July 1998 arXiv papers — page 4

F. Eisele

New structure function measurements from fixed target experiments and especially HERA are reviewed. The extraction of parton distributions from these measurements is discussed with special emphasis on systematic problems. Finally the present uncertainty of our knowledge on parton distributions and on the strong coupling constant from DIS are dicussed.

Kamiokande Collaboration

In order to calibrate the Super-Kamiokande experiment for solar neutrino measurements, a linear accelerator (LINAC) for electrons was installed at the detector. LINAC data were taken at various positions in the detector volume, tracking the detector response in the variables relevant to solar neutrino analysis. In particular, the absolute energy scale is now

M. M. Aggarwal, A. Agnihotri, Z. Ahammed, P. V. K. S. Baba

A high granularity preshower detector has been fabricated and installed in the WA98 Experiment at the CERN SPS for measuring the spatial distribution of photons produced in the forward region in lead ion induced interactions. Photons are counted by detecting the preshower signal in plastic scintillator pads placed behind a 3 radiation length thick lead conve

Fabian H. Gaioli, Edgardo T. Garcia Alvarez

A common feature of reparametrization invariant theories is the difficulty involved in identifying an appropriate evolution parameter and in constructing a Hilbert space on states. Two well known examples of such theories are the relativistic point particle and the canonical formulation of quantum gravity. The strong analogy between them (specially for minis

Claus Lämmerzahl

The role of the Equivalence Principle (EP) in classical and quantum mechanics is reviewed. It is shown that the weak EP has a counterpart in quantum theory, a Quantum Equivalence Principle (QEP). This implies that also in the quantum domain the geometrisation of the gravitational interaction is an operational procedure similar to the procedure in classical p

A. Alan Middleton

The density and correlations of topological defects are investigated numerically in a model of a d=2 elastic medium subject to a periodic quenched random potential. The computed density of defects decreases approximately exponentially with the defect core energy. Comparing the defect-free ground state with the ground state with defects, it is found that the

Haranath Ghosh

Thermal behaviour of superconductors with complex order parameter symmetry is studied within a weak coupling theory. It is shown numerically, that the thermal nature of the different components of complex order parametrs are qualitatively different. Within the complex order parameter scenario, the recent experimental observations by Krishna {\it et al.}, [Sc

A. Gabrielli, R. Cafiero, G. Caldarelli

We study the boundary effects in invasion percolation with and without trapping. We find that the presence of boundaries introduces a new set of surface critical exponents, as in the case of standard percolation. Numerical simulations show a fractal dimension, for the region of the percolating cluster near the boundary, remarkably different from the bulk one

Alexander Altland, B. D. Simons, D. Taras-Semchuk

Thermodynamic and transport properties of mesoscopic conductors are strongly influenced by the proximity of a superconductor: An interplay between the large scale quantum coherent wave functions in the normal mesoscopic and the superconducting region, respectively, leads to unusual mechanisms of quantum interference. These manifest themselves in both the mea

M. J. Graf, S. -K. Yip, J. A. Sauls

We present theoretical calculations of the thermal conductivity for the accidental degeneracy and enlarged symmetry group models that have been proposed to explain the phase diagram of UPt3. The order parameters for these models possess point nodes or cross nodes, reflecting the broken symmetries of the ground state. These broken symmetries lead to robust pr

M. N. Popova, A. B. Sushkov, S. A. Golubchik, B. N. Mavrin

We have measured far infrared reflectance and transmittance spectra as well as Raman scattering spectra of α'-NaV2O5 single crystals for all the principal polarizations. The temperature range above the phase transition temperature T_c=35 K was investigated, mainly. On the basis of this experimental study and of the lattice dynamics calculations we conclu

M. M. Sanchez, A. Avella, F. Mancini

The one-dimensional Hubbard model at half-filling is studied in the framework of the Composite Operator Method using a static approximation. A solution characterized by strong antiferromagnetic correlations and a gap for any nonzero on-site interaction U is found. The corresponding ground-state energy, double occupancy and specific heat are in excellent agre

O. Derzhko, T. Krokhmalskii

Using numerical approach developed recently we obtained the transverse dynamic structure factor for the spin-1/2 transverse XX chain with correlated Lorentzian disorder.

B. V. Chirikov, D. L. Shepelyansky

By different methods we show that for dynamical chaos in the standard map with critical golden curve the Poincaré recurrences P(τ) and correlations C(τ) asymptotically decay in time as P ~ C/τ~ 1/τ^3. It is also explained why this asymptotic behavior starts only at very large times. We argue that the same exponent p=3 should be also valid for a general chaos

Walter Kob, Jean-Louis Barrat

We discuss the relaxation dynamics of a simple structural glass which has been quenched below its glass transition temperature. We demonstrate that time correlation functions show strong aging effects and investigate in what way the fluctuation dissipation theorem is violated.

Thomas Papenbrock, George F. Bertsch

We study the time evolution of a system of interacting bosons in a harmonic trap. In the low-energy regime, the quantum system is not ergodic and displays rather large fluctuations of the ground state occupation number. In the high energy regime of classical physics we find nonergodic behavior for modest numbers of trapped particles. We give two conditions t

A. Weiße, H. Fehske

The effects of quantum lattice fluctuations on the Peierls transition are studied within the one--dimensional Holstein molecular crystal model by means of exact diagonalization methods. Applying a very efficient variational Lanczos technique, the ground--state phase diagram is obtained in excellent agreement with predictions of recent density matrix renormal

V. A. Kashurnikov, N. V. Prokof'ev, B. V. Svistunov, M. Troyer

We demonstrate that the ``worm'' algorithm allows very effective and precise quantum Monte Carlo (QMC) simulations of spin systems in a magnetic field, and its auto-correlation time is rather insensitive to the value of H at low temperature. Magnetization curves for the $s=1/2$ and $s=1$ chains are presented and compared with existing Bethe ansatz an

J. Timmer

Surrogate data testing is a method frequently applied to evaluate the results of nonlinear time series analysis. Since the null hypothesis tested against is a linear, gaussian, stationary stochastic process a positive outcome may not only result from an underlying nonlinear or even chaotic system, but also from e.g. a non-stationary linear one. We investigat

R. Carretero-González, S. Ørstavik, J. Huke, D. S. Broomhead

The computation of the entire Lyapunov spectrum for extended dynamical systems is a very time consuming task. If the system is in a chaotic spatio-temporal regime it is possible to approximately reconstruct the Lyapunov spectrum from the spectrum of a sub-system in a very cost effective way. In this work we present a new rescaling method, which gives a signi

K. W. Chan, T. L. Roellig, T. Onaka, I. Yamamura

Using the Mid-Infrared Spectrometer (MIRS) on board the Infrared Telescope in Space (IRTS) we obtained the 4.5 to 11.7 micron spectra of the stellar populations and diffuse interstellar medium in the Galactic bulge (l = 8.7 degree, b = 2.9, 4.0, 4.7, and 5.7 degree). Below galactic latitudes of 4.0 degree, the mid-infrared background spectra in the bulge are

Geraint F. Lewis, Scott C. Chapman, Rodrigo A. Ibata, Michael J. Irwin

With an inferred bolometric luminosity of $5\times10^{15}{\rm \lsun}$, the recently identified z=3.87, broad absorption line quasar APM 08279+5255 is apparently the most luminous object currently known. As half of its prodigious emission occurs in the infrared, APM 08279+5255 also represents the most extreme example of an Ultraluminous Infrared Galaxy. Here,

Andrea Ferrara, Simone Marri

We discuss some aspects concerning the formation and the impact of the first luminous structures in the universe (PopIIIs), with particular emphasis on their feedback effects on subsequent galaxy formation. We argue that supernovae in these objects might provide, if detected, important constraints for cosmological models. Some of these constraints come from

Rosa A. Gonzalez, Andrew S. Fruchter, Boris Dirsch

We develop the ``simulated extinction method'' to measure average foreground Galactic extinction from field galaxy number-counts and colors. The method comprises simulating extinction in suitable reference fields by changing the isophotal detection limit. This procedure takes into account selection effects, in particular, the change in isophotal dete

James C. Lombardi, Alison Sills, Frederic A. Rasio, Stuart L. Shapiro

We have performed a series of systematic tests to evaluate the effects of spurious transport in three-dimensional smoothed particle hydrodynamics (SPH) calculations. Our tests investigate (i) particle diffusion, (ii) shock heating, (iii) numerical viscosity, and (iv) angular momentum transport. The results are useful for quantifying the accuracy of the SPH s

Richard S Ellis

Galaxies represent the visible fabric of the Universe and there has been considerable progress recently in both observational and theoretical studies. The underlying goal is to understand the present-day diversity of galaxy forms, masses and luminosities. Popular models predict the bulk of the population assembled recently, in apparent agreement with optical

Peter H. Hauschildt, France Allard, E. Baron

We present our NextGen Model Atmosphere grid for low mass stars for effective temperatures larger than $3000\K$. These LTE models are calculated with the same basic model assumptions and input physics as the VLMS part of the NextGen grid so that the complete grid can be used, e.g., for consistent stellar evolution calculations and for internally consistent a

C. Adami, A. Mazure

We use the Minimal Spanning Tree to characterize the aggregation level of given sets of points. We test 3 distances based on the histogram of the MST edges to discriminate between the distributions. We calibrate the method by using artificial sets following Poisson, King or NFW distributions. The distance using the mean, the dispersion and the skewness of th

M. Turler, S. Paltani, T. J. -L. Courvoisier, M. F. Aller

We present a wide multi-wavelength database of most observations of the quasar 3C 273 obtained during the last 30 years. This database is the most complete set of observations available for an active galactic nucleus (AGN). It contains nearly 20'000 observations grouped together into 70 light curves covering 16 orders of magnitude in frequency from the r

Michael L. Norman, Paschalis Paschos, Tom Abel

We describe an approach for incorporating radiative transfer into 3D hydrodynamic cosmological simulations. The method, while approximate, allows for a self-consistent treatment of self-shielding and shadowing, diffuse and point sources of radiation, and frequency dependent transfer. Applications include photodissociation, photoheating, and photoionization o

Mariano Mendez, Michiel van der Klis, Rudy Wijnands, Eric C. Ford

We present new Rossi X-ray Timing Explorer observations of the low-mass X-ray binary 4U 1608-52 during the decay of its 1998 outburst. We detect by a direct FFT method the existence of a second kilohertz quasi-periodic oscillation (kHz QPO) in its power density spectrum, previously only seen by means of the sensitivity-enhancing `shift and add' technique

F. Hulleman, J. J. M. in 't Zand, J. Heise

We report the discovery of the X-ray transient SAX J2103.5+4545 which was active from February to September 1997. The observed peak intensity of 20 mCrab (2 to 25 keV) occurred on April 11. An analysis of data obtained around the time of the peak revealed a pulsed signal with a period of 358.61 +/- 0.03 s on MJD 50569. The pulse profile has a pulsed fraction

Michael A. Nowak, Brian A. Vaughan, Joern Wilms, James B. Dove

We present timing analysis for a Rossi X-ray Timing Explorer observation of Cygnus X-1 in its hard/low state. This was the first RXTE observation of Cyg X-1 taken after it transited back to this state from its soft/high state. RXTE's large effective area, superior timing capabilities, and ability to obtain long, uninterrupted observations have allowed us

Rachel S. Somerville, Gerard Lemson, Tsafrir S. Kolatt, Avishai Dekel

We evaluate the accuracy of semi-analytic merger-trees by comparing them with the merging histories of dark-matter halos in N-body simulations, focusing on the joint distribution of the number of progenitors and their masses. We first confirm that the halo mass function as predicted directly by the Press-Schechter (PS) model deviates from the simulations by

Elena Accomando, Alessandro Ballestrero, Marco Pizzio

We study higgs physics at future $e^+e^-$ colliders taking into account the full set of Feynman diagrams for six fermion final states, which are produced for higgs masses near or above the two $W$'s threshold. In particular we examine events where one isolated lepton or two isolated leptons of different flavours signal the presence of two $\rm W^*$'s

Andrei Linde

The open inflation scenario based on the theory of bubble formation in the models of a single scalar field suffered from a fatal defect. In all the versions of this scenario known so far, the Coleman-De Luccia instantons describing the creation of an open universe did not exist. We propose a simple one-field model where the CDL instanton does exist and the o

Miao Li

The AdS/CFT correspondence provides valuable constraints on the possible exact form of various physical quantities in the ${\cal N}=4$ super Yang-Mills theory in the large N limit. We examine the free energy as the expansions in a small as well as in a large 't Hooft parameter $λ$. We argue that it is impossible to smoothly extrapolate from the weak coup

Li-Xin Li, Bohdan Paczyński

Mergers of neutron stars (NS+NS) or neutron stars and stellar mass black holes (NS+BS) eject a small fraction of matter with a sub-relativistic velocity. Upon rapid decompression nuclear density medium condenses into neutron rich nuclei, most of them radioactive. Radioactivity provides a long term heat source for the expanding envelope. A brief transient has

David W. Hogg, Andrew S. Fruchter

The observed redshifts and magnitudes of the host galaxies of gamma-ray bursts (GRBs) are compared with the predictions of three basic GRB models, in which the comoving rate density of GRBs is (1) proportional to the cosmic star formation rate density, (2) proportional to the total integrated stellar density and (3) constant. All three models make the assump

Alan Chodos, Sarah Groff

In single-bubble sonoluminescence, a bubble trapped by a sound wave in a flask of liquid is forced to expand and contract; exactly once per cycle, the bubble emits a very sharp ($< 50 ps$) pulse of visible light. This is a robust phenomenon observable to the naked eye, yet the mechanism whereby the light is produced is not well understood. One model that has

Marc Chemtob, Grégory Moreau

We examine the effects of the lepton number violating R parity odd interactions, $λ_{ijk} $, on single production of fermion (charginos and neutralinos) and scalar (sleptons and sneutrinos) superpartners at leptonic colliders for center of mass energies up to $500GeV - 1TeV$. The probability amplitudes for all the five relevant $2 \to 2$ body processes and t

V. G. Zima, S. O. Fedoruk

The transition amplitude is obtained for a free massive particle of arbitrary spin by calculating the path integral in the index-spinor formulation within the BFV-BRST approach. None renormalizations of the path integral measure were applied. The calculation has given the Weinberg propagator written in the index-free form with the use of index spinor. The ch

Erik Kuulkers

4U 1630-47 is a black-hole X-ray transient with one of the shortest recurrence times. Despite its regular outburst behaviour little is known about this source. Only recently has attention to this system increased. I discuss there the basic known (X-ray) properties of 4U 1630-47 and report on X-ray and radio observations obtained during its recent outburst, s

Hagen Kleinert

The path integral for a point particle in a Coulomb potential is solved in momentum space. The solution permits us to give for the first time a negative answer to an old question of quantum mechanics in curved spaces raised in 1957 by DeWitt, whether the Hamiltonian of a particle in a curved space contains an additional term proportional to the curvature sca

Pilar G. Estevez, Pilar R. Gordoa

This paper discusses two equations with the conditional Painleve property. The usefulness of the singular manifold method as a tool for determining the non-classical symmetries that reduce the equations to ordinary differential equations with the Painleve property is confirmed once more

George B. Cvijanovich

A notion of quantization is proposed that is independent of the original statistical interpretation of the distribution of energy in a photon gas or of the quantization of angular momentum in hydrogen atom. Such a procedutre implies the existance of finite space-time four-interval that any relativistic preparation and measurement of a physical event requires

L. Vaidman

Recently, several authors have criticized the time-symmetrized quantum theory originated by the work of Aharonov et al. (1964). The core of this criticism was a proof, appearing in various forms, which showed that the counterfactual interpretation of time-symmetrized quantum theory cannot be reconciled with standard quantum theory. I argue here that the appa

Chiara Macchiavello

We present an analytical proof of the convergence of the ``quantum privacy amplification&#39;&#39; procedure proposed by D. Deutsch et al. [Phys. Rev. Lett. 77, 2818 (1996)]. The proof specifies the range of states which can be purified by this method.

Elena Rivas, Sean R. Eddy

We describe a dynamic programming algorithm for predicting optimal RNA secondary structure, including pseudoknots. The algorithm has a worst case complexity of ${\cal O}(N^6)$ in time and ${\cal O}(N^4)$ in storage. The description of the algorithm is complex, which led us to adopt a useful graphical representation (Feynman diagrams) borrowed from quantum fi

V. L. Eletsky, B. L. Ioffe, J. I. Kapusta

The mass shift and width broadening of rho-mesons produced in heavy ion collisions is estimated using general formulae which relate the in-medium mass shift of a particle to the real part of the forward scattering amplitude of this particle on constituents of the medium and the width broadening to the corresponding cross section. It is found that the mass in

P. J. Ellis, J. I Kapusta, H. -B. Tang

We generalize the low-energy theorems of gluodynamics to finite temperature. Examples of the theorems in the low and high temperature limits are given.

M. Di Toro, V. M. Kolomietz, A. B. Larionov

We consider the propagation and damping of isovector excitations in heated nuclear matter within the Landau Fermi-liquid theory. Results obtained for nuclear matter are applied to calculate the Giant Dipole Resonance (GDR) at finite temperature in heavy spherical nuclei within Steinwedel and Jensen model. The centroid energy of the GDR slightly decreases wit

I. Zakout, H. R. Jaqaman

We study hot nuclear matter in an explicit quark model based on a mean field description of nonoverlapping nucleon bags bound by the self-consistent exchange of scalar and vector mesons as well as the glueball field. The glueball exchange as well as a realization of the broken scale invariance of quantum chromodynamics is achieved through the introduction of

Bruce Hughes, Shmuel Weinberger

This paper surveys the significant progress over the past couple of decades in the theory of stratified spaces through the application of controlled methods as well as through the application of intersection homology.

Bang-He Li, Tian-Jun Li

In this note, we first derive explicit formulas for Kirby-Melvin&#39;s three-manifold invariants $τ_r^{&#39;}$ for all Lens spaces from our results for another set of invariants $ξ_r$ defined by the first author. Then, as a corollary, we obtain formulas for Othsuki&#39;s $τ$ for all Lens spaces.

Vik. S. Kulikov

In this note we give examples of Zariski&#39;s pairs $B_{1,m}, B_{2,m}$ ($m \in N$ and $m \geq 5$) of plane cuspidal curves such that (i) $B_{i,m}$ is the discriminant curve of a generic morphism $f_{i,m}:S_i \to P^2$, $i=1, 2$, (ii) $S_1$ and $S_2$ are homeomorphic surfaces of general type, (iii) $f_{i,m}$ is given by linear three-dimensional subsystem of t

Vik. S. Kulikov

The text of the talk on Workshop on Topology of Algebraic Varieties in honour of Boris Moishezon, Bonn, MPI, Monday July 27, 1998.

Howard A. Masur, Yair N. Minsky

This paper continues a geometric study of Harvey&#39;s Complex of Curves, whose ultimate goal is to apply the theory of hyperbolic spaces and groups to algorithmic questions for the Mapping Class Group and geometric properties of Kleinian representations. The authors&#39; previous result that the complex is delta-hyperbolic was hard to apply because the comp

R. Bikbov, S. Nechaev

We estimate from above the set of knots, $Ω(n,μ)$, generated by closure of n-string 1+1- and 2+1-dimensional braids of irreducible length $μ$ ($μ>>1$) in the limit n>>1.

Luke M. Schubert

The Novikov-Shubin invariants for a non-compact Riemannian manifold M can be defined in terms of the large time decay of the heat operator of the Laplacian on square integrable p-forms on M. For the (2n+1)-dimensional Heisenberg group H, the Laplacian can be decomposed into operators in the conjugate of the generalised Bargmann representations which, when re

Sheldon Axler, Dechao Zheng

In this paper we prove that if S equals a finite sum of finite products of Toeplitz operators on the Bergman space of the unit disk, then S is compact if and only if the Berezin transform of S equals 0 on the boundary of the disk. This result is new even when S equals a single Toeplitz operator. Our main result can be used to prove, via a unified approach, s

M. G. Harris

The meander problem is a combinatorial problem which provides a toy model of the compact folding of polymer chains. In this paper we study various questions relating to the enumeration of meander diagrams, using diagrammatical methods. By studying the problem of folding tree graphs, we derive a lower bound on the exponential behaviour of the number of connec

R. Ferrari, P. A. Grassi

We propose an algorithm, based on Algebraic Renormalization, that allows the restoration of Slavnov-Taylor invariance at every order of perturbation expansion for an anomaly-free BRS invariant gauge theory. The counterterms are explicitly constructed in terms of a set of one-particle-irreducible Feynman amplitudes evaluated at zero momentum (and derivatives

B. G. Sidharth

We examine how the consequences which follow from a recent model, both in cosmology and at the elementary particle level have since been observationally and experimentally confirmed. Some of the considerations of the model are also justified from alternative viewpoints. It is also shown how the standard Big Bang and quark models can be recovered from the abo

Gustav W. Delius

We restrict affine Toda field theory to the half-line by imposing certain boundary conditions at $x=0$. The resulting theory possesses the same spectrum of solitons and breathers as affine Toda theory on the whole line. The classical solutions describing the reflection of these particles off the boundary are obtained from those on the whole line by a kind of

Shoichi Ichinose

The general structure of the conformal anomaly and the dilaton&#39;s effect to it are analysed. First we give a new formal proof of the statement that the conformal anomaly, in the theory which is conformal invariant at the classical level, is conformal invariant. The heat-kernel regularization and Fujikawa&#39;s method are taken for the analysis. We present

R. D. Peccei

I begin these lectures by examining the transformation properties of quantum fields under the discrete symmetries of Parity, P, Charge Conjugation, C, and Time Reversal, T. With these results in hand, I then show how the structure of the Standard Model helps explain the conservation/violation of these symmetries in various sectors of the theory. This discuss

R. D. Peccei

I discuss how anomalies affect classical symmetries and how, in turn, the non-trivial nature of the gauge theory vacuum makes these quantum corrections troublesome. Although no solution seems in sight for the cosmological constant problem, I examine three possible approaches to the strong CP problem involving vacuum dynamics, an additional chiral symmetry, a

K. Golec-Biernat, M. Wusthoff

We present a model based on the concept of saturation for small $Q^2$ and small $x$. With only three parameters we achieve a good description of all Deep Inelastic Scattering data below $x=0.01$. This includes a consistent treatment of charm and a successful extrapolation into the photoproduction regime. The same model leads to a roughly constant ratio of di

Yuval Grossman, Mihir P. Worah

The simplest explanation for the observed deficit of atmospheric muon neutrinos is that they have oscillated into tau or sterile neutrinos with an oscillation length of the order of the Earth diameter. In order to confirm this hypothesis, all other possible explanations should be ruled out. We propose that a viable alternative hypothesis is that the muon neu

V. Skalozub, M. Bordag

Phase transitions induced by high temperatures and strong magnetic fields are investigated in the Standard model. The consistent effective potential including the one-loop and ring diagram contributions is calculated and investigated for the wide range of the fields, temperatures and Higgs boson mass $m_H$. All other particles - fermions and bosons - are tak

Jun Cao, Fu-Guang Cao, Tao Huang, Bo-Qiang Ma

The electromagnetic transition form factors of $η$ and $η&#39;$ are calculated in the light-cone perturbation theory. We show that it is unreliable to determine the η-\etap&#39;$ mixing angle without any additional normalization conditions other than their decay widthes to two photons. The possible intrinsic $c\bar{c}$ component in the flavor singlet is inve

Xiao-Gang He, Wei-Shu Hou

We show that the study of certain observables in the angular distribution in $B\to J/ψK^*$ provide clear test for CP vioaltion beyond the Standard Model. These observables vanish in SM, but in models beyond SM some of them can be large enough to be measured at B factories.

H. Weigel, L. Gamberg, H. Reinhardt, O. Schroeder

We study nucleon structure functions within the bosonized version of the Nambu-Jona-Lasinio (NJL) model in which the nucleon emerges as the soliton in the chiral field. Upon boosting to the infinite momentum frame and performing the $q^2$-evolution in the context of the Gottfried sum rule for electron nucleon scattering we determine the intrinsic scale $μ^2$

R. Delbourgo, A. A. Rawlinson, M. D. Scadron

We show that the finite difference, $-iπ^2 m^2$, between quadratic and logarithmic divergent integrals $\int d^4p[m^2(p^2-m^2)^{-2}-(p^2-m^2)^{-1}]$, as encountered in the linear $σ$ model, is in fact regularization independent.

R. Delbourgo, M. D. Scadron

This paper is the SU(3) extension of the dynamically generated SU(2) linear $σ$ model Lagrangian worked out previously using dimensional regularization. After discussing the quark-level Goldberger-Treiman relations for SU(3) and the related gap equations, we dynamically generate the meson cubic and quartic couplings. This also constrains the meson-quark coup

Ji-Ho Jang, Pyungwon Ko

A new method to extract the weak phase $\gamma$ is suggested by exploiting B ---> D K^{(*)} decay modes that are not Cabibbo suppressed, using the isospin relations, and ignoring the annihilation diagram as usual. Assuming $3 \times 10^8 B\bar{B}$ pair at $B$ factories, one can determine $\gamma$ with $3-\sigma$ accuracy for 80^o < $\gamma$ < 150^o using B -

A. Dobado, J. R. Pelaez

In the near future, the DIRAC collaboration will measure pion-pion scattering lengths with great precision. Those measurements are likely to shed some light on the problem of the size of the chiral quark-antiquark condensate. Although it is usually assumed to be as a large as (-225 MeV)^3, in the last years a more general approach, has been developed to acco

A. Curioni, G. Mannocchi, L. Periale, P. Picchi

We propose an experiment to test the hypothesis that the reported anomaly on atmospheric neutrino fluxes is due to nu_mu <-> nu_x oscillations. It will rely both on a disappearance technique, exploiting the method of the dependence of the event rate on L/E, which was recently shown to be effective for detection of neutrino oscillation and measurement of the

Daniel Tilley, Roy Maartens

We give a comprehensive analysis of how scalar and tensor perturbations evolve in cosmologies with a smooth transition from power-law-like and de Sitter-like inflation to a radiation era. Analytic forms for the super-horizon and sub-horizon perturbations in the inflationary and radiation dominated eras are found.

C. D. Batista, J. M. Eroles, M. Avignon, B. Alascio

Using the Lanczos method in linear chains we study the ground state of the double exchange model including an antiferromagnetic super-exchange in the low concentration limit. We find that this ground state is always inhomogeneous, containig ferromagnetic polarons. The extention of the polaron spin distortion, the dispersion relation and their trapping by imp

Seung-Yeon Kim, Richard J. Creswick

The microcanonical transfer matrix is used to study the distribution of Yang-Lee zeros of the $Q$-state Potts model in the complex magnetic-field ($x=e^{βh}$) plane for the first time. Finite size scaling suggests that at (and below) the critical temperature the zeros lie close to, but not on, the unit circle with the two exceptions of the critical point $x=

Masahito Ueda, Kerson Huang

We calculate the decay amplitude of a harmonically trapped Bose-Einstein condensate with attractive interaction via the Feynman path integral. We find that when the number of particles is less than a critical number, the condensate decays relatively slowly through quantum tunneling. When the number exceeds the critical one, a &#34;black hole&#34; opens up at

J. Eroms, M. Zitzlsperger, D. Weiss, J. H. Smet

We investigated the magnetotransport properties of high-mobility InAs/GaSb antidot lattices. In addition to the usual commensurability features at low magnetic field we found a broad maximum of classical origin around 2.5 T. The latter can be ascribed to a class of rosetta type orbits encircling a single antidot. This is shown by both a simple transport calc

Jonathan Doye, Daan Frenkel

Based upon kinetic Monte Carlo simulations of crystallization in a simple polymer model we present a new picture of the mechanism by which the thickness of lamellar polymer crystals is constrained to a value close to the minimum thermodynamically stable thickness, l_{min}. The free energetic costs of the polymer extending beyond the edges of the previous cry

J-M Drouffe, C Godreche

We study the dynamics of a class of two dimensional stochastic processes, depending on two parameters, which may be interpreted as two different temperatures, respectively associated to interfacial and to bulk noise. Special lines in the plane of parameters correspond to the Ising model, voter model and majority vote model. The dynamics of this class of mode

A. Avella, F. Mancini, M. M. Sanchez, R. Sridhar

We propose a theoretical framework to describe the ladder systems. The N-chain Hubbard model has been studied within the Composite Operator Method. In this scheme of calculations the single-particle Green&#39;s function for any number of coupled chains is obtained by solving self-consistently a system of integral equations.

Paulo Murilo Castro de Oliveira

The Broad Histogram is a method designed to calculate the energy degeneracy g(E) from microcanonical averages of certain macroscopic quantities Nup and Ndn. These particular quantities are defined within the method, and their averages must be measured at constant energy values, i.e. within the microcanonical ensemble. Monte Carlo simulational methods are use

I. V. Stasyuk, A. M. Shvaika

Energy spectrum and thermodynamics of the pseudospin-electron model introduced at the consideration of the anharmonicity effects in high-$T_c$ superconductors are investigated in the dynamical mean field approximation ($d=\infty$ limit). In the limit of zero electron correlation $U\to 0$ this model is analytically exactly soluble within this approach: in the

Sergei Fedotov

A new asymptotic method is presented for the analysis of the traveling waves in the one-dimensional reaction-diffusion system with the diffusion with a finite velocity and Kolmogorov-Petrovskii-Piskunov kinetics. The analysis makes use of the path-integral approach, scaling procedure and the singular perturbation techniques involving the large deviations the

Kicheon Kang

We study resonant tunneling through an interacting quantum dot coupled to normal metallic and superconducting leads. We show that large Coulomb interaction gives rise to novel effects in Andreev transport. Adopting an exact relation for the Green&#39;s function, we find that at zero temperature, the linear response conductance is enhanced due to Kondo-Andree

Andres Aguado, Andres Ayuela, Jose M. Lopez, Julio A. Alonso

Ab initio Perturbed Ion cluster-in-the-lattice calculations of the impurity centers NaI:Tl+ and CsI:Tl+ are pressented. We study several active clusters of increasing complexity and show that the lattice relaxation around the Tl+ impurity implies the concerted movement of several shells of neighbors. The results also reveal the importance of considering a se

M. J. Steel, M. K. Olsen, L. I. Plimak, P. D. Drummond

We introduce the study of dynamical quantum noise in Bose-Einstein condensates through numerical simulation of stochastic partial differential equations obtained using phase space representations. We derive evolution equations for a single trapped condensate in both the positive-$P$ and Wigner representations, and perform simulations to compare the predictio

Masayuki Hagiwara, Kazuhiko Minami, Yasuo Narumi, Keiji Tatani

We report the results of magnetic measurements on a powder sample of NiCu(pba)(D_2O)_3 \cdot 2D_2O$ (pba=1,3-propylenebis(oxamato)) which is one of the prototypical examples of an $S$=1/2 and 1 ferrimagnetic chain. Susceptibility($χ$) shows a monotonous increase with decreasing temperature (T) and reaches a maximum at about 7 K. In the plot of $χT$ versus $T

S. S. Manna

The culling process in Bootstrap Percolation is Abelian since the final stable configuration does not depend on the details of the updating procedure. An efficient algorithm is devised using this idea for the determination of the bootstrap percolation threshold in two dimension which takes $L^2$ time compared to the $L^3 \log L$ in the conventional method. A

Gang Su, Masuo Suzuki

A universal relation connecting Fermi surface (FS) to the symmetry of the gap function in BCS-like superconductors is derived. It is found that the shape of the FS can be deduced directly from the symmetry of the superconducting gap function, and is also influenced by the next nearest-neighbor overlapping. The application of this relation to cuprate supercon

Eric L. Bolda, Dan F. Walls

A phase-slip in the fringes of an interference pattern is an unmistakable characteristic of vorticity. We show dramatic two-dimensional simulations of interference between expanding condensate clouds with and without vorticity. In this way, vortices may be detected even when the core itself cannot be resolved.

Jonathan Doye, David Wales

In recent experiments on sodium chloride clusters structural transitions between nanocrystals with different cuboidal shapes were detected. Here we determine reaction pathways between the low energy isomers of one of these clusters, (NaCl)35Cl-. The key process in these structural transitions is a highly cooperative rearrangement in which two parts of the na

M. K. Stephen Yeung, Steven H. Strogatz

We analyze the dynamics of a solid-state laser driven by an injected sinusoidal field. For this type of laser, the cavity round-trip time is much shorter than its fluorescence time, yielding a dimensionless ratio of time scales $σ\ll 1$. Analytical criteria are derived for the existence, stability, and bifurcations of phase-locked states. We find three disti

Sang-Yoon Kim

The critical behavior for intermittency is studied in two coupled one-dimensional (1D) maps. We find two fixed maps of an approximate renormalization operator in the space of coupled maps. Each fixed map has a common relavant eigenvaule associated with the scaling of the control parameter of the uncoupled one-dimensional map. However, the relevant ``coupling