September 1996 arXiv papers — page 13

Mark de Wild Propitius

In this talk I describe recent work (hep-th/9606029) in which I classified all conceivable 2+1 dimensional Chern-Simons (CS) theories with continuous compact abelian gauge group or finite abelian gauge group. The CS theories with finite abelian gauge group that can be obtained from the spontaneous breakdown of a CS theory with gauge group the direct product

Sudipta Mukherji

We study the Brans-Dicke model in the presence of an axion. The dynamical equations are solved when the fields are space independent and the metric is spatially flat. It is found that at late time the scale factor undergoes decelerated expansion but the dilaton grows large. At early time, scale factor and the dilaton approach constants.

Eric Braaten, Agustin Nieto

The low-density expansion for a homogeneous interacting Bose gas at zero temperature can be formulated as an expansion in powers of $\sqrt{ρa^3}$, where $ρ$ is the number density and $a$ is the S-wave scattering length. Logarithms of $ρa^3$ appear in the coefficients of the expansion. We show that these logarithms are determined by the renormalization proper

T. Banks, M. Dine

This is the text of a talk given at the Inaugural Conference of the Asia Pacific Center for Theoretical Physics, Seoul, Korea, June 9, 1996. If nature is described by string theory, and if the compactification radius is large (as suggested by the unification of couplings), then the theory is in a regime best described by the low energy limit of $M$-theory. W

P. Maraner

A quantal guiding center theory allowing to systematically study the separation of the different time scale behaviours of a quantum charged spinning particle moving in an external inhomogeneous magnetic filed is presented. A suitable set of operators adapting to the canonical structure of the problem and generalizing the kinematical momenta and guiding cente

M. Baker

We use the assumption of electric-magnetic duality to express the heavy quark potential in QCD in terms of a Wilson Loop $W_{eff}(Γ)$ determined by the dynamics of a dual theory which is weakly coupled at long distances. The classical approximation gives the leading contribution to $W_{eff}(Γ)$ and yields a velocity dependent heavy quark potential which for

Kingman Cheung, Wai-Yee Keung, Tzu Chiang Yuan

The conventional color-singlet model was challenged by the recent data on quarkonium production. Discrepancies in production rates were observed at the Tevatron, at LEP, and in fixed-target experiments. The newly advocated color-octet mechanism provides a plausible solution to the anomalous quarkonium production observed at the Tevatron. The color-octet mech

Thomas G. Rizzo

The search reaches for both scalar($S$) and vector($V$) leptoquarks at future hadron colliders are summarized. In particular we evaluate the production cross sections of both leptoquark types at TeV33 and LHC as well as the proposed 60 and 200 TeV colliders through both quark-antiquark annihilation and gluon-gluon fusion: $q \bar q, gg \to SS,VV$. Experiment

M. Beneke, V. M. Braun, L. Magnea

We have calculated the contributions proportional to $β_0^nα_s^{n+1}$ to the longitudinal fragmentation function in $e^+e^-$ annihilation to all orders of perturbation theory. We use this result to estimate higher-order perturbative corrections and nonperturbative corrections to the longitudinal cross section $σ_L$ and discuss the prospects of determining $α

A. Vairo

In this paper the problem of the gauge in a bound state calculation is discussed. In particular, in order to verify the gauge invariance in the energy levels expansion, some set of gauge invariant contributions are given.

Stefano Catani

I present a theoretical discussion of the uncertainties related to the QCD analysis of the proton structure function $F_2(x,Q^2)$ at small $x$. The role played by the `unphysical' gluon density is pointed out. It is shown how the study of more observables can reduce the theoretical uncertainty and, in particular, an alternative method of analysis, based

A. E. Bergan, J. O. Eeg

We consider the contribution to $K \rightarrow 2 π$ decays from the non-diagonal $s \ra d$ quark transition amplitude. First, we calculate the most important part of the $s \rightarrow d$ transition, the so-called self-penguin amplitude $\sim G_F α_s$, including the heavy top-quark case. Second, we calculate the matrix element of the $s \rightarrow d$ transi

Paul B. Mackenzie

I discuss old and new determinations of the light quark masses using lattice QCD. Most lattice results using various approximations can be fit together in a simple picture which is consistent with lower values than conventionally supposed: in the quenched approximation for the strange quark mass in the MS bar scheme, m_s(2 GeV) = 95 (16) MeV, and for the ave

D. Kharzeev

The suppression of quarkonium production in nucleus-nucleus collisions was originally proposed as a signal of colour deconfinement. Strong ``anomalous" J/ψsuppression in Pb-Pb collisions has been reported at this Conference by the NA50 Collaboration. Is this suppression really anomalous? Can we conclude that the quark-gluon plasma is already discovered?

