January 1998 arXiv papers — page 2

T. A. Jacobson, G. E. Volovik

Event horizons for fermion quasiparticles naturally arise in moving textures in superconductors and Fermi superfluids. We discuss the example of a planar soliton moving in superfluid 3He-A, which is closely analogous to a charged rotating black hole. The moving soliton will radiate quasiparticles via the Hawking effect at a temperature of about 5 μK, and via

Rong-Gen Cai

The one-loop effective action for QED in curved spacetime contains equivalence principle violating interactions between the electromagnetic field and the spacetime curvature. These interactions lead to the dependence of photon velocity on the motion and polarization directions. In this paper we investigate the gravitational analogue to the electromagnetic bi

Ursula Carow-Watamura, Satoshi Watamura

The differential algebra on the fuzzy sphere is constructed by applying Connes' scheme. The U(1) gauge theory on the fuzzy sphere based on this differential algebra is defined. The local U(1) gauge transformation on the fuzzy sphere is identified with the left $U(N+1)$ transformation of the field, where a field is a bimodule over the quantized algebra $\

Saburo Higuchi

A Hamiltonian cycle of a graph is a closed path which visits each of the vertices once and only once. In this article, Hamiltonian cycles on planar random lattices are considered. The generating function for the number of Hamiltonian cycles is obtained and its singularity is studied. Relation to two-dimensional quantum gravity is discussed.

Juan M. Maldacena, Andrew Strominger

Quantum gravity in 2+1 dimensions with a positive cosmological constant can be represented as an SL(2,C) Chern-Simons gauge theory. The symmetric vacuum of this theory is a degenerate configuration for which the gauge fields and spacetime metric vanish, while de Sitter space corresponds to a highly excited thermal state. Carlip's approach to black hole e

Dietrich Bodeker

We consider time dependent correlation functions of non-abelian gauge fields at finite temperature. An effective theory for the soft ($p\sim g^2 T$) field modes is derived by integrating out the field modes with momenta of order $T$ and of order $g T$ in a leading logarithmic approximation. In this effective theory the time evolution of the soft fields is de

Michal Horodecki, Pawel Horodecki, Ryszard Horodecki

It is shown that if a mixed state can be distilled to the singlet form, it must violate partial transposition criterion [A. Peres, Phys. Rev. Lett. 76, 1413 (1996)]. It implies that there are two qualitatively different types of entanglement: ``free'' entanglement which is distillable, and ``bound'' entanglement which cannot be brought to the

Matteo G. A. Paris

We address the problem of determining whether or not a harmonic oscillator has been perturbed by an external force. Quantum detection and estimation theory has been used in devising optimum measurement schemes. Detection probability has been evaluated for different initial state preparations of oscillator. The corresponding lower bounds on minimum detectable

A. V. Chizhov, V. De Renzi, M. G. A. Paris

A two-step detection strategy is suggested for the precise measurement of the optical phase-shift. In the first step an unsharp, however, unbiased joint measurement of the phase and photon number is performed by heterodyning the signal field. Information coming from this step is then used for suitable squeezing of the probe mode to obtain a sharp phase distr

E. Epelbaoum, W. Glöckle, Ulf-G. Meißner

We construct the two- and three-nucleon potential based on the most general chiral effective pion-nucleon Lagrangian using the method of unitary transformations. For that, we develop a power counting scheme consistent with this projection formalism. In contrast to previous results obtained in old-fashioned time-ordered perturbation theory, the method employe

Carsten Greiner, Juergen Schaffner-Bielich

The properties of strange quark matter and strange hadronic matter and their finite counterparts (strangelets and MEMOs) are reviewed. The production of strange matter in heavy-ion collision and the appearance of strange matter in neutron stars are discussed.

N. Soic, D. Cali, S. Cherubini, E. Costanzo

In a measurement of the 9Be(7Li,alpha 7Li)n alpha reaction at E = 52 MeV it is unambigously established for the first time that the 9Be excited states around 6.5 and 11.3 MeV decay into the alpha + 5He channel. This fact may support previous claims that the 11.3 MeV state is also a member of the ground state rotational band.

