August 2001 arXiv papers — page 21

Andrey A. Sukhorukov, Yuri S. Kivshar

We study spatial optical solitons in a one-dimensional nonlinear photonic crystal created by an array of thin-film nonlinear waveguides, the so-called Dirac-comb nonlinear lattice. We analyze modulational instability of the extended Bloch-wave modes and also investigate the existence and stability of bright, dark, and ``twisted'' spatially localized

A. M. Rucklidge, M. Silber, J. Fineberg

We examine three experimental observations of Faraday waves generated by two-frequency forcing, in which a primary hexagonal pattern becomes unstable to three different superlattice patterns. We use the symmetry-based approach developed by Tse et al. to analyse the bifurcations involved in creating the three new patterns. Each of the three examples reveals a

Emil Nissimov, Svetlana Pacheva

We study additional non-isospectral symmetries of constrained (reduced) N=2 supersymmetric KP hierarchies of integrable ``soliton''-like evolution equations. These symmetries are shown to form an infinite-dimensional non-Abelian superloop superalgebra. Furthermore we study the general Darboux-Backlund (DB) transformations (including adjoint-DB and bi

J. Scott Carter, Daniel Jelsovsky, Seiichi Kamada, Laurel Langford

The 2-twist spun trefoil is an example of a sphere that is knotted in 4-dimensional space. Here this example is shown to be distinct from the same sphere with the reversed orientation. To demonstrate this fact a state-sum invariant for classical knots and knotted surfaces is developed via a cohomology theory of racks and quandles (also known as distributive

Feng Xu

We demonstrate the equivalence of Kazama-Suzuki cosets $G(m,n,k)$ and $G(k,n,m)$ based on complex Grassmannians by proving that the corresponding conformal precosheaves are isomorphic. We also determine all the irreducible representations of the conformal precosheaves.

Paolo Piccione, Daniel V. Tausk

We prove a generalized version of the Morse index theorem for geodesics endowed with a non positive definite metric tensor (semi-Riemannian manifolds). We apply the result to obtain lower estimates on the number of geodesics joining two fixed non conjugate points in certain classes of manifolds. More specifically, we consider semi-Riemannian manifolds $(M,\m

T. Mansour

We study generating functions for the number of permutations in $S_n$ subject to set of restrictions. One of the restrictions belongs to $S_3$, while the others to $S_k$. It turns out that in a large variety of cases the answer can be expressed via continued fractions, and Chebyshev polynomials of the second kind.

Friedrich Haslinger

In this paper we obtain a necessary and sufficient condition for the canonical solution operator to $\overline \partial $ restricted to radial symmetric Bergman spaces to be a Hilbert-Schmidt operator. We also discuss compactness of the solution operator in spaces of entire functions in one variable. In the sequel we consider several examples and also treat

Georgia Benkart, Sarah Witherspoon

We determine the finite-dimensional simple modules for two-parameter quantum groups corresponding to the general linear and special linear Lie algebras gl_n and sl_n, and give a complete reducibility result. These quantum groups have a natural n-dimensional module V. We prove an analogue of Schur-Weyl duality in this setting: the centralizer algebra of the q

Miles Reid

I show that the weighted projective line PP(2,3) has an embedding PP(2,3) into PP(4,5,6,9) whose image Gamma is contained in a quasismooth K3 hypersurface X_24 in PP(4,5,6,9). The pair (Gamma in X_24) unprojects to the codimension 4 K3 surface Y in PP(4,5,5,6,7,8,9) with Basket = [1/2(1,1), 1/5(1,4), 1/5(2,3), 1/9(4,5)], Hilbert Numerator = 1 - t^12 - t^13 -

W. A. Carnielli, J. Marcos

A thorough investigation of the foundations of paraconsistent logics. Relations between logical principles are formally studied, a novel notion of consistency is introduced, the logics of formal inconsistency, and the subclasses of C-systems and dC-systems are defined and studied. An enormous variety of paraconsistent logics in the literature is shown to con

Friedrich Haslinger

We first show that the canonical solution operator to d-bar restricted to (0,1)-forms with holomorphic coefficients can be expressed by an integral operator using the Bergman kernel. This result is used to prove that in the case of the unit disc in C the canonical solution operator to d-bar restricted to (0,1)-forms with holomorphic coefficients is a Hilbert

Sarah J. Witherspoon

We give a Clifford correspondence for an algebra A over an algebraically closed field, that is an algorithm for constructing some finite-dimensional simple A-modules from simple modules for a subalgebra and endomorphism algebras. This applies to all finite-dimensional simple A-modules in the case that A is finite-dimensional and semisimple with a given semis

Siddhartha Bhattacharya

An algebraic $Z^{d}$-action is an action of $Z^{d}$ on a compact abelian group $X$ by automorphisms of $X$. We prove that for $d \ge 8$, there exist mixing zero entropy algebraic $Z^{d}$-actions which do not exhibit isomorphism rigidity property.