F. Cornet, R. Graciani, J. I. Illana

The possibility of testing trilinear neutral gauge boson couplings in radiative neutral current scattering at HERA is analyzed using a Monte Carlo program that includes the Standard Model at tree level and the anomalous vertices. Acceptance and isolation cuts are applied as well as optimized cuts to enhance the signal from new physics. The bounds on Zγγcoupl

Stephan Narison

I present a more refined analysis of the mass-splittings between the different heavy quarkonia states, using {\it new double ratios} of exponential moments of different two-point functions. Then, I test the validity of the $1/m$-expansion, extract $α_s(M_Z)=0.127\pm 0.011$ from $M_{χ_c(P^1_1)} - M_{χ_c(P^3_1)}$, and provide a new estimate of the gluon conden

A. A. Penin, V. A. Rubakov, P. G. Tinyakov, S. V. Troitsky

In many theories with flat directions of scalar potential, static vortex solutions do not exist for a generic choice of vacuum. In two Euclidean dimensions, we find their substitutes --- constrained instantons consisting of compact core formed by Abrikosov--Nielsen--Olesen vortex and long-ranged cloud of modulus field. In (3+1) dimensions, an initial compact

P. Aurenche, F. Gelis, R. Kobes, E. Petitgirard

We discuss the bremsstrahlung production of soft real and virtual photons in a quark-gluon plasma at thermal equilibrium beyond the Hard Thermal Loop (HTL) resummation. The physics is controlled by the ratio $Q^2/q_0^2$ of the virtuality to the energy. When $Q^2/q_0^2$ is much smaller than $g^2$, where $g$ is the strong coupling constant, the emission rate i

Erwin Mirkes, Dieter Zeppenfeld

The production of forward jets of transverse momentum $p_T(j)\approx Q$ and large momentum fraction $x_{jet}\gg x$ probes the onset of BFKL dynamics at HERA. A full ${\cal O}(α_s^2)$ calculation of the inclusive forward jet cross section is presented and compared to the expected BFKL cross section.

Vadim A. Kuzmin

We claim that there might exist a new interaction leading to very fast baryon-number violating processes quite observable in the laboratory conditions, provided all three generations are simultaneously involved.

Davison E. Soper

Parton distribution functions give the probability to find partons (quarks and gluons) in a hadron as a function of the fraction x of the proton's momentum carried by the parton. They are conventionally defined in terms of matrix elements of certain operators. They are determined from experimental results on short distance scattering of the partons. Inte

C. R. Allton, V. Gimenez, L. Giusti, F. Rapuano

We present a study of ${\cal O}(2000)$ (quenched) lattice configurations from the APE collaboration, for $6.0\leβ\le 6.4$ using both the Wilson and the SW-Clover fermion action. We determine the light hadronic spectrum and meson decay constants. We extract the inverse lattice spacing using data at the simulated values of the quark mass. We find an agreement

Roy Wensley

In the quenched approximation we use the abelian and monopole fields from abelian projection in SU(2) lattice gauge theory to numerically compute the value of the chiral condensate. The condensate calculated using abelian projection is observed to vanish at the same critical temperature as the full SU(2) theory predicts.

A. Duncan, E. Eichten, H. Thacker

A method for computing electromagnetic properties of hadrons in lattice QCD is described. The electromagnetic field is introduced dynamically, using a noncompact formulation. Employing enhanced electric charges, the dependence of the pseudoscalar meson mass on the (anti)quark charges and masses can be accurately calculated. At $β=5.7$ with Wilson action, the

M. V. Diwan, J. Frank, A. Gordeev, S. Kettell

We propose a new experiment at the AGS to search for the T-violating polarization of the muon normal to the decay plane of the K+ to mu+ pi0 nu decay. Motivated by the need for a stronger CP violation source to account for the baryon asymmetry of the Universe, the experiment aims to search for T-violation beyond the Standard Model. The experiment will be per