Victor G. Kac, Weiqiang Wang, Catherine H. Yan

We show that there are precisely two, up to conjugation, anti-involutions sigma_{\pm} of the algebra of differential operators on the circle preserving the principal gradation. We classify the irreducible quasifinite highest weight representations of the central extension \hat{D}^{\pm} of the Lie subalgebra of this algebra fixed by - sigma_{\pm}, and find th

Claude LeBrun

We show by example that the Chern numbers c_1^3 and c_1 c_2 of a complex 3-fold are not determined by the topology of the underlying smooth compact 6-manifold. In fact, we observe that infinitely many different values of a Chern number can be achieved by (integrable) complex structures on a fixed 6-manifold.

M. E. Knutt-Wehlau, R. B. Mann

We describe in superspace a classical theory of two dimensional $(1,1)$ cosmological dilaton supergravity coupled to a massive superparticle. We give an exact non-trivial superspace solution for the compensator superfield that describes the supergravity, and then use this solution to construct a model of a two-dimensional supersymmetric black hole.

Georges Girardi, Richard Grimm

The superspace geometry of Chern-Simons forms is shown to be closely related to that of the 3-form multiplet. This observation allows to simplify considerably the geometric structure of supersymmetric Chern-Simons forms and their coupling to linear multiplets. The analysis is carried through in U_K(1) superspace, relevant at the same time for supergravity-ma

P. Claus, B. de Wit, M. Faux, B. Kleijn

We review the coupling of N=2 supergravity to vector-tensor multiplets, based on the method of superconformal multiplet calculus.

Thomas Nowotny, Manfred Requardt

Starting from the working hypothesis that both physics and the corresponding mathematics have to be described by means of discrete concepts on the Planck-scale, one of the many problems one has to face is to find the discrete protoforms of the building blocks of continuum physics and mathematics. In the following we embark on developing such concepts for irr

L. G. Mardoyan, A. N. Sissakian

This article deals with a nonrelativistic quantum mechanical study of a charge-dyon system with the SU(2)--monopole in five dimensions. The Schrödinger equation for this system is separable in the hyperspherical and parabolic coordinates. The problem of interbasis expansion of the wave functions is completely solved. The coefficients for the expansion of the

Teiji Kunihiro

The perturbative renormalization group(RG) equation is applied to resum divergent series of perturbative wave functions of quantum anharmonic oscillator. It is found that the resummed series gives the cumulant of the naive perturbation series. It is shown that a reorganization of the resummed series reproduce the correct asymptotic form of the wave function

A. Khodjamirian, R. Rückl

Applications of QCD sum rules to exclusive decays of heavy mesons are reviewed. In detail, we discuss the calculations of the B and $D$ decay constants, the heavy-to-light form factors $f^+(p^2)$ and $f^0(p^2)$, and the strong couplings $g_{B^*Bπ}$ and $g_{D^*Dπ}$. Predictions are presented for the semileptonic weak decays $B \to π\bar{l} ν_l$ and $B \to ρ\b

S. Frixione

I present a definition of the cross section for the production of an isolated photon plus $n$ jets which only depends upon direct photon production, and it is independent of the parton-to-photon fragmentation contribution. This prescription, based on a modified cone approach which implements the isolation condition in a smooth way, treats in the same way qua

V. Barger

The potential of muon colliders to address fundamental physics issues is explored, with emphasis on understanding the nature of electroweak symmetry breaking. The $s$-channel production of Higgs bosons, unique to a muon collider, along with precision measurements of W^+W^-, t\bar t, and Zh thresholds would determine the properties of Higgs bosons and test el

V. Barger

The phenomenological implications of a low-energy supersymmetry are surveyed, with particular attention given to unification constraints and the role of a large top quark Yukawa couplings. Generic expectations for sparticle mass spectra are presented along with prospects for their discovery and study at present and future colliders.

Kenzo Ogure, Joe Sato

The critical exponents and the critical amplitude ratio of the scalar model are determined using finite-temperature field theory with auxiliary mass. A new numerical method is developed to solve an evolution equation. The results are discussed in comparison with values obtained from the other methods.

