December 1998 arXiv papers — page 3

D. Blaschke, G. Burau, M. K. Volkov, V. L. Yudichev

We consider an extended Nambu--Jona-Lasinio (NJL) model for the light meson sector of QCD where unphysical quark production thresholds are excluded by an infrared cut-off on the momentum integration within quark loop diagrams. This chiral quark model conserves the low energy theorems. The infrared cut-off is fixed selfconsistently by the dynamically generate

K. Naito, K. Yoshida, Y. Nemoto, M. Oka

We study the finite quark mass effects of the low-energy QCD using the improved ladder Schwinger-Dyson and Bethe-Salpeter equations which are derived in the manner consistent with the vector and axial-vector Ward-Takahashi identities. The non-perturbative mass-independent renormalization allows us to calculate the quark condensate for a non-zero quark mass.

Yong Liu

In this work, the postulation that weak CP phase originates in a certain geometry, is further discussed. According to this postulation, the weak CP phase is determined by three mixing angles. So, if we can determine experimentally three elements of the Cabibbo-Kobayashi-Maskawa matrix, we can then determine the whole CKM matrix and correspondingly, the unita

N. Gagunashvili

A new algorithm for extraction of asymmetries from polarized lepton-nucleon scattering data is proposed. The algorithm is stable to set-up acceptance and/or luminosity monitor acceptance variations. A statistical test for checking the data quality is proposed.

Kazushige Machida, Masanori Ichioka

We show that the lightly doped La_{2-x}Sr_{x}CuO_{4} can be described in terms of a stripe magnetic structure or soliton picture. The internal relationship between the recent neutron observation of the diagonal (x=0.05) to vertical (x >= 0.06) stripe transition, which was predicted, and the concomitant metal-insulator transition is clarified by this solitoni

David McDavid

A new polarimeter called AnyPol has been used at Limber Observatory for four years to annually monitor the broadband linear polarization of a sample of bright northern Be stars. This is the fourth report on a program started in 1985 at McDonald Observatory and the first one to come entirely from the new installation. Although no variability was detected at t

A. D. Kaminker, C. J. Pethick, A. Y. Potekhin, V. Thorsson

Neutrino-pair bremsstrahlung by relativistic degenerate electrons in a neutron-star crust at densities (10^9 - 1.5x10^{14}) g/cm^3 is analyzed. The processes taken into account are neutrino emission due to Coulomb scattering of electrons by atomic nuclei in a Coulomb liquid, and electron-phonon scattering and Bragg diffraction (the static-lattice contributio

Supriya Kar

We investigate the dynamics of an arbitrary Dirichlet (D-) string in presence of general curved backgrounds following a path-integral formalism. In particular, we consider the interaction of D-string with the massless excitations of closed string in open bosonic string theory. The background fields induce invariant curvatures on the D-string manifold and the

S. C. Woon

A generalization of a well-known relation between the Riemann zeta function $\zeta(s)$ and Bernoulli numbers $B_n$ is obtained. The formula is a new representation of the Riemann zeta function in terms of a nested series of Bernoulli numbers.

C. P. Burgess, C. A. Lutken

We argue that the large discrete symmetry group of quantum Hall systems is insufficient in itself to determine the complete beta function for the scaling of the conductivities, $σ_{xx}$ and $σ_{xy}$. We illustrate this point by showing that a recent ansatz for this function is one of a many-parameter family. A clean prediction for the delocalization exponent

Oleg Lebedev

We study implications of spontaneous CP-violation in minimal susy models for CP-asymmetries in rare $B,\bar B$-decays. In particular, we estimate characteristic values of the angles of the unitarity triangle and show that sizeable CP-violating effects result from $B-\bar B$ mixing only. Significant deviations from the SM predictions are pointed out.