Dong Lai, Alan G. Wiseman

We study how the neutron-star equation of state affects the onset of the dynamical instability in the equations of motion for inspiraling neutron-star binaries near coalescence. A combination of relativistic effects and Newtonian tidal effects cause the stars to begin their final, rapid, and dynamically-unstable plunge to merger when the stars are still well

Bruce Allen, Ram Brustein

A characteristic spectrum of relic gravitational radiation is produced by a period of ``stringy inflation" in the early universe. This spectrum is unusual, because the energy-density rises rapidly with frequency. We show that correlation experiments with the two gravitational wave detectors being built for the Laser Interferometric Gravitational Observatory

Carlos O. Lousto, Richard H. Price

We compute gravitational radiation waveforms, spectra and energies for a point particle of mass $m_0$ falling from rest at radius $r_0$ into a Schwarzschild hole of mass $M$. This radiation is found to lowest order in $(m_0/M)$ with the use of a Laplace transform. In contrast with numerical relativity results for head-on collisions of equal-mass holes, the r

Vijay S. Pande, Alexander Yu. Grosberg, Chris Joerg, Mehran Kardar

Polyampholytes (PAs) are heteropolymers with long range Coulomb interactions. Unlike polymers with short range forces, PA energy levels have non-vanishing correlations and are thus very different from the Random Energy Model (REM). Nevertheless, if charges in the PA globule are screened as in a regular plasma, PAs freeze in REM fashion. Our results shed ligh

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

We show that some of the low temperature transport coefficients (e.g., electrical and thermal conductivities, viscosity and sound attenuation) are {\it universal}, i.e., independent of the impurity concentration and phase shift for specific classes of unconventional superconductors. The existence of a universal limit depends on the symmetry of the order para

Jan Brinckmann

A Slave-Boson perturbational approach to ground-state properties of the $U\to\infty$ periodic Anderson model is derived as an expansion around the Atomic Limit ($V=0$). In the case of zero temperature any constraint-integral or limiting procedure can be avoided, a gauge-symmetry broken Mean-Field phase is not involved. Physical quantities like the wave vecto

Paolo Tommasini, A. F. R. de Toledo Piza

We investigate ground-state and thermal properties of a system of non-relativistic bosons interacting through repulsive, two-body interactions in a self-consistent gaussian mean-field approximation wich consists in writing the variational determined density operator as the most general gaussian functional of the quantized field operators. Finite temperature

M. Kolesik, H. L. Richards, M. A. Novotny, Per Arne Rikvold

We present results obtained with various types of heterogeneous nucleation in a kinetic Ising model of magnetization switching in single-domain ferromagnetic nanoparticles. We investigate the effect of the presence of the system boundary and make comparison with simulations on periodic lattices. We also study systems with bulk disorder and compare how two di

Y. Sasago, K. Uchinokura, A. Zheludev, G. Shirane

Bulk magnetic measurements and inelastic neutron scattering were used to investigate the spin-singlet ground state and magnetic gap excitations in BaCuSi2O6, a quasi-2-dimensional antiferromagnet with a bilayer structure. The results are well described by a model based on weakly interacting antiferromagnetic dimers. A strongly temperature-dependent dispersio

D. R. Reichman, F. L. H. Brown, P. Neu

The dynamics of the dissipative two-level system at zero temperature is studied using three different cumulant expansion techniques. The relative merits and drawbacks of each technique are discussed. It is found that a new technique, the non-crossing cumulant expansion, appears to embody the virtues of the more standard cumulant methods.

D. Jezek, M. Guilleumas, M. Pi, M. Barranco

We have investigated the quantum-to-thermal crossover temperature T* for cavitation in liquid helium mixtures up to 0.05 3He concentrations. With respect to the pure 4He case, T* is sizeably reduced, to a value below 50 mK for 3He concentrations above 0.02. As in pure 4He, the homogeneous cavitation pressure is systematically found close to the spinodal pres

J. P. Dekker, A. Lodder, R. Zeller, A. F. Tatarchenko

It is shown that the Brillouin zone integral for the interstitial KKR-Green function can be evaluated accurately by taking proper care of the free-electron singularities in the integrand. The proposed method combines two recently developed methods, a supermatrix method and a subtraction method. This combination appears to provide a major improvement compared