W. Schroers, I. Bornig, C. Schulzky, K. Goeke

We calculate the energy of electroweak sphalerons including one-loop fermionic corrections. This calculation has previously been done by adding the correction to the tree-level sphaleron and interpreting the resulting energy as the 1-loop energy. However, in this paper we calculate the energy by doing a full renormalisation of the parameters on 1-loop-level

M. Masip, R. Munoz-Tapia, A. Pomarol

In supersymmetric models extended with a gauge singlet the mass of the lightest Higgs boson has contributions proportional to the adimensional coupling $\lambda$. In minimal scenarios, the requirement that this coupling remains perturbative up to the unification scale constrains $\lambda$ to be smaller than $\approx 0.7$. We study the maximum value of $\lamb

K. Gallmeister, B. Kämpfer, O. P. Pavlenko

We analyze the opportunity to observe thermal dileptons emitted off deconfined matter resulting in heavy-ion collisions at RHIC and LHC energies. Special kinematical conditions provided by the detector systems PHENIX and ALICE, and the so-called $M_\perp$ scaling behavior of thermal dilepton spectra are taken into account. Our considerations include energy l

Jarkko Ahonen

We calculate numerically the electrical conductivity $σ$, heat conductivity $κ$ and shear viscosity $η$ of the hot plasma present in the early universe for the temperature interval $1\MeV\lsim T\lsim 10\GeV$. We use the Boltzmann collision equation to compute all the scattering matrix elements and regulate them by the thermal masses of the $t$- and $u$-chann

K. G. Chetyrkin, R. Harlander, M. Steinhauser

We consider the three-loop singlet diagrams induced by axial-vector, scalar and pseudo-scalar currents. Expansions for small and large external momentum $q$ are presented. They are used in combination with conformal mapping and Padé approximations in order to arrive at results for the polarization functions valid for all $q^2$. Results are presented for the

R. Foot, R. R. Volkas, O. Yasuda

The $ν_μ \to ν_τ$ and $ν_μ \to ν_s$ solutions to the atmospheric neutrino problem are compared with SuperKamiokande data. The differences between these solutions due to matter effects in the Earth are calculated for the ratio of $μ$-like to $e$-like events and for up-down flux asymmetries. These quantities are chosen because they are relatively insensitive t

Christopher Beetle

We consider the quantization of the midi-superspace associated with a class of spacetimes with toroidal isometries, but without the compact spatial hypersurfaces of the well-known Gowdy models. By a symmetry reduction, the phase space for the system at the classical level can be identified with that of a free massless scalar field on a fixed background space

B. Reznik

We present a first-quantized treatment of the back reaction on an accelerated particle detector. The accelerated detector is described as a first quantized, charged, pointlike particle in a constant field with internal energy levels. A quantum version of canonically conjugate future and past Rindler horizon operators is introduced to facilitate the calculati

Carlos F. Sopuerta

In this paper we have applied the generalized Kerr-Schild transformation finding a new family of stationary perfect-fluid solutions of the Einstein field equations. The procedure used combines some well-known techniques of null and timelike vector fields, from which some properties of the solutions are studied in a coordinate-free way. These spacetimes are a

H. J. Mosquera Cuesta, J. C. N. de Araujo, O. D. Aguiar, J. E. Horvath

In this letter we suggest a scenario for simultaneous emission of gravitational-wave and $γ$-ray bursts (GRBs) from soft gamma-ray repeaters (SGRs). we argue that both of the radiations can be generated by a super-Eddington accreting neutron stars in X-ray binaries. In this model a supercritical accretion transient takes back onto the remnant star the disk l

Luc Blanchet

This paper constructs the multipole expansion (in general relativity) of the gravitational field generated by a slowly-moving isolated source. We introduce some definitions for the source multipole moments, valid to all orders in a post-Newtonian expansion, and depending in a well-defined way on the total stress-energy pseudo-tensor of the material and gravi

Jacques Bros, Henri Epstein, Ugo Moschella

We propose a general framework for quantum field theory on the de Sitter space-time (i.e. for local field theories whose truncated Wightman functions are not required to vanish). By requiring that the fields satisfy a weak spectral condition, formulated in terms of the analytic continuation properties of their Wightman functions, we show that a geodesical ob

Rong-Gen Cai, Jeong-Young Ji, Kwang-Sup Soh

We investigate the ultrarelativistic limits of dilaton black holes, black $p$-branes (strings), multi-centered dilaton black hole solutions and black $p$-brane (string) solutions when the boost velocity approaches the speed of light. For dilaton black holes and black $p$-branes (boost is along the transverse directions), the resulting geometries are gravitat