Haru-Tada Sato, Michael G. Schmidt

Based on the world-line formalism with a sewing method, we derive the Yang-Mills effective action in a form useful to generate the Bern-Kosower-type master formulae for gluon scattering amplitudes at the two-loop level. It is shown that four-gluon ($Φ^4$ type sewing) contributions can be encapsulated in the action with three-gluon ($Φ^3$ type) vertices only,

J. L. Chkareuli, C. D. Froggatt

We argue that flavour mixing, both in the quark and charged lepton sector, is basically determined by the lightest family mass generation mechanism. So, in the chiral symmetry limit when the up and down quark masses vanish, all the quark mixing angles vanish. This mechanism is not dependent on the number of quark-lepton families nor on any ``vertical'&#3

T. G. Steele, K. Kostuik, J. Kwan

QCD Laplace sum-rules must satisfy a fundamental (Holder) inequality if they are to consistently represent an integrated hadronic cross-section. After subtraction of the pion-pole, the Laplace sum-rule of pion currents is shown to violate this fundamental inequality unless the up and down quark masses are sufficiently large, placing a lower bound on the 1.0

Chitoshi Yasuda, Akihide Oguchi

The spin-wave theory and the coherent potential approximation are applied to a spin S Heisenberg antiferromagnet with nonmagnetic impurities on square lattice. The impurity effects are taken into account by substituting S(1-x) for S and using the coherent potential approximation to the exchange interaction, where x is the impurity concentration. At T=0 for S

Dalibor Kekez, Dubravko Klabucar

For the spacelike momenta k of the virtual photon gamma^*, the pi^0(p) gamma^*(k) gamma(k') transition form factor is considered in the coupled Schwinger-Dyson and Bethe-Salpeter approach in conjunction with the generalized impulse approximation using the dressed quark-photon-quark vertices of the Ball-Chiu and Curtis-Pennington type. These form factors

Reginald T. Cahill, Christopher M. Klinger

Generalising results from Godel and Chaitin in mathematics suggests that self-referential systems contain intrinsic randomness. We argue that this is relevant to modelling the universe and show how three-dimensional space may arise from a non-geometric order-disorder model driven by self-referential noise.

Martin Roetteler, Thomas Beth

We present a family of non-abelian groups for which the hidden subgroup problem can be solved efficiently on a quantum computer.

F. A. B. Coutinho, Y. Nogami, Lauro Tomio

For the electric polarizability of a bound system in relativistic quantum theory, there are two definitions that have appeared in the literature. They differ depending on whether or not the vacuum background is included in the system. A recent confusion in this connection is clarified.

F. A. B. Coutinho, Y. Nogami, Lauro Tomio

Regarding the Pauli principle in quantum field theory and in many-body quantum mechanics, Feynman advocated that Pauli's exclusion principle can be completely ignored in intermediate states of perturbation theory. He observed that all virtual processes (of the same order) that violate the Pauli principle cancel out. Feynman accordingly introduced a presc

V. A. Kalatsky, V. L. Pokrovsky

Spectra and magnetic properties of large spins $J$, placed into a crystal electric field (CEF) of an arbitrary symmetry point group, are shown to change drastically when $J$ changes by 1/2 or 1. At a fixed field symmetry and configuration of its $N$ extrema situated at $p$-fold symmetry axis, physical characteristics of the spin depend periodically on $J$ wi

Apoorva Patel

Feynman's path integrals provide a hidden variable description of quantum mechanics (and quantum field theories). The time evolution kernel is unitary in Minkowski time, but generically it becomes real and non-negative in Euclidean time. It follows that the entangled state correlations, that violate Bell's inequalities in Minkowski time, obey the ine

E. G. Bessonov, K. -J. Kim, F. Willeke

A new scheme for the two-dimensional cooling of ion beams in storage rings is suggested in which ions interact with a counterpropagating broad-band laser beam. The interaction region in the direction of the ion movement is much less then the wavelength of the ion betatron oscillations. The laser beam in the orbit plane has sharp flat edge directed to the ion

Stepan G. Mashnik, Arnold J. Sierk

Recent improvements to the Cascade-Exciton Model (CEM) of nuclear reactions are briefly described. They concern mainly the cascade stage of reactions and a better description of nuclei during the preequilibrium and evaporation stages of reactions. The development of the CEM concerning fission is given in a separate talk at this conference. The increased accu

Jia-Lun Ping, Fan Wang, T. Goldman

The quark delocalization and color screening model is used for a systematic study of the effective potential between baryons in the u,d and s sector. The model is constrained by the properties of baryons and N-N scattering. The effective potentials for the N-N (IJ=01,10,11,00) channels and the N-Lambda and N-Sigma (IJ = (1/2)1, (1/2)0, (3/2)1, (3/2)0) channe