Jordi Faraudo, Javier Bafaluy

In this paper we analyze the influence of transport mechanisms (diffusion and sedimentation) on the structure of monolayers of particles irreversibly adsorbed on a line. We focus our attention on the dependence of the radial distribution function $g(r)$ and the saturation coverage $θ_\infty$ on the gravitational Péclet number $N_g$. First, we study the proba

Bosiljka Tadic

We simulate Barkhausen avalanches on fractal clusters in a two-dimensional diluted Ising ferromagnet with an effective Gaussian random field. We vary the concentration of defect sites $c$ and find a scaling region for moderate disorder, where the distribution of avalanche sizes has the form $D(s,c,L) = s^{-(1+τ(c))}{\cal{D}}(sL^{-D_s(c)})$. The exponents $τ(

M. Guilleumas, M. Barranco, D. M. Jezek, R. J. Lombard

Using a functional-integral approach, we have determined the temperature below which cavitation in liquid helium is driven by thermally assisted quantum tunneling. For both helium isotopes, we have obtained the crossover temperature in the whole range of allowed negative p essures. Our results are compatible with recent experimental results on 4He.

S. Nonnenmacher, A. Voros

Using coherent-state representations of quantum mechanics (Bargmann, Husimi, and stellar representations), we describe analytically the phase-space structure of the general eigenstates corresponding to a 1-dimensional bilinear hyperbolic Hamiltonian, H=pq or equivalently H=1/2(P^2-Q^2). Their semi-classical behaviour is discussed for eigenvalues either near

Nick Kaiser, Andrew Jaffe

We describe the statistical properties of light rays propagating though a random sea of gravity waves and compare with the case for scalar metric perturbations from density inhomogeneities. For scalar fluctuations the deflection angle grows as the square-root of the path length $D$ in the manner of a random walk, and the rms displacement of a ray from the un

A. C. Quillen

We compare stellar orbits in an early (NGC 4314) and a late-type barred galaxy (NGC 1073). We find that these bars are cold in the sense that the majority of stars can be described as being nearby to periodic orbits. We place limits of (65km/s)^2 and (50km/s)^2 on the components of the diagonalized velocity dispersion ellipsoid matrix for stars in the bars o

Hara Papathanassiou, Peter Meszaros

We calculate the spectra expected from unsteady relativistic wind models of gamma-ray bursts, suitable for events of arbitrary duration. The spectral energy distribution of the burst is calculated over photon energies spanning from eV to TeV, for a range of event durations and variability timescales. The relative strength of the emission at different wavelen

B. Allen, R. R. Caldwell, E. P. S. Shellard, A. Stebbins

We simulate the anisotropy in the cosmic microwave background (CMB) induced by cosmic strings. By numerically evolving a network of cosmic strings we generate full-sky CMB temperature anisotropy maps. Based on $192$ maps, we compute the anisotropy power spectrum for multipole moments $\ell \le 20$. By comparing with the observed temperature anisotropy, we se

A. Kudlicki, T. Plewa, M. Rozyczka

We present a new Eulerian code able to follow the evolution of large-scale structures in the Universe in the weakly nonlinear regime. We compare test results with a N-body code and analytical results.

Juergen Ehlers, Thomas Buchert

The ``Newtonian'' theory of spatially unbounded, self--gravitating, pressureless continua in Lagrangian form is reconsidered. Following a review of the pertinent kinematics, we present alternative formulations of the Lagrangian evolution equations and establish conditions for the equivalence of the Lagrangian and Eulerian representations. We then dis

Tomonori Totani, Katsuhiko Sato

The neutrino spin-flavor conversion of \barν_e and ν_μwhich is induced by the interaction of the Majorana neutrino magnetic moment and magnetic fields in the collapse-driven supernova is investigated in detail. We calculate the conversion probability by using the latest precollapse models of Woosley and Weaver (1995), and also those of Nomono and Hashimoto (

Adam Parusinski, Zbigniew Szafraniec

We show that on real algebraic sets algebraically constructible functions coincide with the finite sums of signs of polynomials. Then we give some applications.