L. M. de Menezes

The gravitational analog of the electromagnetic Poynting vector is constructed using the field equations of general relativity in the Hilbert gauge. It is found that when the gravitational Poynting vector is applied to the solution of the linear mass quadrupole oscillator, the correct gravitational quadrupole radiation flux is obtained. Further to this, the

Milan Mijic

The cosmological particle production in a $k=0$ expanding de Sitter universe with a Hubble parameter $H_0$ is considered for various values of mass or conformal coupling of a free, scalar field. One finds that, for a minimally coupled field with mass $0 \leq m^2 < 9 H_0^2/4$ (except for $m^2= 2H_0^2$), the one-mode occupation number grows to unity soon after

Dirk K. Morr, Joerg Schmalian, Raivo Stern, Charles P. Slichter

Recent NMR experiments on $YBa_2(Cu_{1-x}Ni_x)_3O_{6+δ}$ (Bobroff et al. Phys. Rev. Lett. 79, 2117 (1997)) have shown that Ni impurities provide an important probe for the momentum dependence of the static spin susceptibility $χ&#39;(q)$. Combining the measurements of the $^{17}$O line width $Δν$ with those of the Gaussian relaxation time $T_{2G}$, we find t

P. Horsch, F. Mack

The present understanding of the electronic and magnetic properties of $α&#39;$-NaV$_2$O$_5$ is based on the hypothesis of strong charge disproportionation into V$^{4+}$ and V$^{5+}$, which is assumed to lead to a spin-1/2 Heisenberg chain system. A recent structure analysis shows, however, that the V-ions are in a mixed valence state and indistiguishable. W

F. Zhou, B. Spivak

In this paper we develop a theory of mesoscopic fluctuations in disordered thin superconducting films in a parallel magnetic field. At zero temperature and sufficiently strong magnetic field the system undergoes a phase transition into a state characterized by a superfluid density, which is random in sign. Consequently, in this region, random supercurrents a

S. Das Sarma, P. Punyindu

A limited mobility nonequilibrium solid-on-solid dynamical model for kinetic surface growth is introduced as a simple description for the morphological evolution of a growing interface under random vapor deposition and surface diffusion bias conditions. Large scale stochastic Monte Carlo simulations using a local coordination dependent instantaneous relaxati

D. R. C. Dominguez

The generalization properties of an attractive network of non monotonic neurons which infers concepts from samples are studied. The macroscopic dynamics for the overlap between the state of the neurons with the concepts, well as the activity of the neurons, are obtained and searched for through its numerical behavior. Complex behavior leading from fixed poin

M. J. Calderon, L. Brey

We have used Monte Carlo simulation techniques to obtain the magnetic phase diagram of the double exchange Hamiltonian. We have found that the Berry&#39;s phase of the hopping amplitude has a negligible effect in the value of the magnetic critical temperature. To avoid finite size problems in our simulations we have also developed an approximated expression

A. Lodder, Yu. V. Nazarov

We present numerical results for the local density of states in semiclassical Andreev billiards. We show that the energy gap near the Fermi energy develops in a chaotic billiard. Using the same method no gap is found in similar square and circular billiards.

Matteo Marsili, Yi-Cheng Zhang

We introduce a simple stochastic dynamics for game theory. It assumes ``local&#39;&#39; rationality in the sense that any player climbs the gradient of his utility function in the presence of a stochastic force which represents deviation from rationality in the form of a ``heat bath&#39;&#39;. We focus on particular games of a large number of players with a

Ron Lifshitz

The notion of magnetic symmetry is reexamined in light of the recent observation of long range magnetic order in icosahedral quasicrystals [Charrier et al., Phys. Rev. Lett. 78, 4637 (1997)]. The relation between the symmetry of a magnetically-ordered (periodic or quasiperiodic) crystal, given in terms of a ``spin space group,&#39;&#39; and its neutron diffr

Thaisa Storchi-Bergmann, Roberto Cid Fernandes, Henrique R. Schmitt

We investigate the nature of the optical continuum and stellar population in the central kpc of the Seyfert 2s Mrk 348, Mrk 573, NGC 1358 and Mrk 1210 using long-slit spectra obtained along the radio or extended emission axis. These galaxies are known to have polarized continuum-including polarized broad lines in Mrk 348 and Mrk 1210--and previous studies in