F. Bellemann, A. Berg, J. Bisplinghoff, G. Bohlscheid

The cross section of the pd -> 3He pi+ pi - reaction has been measured at the MOMO facility in a kinematically complete experiment at a c. m. excess energy of Q = 70 MeV. The energy and angular distributions show that the reaction is dominated by p-wave pi+ pi- pairs. This is in complete contrast to the results of inclusive measurements at somewhat higher en

Gaetano Fiore, John Madore

We briefly describe how to introduce the basic notions of noncommutative differential geometry on the 3-dim quantum space covariant under the quantum group of rotations $SO_q(3)$.

Gaetano Fiore

Any deformation of a Weyl or Clifford algebra can be realized through some change of generators in the undeformed algebra. Here we briefly describe and motivate our systematic procedure for constructing all such changes of generators for those particular deformations where the original algebra is covariant undersome Lie group and the deformed algebra is cova

Zu-Guo Yu, Fu-Yao Ren, Jin-Rong Liang

Under weaker condition than that of Riedi & Mandelbrot, the Hausdorff (and Hausdorff-Besicovitch) dimension of infinite self-similar set K which is the invariant compact set of infinite contractive similarities {S_j(x)} satisfying open set condition is obtained. It is proved (under some additional hypotheses) that the mean quadratic variation of infinite sel

Bruce E. Sagan

We survey three methods for proving that the characteristic polynomial of a finite lattice factors over the nonnegative integers and indicate how they have evolved recently. The first technique uses geometric ideas and is based on Zaslavsky's theory of signed graphs. The second approach is algebraic and employs results of Saito and Terao about free hyper

V. Ch. Zhukovsky, V. V. Khudyakov, I. V. Mamsurov

Different models with nonabelian homogeneous condensate fields are considered in the one-loop approximation. Effective action in a model of gluodynamics in curved space is calculated. Free energy and its minimum in a (2+1)-dimensional model of QCD are investigated. Photon polarization operator (PO) is obtained.

Yukiko Ohtake

We study the BPS spectrum of four dimensional N=2 SU(2) theory with massive fundamental matters using the D3-brane probe. Since the BPS states are realized by string webs subject to the BPS conditions, we determine explicitly the configurations of such webs. It is observed that there appear BPS string webs with multiple of junctions corresponding to the fact

Freddy P. Zen, Hendry I. Elim

The soliton solution of the integrable coupled nonlinear Schrodinger equation (NLS) of Manakov type is investigated by using Zakharov-Shabat (ZS) scheme. We get the bright N-solitons solution by solving the integrable uncoupled NLS of Manakov type. We also find that there is an elastic collision of the bright N-solitons.

Chi-Yee Cheung, Wei-Min Zhang

In this paper we obtain a heavy meson bound state equation from the heavy quark equation of motion in heavy quark effective theory (HQET) and the heavy meson effective field theory we developed very recently. The bound state equation is a covariant extention of the light-front bound state equation for heavy mesons derived from light-front QCD and HQET. We de

F. Chishtie, V. Elias, T. G. Steele

Asymptotic Pade-approximant methods are utilized to estimate the leading-order unknown (i.e., not-yet-calculated) contributions to the perturbative expansions of two-current QCD correlation functions obtained from scalar-channel fermion and gluon currents, as well as from vector-channel fermion currents. Such contributions to the imaginary part of each corre

V. Novikov

The following 5 lectures are devoted to key ideas in field theory and in the Standard Model.

Ashok Goyal, V. K. Gupta, Kanupriya, Vinita Tuli

We study the effect of magnetic field on the dominant neutrino emission processes in neutron stars.The processes are first calculated for the case when the magnetic field does not exceed the critical value to confine electrons to the lowest Landau state.We then consider the more important case of intense magnetic field to evaluate the direct URCA and the neu

Maria Krawczyk

The status of the Higgs boson search in the Standard Model and beyond it is presented.

B. Lampe

I discuss one-loop QCD corrections to the forward backward asymmetry of the b-quark at LEP in a way appropriate to the present experimental procedure. I try to give insight into the structure of the corrections and elucidate some questions which have been raised by experimental experts. Furthermore, I complete and comment on results given in the literature.