U. Bandow, D. Einfeld, T. Hezel, H. O. Moser

Third order tracking calculations show that a wavelength shifter on the basis of a commercially available 12 T split-pair solenoid is compatible with the ANKA storage ring

Mark Gross, Sorin Popescu

We study the equations of abelian surfaces embedded in P^{n-1} with a line bundle of polarization of type (1,n). For n>9, we show that the ideal of a general abelian surface with this polarization is generated by quadrics, and if the embedding is Heisenberg invariant, we give a very specific description of these quadrics. These quadrics are produced using a

Sora Cho, Matthew P. A. Fisher

We study numerically conductance fluctuations near the integer quantum Hall effect plateau transition. The system is presumed to be in a mesoscopic regime, with phase coherence length comparable to the system size. We focus on a two-terminal conductance G for square samples, considering both periodic and open boundary conditions transverse to the current. At

Cristiano Porciani

We study the evolution of the mass autocorrelation function by describing the growth of density fluctuations through the Zel'dovich approximation. The results are directly compared with the predictions of the scaling hypothesis for clustering evolution extracted from numerical simulations (Hamilton et al. 1991), as implemented by Jain, Mo & White (1995).

L. H. Orr, T. Stelzer, W. J. Stirling

Understanding the pattern of gluon radiation in $t \bar t$ production and decay processes is important for making an accurate determination of the top mass from the momenta of its decay products. The larger energy of the LHC $pp$ collider boosts the top cross section by a factor of 100 compared to that at the Tevatron, but it also increases the amount of add

Daniel F. Litim

We analyse approximate solutions to an exact renormalisation group equation with particular emphasis on their dependence on the regularisation scheme, which is kept arbitrary. Physical quantities related to the coarse-grained potential of scalar QED display universal behaviour for strongly first-order phase transitions. Only subleading corrections depend on

J. Kierfeld

Applying a Lindemann-like criterion obtained previously by Kierfeld, Nattermann and Hwa [Phys. Rev. B 55, 626 (1997)], we estimate the magnetic field and temperature for a high-$T_c$ superconductor, at which a topologically ordered vortex glass phase becomes unstable with respect to a disorder-induced formation of dislocations. The employed criterion is show

Jochen Brüning, Matthias Lesch

Motivated by the work of Vishik on the analytic torsion we introduce a new class of generalized Atiyah-Patodi-Singer boundary value problems. We are able to derive a full heat expansion for this class of operators generalizing earlier work of Grubb and Seeley. As an application we give another proof of the gluing formula for the eta invariant. Our class of b

Juergen Eschke, NA35 Collaboration

The NA35 experiment used several independent methods to determine the strange particle production in p+S and S+A collisions. The different techniques show consistent results. Strangeness conservation in full phase space is used as an additional check of the consistency of the data. On the base of the analysis in full phase space it could be shown that strang

F. Bernardeau, R. van de Weygaert, E. Hivon, F. R. Bouchet

Analytical studies based on perturbative theory have shown that the moments of the Probability Distribution Function (PDF) of the local smoothed velocity divergence are expected to have a very specific dependence on the density parameter Omega in the quasi-linear regime. This dependence is particularly interesting as it does not involve the possible bias bet

Youichirou Iino, Masatoshi Imada

Effects of nonmagnetic impurity doping on an AF spin-1/2 Heisenberg ladder system are studied by the QMC method. A single nonmagnetic impurity induces a localized spin-1/2 moment accompanied by "static" and enhanced AF correlations around it. Small and finite concentration of impurities induces a remarkable change of magnetic and thermodynamic proper

H. E. Bond, S. Kawaler, R. Ciardullo, R. Stover

We report on a global CCD time-series photometric campaign to decode the pulsations of the nucleus of the planetary nebula NGC1501. The star is hot and hydrogen-deficient, similar to the pre-white-dwarf PG 1159 stars. NGC1501 shows pulsational brightness variations of a few percent with periods ranging from 19 to 87 minutes. The variations are very complex,

L. S. F. Olavo

In this continuation paper we will address the problem of tunneling. We will show how to settle this phenomenon within our classical interpretation. It will be shown that, rigorously speaking, there is no tunnel effect at all.