Roberto Cid Fernandes, Thaisa Storchi-Bergmann, Henrique R. Schmitt

We present results of a long-slit spectroscopic study of 39 active and 3 normal galaxies. Stellar absorption features, continuum colors and their radial variations are analyzed in an effort to characterize the stellar population in these galaxies and detect the presence of a featureless continuum underlying the starlight spectral component. Spatial variation

B. A. McLeod, G. M. Bernstein, M. J. Rieke, D. W. Weedman

We present near infrared observations of the red gravitational lens system MG0414+0534. Our images are of sufficient quality to allow photometry of all four QSO images and the lens galaxy. The observations show that the K-band brightnesses of the components are more similar to the radio brightnesses than to the optical and thus support the notion that the sy

Jeffrey A. Willick, Michael A. Strauss

This is the second in a series of papers in which we compare Tully-Fisher (TF) data from the Mark III Catalog with predicted peculiar velocities based on the IRAS galaxy redshift survey and gravitational instability theory, using a rigorous maximum likelihood method called VELMOD. In Paper I (Willick et al. 1997b), we we applied the method to a $cz_{LG} \leq

G. I. Ogilvie

The theory of waves and instabilities in a differentially rotating disc containing a poloidal magnetic field is developed within the framework of ideal magnetohydrodynamics. A continuous spectrum, for which the eigenfunctions are localized on individual magnetic surfaces, is identified but is found not to contain any instabilities associated with differentia

John E. Gizis

We present spectroscopic observations of two halo M subdwarfs which have H alpha emission lines. We show that in both cases close companions are the most likely cause of the chromospheric activity in these old, metal-poor stars. We argue that Gl 781 A&#39;s unseen companion is most likely a cool helium white dwarf. Gl 455 is a near-equal-mass M subdwarf (sdM

I. A. G. Snellen, R. T. Schilizzi, A. G. de Bruyn, G. K. Miley

A relativistic radio component, which moves in a direction close to the sky plane, will increase in flux density when it decelerates. This effect is the basis for the qualitative model for GPS galaxies we present in this paper, which can explain their low-variability convex spectrum, their compact double or compact symmetric morphology, and the lack of GPS q

M. Dietrich, B. M. Peterson, P. Albrecht

Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-95 are presented. The broad-band fluxes (B, V, R, and I), the spectrophotometric optical continuum flux F(5177) and the integrated emission-line fluxes of Ha, Hb, Hg, HeI, and HeII all show a nearly monotonic increase with episodes of milder short-term variations superposed. The amplit

V. Le Brun, J. Bergeron

We present further observational results on our Lya-only absorber identification project at low and intermediate redshifts. We combine CFHT/MOS imaging and spectroscopic observations of 25 galaxies in the field of the quasar 3C286 (z_e = 0.849) with HST/FOS spectrum of the quasar between 1600 and 3000 A and HST/WFPC2 high spatial resolution imaging of some g

Mordehai Milgrom

I estimate Modified-Dynamics (MOND), median M/L values for recently published catalogues of galaxy groups. While the median, Newtonian M/L values quoted for these catalogues are 110-200 solar units, the corresponding values for MOND are less than 10 solar units.

Paul J. Francis, Bruce E. Woodgate, Anthony C. Danks

We present a detailed study of a rich galaxy cluster at z=2.38. We demonstrate that this cluster contains large overdensities of damped Ly-alpha absorption lines, of Ly-alpha emitting galaxies and of extremely red objects. The overdensity of extremely red objects in this field demonstrates that many are high z galaxies. The huge overdensities we measure for

Sujan Sengupta

The ohmic decay of magnetic fields confined within the crust of neutron stars is considered by incorporating both the effect of neutron star cooling and the effect of space-time curvature produced by the intense gravitational field of the star. For this purpose a stationary and static gravitational field has been considered with the standard as well as the a

Luca Zampieri, Monica Colpi, Stuart L. Shapiro, Ira Wasserman

We present results from a fully relativistic investigation of matter fallback in a supernova, assuming that the central compact star is a black hole (BH). Our goal is to answer the following questions: can we infer from the light curve whether a stellar black hole (BH) has formed in the aftermath of a supernova explosion ? Did SN1897A produce a BH and, if so

Mikael Sahrling, Gilles Chabrier

In dense stars the nuclear reaction rates are influenced by screening effects arising from both ions and electrons. In this paper we calculate the enhancement factors due to electron polarization in the high-density, degenerate and relativistic regime, for non-resonant nuclear reaction rates. In an earlier analysis, Sahrling had proposed the possibility that

Bipin R. Desai, D. P. Roy

In a SUSY GUT model responsible for generating symmetric quark mass matrices at the GUT scale (mu = Lamda) we assume that the top-Yukawa coupling, lamda_t, becomes infinite at that scale. As a consequence, the MSSM renormalization group equations for quark Yukawa couplings exhibit hierarchical solutions which lead to a pattern of texture zeroes in quark mass

Zlatko Tesanovic

A theory of critical fluctuations in extreme type-II superconductors subjected to a finite but weak external magnetic field is presented. It is shown that the standard Ginzburg-Landau representation of this problem can be recast, with help of a novel mapping, as a theory of a new &#34;superconductor&#34;, in an effective magnetic field whose overall value is

Patrick M. Gilmer

We study the behavior of the Witten-Reshetikhin-Turaev SU(2) invariants of links in L(p,q) as a function of the level r-2. They are given by 1 over the square root of r times one of p Laurent polynomials evaluated at e to the 2 pi i divided by 4pr. The congruence class of r modulo p determines which polynomial is applicable. If p is zero modulo four, the mer

David Biron, Ofer Biham, Eli Biham, Markus Grassl

Grover&#39;s algorithm for quantum searching of a database is generalized to deal with arbitrary initial amplitude distributions. First order linear difference equations are found for the time evolution of the amplitudes of the r marked and N-r unmarked states. These equations are solved exactly. An expression for the optimal measurement time T \sim O(\sqrt{

Mukul S. Laad, Stefan Blawid

We explain the anomalous features in the Hall data observed experimentally in the normal state of the high-Tc superconductors. We show that a consistent treatment of the local spin fluctuations in a model with x-ray edge singularities in d=oo reproduces the temperature and the doping dependence of the Hall constant as well as the Hall angle in the normal sta

Marie Treyer, Caleb Scharf, Ofer Lahav, Keith Jahoda

We present an attempt to measure the large angular scale fluctuations in the X-Ray Background (XRB) from the HEAO1-A2 data, expressed in terms of spherical harmonics. We model the harmonic coefficients assuming a power spectrum and an epoch-dependent bias parameter, and using a phenomenological scenario describing the evolution of the X-ray sources. From the

A. C. Cosentini, M. Capone, L. Guidoni, G. B. Bachelet

Fixed-node Green&#39;s function Monte Carlo calculations have been performed for very large 16x6 2D Hubbard lattices, large interaction strengths U=10,20, and 40, and many (15-20) densities between empty and half filling. The nodes were fixed by a simple Slater-Gutzwiller trial wavefunction. For each value of U we obtained a sequence of ground-state energies

S. Hanany, A. H. Jaffe, E. Scannapieco

We analyze the effects of the detector response time on bolometric measurements of the anisotropy of the cosmic microwave background (CMB). We quantify the effect in terms of a single dimensionless parameter $L$ defined as the ratio between the time the beam sweeps its own size and the bolometer response time. As $L$ decreases below $\sim 2.5$ the point sour

E. -M. Ilgenfritz, H. Markum, M. Müller-Preussker, S. Thurner

We test a new parametrization of a suitably truncated classically perfect action for SU(2) pure gauge theory with respect to self-consistency and locate the deconfinement transition on a 12^3X4 lattice. Using the technique of smoothing (blocking followed by inverse blocking) we demonstrate clustering of action and topological charge density. Concentrating on

C. M. Cress, M. Kamionkowski

We develop the formalism required to interpret, within a CDM framework, the angular clustering of sources in a deep radio survey. The effect of nonlinear evolution of density perturbations is discussed as is the effect of the assumed redshift distribution of sources. We also investigate what redshift ranges contribute to the clustering signal at different an

M. Barrio, R. Helling, G. Polhemus

We calculate the spin dependent static force between two D0-branes in Matrix theory. Supersymmetry relates velocity dependent potentials to spin dependent potentials. The well known v^4/r^7 term is related to a theta^8/r^11 term, where theta is the relative spin of the D0-branes. We calculate this term, confirming that it is the lowest order contribution to

Joan S. Birman, Michael D. Hirsch

The topological underpinnings are presented for a new algorithm which answers the question: `Is a given knot the unknot?&#39; The algorithm uses the braid foliation technology of Bennequin and of Birman and Menasco. The approach is to consider the knot as a closed braid, and to use the fact that a knot is unknotted if and only if it is the boundary of a disc

A. Dedes, A. B. Lahanas, K. Tamvakis

The predictions of the MSSM are discussed in the light of recent LEP and SLD precision data. The full supersymmetric one loop corrections to the effective weak mixing angle, experimentally determined in LEP and SLD experiments, are considered. It is demonstrated, both analytically and numerically, that, potentially dangerous, large logarithmic sparticle corr

Mitsuo Abe, Noboru Nakanishi

The conformal-gauge two-dimensional quantum gravity is formulated in the framework of the BRS quantization and solved completely in the Heisenberg picture: All n-point Wightman functions are explicitly obtained. The field-equation anomaly is shown to exist as in other gauges, but there is no other subtlety. At the critical dimension D=26 of the bosonic strin

Jens Eggers, Hermann Riecke

The motion of a thin layer of granular material on a plate undergoing sinusoidal vibrations is considered. We develop equations of motion for the local thickness and the horizontal velocity of the layer. The driving comes from the violent impact of the grains on the plate. A linear stability theory reveals that the waves are excited non-resonantly, in contra

D. Blaschke, H. Grigorian, G. Poghosyan, C. D. Roberts

We explore the consequences of an equation of state (EOS) obtained in a confining Dyson-Schwinger equation model of QCD for the structure and stability of nonstrange quark stars at finite-T, and compare the results with those obtained using a bag-model EOS. Both models support a temperature profile that varies over the star's volume and the consequences of t

Csaba Csaki, Witold Skiba

We present a systematic study of N=1 supersymmetric gauge theories which are in the Coulomb phase. We show how to find all such theories based on a simple gauge group and no tree-level superpotential. We find the low-energy solution for the new theories in terms of a hyperelliptic Seiberg-Witten curve. This work completes the study of all N=1 supersymmetric

G. M. D&#39;Ariano, C. Macchiavello, L. Maccone

We analyze and compare the characterization of a quantum device in terms of noise, transmitted bit-error-rate (BER) and mutual information, showing how the noise description is meaningful only for Gaussian channels. After reviewing the description of a quantum communication channel, we study the insertion of an amplifier. We focus attention on the case of di

S. Choi, S. A. Morgan, K. Burnett

The method of phenomenological damping developed by Pitaevskii for superfluidity near the $λ$ point is simulated numerically for the case of a dilute, alkali, inhomogeneous Bose-condensed gas near absolute zero. We study several features of this method in describing the damping of excitations in a Bose-Einstein condensate. In addition, we show that the metho

J. Gao, Dong-Sheng Guo, Yong-Shi Wu

We suggest that electron-laser interactions can give rise to resonance phenomena as the intensity varies. A new QED perturbation theory is developed, in which the coupling between an electron and the second quantized laser mode is treated nonperturbatively. We predict, for example, the above-threshold ionization rate shows peaks at intensities with integer p

Yu. Arestov, R. M. Santilli, V. Solovianov

We review the available evidence according to which physical media alter the Minkowskian spacetime with consequential alteration of the speed of light; we point out the apparent emergence of superluminal speeds within the hyperdense hadrons; and we point out the lack of conclusive character of the available related measure, those on the behaviour of the mean

Eyvind Aker, Knut Jorgen Maloy, Alex Hansen

We have simulated the temporal evolution of pressure due to capillary and viscous forces in two-phase drainage in porous media. We analyze our result in light of macroscopic flow equations for two-phase flow. We also investigate the effect of the trapped clusters on the pressure evolution and on the effective permeability of the system. We find that the capi

Thomas D. Cohen

The importance of the spectral density of the Dirac operator in studying spontaneous chiral symmetry breaking and anomalous U(1) axial symmetry breaking are reviewed. It is shown that both types of symmetry breaking can be traced to effects of modes near zero virtuality. Above T_c, where chiral symmetry is restored, it is shown on general grounds that (in th