Reginald T. Cahill, Susan M. Gunner

The Global Colour Model (GCM) of QCD is a quark-gluon quantum field theory that very successfully models QCD for low energy hadronic processes. An effective gluon correlator models the interaction between quark currents. Functional integral calculus allows the GCM to be hadronised (i.e. expressed in terms of meson and baryon fields). The dominant configurati

SELEX Collaboration, J. Russ

The SELEX experiment (E781) at Fermilab is a 3-stage magnetic spectrometer for the high statistics study of charm hadroproduction out to large x_F using 600 GeV Sigma^-, p and pi beams. The main features of the spectrometer are: high precision silicon vertex system, broad-coverage particle identification with TRD and RICH, 3-stage lead glass photon detector.

Benjamin Paul, Michael Schulz, Harry L. Frisch

A phantom network of Gaussian chains far from the point of gelation can be described as a gas of interacting particles represented by the cross links. The type of particles varies with the network functionality, whereas the type of interaction depends on the properties of the connecting chains. In a mean field approximation the Equation of State can be calcu

S. Ciuchi, F. de Pasquale

We apply the Dynamical Mean Field Theory to the problem of charge ordering. In the normal state as well as in the Charge Ordered (CO) state the existence of polarons, i.e. electrons strongly coupled to local lattice deformation, is associated to the qualitative properties of the Lattice Polarization Distribution Function (LPDF). At intermediate and strong co

Bogdan R. Bulka

A short review of correlated electrons in molecular systems has been performed. Main attention has been focussed on ET salts, which are the d=2 systems. They show the Mott transition in high temperatures and the transition from the antiferromagnetic to the superconducting phase in low temperatures, under a (chemical) pressure. Physical properties (the electr

O. Pla, F. Guinea, E. Louis, S. V. Ghaisas

We study the dynamics of cracks in brittle materials when the velocity of the crack is comparable to the sound velocity by means of lattice simulations. Inertial and damped dynamics are analyzed. It is shown that dissipation strongly influences the shape of the crack. While inertial cracks are highly unstable, dissipation can stabilize straight cracks. Our r

F. Richter, L. Finegold, G. Rapp

In the mimetic membrane system of phosphatidylcholine bilayers, thickening (pre-critical behavior, anomalous swelling) of the bilayers is observed, in the vicinity of the main transition, which is non-linear with temperature. The sterols cholesterol and androsten are used as sensors in a time-resolved simultaneous small- and wide angle x-ray diffraction stud

J. S. Thakur, D. Neilson

We propose a mechanism for the recently reported destabilization by an in-plane magnetic field of the conducting phase of low density electrons in 2D. We apply our self-consistent approach based on the memory function formalism to the fully spin polarized electron system. This takes into account both disorder and exchange-correlation effects. We show that sp

Luis A. Anchordoqui

The problem of predicting the upper cut-off of the cosmic ray spectrum is re-examined. Some aspects of extremely high energy interactions and their implications for the interpretation of giant air showers are also discussed.

Eva K. Grebel

The star formation histories of Local Group (LG) dwarf galaxies and more distant potential LG members are reviewed. Problems in defining the spatial extent of the LG and membership are briefly discussed. The morphological types found in the LG are presented, and it is suggested that we see continuous evolution from low-mass dwarf irregulars (dIrrs) to dwarf

Martin Erdmann

Recent experimental results on the partonic structure of the photon and on the color singlet exchange in strong interaction processes are reviewed. At the LEP electron-positron and HERA lepton-proton colliders, complementary and consistent measurements have been achieved on the quark-gluon structure of quasi-real and virtual photons. At the HERA lepton-proto

Hugo Garcia-Compean

The study of brane-antibrane configurations in string theory leads to the understanding of supersymmetric D$p$-branes as the bound states of higher dimensional branes. Configurations of pairs brane-antibrane do admit in a natural way their description in terms of K-theory. We analyze configurations of brane-antibrane at fixed point orbifold singularities in