V. B. Lebedev, P. H. Diamond

The development and time evolution of a transport barrier in a magnetically confined plasma with non-monotonic, nonlinear dependence of the anomalous flux on mean gradients is analyzed. Upon consideration of both the spatial inhomogeneity and the gradient nonlinearity of the transport coefficient, we find that the transition develops as a bifurcation front w

U. Zückert, R. Alkofer, H. Weigel, H. Reinhardt

A hybrid model for baryons based on a dynamical interplay between relativistic three--quark bound states and soliton configurations of mesons is constructed. The Bethe-Salpeter equation for diquarks and the Faddeev equation for diquark-quark bound states in the background of a soliton is solved. The results show that baryons are very much like hybrids contai

Joseph H. Silverman

The set of morphisms $\f:\PP^1\to\PP^1$ of degree $d$ is parametrized by an affine open subset $\Rat_d$ of $\PP^{2d+1}$. We consider the action of~$\SL_2$ on $\Rat_d$ induced by the {\it conjugation action\/} of $\SL_2$ on rational maps; that is, $f\in\SL_2$ acts on~$\f$ via $\f^f=f^{-1}\circ\f\circ f$. The quotient space $\M_d=\Rat_d/\SL_2$ arises very natu

Eric D'Hoker, I. M. Krichever, D. H. Phong

We determine the effective prepotential for N=2 supersymmetric SU(N_c) gauge theories with an arbitrary number of flavors N_f < 2N_c, from the exact solution constructed out of spectral curves. The prepotential is the same for the several models of spectral curves proposed in the literature. It has to all orders the logarithmic singularities of the one-loop

H. Fujisaki, K. Nakagawa

The thermofield dynamics of the D=26 closed bosonic thermal string theory is described in proper reference to the thermal duality symmetry as well as the thermal stability of modular invariance in association with the global phase structure of the bosonic thermal string ensemble.

M. Napsuciale, J. L. Lucio M.

We study the radiative decays of the decuplet $(3/2 \to 1/2 γ)$ using Heavy Baryon Chiral Perturbation Theory (HBChPT). We emphasize the problems faced by the interacting spin 3/2 field theory. We argue that, to lowest order in the $1/m$ expansion, HBChPT provides a framework where R-invariance and the appropiated constraints for the interacting spin 3/2 fie

A. Lebedev, L. Sinclair, E. Strickland, J. Vazdik

Colour coherence in hard photoproduction is considered using the Monte Carlo event generators PYTHIA and HERWIG. Significant effects in the parton shower are found using multijet observables for direct and resolved photon induced reactions. The particle flow in the interjet region of direct processes shows a strong influence of string fragmentation effects.

M. Burkardt, H. El-Khozondar

We investigate a 3+1 dimensional toy model that exhibits spontaneous breakdown of chiral symmetry, both in a light-front (LF) Hamiltonian and in a Euclidean Schwinger-Dyson (SD) formulation. We show that both formulations are completely equivalent --- provided the renormalization is properly done. For the model considered, this means that if one uses the sam

E. Shuryak

In the recent years we have learned that light quarks play a crucial role in QCD-like theories, transforming it to many different phases. We review what is known about them, both from lattice and non-lattice approaches. A particularly simple mechanism of the QCD chiral restoration phase transition is discussed first: it suggests that it is a transition from

Thomas G. Rizzo

The search reaches for new gauge bosons at future hadron and lepton colliders are summarized for a variety of extended gauge models. Experiments at these energies will vastly improve over present limits and will easily discover a $Z&#39;$ and/or $W&#39;$ in the multi-TeV range. [To appear in the Proceedings of the 1996 DPF/DPB Summer Study on New Directions

C. Arvanitis, F. Geniet, J. -L. Kneur, A. Neveu

We develop a &#34;variational mass&#34; expansion approach, recently introduced in the Gross--Neveu model, to evaluate some of the order parameters of chiral symmetry breakdown in QCD. The method relies on a reorganization of the usual perturbation theory with the addition of an &#34;arbitrary quark mass $m$, whose non-perturbative behaviour is inferred part

Z. Kunszt, W. J. Stirling

The HERA diffractive structure function data are interpreted in terms of `diffractive parton distributions&#39; which satisfy DGLAP evolution. These distributions are modeled assuming that the scattering takes place off a colour singlet `pomeron&#39; target. A quantitative test of the universality of diffractive parton distributions is proposed.