P. Maris, C. D. Roberts, S. Schmidt

Using a confining, Dyson-Schwinger equation model of QCD at finite temperature (T) and chemical potential (mu) we study the behaviour of <q-bar q>, m_pi, f_pi and the masses of the rho- and phi-mesons. For each of these quantities there is a necessary anticorrelation between its response to T and its response to mu. (-<q-bar q>) and f_pi decrease with T and

H. Aktas, N. Buget, A. K. Ciftci, N. Meric

A new method has been considered to investigate the scattering reactions with photons on fully ionized nuclei. To induce $γ$-nucleus collisions a free electron laser and a heavy ion synchrotron have been considered bringing them together. Main parameters of the collider (especially LHC and HERA for the acceleration of nuclei) have been estimated. Rough calcu

David N. Yetter

We describe q-analogues of the 4-vertices in the Spin(4)-recoupling theory introduced by Barrett and Crane in gr-qc/9709028 using Kauffman-Lins SU(2)-recoupling theory in each factor and generalize them to obtain operators with the symmetry properties of unframed n-vertices. The elementary properties of the resulting invariants of embedded unframed graphs ar

Shlomo Gelaki, Sara Westreich

In this paper we consider some properties of semisimple Hopf algebras of dimension pq where p and q are distinct primes. These properties are useful for classification of such Hopf algebras. In particular, we show that for such a Hopf algebra H, if H and H^* are of Frobenius type then H or H^* is a group algebra.

Enrique Arrondo, Beatriz Grana

We characterize the vector bundles on G(1,4) that have no intermediate cohomology. We obtain them from extensions of the universal bundles and others related with them. In particular, we get a characterization of the universal vector bundles from their cohomology.

Neil P. Strickland

We compute the completed E(n) cohomology of the classifying spaces of the symmetric groups, and relate the answer to the theory of finite subgroups of formal groups.

E. N. Selivanova

The aim of this paper is to describe a class of conservative systems on $S^2$ possessing an integral cubic in momenta. We prove that this class of systems consists off the case of Goryachev-Chaplygin, the one-parameter family of systems which has been found by the author in the previous paper (dg-ga/9711005) and a new two-parameter family of conservative sys

Saurya Das, Arundhati Dasgupta, P. Ramadevi, Tapobrata Sarkar

We consider the gravitational scattering of point particles in four dimensions, at Planckian centre of mass energy and low momentum transfer, or the eikonal approximation. The scattering amplitude can be exactly computed by modelling point particles by very generic metrics. A class of such metrics are black hole solutions obtained from dimensional reduction

Prasanta K. Tripathy

We study the domain wall soliton solutions in the relativistic self-dual Maxwell Chern-Simons model in 1+1 dimensions obtained by the dimensional reduction of the 2+1 model. Both topological and nontopological self-dual solutions are found in this case. A la BPS dyons here the Bogomol&#39;ny bound on the energy is expressed in terms of two conserved quantiti

M. Gomes, J. M. C. Malbouisson, A. J. da Silva

We study the nonrelativistic limit of the quantum theory of a Chern-Simons field minimally coupled to a scalar field with quartic self-interaction. The renormalization of the relativistic model, in the Coulomb gauge, is discussed. We employ a procedure to calculate scattering amplitudes for low momenta that generates their $|p|/m$ expansion and separates the

C. Schweigert, J. Fuchs

The boundary conditions of a non-trivial string background are classified. To this end we need traces on various spaces of conformal blocks, for which generalizations of the Verlinde formula are presented.

J. Fuchs, C. Schweigert

We outline the structure of boundary conditions in conformal field theory. A boundary condition is specified by a consistent collection of reflection coefficients for bulk fields on the disk together with a choice of an automorphism ωof the fusion rules that preserves conformal weights. Non-trivial automorphisms ωcorrespond to D-brane configurations for arbi

J. Manjavidze

The unitary transformation of path-integral differential measure is described. The main properties of perturbation theory in the phase space of action-angle, energy-time variables are investigated. The measure in cylindrical coordinates is derived also. The dependence of perturbation theory contributions from global (topological) properties of corresponding

Nobuhito Maru

We study the confining phase structure on {\cal N}=1 supersymmetric SO(12) gauge theory with N_f \le 7 vectors and one spinor. The explicit form of low energy superpotentials for N_f \le 7 are derived after gauge invariant operators relevant in the effective theory are identified via gauge symmetry breaking pattern. The resulting confining phase structure is