Konstantin Borozdin, Mikhail Revnivtsev, Sergey Trudolyubov, Chris Shrader

We present our analysis of the high-energy radiation from black hole (BH) transients, using archival data obtained primarily with RXTE observatory, and a comprehensive test of the bulk motion Comptonization (BMC) model for the high-soft state continuum. The emergent spectra of over 30 separate measurements of GRO J1655-40, GRS 1915+105, GRS 1739-278, 4U 1630

F. A. Dilkes, D. G. C. McKeon, Christian Schubert

We further develop the new approach, proposed in part I (hep-th/9807072), to computing the heat kernel associated with a Fermion coupled to vector and axial vector fields. We first use the path integral representation obtained for the heat kernel trace in a vector-axialvector background to derive a Bern-Kosower type master formula for the one-loop amplitude

D. Müller

We apply the so-called conformal subtraction scheme to predict perturbatively exclusive processes beyond leading order. Taking into account evolution effects, we study the scheme dependence for the photon-to-pion transition form factor and the electromagnetic pion form factor at next-to-leading order for different pion distribution amplitudes. Relying on the

Georg Goeppert, Hermann Grabert, Christian Beck

We consider quantum fluctuations of the charge on a small metallic grain caused by virtual electron tunneling to a nearby electrode. The average electron number and the effective charging energy are determined by means of perturbation theory in the tunneling Hamiltonian. In particular we discuss the dependence of charging effects on the number N of tunneling

A. Delgado, A. Pomarol, M. Quiros

We analyze some features of the role that extra dimensions, of radius $R$ in the TeV$^{-1}$ range, can play in the soft breaking of supersymmetry and the spontaneous breaking of electroweak symmetry. We use a minimal model where the gauge and Higgs sector of the MSSM are living in the bulk of five dimensions and the chiral multiplets in a four-dimensional bo

Mathis Plapp, Alain Karma

Experiments have widely shown that a steady-state lamellar eutectic solidification front is destabilized on a scale much larger than the lamellar spacing by the rejection of a dilute ternary impurity and forms two-phase cells commonly referred to as `eutectic colonies'. We extend the stability analysis of Datye and Langer for a binary eutectic to include

S. Dawson, L. Reina

We investigate the inclusive production of the Higgs bosons of the minimal supersymmetric model with a heavy quark pair, ($t {\bar t}$ and $b {\bar b}$), in e^+e^- collisions at high energies, $\sqrt{s}=500 GeV$ and $\sqrt{s}=1 TeV$. The ${\cal O}(α_s)$ QCD radiative corrections are included and the dependence of the production rates on the parameters of the

G. E. Volovik

There are several classes of homogeneous Fermi-systems which are characterized by the topology of the energy spectrum of fermionic quasiparticles: (1) Gapless systems with a Fermi-surface; (2) Systems with a gap in their spectrum; (3) Gapless systems with topologically stable point nodes (Fermi points); and (4) Gapless systems with topologically unstable lin

Yu. L. Dokshitzer, G. Marchesini, G. P. Salam

We show that taking into account the interplay between perturbative and non-perturbative effects, the power-suppressed shift to the broadening distributions becomes B dependent, and the non-perturbative contribution to the mean values becomes proportional to 1/(Q\sqrt{\as(Q)}). The new theoretical treatment greatly improves the consistency of the phenomenolo

Prakash Mathews, Sreerup Raychaudhuri, K. Sridhar

In scenarios motivated by string theories, it is possible to have extra Kaluza-Klein dimensions compactified to rather large magnitudes, leading to large effects of gravity at scales down to a TeV. The effect of the spin-2 Kaluza-Klein modes on the deep-inelastic cross-section at HERA is investigated. We find that the data can be used to obtain bounds on the

Chong-Sun Chu, Pei-Ming Ho

In this paper we consider the quantization of open strings ending on D-branes with a background B field. We find that spacetime coordinates of the open string end-points become noncommutative, and correspondingly the D-brane worldvolume also becomes noncommutative. This provides a string theory derivation and generalization of the noncommutativity obtained p

M. Beccaria, P. Ciafaloni, D. Comelli, F. M. Renard

We examine the possibility that SUSY particles are light, i.e. have a mass just beyond the final kinematical reach of LEP2. In this case, even if light particles are not directly detected, their virtual effects are enhanced by a ``close to threshold'' resonance in the s-channel. We find that this resonant effect is absent in the case of light sfermio

G. Vidal, J. I. Latorre, P. Pascual, R. Tarrach

The optimal and minimal measuring strategy is obtained for a two-state system prepared in a mixed state with a probability given by any isotropic a priori distribution. We explicitly construct the specific optimal and minimal generalized measurements, which turn out to be independent of the a priori probability distribution, obtaining the best guesses for th

Hidetoshi Awata, Shinji Hirano

We study the large N limit of matrix models of M5-branes, or (2,0) six-dimensional superconformal field theories, by making use of the Bulk/Boundary correspondence. Our emphasis is on the relation between the near-horizon limit of branes and the light-like limit of M-theory. In particular we discuss a conformal symmetry in the D0 + D4 system, and interpret i

J. J. Ruiz-Lorenzo, C. L. Ullod

We consider a microcanonical local algorithm to be applied on the $\pm J$ spin glass model. We have compared the results coming from a microcanonical Monte Carlo simulation with those from a canonical one: Thermalization times, spin glass susceptibilities and Binder parameters. For a fixed lattice size we found different results between the two thermodynamic

J. Mesot, M. R. Norman, H. Ding, M. Randeria

Comparing ARPES measurements on Bi2212 with penetration depth data, we show that a description of the nodal excitations of the d-wave superconducting state in terms of non-interacting quasiparticles is inadequate, and we estimate the magnitude and doping dependence of the Landau interaction parameter which renormalizes the linear T contribution to the superf

Peng Zhou, S. Swain

We propose a method to observe phase-dependent spectra in resonance fluorescence, employing a two-level atom driven by a strong coherent field and a weak, amplitude-fluctuating field. The spectra are similar to those which occur in a squeezed vacuum, but avoid the problem of achieving squeezing over a $4π$ solid angle. The system shows other interesting feat

V. M. Red'kov

The paper concerns a problem of Dirac fermion doublet in the external monopole potential arisen out of embedding the Abelian monopole solution in the non-Abe- lian scheme. In this particular case, the Hamiltonian is invariant under some symmetry operations consisting of an Abelian subgroup in the complex rotational group SO(3.C). This symmetry results in a c

V. M. Red'kov

Particles of spin 1/2 and 1 in external Abelian monopole field are considered. P-inversion like operators N-s commuting with the respective Hamiltonians are constructed: N(bisp.) is diagonalized onto the relevant wave functions, whereas N(vect.) does not. Such a paradox is rationalized through noting that both these operators are not self-conjugate. It is sh

L. I. Ognev

The effect of capture of X-ray beam into narrow submicron capillary was investigated with account for diffraction and decay of coherency by roughness scattering in transitional boundary layer. In contrast to well-known Andronov-Leontovich approach the losses do not vanish at zero gliding angle and scale proportional to the first power of roughness amplitude

H1 SpaCal Group, R. -D. Appuhn et al

The electronic system developed for the SpaCal lead/scintillating-fibre calorimeters of the H1 detector in operation at the HERA ep collider is described in detail and the performance achieved during H1 data-taking is presented. The 10 MHz bunch crossing rate of HERA puts severe constraints on the requirements of the electronics. The energy and time readout

Chris Leemann

A closer look (with hindsight) at Newtonian and relativistic kinematics reveals two things. Not surprisingly, Newtonian time remains the empty and artificial - albeit useful - figment it is known to be. Quite unexpectedly however it turns out that with an only slightly more physical time-concept, time and space remain separate entities and simultaneity of ev

Igor Mitkov, Konstantin Kladko, A. R. Bishop

We study the stabilization of localized structures by discreteness in one-dimensional lattices of diffusively coupled nonlinear sites. We find that in an external driving field these structures may lose their stability by either relaxing to a homogeneous state or nucleating a pair of oppositely moving fronts. The corresponding bifurcation diagram demonstrate

Ulrich Mosel

In this talk I first discuss predictions based on QCD sum rules and on hadronic models for the properties of vector mesons in the nuclear medium. I then describe possible experimental signatures and show detailed predictions for dilepton invariant mass spectra with a special emphasis on nuclear reactions involving elementary incoming beams and nuclear target

George A. Hagedorn, Alain Joye

We construct approximate solutions to the time--dependent Schrödinger equation $i \hbar (\partial ψ)/(\partial t) = - (\hbar^2)/2 Δψ+ V ψ$ for small values of $\hbar$. If $V$ satisfies appropriate analyticity and growth hypotheses and $|t|\le T$, these solutions agree with exact solutions up to errors whose norms are bounded by $C \exp{-γ/\hbar}$, for some $

A. Joye, F. Monti, S. Guerin, H. R. Jauslin

We formulate an adiabatic theorem adapted to models that present an instantaneous eigenvalue experiencing an infinite number of crossings with the rest of the spectrum. We give an upper bound on the leading correction terms with respect to the adiabatic limit. The result requires only differentiability of the considered spectral projector, and some geometric

Dominik Rogula

Topological defects in crystalline lattices are considered. In relation to physical realizability of such defects, criteria for geometric compatibility of the lattice distortions are formulated. For 2D lattices it is shown that the answer to the question of existence of distortion fields which are both geometrically compatible and homotopically non-trivial i

Arnold Knopfmacher, Helmut Prodinger

For words of length n, generated by independent geometric random variables, we consider the average value and the average position of the r-th left-to-right maximum, for fixed r and large n.

Eduardo Eyras, Yolanda Lozano

An effective action for the M9-brane is proposed. We study its relation with other branes via dualities. Among these, we find actions for branes which are not suggested by the central charges of the Type II superalgebras.

A. E. Santana, F. C. Khanna, Y. Takahashi

A vector space G is introduced such that the Galilei transformations are considered linear mappings in this manifold. The covariant structure of the Galilei Group (Y. Takahashi, Fortschr. Phys. 36 (1988) 63; 36 (1988) 83) is derived and the tensor analysis is developed. It is shown that the Euclidean space is embedded the (4,1) de Sitter space through in G.

F. C. Khanna, A. E. Santana, A. Matos Neto, J. D. M. Vianna

In this work we apply the Lie group representation method introduced in the real time formalism for finite-temperature quantum-field theory, thermofield dynamics, to derive a spinorial density matrix equation. Symmetry properties of such equation are analysed, and as a basic result it is shown that one solution is the generalised density matrix operator prop

Piet Claus

We present a construction of the superspace of maximally supersymmetric adS_{p+2} x S^{d-p-2} near-horizon geometry based entirely on the supergravity constraints of which the bosonic space is a solution. Besides the geometric superfields, i.e. the vielbeine and the spinconnection, we also derive the isometries of the superspace together with the compensatin

Jerzy A. Przeszowski

The canonical quantization on a single light front is performed for the Abelian gauge fields with the Weyl gauge coupled with fermion field currents. The analysis is carried separately for 1+1 dimensions and for higher dimensions. The Gauss law, implemented weakly as the condition on states, selects physical subspace with the Poincare covariance recovered. T

Ming Yu, Bo Zhang

Light-cone gauge quantization procedures are given, for superstring theory on $AdS_3$ space charged with NS-NS background, both in NSR and GS formalism. The spacetime (super)conformal algebras are constructed in terms of the transversal physical degrees of freedom. The spacetime conformal anomaly agrees with that of covariant formalism, provided that the wor

R. Myrzakulov

The gauge equivalent counterparts of the some (1+1)-, or (2+0)-dimensional sigma models with potentials are found. The gauge equivalence between the some soliton equations of spin-phonon systems and the Yajima-Oikawa and Ma equations are also established.

Yeuk-Kwan E. Cheung, Ori J. Ganor, Morten Krogh, Andrei Yu. Mikhailov

We show that the moduli space of the $(2,0)$ and little-string theories compactified on $T^3$ with R-symmetry twists is equal to the moduli space of U(1) instantons on a non-commutative $T^4$. The moduli space of $U(q)$ instantons on a non-commutative $T^4$ is obtained from little-string theories of NS5-branes at $A_{q-1}$ singularities with twists. A large

Frithjof Karsch, Martin Lütgemeier

We analyze the finite temperature phase diagram of$QC$ with fermions in the adjoint representation. The simulations performed with four dynamical Majorana fermions show that the deconfinement and chiral phase transitions occur at two distinct temperatures. While the deconfinement transition is first order at T_d we find evidence for a continuous chiral trans

G. Thorleifsson, P. Bialas, B. Petersson

In the weak-coupling limit, kappa_0 going to infinity, the partition function of simplicial quantum gravity is dominated by an ensemble of triangulations with the ratio N_0/N_D close to the upper kinematic limit. For a combinatorial triangulation of the D--sphere this limit is 1/D. Defining an ensemble of maximal triangulations, i.e. triangulations that have

A. T. Doyle

The latest structure function results, as presented at the ICHEP98 conference, are reviewed. A brief introduction to the formalism and the status of global analyses of parton distributions is given. The review focuses on three experimental areas: fixed-target results and their constraints on the parton densities at high $x$; spin structure and spin parton de

A. A. Saharian

We investigate the evolution of the homogeneous and isotropic universe within the framework of the effective string gravity with string-loop modifications of dilaton couplings. In the case of barotropic perfect fluid as a nongravitational source the set of cosmological equations is presented in the form of the third-order autonomous dynamical system. The cas

S. V. Kravchenko, D. Simonian, K. Mertes, M. P. Sarachik

In the dilute two-dimensional electron system in silicon, we show that the temperature below which Shubnikov-de Haas oscillations become apparent is approximately the same as the temperature below which an exponential decrease in resistance is seen in B=0, suggesting that the anomalous behavior in zero field is observed only when the system is in a degenerat

P. J. Forrester, G. Honner

The zeros of complex Gaussian random polynomials, with coefficients such that the density in the underlying complex space is uniform, are known to have the same statistical properties as the zeros of the coherent state representation of one-dimensional chaotic quantum systems. We extend the interpretation of these polynomials by showing that they also arise

J. L. Cohn, G. S. Nolas, V. Fessatidis, T. H. Metcalf

The thermal conductivity of polycrystalline semiconductors with type-I clathrate hydrate crystal structure is reported. Ge clathrates (doped with Sr and/or Eu) exhibit lattice thermal conductivities typical of amorphous materials. Remarkably, this behavior occurs in spite of the well-defined crystalline structure and relatively high electron mobility ($\sim

Boldizsar Janko

In the presence of an external magnetic field, the low lying elementary excitations of a d-wave superconductor have quantized energy and their momenta are locked near the node direction. It is argued that these discrete states can most likely be detected by a local probe, such as a scanning tunneling microscope. The low temperature local tunneling conductanc

V. I. Tsebro, O. E. Omel'yanovskii, E. F. Kukovitskii, N. A. Sainov

Bulk samples of carbon multilayer nanotubes with the structure of nested cones (fishbone structure) suitable for transport measurements, were prepared by compressing under high pressure (~25 kbar) a nanotube precursor synthesized through thermal decomposition of polyethylene catalyzed by nickel. The structure of the initial nanotube material was studied usin

Serge Galam, Alain Mauger

An universal invariant for site and bond percolation thresholds (p_{cs} and p_{cb} respectively) is proposed. The invariant writes {p_{cs}}^{1/a_s}{p_{cb}}^{-1/a_b}=δ/d where a_s, a_b and δare positive constants,and d the space dimension. It is independent of the coordination number, thus exhibiting a topology invariance at any d.The formula is checked again

A. A. Gorbatsevich, V. V. Kapaev, Yu. V. Kopaev, I. V. Kucherenko

A new phenomenon is observed experimentally in a heavily doped asymmetric quantum-size structure in a magnetic field parallel to the quantum-well layers - a transverse magnetoresistance which is asymmetric in the field (there can even be a change in sign) and is observed in the case that the structure has a built-in lateral electric field. A model of the eff

K. Byczuk, T. Dietl

The form of an effective electron-electron interaction in a quantum wire with a large static dielectric constant is determined and the resulting properties of the electron liquid in such a one-dimensional system are described. The exchange and correlation energies are evaluated and a possibility of a paramagnetic-ferromagnetic phase transition in the ground

S. Brehmer, H. -J. Mikeska, M. Mueller, N. Nagaosa

We investigate the influence of biquadratic exchange interactions on the low-lying excitations of a S=1/2-ladder using perturbation theory, numerical diagonalization of finite systems and exact results for ladders with matrix product ground states. We consider in particular the combination of biquadratic exchange interactions corresponding to ring exchange o