Stefan Waldmann

In this contribution to the proceedings of the 68eme Rencontre entre Physiciens Theoriciens et Mathematiciens on Deformation Quantization I shall report on some recent joint work with Henrique Bursztyn on the representation theory of *-algebras arising from deformation quantization as I presented this in my talk.

Georgia Benkart, Sarah Witherspoon

We investigate two-parameter quantum groups corresponding to the general linear and special linear Lie algebras gl_n and sl_n. We show that these quantum groups can be realized as Drinfel'd doubles of certain Hopf subalgebras with respect to Hopf pairings. Using the Hopf pairing, we construct a corresponding R-matrix and a quantum Casimir element. We dis

Juergen Hausen

We characterize embeddability of algebraic varieties into smooth toric varieties and prevarieties. Our embedding results hold also in an equivariant context and thus generalize a well known embedding theorem of Sumihiro on quasiprojective G-varieties. The main idea is to reduce the embedding problem to the affine case. This is done by constructing equivarian

A. A'Campo-Neuen, J. Hausen, S. Schroeer

Generalizing cones over projective toric varieties, we present arbitrary toric varieties as quotients of quasiaffine toric varieties. Such quotient presentations correspond to groups of Weil divisors generating the topology. Groups comprising Cartier divisors define free quotients, whereas $\QQ$-Cartier divisors define geometric quotients. Each quotient pres

A. A. Bytsenko

The asymptotic expansion of the heat kernel associated with Laplace operators is considered for general irreducible rank one locally symmetric spaces. Invariants of the Chern-Simons theory of irreducible U(n)- flat connections on real compact hyperbolic 3-manifolds are derived

Michael D. Turner

We formulate a method of performing non-perturbative calculations in quantum field theory, based upon a derivative expansion of the exact renormalization group. We then proceed to apply this method to the calculation of critical exponents for three dimensional O(N) symmetric theory. Finally we discuss how the approximation scheme manages to reproduce some ex

M. Kirchbach, D. V. Ahluwalia

After a brief review of the celebrated 1941 paper of Rarita and Schwinger on the theory of particles with half-integral spins, we present an {\em ab initio} construct of the representation space relevant for the description of spin-3/2 particles. The chosen example case of spin-3/2 shows that covariance of a wave equation, and that of the imposed supplementa

Xingang Chen, Huidong Guo, Erick J. Weinberg

We investigate the applicability of the moduli space approximation in theories with unbroken non-Abelian gauge symmetries. Such theories have massless magnetic monopoles that are manifested at the classical level as clouds of non-Abelian field surrounding one or more massive monopoles. Using an SO(5) example with one massive and one massless monopole, we com

J. Douari, El H. El Kinani

The fractional supersymmetry in the case of the non-relativistic motion of one anyon with fractional spin is realized. Thus the associated Hamiltonian is discussed.

Adam Lewandowski, Raman Sundrum

We demonstrate the classical stability of the weak/Planck hierarchy within the Randall-Sundrum scenario, incorporating the Goldberger-Wise mechanism and higher-derivative interactions in a systematic perturbative expansion. Such higher-derivative interactions are expected if the RS model is the low-energy description of some more fundamental theory. Generica

G. Weiglein

Theoretical implications of the possible observation of a Higgs boson with a mass of about 115 GeV at LEP are discussed. Within the Standard Model a Higgs boson in this mass range agrees well with the indirect constraints from electroweak precision data. However, it would nevertheless point towards physics beyond the Standard Model, in particular to Supersym

Savas Dimopoulos, Roberto Emparan

In string theory, black holes have a minimum mass below which they transition into highly excited long and jagged strings --- ``string balls''. These are the stringy progenitors of black holes; because they are lighter, in theories of TeV-gravity, they may be more accessible to the LHC or the VLHC. They share some of the characteristics of black hole

S. Fortunato, H. Satz

The q-state Potts model can be formulated in geometric terms, with Fortuin-Kasteleyn (FK) clusters as fundamental objects. If the phase transition of the model is second order, it can be equivalently described as a percolation transition of FK clusters. In this work, we study the percolation structure when the model undergoes a first order phase transition.

T. Watari, T. Yanagida

The semi-simple unification model based on SU(5)_GUT \times U(3)_H gauge group is an interesting extension of the minimal SU(5)_GUT grand unification theory (GUT), since it solves the two serious problems in the standard GUT: the triplet-doublet splitting problem and the presence of dangerous dimension five operators for proton decay. Here, the extra U(3)_H

C. S. Kim, B. H. Lim, Sechul Oh

Charmless hadronic decays of B mesons to a vector meson (V) and a tensor meson (T) are analyzed in the frameworks of both flavor SU(3) symmetry and generalized factorization. We also make comments on B decays to two tensor mesons in the final states. Certain ways to test validity of the generalized factorization are proposed, using $B \to VT$ decays. We calc

R. Foot, R. R. Volkas

We show that the anomalous acceleration of the Pioneer 10/11 spacecraft can be explained if there is some mirror gas or mirror dust in our solar system.

Daniele Fargion, Marco Grossi, P. G. De Sanctis Lucentini, C. Di Troia

The Ultra High Energy Cosmic Ray UHECR, by UHE neutrino-relic neutrino Z showering in Hot Dark Halos HDM, should exhibits an energy spectra and an anisotropy reflecting (also) the relic neutrino masses and their hierarchical HDM halo clustering. A twin light neutrino mass splitting may reflect to twin Z resonance and into a complex UHECR spectra modulation,

Tommy Ohlsson

In this talk, we consider the interplay of fundamental and matter-induced T-violating effects in neutrino oscillations in matter. We present a simple approximative analytical formula for the T-violating probability asymmetry for three flavor neutrino oscillations in matter with an arbitrary density profile. We also discuss some implications of the obtained r

L. Giusti, C. Hoelbling, C. Rebbi

We present the results of a computation of the sum of the strange and average up-down quark masses with overlap fermions in the quenched approximation. Since the overlap regularization preserves chiral symmetry at finite cutoff and volume, no additive quark mass renormalization is required and the results are O(a) improved. Our simulations are performed at b

Philipp Rufenacht, Urs Wenger

We present a method for constructing classically perfect anisotropic actions for SU(3) gauge theory based on an isotropic Fixed Point Action. The action is parametrised using smeared (``fat'') links. The construction is done explicitly for anisotropy $ξ=a_s/a_t=2$ and 4. The corresponding renormalised anisotropies are determined using the torelon dis

The FOCUS Collaboration

We describe the algorithm used to identify charged tracks in the fixed-target charm-photoproduction experiment FOCUS.

K. Abe

We report measurements for two-body charmless B decays with an eta' meson in the final state. Using 11.1X10^6 BBbar pairs collected with the Belle detector, we find BF(B^+ ->eta'K^+)=(79^+12_-11 +-9)x10^-6 and BF(B^0 -> eta'K^0)=(55^+19_-16 +-8)x10^-6, where the first and second errors are statistical and systematic, respectively. No signal is ob

E. N. Glass

The Bach tensor and a vector which generates conformal symmetries allow a conserved four-current to be defined. The Bach four-current gives rise to a quasilocal two-surface expression for power per luminosity distance in the Vaidya exterior of collapsing fluid interiors. This is interpreted in terms of entropy generation.

R. Prozorov, R. W. Giannetta, S. L. Bud'ko, P. C. Canfield

Measurements of the penetration depth $λ(T,H)$ in the presence of a DC magnetic field were performed in $MgB_2$ wires. In as-prepared wires $λ(T,H<130 Oe)$ shows a strong diamagnetic downturn below $\approx 10 K$. A DC magnetic field of $130 Oe$ completely suppressed the downturn. The data are consistent with proximity coupling to a surface $Mg$ layer left d

A. V. Razumov, Yu. G. Stroganov

This work as an extension of our recent paper where we have found a numerical evidence for the fact that the numbers of the states of the fully packed loop (FPL) model with fixed link-patterns coincide with the components of the ground state vector of the dense O(1) loop model for periodic boundary conditions and an even number of sites. Here we give two new

Inanc Adagideli, Paul M. Goldbart

Andreev billiards are finite, arbitrarily-shaped, normal-state regions, surrounded by superconductor. At energies below the superconducting gap, single-quasiparticle excitations are confined to the normal region and its vicinity, the essential mechanism for this confinement being Andreev reflection. This Paper develops and implements a theoretical framework