Jiri Hoogland, Ronald Kleiss

In Quasi-Monte Carlo integration, the integration error is believed to be generally smaller than in classical Monte Carlo with the same number of integration points. Using an appropriate definition of an ensemble of quasi-randompoint sets, we derive various results on the probability distribution of the integration error, which can be compared to the standar

W. L. van Neerven

A review is presented on all higher order QCD corrections to deep inelastic structure functions. The implications of these corrections for polarized and unpolarized deep inelastic lepton-hadron scattering will be discussed.

Tomonori Totani, Katsuhiko Sato

We investigate to what extent the oscillation or conversion of neutrinos enhances the expected event rate of the supernova relic neutrino background (SRN) at the Super-Kamiokande detector (SK). The SRN \barν_e&#39;s can be almost completely exchanged with ν_μ-like neutrinos by the MSW oscillation under the inverse mass hierarchy with Δm^2 ~ 10^{-8}--10^5 [eV

Robert Joynt

Neutron scattering experiments have recently been performed in the superconducting state of UPt3 to determine the structure of the vortex lattice. The data show anomalous field dependence of the aspect ratio of the unit cell in the B phase. There is apparently also a change in the effective coherence length on the transition from the B to the C phases. Such

N. Dupuis

We study the metal-insulator transition (MIT) in weakly coupled disordered planes on the basis of a Non-Linear Sigma Model (NL$σ$M). Using two different methods, a renormalization group (RG) approach and an auxiliary field method, we calculate the crossover length between a 2D regime at small length scales and a 3D regime at larger length scales. The 3D regi

Yu. M. Pis`mak

The master equations describing processes of biological evolution in the framework of the random neighbor Bak-Sneppen model are studied. For the eqosystem of $N$ species they are solved exactly and asymptotical behavior of this solution for large $N$ is analyzed.

Markus Nauroth, Walter Kob

Using a molecular dynamics computer simulation we determine the temperature dependence of the partial structure factors for a binary Lennard-Jones system. These structure factors are used as input data to solve numerically the wave-vector dependent mode-coupling equations in the long time limit. Using the so determined solutions, we compare the predictions o

Hideaki Ujino, Miki Wadati

The Hi-Jack symmetric polynomials, which are associated with the simultaneous eigenstates for the first and second conserved operators of the quantum Calogero model, are studied. Using the algebraic properties of the Dunkl operators for the model, we derive the Rodrigues formula for the Hi-Jack symmetric polynomials. Some properties of the Hi-Jack polynomial

Hans Weber, Henrik Jeldtoft Jensen

We have studied the linear resistance of a three dimensional lattice Superconductor model in the London limit London lattice model by Monte Carlo simulation of the vortex loop dynamics. We find excellent finite size scaling at the phase transition. We determine the dynamical exponent $z = 1.51$ for the isotropic London lattice model.

J. T. Chalker, V. E. Kravtsov, I. V. Lerner

The statistics of energy levels for a disordered conductor are considered in the critical energy window near the mobility edge. It is shown that, if critical wave functions are multifractal, the one-dimensional gas of levels on the energy axis is ``compressible&#39;&#39;, in the sense that the variance of the level number in an interval is $< (δN)^{2} > = χ<

Eric M. Kramer, Thomas A. Witten

We discuss an M-dimensional phantom elastic manifold of linear size L crushed into a small sphere of radius R << L in N-dimensional space. We investigate the low elastic energy states of 2-sheets (M=2) and 3-sheets (M=3) using analytic methods and lattice simulations. When N \geq 2M the curvature energy is uniformly distributed in the sheet and the strain en

Debabrata Biswas

We review some properties of periodic orbit families in polygonal billiards and discuss in particular a sum rule that they obey. In addition, we provide algorithms to determine periodic orbit families and present numerical results that shed new light on the proliferation law and its variation with the genus of the invariant surface. Finally, we deal with cor

Charles H. Lineweaver

The largest anisotropy in the cosmic microwave background (CMB) is the $\approx 3$ mK dipole assumed to be due to our velocity with respect to the CMB. Over the past ten years the precision of our knowledge of the dipole has increased by a factor of ten. We discuss the most recent measurement of this dipole obtained from the four year COBE Differential Micro

Suzanne M. Linder

I explore the hypothesis that Ly$α$ absorption at low redshift is caused by the outer regions of extended galaxy disks, including those of dwarf and low surface brightness galaxies. McGaugh (1996) has shown that the distribution of central galaxy surface brightnesses may be flat to 25 B mag arcsec$^{-2}$ or fainter. A population of galaxies is simulated base

P. Marziani, M. Calvani, J. W. Sulentic

A systematic difference in alignment between the central black hole spin and the angular momentum of the accreting gas may help explain several differences found in the optical and UV HST spectra of radio loud and radio quiet AGN.

