

We consider the precession of isolated neutron stars in which superfluid is not pinned to the stellar crust perfectly. In the case of perfect pinning, Shaham (1977) showed that there are no slowly oscillatory, long-lived modes. When the assumption of perfect pinning is relaxed, new modes are found that can be long-lived, but are expected to be damped rather

A. Schwartz, M. Dressel, G. Gruner, V. Vescoli

We have measured the electrodynamic response in the metallic state of three highly anisotropic conductors, (TMTSF)_2 X, where X=PF_6, AsF_6, or ClO_4, and TMTSF is the organic molecule tetramethyltetraselenofulvalene. In all three cases we find dramatic deviations from a simple Drude response. The optical conductivity has two features: a narrow mode at zero

R. J. Fries, A. Schaefer

We calculate the sea quark distribution of the nucleon in a meson cloud model. The novel feature of our calculation is the implementation of a special piNN form factor recently obtained by Holzwarth and Machleidt. This form factor is hard for small and soft for large momentum transfers. We show that this feature leads to a substantial improvement.

J. H. Kühn, A. A. Penin, A. A. Pivovarov

We analyze sum rules for the $Υ$ system with resummation of threshold effects on the basis of the nonrelativistic Coulomb approximation. We find for the pole mass of the bottom quark $m_b=4.75\pm 0.04 GeV$ and for the strong coupling constant $\al_s(M_Z)=0.118\pm 0.006$. The origin of the contradiction between two recent estimates obtained within the same fo

J. H. Field

A model independent analysis is made using the LEP and SLD data on Z decays available at the end of 1996. The effective weak coupling constants of leptons, c quarks and b quarks are extracted. Except for the right-handed b quark coupling, they all agree well with the predictions of the Standard Electroweak Model for $m_t = 172$ GeV and $m_H = 263$ GeV. The r

D. Smirnov, P. Millet, J. Leotin, D. Poilblanc

Polarized infrared reflectivity measurements have been performed on single crystals of the spin-Peierls compound alpha&#39;-NaV2O5 in the temperature range 20-300 K. Pronounced spectral features associated with the formation of the dimerized phase were detected both in the a- and b-polarizations (perpendicular and parallel to the spin-1/2 chains, respectivel

Ruihong Yue, Ryu Sasaki

For one dimensional SU(n) Hubbard model, a pair of Lax operators are derived, which give a set of fundamental equations for the quantum inverse scattering method under both periodic and open boundary conditions. This provides another proof of the integrability of the model under periodic boundary condition.

Takuhiro Kitao, Nobuyoshi Ohta, Jian-Ge Zhou

We study the creation of a fundamental string between D4-branes at angles in string theory. It is shown that $R(-1)^{F}$ part of the one-loop potential of open string changes its sign due to the change of fermionic zero-mode vacua when the branes cross each other. As a result the effective potential is independent of the angles when supersymmetry is partiall

Hideo Mabuchi

I utilize the Caves-Milburn model for continuous position measurements to formulate a broadband version of the Standard Quantum Limit (SQL) for monitoring the position of a free mass, and illustrate the use of Kalman filtering to recover the SQL for estimating a weak classical force that acts on a quantum-mechanical test particle under continuous observation

I. Chepelev, A. A. Tseytlin

We compute the interaction potential between two parallel transversely boosted wrapped membranes (with fixed momentum $p_-$) in D=11 supergravity with compact light-like direction. We show that the supergravity result is in exact agreement with the potential following from the all-order Born-Infeld-type action conjectured to be the leading planar infra-red p

Yuji Satoh

We discuss the propagation of scalars in a large class of non-extremal black hole and black p-brane geometries in generic dimensions. We show that the radial wave equation near the horizon possesses the SL(2,R) structure in every case; approximately it takes the form of the wave equation in the SL(2,R) (AdS_3) background and has a symmetry related to the T-d

Valeri V. Dvoeglazov

The Reply to G. W. Bruhn is added.

S. Schlieder

For quantum mechanical systems an entropy-like quantity $S_q$ is defined. $S_q$ can differ from the usually defined entropy $S$ and $S_q$ may increase with time for an isolated system. The essential condition for the difference between $S$ and $S_q$ is the assumption that the set {\bf A} of observables which can be represented by a measurement is a proper su

Cristopher Moore

This paper has been withdrawn.

Fernando M. Maroto

This paper has been withdrawn by the author due to a crucial error in eq.59. I apologize for the inconveniences.

B. Pesaran, P. P. Mitra

We make available a library of documented IDL .pro files as well as a shareable object library that allows IDL to call routines from LAPACK. The routines are for use in the spectral analysis of time series data. The primary focus of these routines are David Thomson&#39;s multitaper methods but a whole range of functions will be made available in future revis

Yu. L. Dokshitzer

In memoria of Vladimir Naumovich Gribov

G. Rosensteel, J. Troupe

For each real number $Λ$ a Lie algebra of nonlinear vector fields on three dimensional Euclidean space is reported. Although each algebra is mathematically isomorphic to $gl(3,{\bf R})$, only the $Λ=0$ vector fields correspond to the usual generators of the general linear group. The $Λ< 0$ vector fields integrate to a nonstandard action of the general linear

A. V. Afanasjev, G. A. Lalazissis, P. Ring

Single-particle properties at superdeformation are investigated within the Cranked Relativistic Mean Field (CRMF) theory on the example of superdeformed rotational bands observed in the A~140-150 mass region. Applying the effective alignment approach it is shown that CRMF theory provides a reasonable description of the alignment properties of the single-part

Einar Andreas Rodland

The rank 4 locus of a general skew-symmetric 7x7 matrix gives the pfaffian variety in P^20 which is not defined as a complete intersection. Intersecting this with a general P^6 gives a Calabi-Yau manifold. An orbifold construction seems to give the 1-parameter mirror-family of this. However, corresponding to two points in the 1-parameter family of complex st

Bernd Ammann, Christian Baer

We compute the spectrum of the Dirac operator on 3-dimensional Heisenberg manifolds. The behavior under collapse to the 2-torus is studied. Depending on the spin structure either all eigenvalues tend to $\pm\infty$ or there are eigenvalues converging to those of the torus. This is shown to be true in general for collapsing circle bundles with totally geodesi

Marco Billo, Frederik Denef, Pietro Fre, Igor Pesando

We discuss, in the framework of special Kahler geometry, some aspects of the &#34;rigid limit&#34; of type IIB string theory compactified on a Calabi-Yau threefold. We outline the general idea and demonstrate by direct analysis of a specific example how this limit is obtained. The decoupling of gravity and the reduction of special Kahler geometry from local

Cumrun Vafa

Extending previous work on geometric engineering of N=1 Yang-Mills in four dimensions for simply laced ($A_n,D_n,E_{6,7,8}$) gauge groups, we construct local models for all other gauge groups ($B_n,C_n,F_4,G_2$) in terms of F-theory. We compute the radius dependent superpotential upon further compactification on a circle to $d=3$ in the dual M-theory and use

T. Padmanabhan

An attempt is made to describe the `thermodynamics&#39; of semiclassical spacetime without specifying the detailed `molecular structure&#39; of the quantum spacetime, using the known properties of blackholes. I give detailed arguments, essentially based on the behaviour of quantum systems near the event horizon, which suggest that event horizon acts as a mag

Malgorzata Bakalarska, Waclaw Tybor

It is shown that the notoph propagator in the noncovariant longitudinal gauge is equivalent to the covariant Feynmann - like propagator.

Jouko Mickelsson

By studying ordinary chiral fermions in background gauge fields we show that in the case of gauge group SU(3) and space-time dimension 5+1 localized solitons obey $q-$ commutation relations with $q$ not equal to $\pm 1$ but a third root of unity.

Klaus Behrndt

In this article we summarise the brane solutions (instantons, black holes and strings) in 4 dimensions when embedded in N=2 supergravity. Like in 10 dimensions these solutions are related by duality transformations (T-duality, c-map). For the case that the graviphoton has no magnetic charge, we discuss the conformal field theory description of the near-horiz

I. V. Tyutin, Vad. Yu. Zeitlin

The problem of gauge invariance of the physical sector of (2+1)-dimensional Maxwell-Chern-Simons quantum electrodynamics (QED$_{2+1}$) is studied. It is shown that using Proca mass term for the infrared regularization one obtains gauge-invariant fermion mass and the physical mass shell of QED$_{2+1}$ is well-defined in all orders of the perturbation theory.

M. C. Gonzalez-Garcia, H. Nunokawa, O. L. G. Peres, T. Stanev

We discuss the impact of recent experimental results on the determination of atmospheric neutrino oscillation parameters. We use all published results on atmospheric neutrinos, including the preliminary large statistics data of Super-Kamiokande. We re-analyze the data in terms of both $ν_μ\to ν_τ$ and $ν_μ\to ν_e$ channels using new improved calculations of

Tanmay Vachaspati

In the context of current particle physics theories, it is quite likely that topological defects may be present in our universe. An observation of these fossils from the early universe would lead to invaluable insight into cosmology and particle physics, while their absence provides important constraints on particle-cosmology model building. I describe recen

G. Domokos, S. Kovesi-Domokos

The interaction of UHE neutrinos can be observed from outer space. The advantage of the proposed method is that the Earth can be used as an energy filter as well as a target. We sketch the potentials of these observations in searching for particle physics beyond the Standard Model of elementary particle interactions as well as observations of astronomical ob

Michel Davier, Andreas Hoecker

We reevaluate the hadronic contribution to the running of the QED fine structure constant \aqed at $s=M_{\rm Z}^2$. We use data from \ee\ annihilation and $τ$ decays at low energy and at the $q\bar{q}$ thresholds, where resonances occur. Using so-called spectral moments and the Operator Product Expansion (OPE), it is shown that a reliable theoretical predict

G. Domokos, S. Kovesi-Domokos

The existence of magnetic moments of neutrinos points to physics beyond the standard model. Given current upper limits, terrestrial measurements are difficult or completely unfeasible. However, estimates of transition moments can be obtained from observation of objects such as active galactic nuclei (AGN) by means of neutrino telescopes. We describe the way

E. Boos, V. Ilyin, D. Kovalenko, T. Ohl

We present the results of calculations for the process gamma gamma -> W + 2 fermions at a future Photon Linear Collider (PLC). The calculations include at the same time the next-to-leading order Higgs signal and the complete tree level gauge boson background. We present numerical results in the intermediate mass Higgs region 140 GeV < M_H < 2M_W. We propose

Q. H. Zhang

Multi-pion correlation effect on the source distribution is studied. It is shown that multi-pion Bose-Einstein correlation make the average radius of the pion source become smaller. The isospin effect on the pion multiplicity distribution and the source distribution is also discussed.

D. Jido, Y. Nemoto, M. Oka, A. Hosaka

Meson-baryon couplings between positive and negative parity nucleons are investigated using two point correlation functions in the soft meson and the chiral limit. We find that the pi NN* coupling vanishes due to chiral symmetry, while the eta NN* coupling remains finite. We perform an analysis based on the algebraic method for SU(2) chiral symmetry, and fin

Riccardo Barbieri, Alessandro Strumia

Following Chankowski, Ellis and Pokorski we quantify the amount of fine-tuning of input parameters of the Minimal Supersymmetric Standard Model that is needed to respect the lower limits on sparticle and Higgs masses imposed by negative searches so far, direct or indirect. By including the one loop radiative corrections to the effective potential, the amount

M. A. Braun

The odderon intercept $ α$ is recalculated by the variational method based on conformal invariance. The final result is $α=1-0.339 α_s N/π$ in contrast to the published value above unity.

Mayumi Aoki, Noriyuki Oshimo, Akio Sugamoto

Baryogenesis at the electroweak phase transition is discussed within the framework of the supersymmetric standard model. Implications of baryon asymmetry for the electric dipole moment of the neutron are also studied.

Hubert Simma, Douglas Smith

The spectral flow of the low-lying eigenvalues of the improved and unimproved Wilson-Dirac operator is studied on instanton-like configurations and on thermalized quenched configurations at various $β$-values and lattice sizes. We also investigate the space-time localisation and chirality of the corresponding eigenvectors.

I. Montvay

Non-perturbative predictions and numerical simulations in supersymmetric Yang-Mills (SYM) theories are reviewed.

CDF Collaboration, F. Abe et al

We have searched for anomalous production of missing E$_{\rm T}$ ($\mett$), jets, leptons ($e, μ, τ$), $b$-quarks, or additional photons in events containing two isolated, central \mbox{($|η|<1.0$)} photons with \mbox{$\Et>12$~GeV}. The results are consistent with standard model expectations, with the possible exception of one event that has in addition to t

A. Soffer

Several authors have proposed methods to measure the phase $γ$ of the Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle using decays of the type $B\to DK$. We show how to remove uncertainties from these measurements and increase their sensitivity by measuring CP-conserving phases at a charm factory.

Arlen Anderson, Andrew M. Abrahams, Chris Lea

A new approach to gravitational gauge-invariant perturbation theory begins from the fourth-order Einstein-Ricci system, a hyperbolic formulation of gravity for arbitrary lapse and shift whose centerpiece is a wave equation for curvature. In the Minkowski and Schwarzschild backgrounds, an intertwining operator procedure is used to separate physical gauge-inva

N. Bishop, R. Isaacson, R. Gomez, L. Lehner

This paper gives a detailed pedagogic presentation of the central concepts underlying a new algorithm for the numerical solution of Einstein&#39;s equations for gravitation. This approach incorporates the best features of the two leading approaches to computational gravitation, carving up spacetime via Cauchy hypersurfaces within a central worldtube, and usi

The Binary Black Hole Grand Challenge Alliance, :, R. Gomez, L. Lehner

We report new results which establish that the accurate 3-dimensional numerical simulation of generic single-black-hole spacetimes has been achieved by characteristic evolution with unlimited long term stability. Our results cover a selection of distorted, moving and spinning single black holes, with evolution times up to 60,000M.

Jacek Jezierski

It is shown that the axial and polar perturbations of the spherically symmetric black hole can be described in a gauge-invariant way. The reduced phase space describing gravitational waves outside of the horizon is described by the gauge-invariant quantities. Both degrees of freedom fulfill generalized scalar wave equation. For the axial degree of freedom th

M. C. Bento, O. Bertolami, N. J. Nunes

We analyse the spectrum of energy density fluctuations of a dual supergravity model where the dilaton and the moduli are stabilized and sucessful inflation is achieved inside domain walls that separate different vacua of the theory. Constraints on the parameters of the superpotential are derived from the amplitude of the primordial energy density fluctuation

A. Yu. Kamenshchik, I. M. Khalatnikov, A. V. Toporensky

We investigate the simplest cosmological model with the massive real scalar non-interacting inflaton field minimally coupled to gravity. The classification of trajectories in closed minisuperspace Friedmann-Robertson-Walker model is presented.The fractal nature of a set of infinitely bounced trajectories is discussed. The results of numerical calculations ar

Thomas C. Halsey, Alex J. Levine

Capillary forces significantly affect the stability of sandpiles. We analyze the stability of sandpiles with such forces, and find that the critical angle is unchanged in the limit of an infinitely large system; however, this angle is increased for finite-sized systems. The failure occurs in the bulk of the sandpile rather than at the surface. This is relate

Carsten Timm, S. M. Girvin, Patrik Henelius

The magnetization of a two-dimensional ferromagnetic Heisenberg model, which represents a quantum Hall system at filling factor nu=1, is calculated employing a large N Schwinger boson approach. Corrections of order 1/N to the mean field (N=infinity) results for both the SU(N) and the O(N) generalization of the bosonized model are presented. The calculations

C. A. Stafford, R. Kotlyar, S. Das Sarma

Coherent resonant tunneling through an artificial molecule of quantum dots in an inhomogeneous magnetic field is investigated using an extended Hubbard model. Both the multiterminal conductance of an array of quantum dots and the persistent current of a quantum dot molecule embedded in an Aharanov-Bohm ring are calculated. The conductance and persistent curr

G. Dirscherl, B. Schottky, U. Krey

We investigate the influence of different kinds of structure on the learning behaviour of a perceptron performing a classification task defined by a teacher rule. The underlying pattern distribution is permitted to have spatial correlations. The prior distribution for the teacher coupling vectors itself is assumed to be nonuniform. Thus classification tasks

N. Breda, R. A. Broglia, G. Colo`, H. E. Roman

A simple, yet accurate solution of the electron-phonon coupling problem in C_{60} is presented. The basic idea behind it is to be found in the parametrization of the ground state electronic density of the system calculated making use of ab-initio methods, in term of sp$^{2+x}$ hybridized orbitals. This parametrization allows for an economic determination of

Masahito Ueda, Anthony J. Leggett

A Bose-Einstein condensate with attractive interaction can be metastable if it is spatially confined and if the number of condensate bosons $N_0$ is below a certain critical value $N_{\rm c}$. By applying a variational method and the instanton techinique to the Gross-Pitaevskii energy functional, we find analytically the frequency of the collective excitatio

Yoshiaki Mizuno, Takami Tohyama, Sadamichi Maekawa

Recently the superconductivity has been reported in the copper oxides (Sr,Ca)$_{14}$Cu$_{24}$O$_{41}$ with ladders and edge-sharing chains under pressure. In order to understand the mechanism of the superconductivity, it is crucial to clarify the distribution of self-doped holes. From the analysis of the optical conductivity by ionic model and exact diagonal

A. Aldea, P. Gartner, M. Nita

The transport properties of a rectangular mesoscopic plaquette in the presence of a perpendicular magnetic field are studied in a tight-binding model with randomly distributed traps. The longitudinal and Hall resistances are calculted in the four-probe Landauer-Büttiker formalism which accounts automatically both for the quantum coherence and the trapping-in

A. J. Williamson, Alex Zunger, A. Canning

Free standing InP quantum dots have previously been theoretically and experimentally shown to have a direct band gap across a large range of experimentally accessible sizes. We demonstrate that when these dots are embedded coherently within a GaP barrier material, the effects of quantum confinement in conjunction with coherent strain suggest there will be a

Eric Sven Ristad, Robert G. Thomas

We describe a simple variant of the interpolated Markov model with non-emitting state transitions and prove that it is strictly more powerful than any Markov model. More importantly, the non-emitting model outperforms the classic interpolated model on the natural language texts under a wide range of experimental conditions, with only a modest increase in com

Julien Kockelkoren, Fridolin Okkels, Mogens H. Jensen

We study the chaotic behavior of the ``GOY&#39;&#39; shell model by measuring the variation of the maximal Lyapunov exponent with the parameter $ε$ which determines the nature of the second invariant (the generalized ``helicity&#39;&#39; invariant). After a Hopf bifurcation, we observe a critical point at $ε_c \sim 0.38704$ above which the maximal Lyapunov e

D. Pingel, P. Schmelcher, F. K. Diakonos

The general solution of the inverse Frobenius-Perron problem considering the construction of a fully chaotic dynamical system with given invariant density is obtained within the class of one-dimensional unimodal maps. Some interesting connections between this solution and the approach via conjugation transformations are eluminated. The developed method is ap

M. Cencini, G. Lacorata, A. Vulpiani, E. Zambianchi

In this paper we investigate mixing and transport in correspondence of a meandering jet. The large-scale flow field is a kinematically assigned streamfunction. Two basic mixing mechanisms are considered, first separately and then combined together: deterministic chaotic advection, induced by a time dependence of the flow, and turbulent diffusion, described b

Paul N. Arendt,

Maxwell&#39;s equations and the equations governing charged particle dynamics are presented for a rotating coordinate system with the global time coordinate of an observer on the rotational axis. Special care is taken in defining the relevant entities in these equations. Ambiguities in the definitions of the electromagnetic fields are pointed out, and in fac

Sebastiano Ghigna, Ben Moore, Fabio Governato, George Lake

We examine the properties of dark matter halos within a rich galaxy cluster using a high resolution simulation that captures the cosmological context of a cold dark matter universe. The mass and force resolution permit the resolution of 150 halos with circular velocities larger than 80 kms within the cluster&#39;s virial radius of 2 Mpc. This enables an unpr