Andreas Laeuchli, Didier Poilblanc, T. M. Rice, Steven R. White

A lithium dopant in a cuprate spin ladder acts as a vacant (non-magnetic) site accompanied by an extra hole bound by a Coulomb potential. We find that, although the undoped ladder spin gap is not essentially altered by Li doping, a dopant-magnon bound state appears within the gap. Contrary to the case of Zn-doped ladders, we predict that, in the Li-doped lad

Aiichi Iwazaki

Bilayer quantum Hall states at $ν=1$ have been demonstrated to possess a distinguished state with interlayer phase coherence. The state has both excitations of Skyrmion with spin and pseudoSkyrmion with pseudospin. We show that Skyrmion $\leftrightarrow$ pseudoSkyrmion transition arises in the state by changing imbalance between electron densities in both la

Kicheon Kang, Sam Young Cho, Ju-Jin Kim

We study coherent charge transfer between an Aharonov-Bohm ring and a side-attached quantum dot. The charge fluctuation between the two sub-structures is shown to give rise to algebraic suppression of the persistent current circulating the ring as the size of the ring becomes relatively large. The charge fluctuation at resonance provides transition between t

U. C. Tauber, B. Schmittmann, R. K. P. Zia

We investigate the static and dynamic critical behaviour of a uniformly driven bilayer Ising lattice gas at half filling. Depending on the strength of the interlayer coupling J, phase separation occurs across or within the two layers. The former transitions are controlled by the universality class of model A (corresponding to an Ising model with Glauber dyna

P. D. Grigoriev, M. V. Kartsovnik, W. Biberacher, N. D. Kushch

We analyze the beating behavior of the magnetic quantum oscillations in a layered metal under the conditions when the cyclotron energy $\hbar ω_c $ is comparable to the interlayer transfer energy $t$. We find that the positions of the beats in the interlayer resistance are considerably shifted from those in the magnetization oscillations, and predict that th

Hernan A. Makse, Jorge Kurchan

Years ago Edwards proposed a thermodynamic description of dense granular matter, in which the grains (the `atoms&#39; of the system) interact with inelastic forces. The approach is intriguing but is not justified from first principles, and hence, in the absence of conclusive tests of its validity, it has not been widely accepted. We perform a numerical exper

Michael Odenkirchen, Eva K. Grebel, Daniel Harbeck, Walter Dehnen

We have investigated the spatial extent and structure of the Draco dwarf spheroidal galaxy using deep wide-field multicolor CCD photometry from the Sloan Digital Sky Survey (SDSS). Our study covers an area of 27 square degrees around the center of the Draco dwarf. We show that the spatial distribution of Draco&#39;s red giants, red horizontal branch stars an

Donald Q. Lamb, Daniel E. Reichart

We show that, if the long GRBs are produced by the collapse of massive stars, GRBs and their afterglows may provide a powerful probe of cosmology and the early universe.

C. Alard

Metallicity gradients in the Sagittarius dwarf Galaxy (Sgr) are investigated by using infrared photometric data from the 2MASS survey. To search for metallicity effects, the giant branch in a field situated near the Center of the Sgr is compared to the giant branch in a field situated near its southern edge. The contamination of Sgr giant branch by foregroun

P. Romano, T. J. Turner, S. Mathur, I. M. George

We present an analysis of the X-ray variability properties of the NLS1 galaxy Ton S180, based upon a 12-day continuous ASCA observation. We observe flux variations of a factor of 3.5 in the 0.7-1.3 keV band and 3.9 in the 2-10 keV band.Time-resolved spectroscopy (~1d sampling) reveals that the broad `soft hump&#39; component at energies <2 keV shows flux var

T. S. Statler

In order to be in a long-lived configuration, the density in a fluid disk should be constant along streamlines to prevent compressional (PdV) work from being done cyclically around every orbit. In a pure Kepler potential, flow along aligned, elliptical streamlines of constant eccentricity will satisfy this condition. For most density profiles, differential p

Dawn M. Gelino, Thomas E. Harrison, Jerome A. Orosz

We have obtained optical and infrared photometry of the soft x-ray transient prototype V616 Mon (A0620-00). From this photometry, we find a spectral type of K4 for the secondary star in the system, which is consistent with spectroscopic observations. We present J-, H-, and K-band light curves modeled with WD98 and ELC. Combining detailed, independently run m

K. Dimopoulos, T. Prokopec, O. Tornkvist, A. C. Davis

We consider the gravitational generation of the massive Z-boson field of the standard model, due to the natural breaking of its conformal invariance during inflation. The electroweak symmetry restoration at the end of inflation turns the almost scale-invariant superhorizon Z-spectrum into a hypermagnetic field, which transforms into a regular magnetic field

F. Arqueros, J. Ballestrin, M. Berenguel, D. M. Borque

The ``Gamma Ray Astronomy at ALmeria&#39;&#39; (GRAAL) experiment uses 63 heliostat-mirrors with a total mirror area of ~ 2500 m2 from the CESA-1 field to collect Cherenkov light from airshowers. The detector is located in a central solar tower and detects photon-induced showers with an energy threshold of 250 +- 110 GeV and an asymptotic effective detection

Wayne Hu

Power spectra and cross-correlation measurements from the weak gravitational lensing of the cosmic microwave background (CMB) and the cosmic shearing of faint galaxies images will help shed light on quantities hidden from the CMB temperature anisotropies: the dark energy, the end of the dark ages, and the inflationary gravitational wave amplitude. Even with

Jiri Krticka, Jiri Kubat

We show that the so-called Gayley-Owocki (Doppler) heating is important for the temperature structure of the wind of main sequence stars cooler than the spectral type O6. The formula for Gayley-Owocki heating is derived directly from the Boltzmann equation as a direct consequence of the dependence of the driving force on the velocity gradient. Since Gayley-O

S. K. Ghosh, B. Mookerjea, T. N. Rengarajan, S. N. Tandon

Three Galactic star forming regions associated with W3(OH), S209 and S187 have been simultaneously mapped in two trans-IRAS far infrared (FIR) bands centered at ~ 140 and 200 micron using the TIFR 100 cm balloon borne FIR telescope. These maps show extended FIR emission with structures. The HIRES processed IRAS maps of these regions at 12, 25, 60 & 100 micro

D. Petry, the VERITAS Collaboration

The GRANITE III camera of the Whipple Cherenkov Telescope at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona (2300 m a.s.l.) has the highest angular resolution of all cameras used on this telescope so far. The central region of the camera has 379 pixels with an individual angular diameter of 0.12 degrees. This makes the instrument especially

Roberto Soria, Kinwah Wu, Diana Hannikainen, Mike McCollough

The 1998 outburst of XTE J1550-564 started with a hard X-ray spike, rising in less than a day and declining after 3-4 days; at the same time, the soft X-ray flux was rising with a longer timescale (~ 10 days). We suggest that the soft and the initial hard X-ray emission are produced by two different components of the accretion flow: a higher angular momentum

S. Aalto, S. Huttemeister, F. Walter

High resolution observations of CO and 13CO 1--0 in the Medusa (NGC4194) minor merger show the CO/13CO 1--0 intensity ratio (R) increasing from normal values (5-10) in the outer parts of the galaxy to high (>20) values in the central, extended starburst region. Ratios >20 are otherwise typical of more luminous mergers. The Medusa L_FIR/L_CO ratio rivals that

A. Del Popolo, N. E. Ercan, Z. Xia

We study the non-linear evolution of a dust ellipsoid,embedded in a Friedmann flat background universe, in order to determine the evolution of the density of the ellipsoid as the perturbation to it related detaches from general expansion and begins to collapse. We show that while the growth rate of the density contrast of a mass element is enhanced by the sh

Kensuke Imanishi, Masahiro Tsujimoto, Katsuji Koyama

We present results of an X-ray search from bona-fide and candidate brown dwarfs in the Rho Ophiuchi cloud cores with the Chandra X-ray Observatory. The selected areas are two fields near the cloud center and are observed with the ACIS-I array of a 17&#39;x17&#39; size and a ~100 ks exposure. Among 18 bona-fide and candidate brown dwarfs listed by the infrare

M. Magliocchetti, L. Moscardini, G. de Zotti, G. L. Granato

The clustering properties of SCUBA-selected galaxies are investigated within the framework of a unifying scheme relating the formation of QSOs and spheroids. The theoretical angular correlation function is derived for different bias functions, corresponding to different values of the ratio $M_{halo}/M_{sph}$ between the mass of the dark halos hosting such ga

Metin Gurses, Atalay Karasu, Refik Turhan

The recursion operators and symmetries of non-autonomous, (1+1)-dimensional integrable evolution equations are considered. It has been previously observed that the symmetries of the integrable evolution equations obtained through their recursion operators do not satisfy the symmetry equations. There have been several attempts to resolve this problem. It is s

D. Zappala&#39;

The gap between ground and first excited state of the quantum-mechanical double well is calculated using the Renormalization Group equations to the second order in the derivative expansion, obtained within a class of proper time regulators. Agreement with the exact results is obtained both in the strong and weak coupling regime.

E. Comay

The significance of the Lorentz gauge as a constraint on solutions of Maxwellian waves is discussed. It is proved that recent claims of superluminal propagation of electromagnetic waves rely on an erroneous basis.

Boris Malomed, Bao-Feng Feng, Takuji Kawahara

A model consisting of a mixed Kuramoto - Sivashinsky - KdV equation, linearly coupled to an extra linear dissipative equation, is proposed. The model applies to the description of surface waves on multilayered liquid films. The extra equation makes its possible to stabilize the zero solution in the model, opening way to the existence of stable solitary pulse

Leonardo Zapponi

The object of this paper is the study of a class of dessins d&#39;enfants, the so-called diameter four trees. These objects, first introduced by G. Shabat, can be considered as the simplest non trivial example of etale covers of the projective line minus three points. Their arithmetic properties are still mysterious, and their study can inspire the understan

Jonathan A. Scott

Let ΩX be the space of Moore loops on a finite, q-connected, n-dimensional CW complex X, and let R be a subring of Q containing 1/2. Let p(R) be the least non-invertible prime in R. For a graded R-module M of finite type, let FM = M / Torsion M. We show that the inclusion of the sub-Lie algebra P of primitive elements of FH_*(ΩX;R) induces an isomorphism of

Jason Fulman

The asymptotic study of the conjugacy classes of a random element of the finite affine group leads one to define a probability measure on the set of all partitions of all positive integers. Four different probabilistic understandings of this measure are given--three using symmetric function theory and one using Markov chains. This leads to non-trivial enumer

A. Marshakov

The role of associativity or WDVV equations in effective supersymmetric quantum theories is discussed and it is demonstrated that for wide class of their solutions when residue formulas are valid the proof of associativity equations can be reduced to solving the system of ordinary linear equations and depends only upon corresponding matching and nondegenerac

Archil Kobakhidze

We construct SU(5) SUSY GUT in 5D compactified on S^1/Z_2 orbifold where the matter fields are living in the five dimensional bulk. SU(5) symmetry is broken down to the Standard Model gauge group by the orbifold projection which automatically ensures stability of proton in all orders of perturbation theory. The model predicts extra mirror quark-lepton famili

L. B. Bezrukov, A. V. Butkevich

A method for fast simulation of the Cherenkov light generated by electromagnetic showers is described. The parametrization for the longitudinal profile is used and fluctuations and correlations of the parameters are taken into account in a consistent way. Our method dramatically reduces the CPU time and its results are in a rather good agreement with a full

A. V. Kuznetsov, N. V. Mikheev

A general analysis of the three-vertex loop amplitude in a strong magnetic field, based on the asymptotic form of the electron propagator in the field, is performed. In order to investigate the photon-neutrino process gamma gamma -> nu bar nu, the vertex combinations of the scalar-vector-vector (SVV), pseudoscalar-vector-vector (PVV), 3-vector (VVV), and axi

O. F. de Lima

This paper presents a brief review on the reported anisotropic properties of MgB2, in the superconducting state (e.g. upper critical field Hc2, field penetration depth, coherence length, energy gap) as well as in the normal state (e.g., magnetoresistance, compressibility, thermal expansion). So far, the reported results have been obtained using aligned cryst

T. H. Johansen, M. Baziljevich, D. V. Shantsev, P. E. Goa

Magneto-opitcal studies of a c-oriented epitaxial MgB2 film with critical current density 10^7 A/cm^2 demonstrate a breakdown of the critical state at temperatures below 10 K [cond-mat/0104113]. Instead of conventional uniform and gradual flux penetration in an applied magnetic field, we observe an abrupt invasion of complex dendritic structures. When the ap

Philip B. Allen, Ilka B. Bischofs

In the previous paper, it was shown that holes doped into BaBiO3 self-trap as small polarons and bipolarons. These point defects are energetically favorable partly because they undo locally the strain in the charge-density-wave (Peierls insulator) ground state. In this paper the neutral excitations of the same model are discussed. The lowest electronic excit

Ilka B. Bischofs, Vladimir N. Kostur, Philip B. Allen

BaBiO3 is a prototype ``charge ordering system&#39;&#39; forming interpenetrating sublattices with nominal valence Bi(3+) and Bi(5+). It can also be regarded as a three-dimensional version of a Peierls insulator, the insulating gap being a consequence of an ordered distortion of oxygen atoms. When holes are added to BaBiO3 by doping, it remains insulating un

Sher Alam, M. O. Rahman, T. Yanagisawa, H. Oyanagi

The cuprates seem to exhibit statistics, dimensionality and phase transitions in novel ways. The nature of excitations [i.e. quasiparticle or collective], spin-charge separation, stripes [static and dynamics], inhomogeneities, psuedogap, effect of impurity dopings [e.g. Zn, Ni] and any other phenomenon in these materials must be consistently understood. In t

B. Roostaei

Zero temperature phase diagram of XXZ spin chain in external magnetic field is investigated at low energies using path integral approach.It has been shown by spin wave analysis and then by nonlinear sigma model transformation that below some critical field the system undergoes quantum Kosterlitz-Thouless phase transition.Above that critical field for low ani

Sher Alam, H. Oyanagi, S. B. Mohamed, H. Ihara

The results of EXAFS measurements at 300 K for the superconducting compounds Tl$_{0.75}$Cu$_{0.25}$Ba$_{2}$Ca$_{3}$Cu$_4$O$_{y}$ [Tl-1234], TlBa$_{2}$Ca$_{3}$Cu$_{4}$O$_{y}$ [Tl-1212], and CuBa$_{2}$Ca$_{3}$Cu$_{4}$O$_{y}$ [Cu-1234]. are reported. We have measured the EXAFS spectrum for Tl$_{0.75}$Cu$_{0.25}$Ba$_{2}$Ca$_{3}$Cu$_4$O$_{y}$ in the range 10K-300

Alexander Altland

One of the remarkable features of disordered d-wave superconductors is strong sensitivity of long range properties to the microscopic realization of the disorder potential. Particularly rich phenomenology is observed for the -- experimentally relevant -- case of dilute distributions of isolated impurity centers. Building on earlier diagrammatic analyses, the

L. Portinari, A. Moretti, C. Chiosi

We develop a toy-model for the chemical evolution of the intracluster medium, polluted by the galactic winds from elliptical galaxies. The model follows the &#34;galaxy formation history&#34; of cluster galaxies, constrained by the observed luminosity function.

D. R. Goncalves, A. C. S. Friaca, V. Jatenco-Pereira

The formation of quasar broad-line region (BLR) clouds via thermal instability in the presence of Alfven heating has been discussed by Goncalves et al. (1993a, 1996). In particular, these studies showed the relevance of Alfven heating in establishing the stability of BLR clouds in the intercloud medium. The present paper shows the results of time-dependent c

M. Radovich, J. Kahanpaa, D. Lemke

A 180 micron map and strip maps at 120 and 180 microns were obtained for the edge-on starburst galaxy NGC 253 with ISOPHOT, the photometer on board the Infrared Space Observatory. We compare these observations with those obtained by IRAS at 60 micron and 100 micron and derive the far--infrared spectral energy distribution at different locations in the galaxy

Aaron Bergman, Christopher P. Herzog

We calculate the volumes of a large class of Einstein manifolds, namely Sasaki-Einstein manifolds which are the bases of Ricci-flat affine cones described by polynomial embedding relations in C^n. These volumes are important because they allow us to extend and test the AdS/CFT correspondence. We use these volumes to extend the central charge calculation of G

M. Gasperini, F. Piazza, G. Veneziano

We consider a late-time cosmological model based on a recent proposal that the infinite-bare-coupling limit of superstring/M-theory exists and has good phenomenological properties, including a vanishing cosmological constant, and a massless, decoupled dilaton. As it runs away to $+ \infty$, the dilaton can play the role of the quintessence field recently adv

O. Espinosa, J. Gamboa, S. Lepe, F. Mendez

The statistical mechanics of nonrelativistic fermions in a constant magnetic field is considered from the quantum field theory point of view. The fermionic determinant is computed using a general procedure that contains all possible regularizations. The nonrelativistic grand-potential can be expressed in terms polylogarithm functions, whereas the partition f

S. Peng Oh, Zoltan Haiman

The first generation of protogalaxies likely formed out of primordial gas via H2-cooling in cosmological minihalos with virial temperatures of a few 1000K. However, their abundance is likely to have been severely limited by feedback processes which suppressed H2 formation. The formation of the protogalaxies responsible for reionization and metal-enrichment o

J. Lehr, H. Lenske, S. Leupold, U. Mosel

Quantum transport theory is used to calculate the nucleon spectral function in infinite nuclear matter. A self-consistent description is obtained by utilizing the relations between collision rates and correlation functions. Static and dynamical self-energies are taken into account in the single particle propagators. The real parts of the non-static self-ener

Konstantin G. Boreskov, Juan Carlos Lopez V., Alexander V. Turbiner

It is shown that the $F_4$ rational and trigonometric integrable systems are exactly-solvable for {\it arbitrary} values of the coupling constants. Their spectra are found explicitly while eigenfunctions by pure algebraic means. For both systems new variables are introduced in which the Hamiltonian has an algebraic form being also (block)-triangular. These v

E. V. Cherednikova, R. N. Faustov, A. P. Martynenko

The contribution of the proton polarizability to the ground state hyperfine splitting in muonic hydrogen is evaluated on the basis of modern experimental and theoretical results on the proton polarized structure functions. The value of this correction is equal to 4.6(8)\cdot 10^{-4} times the Fermi splitting E_F.

Shigeki Matsutani

Explicit hyperelliptic solutions of the modified Korteweg-de Vries equations without any ambiguous parameters were constructed in terms only of the hyperelliptic $\al$-functions over non-degenerated hyperelliptic curve $y^2 = f(x)$ of arbitrary genus $g$. In the derivation, any $θ$-functions or Baker-Akhiezer functions were not essentially used. Then the Miu

Shigeki Matsutani

In the previous work (J. Geom. Phys. {\bf{39}} (2001) 50-61), the closed loop solitons in a plane, \it i.e., loops whose curvatures obey the modified Korteweg-de Vries equations, were investigated for the case related to algebraic curves with genera one and two. This article is a generalization of the previous article to those of hyperelliptic curves with ge

S. G. Djorgovski, S. M. Castro, D. Stern, A. Mahabal

Discovery of the cosmic reionization epoch would represent a significant milestone in cosmology. We present Keck spectroscopy of the quasar SDSS 1044-0125, at z = 5.73. The spectrum shows a dramatic increase in the optical depth at observed wavelengths lambda >~7550 A, corresponding to z_abs >~ 5.2. Only a few small, narrow transmission regions are present i

R. Mahendiran, C. Marquina, M. R. Ibarra, A. Arulraj

Magnetic, linear thermal expansion (LTE), anisotropic ($λ_t$) and volume ($ω$) magnetostriction properties of Pr$_{0.5}$Sr$_{0.5}$MnO$_3$ were investigated. The LTE decreases smoothly from 300 K without a clear anomaly either around the Curie (T$_C$ = 270 K) or the Neel temperature (T$_N$ = 100 K) and it exhibits hysteresis over a wide temperature range (60

N. Fornengo, M. Maltoni, R. Tomas, J. W. F. Valle

We have reconsidered the atmospheric neutrino anomaly in light of the laetst data from Super-Kamiokande contained events and from Super-Kamiokande and MACRO up-going muons. We have reanalysed the proposed solution to the atmospheric neutrino anomaly in terms of non-standard neutrino-matter interactions (NSI) as well as the standard nu_mu -> nu_tau oscillatio

P. Auscher

This is the text of a series of three lectures given at the CMA of the Australian National University on the recent solution of the square root problem for divergence form elliptic operators, a long-standing conjecture posed by Kato in the early 60&#39;s. In this text, the motivations for this problem and its situation are given. The ideas from harmonic anal

I. Vitev, M. Gyulassy

We study the apparent discrepancy between the standard PQCD predictions for the meson and baryon ratios and multiplicities at moderate high $p_{T} > 2$ GeV and recent experimental measurements in $Au+Au$ collisions at $\sqrt{s}_{NN}=130$ GeV at the Relativistic Heavy Ion Collider (RHIC). We show that the differences, most pronounced in central collisions, ca

Danilo Babusci, Massimo Giovannini

The sensitivity achievable by a pair of VIRGO detectors to stochastic and isotropic gravitational wave backgrounds produced in pre-big-bang models is discussed in view of the development of a second VIRGO interferometer. We describe a semi-analytical technique allowing to compute the signal-to-noise ratio for (monotonic or non-monotonic) logarithmic energy s