Armando M. Howard, Russell M. Kulsrud

We consider the hypothesis that galactic magnetic fields are primordial. We also discuss the various objections to this hypothesis. We assume that there was a magnetic field present in the galactic plasma before the galaxy formed. After the galactic disk formed, the lines of force thread through it and remain connected to the external cosmic medium. They ent

Eric J. Bakker, David L. Lambert, Ewine F. van Dishoeck

Recent optical spectra of post-AGB stars show the presence of C2, CN, and CH+ originating in the circumstellar shell. We present here new, higher resolution spectra which provide constraints on the physical parameters and information on the line profiles. An empirical curve of growth for the C2 Phillips and CN Red system lines in the spectrum of HD 56126 yie

Mario Vietri

I consider a model of GRBs where they arise right before the merging of binary pulsars. Binary pulsars moving through the companion&#39;s magnetic field experience a large, motional electric field $\vec{E}=\vec{v}\wedge\vec{B}/c$, which leads to the release in the pulsar magnetosphere of a pair cascade, and the acceleration of a wind of pure pairs. The energ

Davide Lazzati, Luigi Stella

Besides the narrow peaks originating from the periodic signal, the power spectra of accreting X-ray pulsars display continuum components usually increasing towards low frequencies; these arise from the source aperiodic variability. Most studies so far adopted the view that the periodic and aperiodic variations are independent. However any aperiodic variabili

Koji Takahashi

The evolution of spherical single-mass star clusters driven by two-body relaxation was followed beyond core collapse by numerically solving the orbit-averaged Fokker-Planck equation in energy--angular momentum space. The heating effect by three-body binaries was incorporated in the Fokker-Planck models. The development of velocity anisotropy after the core c

James M. Cline, Pierre-Anthony Lemieux

We reexamine the strength of the first order phase transition in the electroweak theory supplemented by an extra Higgs doublet. The finite-temperature effective potential, $V_{eff}$, is computed to one-loop order, including the summation of ring diagrams, to study the ratio $ϕ_c/T_c$ of the Higgs field VEV to the critical temperature. We make a number of imp

S. Bellucci, S. Krivonos, A. Sorin

We construct the nonlinear $W(sl(N+3),sl(3))$ algebras and find the spectrum of values of the central charge that gives rise, by contracting the $W(sl(N+3),sl(3))$ algebras, to a $W_3$ algebra belonging to the coset $W((sl(N+3),sl(3))/(u(1)\oplus sl(N))$. Part of the spectrum was conjectured before, but part of it is given here for the first time. Using the

I. A. Batalin, K. Bering, P. H. Damgaard

We propose a Lagrangian path integral based on gauge symmetries generated by a symmetric higher-order $Δ$-operator, and demonstrate that this path integral is independent of the chosen gauge-fixing function. No explicit change of variables in the functional integral is required to show this.

Steven Detweiler, Lee H. Brown

We describe a post-Minkowskii approximation of general relativity as a power series expansion in G, Newton&#39;s gravitational constant. Material sources are hidden behind boundaries, and only the vacuum Einstein equations are considered. An iterative procedure is described which, in one complete step, takes any approximate solution of the Einstein equations

Jens Gladikowski, Meik Hellmund

We investigate a generalized non-linear O(3) $σ$-model in three space dimensions where the fields are maps $S^3 \mapsto S^2$. Such maps are classified by a homotopy invariant called the Hopf number which takes integer values. The model exhibits soliton solutions of closed vortex type which have a lower topological bound on their energies. We explicitly compu

Balam A. Willemsen, J. S. Derov, S. Sridhar

The vortex contribution to the dc field (H) dependent microwave surface impedance Z_s = R_s+iX_s of YBa_2Cu_3O_{7-x} thin films was measured using suspended patterned resonators. Z_s(H) is shown to be a direct measure of the flux density B(H) enabling a very precise test of models of flux penetration. Three regimes of field-dependent behavior were observed: