October 1997 arXiv papers — page 17

C. Dawson, G. Martinelli, G. C. Rossi, C. T. Sachrajda

We outline two methods of constructing improved composite operators using Wilson fermions.

Jan Smit

We review recent developments in real-time simulations of SU(2)-Higgs theory near the electroweak transition and related topics.

Joseph Christensen, Terrence Draper, Craig McNeile

We calculate the Isgur-Wise function on the lattice, simulating the light quark with the Wilson action and the heavy quark with a direct lattice implementation of the heavy-quark effective theory. Improved smearing functions produced by a variational technique, MOST, are used to reduce the statistical errors and to minimize excited-state contamination of the

CLEO Collaboration, S. Glenn et al

We have searched for the effective FCNC decays b->s l+l- using an inclusive method. We set upper limits on the branching ratios B(b->s e+e-) < 5.7 10^{-5}, B(b->s mu+mu-) < 5.8 10^{-5}, and B(b->s e+-mu-+) < 2.2 10^{-5} (at 90 %\ C.L.). Combining the di-electron and di-muon decay modes we find: B(b->s l+l-) < 4.2 10^{-5} (at 90 % C.L.).

ZEUS Collaboration

The shape of jets produced in quasi-real photon-proton collisions at centre-of-mass energies in the range $134-277$ GeV has been measured using the hadronic energy flow. The measurement was done with the ZEUS detector at HERA. Jets are identified using a cone algorithm in the $η- ϕ$ plane with a cone radius of one unit. Measured jet shapes both in inclusive

W. Kummer, H. Liebl, D. V. Vassilevich

We demonstrate that in the absence of `matter&#39; fields to all orders of perturbation theory and for all 2D dilaton theories the quantum effective action coincides with the classical one. This resolves the apparent contradiction between the well established results of Dirac quantization and perturbative (path-integral) approaches which seemed to yield non-

S. Bonazzola, E. Gourgoulhon, J. -A. Marck

A general relativistic version of the Euler equation for perfect fluid hydrodynamics is applied to a system of two neutron stars orbiting each other. In the quasi-equilibrium phase of the evolution of this system, a first integral of motion can be derived for certain velocity fields of the neutron star fluid including the (academic) case of co-rotation with

L Chimento, A Jakubi, V Mendez, R Maartens

A recently proposed nonlinear transport equation is used to model bulk viscous cosmologies that may be far from equilibrium, as happens during viscous fluid inflation or during reheating. The asymptotic stability of the de Sitter and Friedmann solutions is investigated. The former is stable for bulk viscosity index $q<1$ and the latter for $q>1$. New solutio

Carolyn S. Gordon, Ruth Gornet, Dorothee Schueth, David. L. Webb

We construct the first examples of continuous families of isospectral Riemannian metrics that are not locally isometric on closed manifolds, more precisely, on $S^n\times T^m$, where $T^m$ is a torus of dimension $m\ge 2$ and $S^n$ is a sphere of dimension $n\ge 4$. These metrics are not locally homogeneous; in particular, the scalar curvature of each metric

Eric Jeckelmann, Steven R. White

We propose a new density matrix renormalization group (DMRG) approach to study lattices including bosons. The key to the new approach is an exact mapping of a boson site containing 2^N states to N pseudo-sites, each with 2 states. The pseudo-sites can be viewed as the binary digits of a boson level. We apply the pseudo-site DMRG method to the polaron problem

G. Daldoss, O. Pilla, G. Viliani

We report on numerical procedures for, and preliminary results on the search for, tunnelling centres in Lennard-Jones clusters, seen as simple model systems of glasses. Several of the double-well potentials identified are good candidates to give rise to two-level systems. The role of boundary effects, and the application of the semiclassical WKB approximatio

T. -D. Albert, R. Flume, K. Ruhlig

We determine the transition amplitude for multi-magnon scattering induced through an inhomogeneous distribution of the coupling constant in the ferromagnetic XXX-model. The two and three particle amplitudes are explicitely calculated at small momenta. This suggests a rather plausible conjecture also for a formula of the general n-particle amplitude.

M. Kaukonen, R. M. Nieminen, P. K. Sitch, G. Jungnickel

We present a study of the effects of Nitrogen and Boron doping on the growth of CVD diamond in the (100) mechanism. These are the first calculations of this type and show that, in accordance with recent experimental results, the presently accepted growth mechanism, that due to Harris, is cataylsed by the presence of subsurface Boron impurities. In contrast,

Gianaurelio Cuniberti, Maura Sassetti, Bernhard Kramer

The complex ac-response of a quasi-one dimensional electron system in the one-band approximation with an interaction potential of finite range is investigated. It is shown that linear response is exact for this model. The influence of the screening of the electric field is discussed. The complex absorptive conductance is analyzed in terms of resistive, capac

Ulrich J. Gossmann, Andrei Manolescu, Rolf R. Gerhardts

We calculate the single-particle states of a two-dimensional electron gas (2DEG) in a perpendicular quantizing magnetic field, which is periodic in one direction of the electron layer. We discuss the modulation of the electron density in this system and compare it with that of a 2DEG in a periodic electrostatic potential. We take account of the induced poten

Pavel Exner, Milos Tater

We discuss differences between the exact S-matrix for scattering on serial structures and a known factorized expression constructed of single-element S-matrices. As an illustration, we use an exactly solvable model of a quantum wire with two point impurities.

T. Portengen, J. R. Chapman, V. Nikos Nicopoulos, N. F. Johnson

A novel type of charged excitation, known as a Skyrmion, has recently been discovered in quantum Hall systems with filling factor near ν= 1. A Skyrmion -- which can be thought of as a topological twist in the spin density of the electron gas -- has the same charge as an electron, but a much larger spin. In this review we present a detailed theoretical invest

Fridolin Okkels, Mogens H. Jensen

The detailed dynamics around intermittency bursts is investigated in turbulent shell models. We observe that the amplitude of the high wave number velocity modes vanishes before each burst, meaning that the fixed point in zero and not the Kolmogorov fixed point determines the intermittency. The phases of the field organize during the burst, and after a burst

R. R. Caldwell, Paul J. Steinhardt

An alternative to the standard cold dark matter model has been recently proposed in which a significant fraction of the energy density of the universe is due to a dynamical scalar field ($Q$) whose effective equation-of-state differs from that of matter, radiation or cosmological constant ($Λ$). In this paper, we determine how the Q-component modifies the pr

E. J. Kerins

Recent results from gravitational microlensing experiments, such as MACHO, indicate that a substantial fraction of the Galactic dark matter (DM) is in compact form, with a typical mass in the range ~0.05 - 1 Mo. This mass range favours the DM being either low-mass hydrogen-burning stars or white-dwarf remnants of an early stellar population. There appears ho

Philip R. Maloney, Mitchell C. Begelman

The radiation-driven warping instability discovered by Pringle holds considerable promise as the mechanism responsible for producing warped, precessing accretion disks in X-ray binaries. This instability is an inherently global mode of the disk, thereby avoiding the difficulties with earlier models for the precession. Here we follow up earlier work to study

C. D. Wilson, F. Combes

We have obtained sensitive upper limits on the CO J=2-1 and CO J=3-2 emission lines for five faint blue galaxies with redshifts $z\sim 0.5$ using the IRAM 30~m telescope. These observations would have been able to detect the luminous infrared galaxy IRAS F10214+4724 if it were located at this redshift and unlensed. However, they are not sensitive enough to d

Michael Thierbach, Reinhard Schlickeiser, Richard Wielebinski

We present the preparation for an observation of the Sunyaev-Zeldovich (SZ) effect with the 100m telescope in Effelsberg. We calculate the expected diminution of the cosmic microwave background radiation (CMB) at radio wavelength towards a small sample of clusters of galaxies: A85, A665, and Cl0016+16. We obtain the required parameters from the X-ray analysi

L. Kedziora-Chudczer, D. L. Jauncey, M. H. Wieringa, M. A. Walker

We have observed profound variability in the radio flux density of the quasar PKS 0405-385 on timescales of less than an hour; this is unprecedented amongst extragalactic sources. If intrinsic to the source, these variations would imply a brightness temperature 10^21 K, some nine orders of magnitude larger than the inverse Compton limit for a static synchrot

A. Martinelli, F. Matteucci, S. Colafrancesco

Models of chemical evolution of elliptical galaxies taking into account different escape velocities at different galactocentric radii are presented. As a consequence of this, the chemical evolution develops differently in different galactic regions; in particular, we find that the galactic wind, powered by supernovae (of type II and I) starts, under suitable

Mark R. Metzger, John A. R. Caldwell, Paul L. Schechter

A catalog of Cepheid variables is used to probe the kinematics of the Galactic disk. Radial velocities are measured for eight distant Cepheids toward l = 300; these new Cepheids provide a particularly good constraint on the distance to the Galactic center, R_0. We model the disk with both an axisymmetric rotation curve and one with a weak elliptical componen

Cheryl Frost, Robert Cannon, John Lattanzio, Peter Wood

It is currently accepted that Hot-Bottom-Burning (HBB) in intermediate-mass asymptotic giant branch (AGB) stars prevents the formation of C~stars. Nevertheless, we present in this paper the results of some detailed evolutionary calculations which show that even with HBB we obtain C~stars at the highest luminosities reached on the AGB. This is due to mass-los

Mark Gross

In 1996, Strominger, Yau and Zaslow made a conjecture about the geometric relationship between two mirror Calabi-Yau manifolds. Roughly put, if X and Y are a mirror pair of such manifolds, then X should possess a special Lagrangian torus fibration $f:X\to B$ such that Y is obtained by dualizing the fibration f. This leaves a huge amount to be done to verify

Paolo Sibani, Michael Brandt, Preben Alstroem

Macroevolution is considered as a problem of stochastic dynamics in a system with many competing agents. Evolutionary events (speciations and extinctions) are triggered by fitness records found by random exploration of the agents&#39; fitness landscapes. As a consequence, the average fitness in the system increases logarithmically with time, while the rate o

Carlos Castro, Jerzy Plebanski

We present in detail a class of solutions to the $4D SU(\infty)$ Moyal Anti Self Dual Yang Mills equations that are related to $reductions$ of the generalized Moyal Nahm quations using the Ivanova-Popov ansatz. The former yields solutions to the ASDYM/SDYM equations for arbitary gauge groups. A further dimensional reduction yields solutions to the Moyal Anti

J. Urban, F. Krauss, U. Jentschura, G. Soff

We present a calculation of the B0-B0--mixing including Next--to--Leading Order (NLO) QCD corrections within the Two Higgs Doublet Model (2HDM). The QCD corrections at NLO are contained in the factor denoted by eta_2 which modifies the result obtained at the lowest order of perturbation theory. In the Standard Model case, we confirm the results for eta_2 obt

Stanley L. Robertson

%auto-ignore This paper has been withdrawn by the author. The attribution of hard spectral features of x-ray novae to neutron star surfaces and gap accretion was incorrect.

M. Avila

Wavefunctions of a relativistic heavy quark-light quark $(Q,q)$ system described by a Dirac hamiltonian are analyzed. By assuming that the confinement potential is a Lorentz scalar (S), the slope of the Isgur-Wise function is calculated at zero recoil point. The result obtained is $ξ^\prime(1)=-0.93\pm 0.05.$ This means that the solutions are perfectly consi

G. A. Lalazissis, D. Vretenar, W. Pöschl, P. Ring

The Relativistic Hartree Bogoliubov theory is applied in the mean-field approximation to the description of properties of light nuclei with large neutron excess. Pairing correlations and the coupling to particle continuum states are described by finite range two-body forces. Using standard parameter sets for the mean-field Lagrangian and the pairing interact

Kei Iida

Effects of energy dissipation on quantum nucleation of two-flavor quark matter in dense nuclear matter encountered in neutron star cores are examined at low temperatures. We find that low-energy excitations of nucleons and electrons reduce the nucleation rate exponentially via their collisions with the surface of a quark matter droplet.

Mikhail Feldman

We consider two variational evolution problems related to Monge-Kantorovich mass transfer. These problems provide models for collapsing sandpiles and for compression molding. We prove the following connection between these problems and nonlocal geometric curvature motion: The distance functions to surfaces moving according to certain nonlocal geometric laws

Loukas Grafakos, Atanas Stefanov

Convolution type Calderón-Zygmund singular integral operators with rough kernels $\pv \Om(x)/|x|^n$ are studied. A condition on $\Om$ implying that the corresponding singular integrals and maximal singular integrals map $L^p \to L^p$ for $1<p<\nf$ is obtained. This condition is shown to be different from the condition $\Om\in H^1(\sn)$.

Franco Ferrari, Jan T. Sobczyk

An operator formalism for bosonic $β-γ$ systems on arbitrary algebraic curves is introduced. The classical degrees of freedom are identified and their commutation relations are postulated. The explicit realization of the algebra formed by the fields is given in a Hilbert space equipped with a bilinear form. The construction is based on the &#34;gaussian&#34;

M. K. Parida

In two-step breaking of a class of grand unified theories including SO(10),we prove a theorem showing that the scale $M_I$ where the Pati-Salam gauge symmetry with parity breaks down to the standard gauge group,has vanishing corrections due to all sources emerging from higher scales $ μ>M_I$ such as the one-loop and all higher loop effects,the GUT-threshold,

Zhenmin He, Xiaoxia Yao, Chungui Duan, Guanglie Li

In order to overcome the shortcoming of nonconservation of nuclear momentum existing in the original $Q^2$-rescaling model(O$Q^2$RM) and avoid introducing nuclear shadowing factor, we proposed a double $Q^2$-rescaling model(D$Q^2$RM) for the parton distributions of the bound nucleon. Using the experimental data of lepton-nucleus deep inelastic scattering(DIS

R. Mansouri, K. Nozari

A systematic rotation of the plane of polarization of electromagnetic radiation propagating over cosmological distances has been claimed to be detected by Nodland and Ralston.Taking the finite rotating universe of Oszvath and Schücking as a toy model for the actual universe,we calculate the rotation of the plane of polarization of electromagnetic waves in th

M. J. Martins

We exhibit explicitly the intertwiner operator for the monodromy matrices of the recent proposed SU(N) Hubbard model [5]. This produces a new family of non-additive R-matrices and generalizes an earlier result by Shastry [2].

Mark A. Peterson

The general equations of motion for two dimensional Laplacian growth are derived using the conformal mapping method. In the singular case, all singularities of the conformal map are on the unit circle, and the map is a degenerate Schwarz-Christoffel map. The equations of motion describe the motions of these singularities. Despite the typical fractal-like out

D. R. Xiong, L. Deng, Q. L. Cheng

We have performed a linear pulsational stability survey of 6 series of long period variable models with M=1.0 Msun, L=3000 - 8000Lsun, and (X,Z)= (0.700,0.020),(0.735,0.005). The dynamic and thermodynamic couplings between convection and oscillations are treated by using a statistical theory of nonlocal and time-dependent convection. The results show that th

D. R. Xiong, Q. L. Cheng, L. Deng

Using a nonlocal time-dependent theory of convection, we have calculated the linear non-adiabatic oscillations of the Horizontal Branch (HB) stars, with both the dynamic and thermodynamic coupling between convection and oscillations carefully treated. Turbulent pressure and turbulent viscosity have been included consistently in our equations of non-adiabatic

S. E. Parkhomenko

The transformation properties of the N=2 Virasoro superalgebra generators under Poisson-Lie T-duality in (2,2)-superconformal WZNW and Kazama-Suzuki models is considered. It is shown that Poisson-Lie T-duality acts on the N=2 super-Virasoro algebra generators as a mirror symmetry does: it unchanges the generators from one of the chirality sectors while in an

Francesco Toppan

We review some basic features of the Lie-algebraic classification of W-algebras and related integrable hierarchies in 1+1 dimensions, pointing out the role of affine Lie algebras. We emphasize that the supersymmetric extensions of the above construction possibly lead, though some questions are still opened, to the classification of supersymmetric hierarchies

A. Mondragon, E. Hernandez

We study the complex geometric phase acquired by the resonant states of an open quantum system which evolves irreversibly in a slowly time dependent environment. In analogy with the case of bound states, the Berry phase factors of resonant states are holonomy group elements of a complex line bundle with structure group C*. In sharp contrast with bound states

Seok-Jin Kang, Masaki Kashiwara

Motivated by the work of Nakayashiki on the inhomogeneous vertex models of 6-vertex type, we introduce the notion of crystals with head. We show that the tensor product of the highest weight crystal of level k and the perfect crystal of level l is isomorphic to the tensor product of the perfect crystal of level l-k and the highest weight crystal of level k.

C Alexa, D Vrinceanu

The flow of the relativistic imperfect fluid in two dimensions is discussed. We calculate the symmetry group of the energy-momentum tensor conservation equation in the ultrarelativistic limit. Group-invariant solutions for the incompressible fluid are obtained

A. L. Koshkarov

Continuous dual symmetry in electrodynamics, Yang-Mills theory and gravitation is investigated. Dual invariant which leads to badly nonlinear motion equations is chosen as a Lagrangian of the pure classical dual nonlinear electrodynamics. In a natural manner some dual angle which is determined by the electromagnetic strengths at the point of the time-space a

A. V. Bratchikov

Operator quantization of the WZNW theory invariant with respect to an affine Kac-Moody algebra $\hat g$ with constrained $\hat {u}(1)^d$ currents is performed using Dirac&#39;s procedure. Upon quantization the initial energy-momentum tensor is replaced by the $g/u(1)^d$ coset construction. The $\hat {su}(2)$ WZNW theory with a constrained $\hat u(1)$ current

S. Kalyana Rama

We imagine the strings on the stretched horizon of any $d$ space-time dimensional black hole to be bits of polymer. Then, proposing an interaction between these bits we obtain the size of the configuration, and thus of the black hole, using the scaling laws. The transition from a typical black hole state to a typical string state has a simple explanation, wh

A. S. Deakin, V. Elias, A. H. Fariborz, Ying Xue

There is a need to go beyond the narrow resonance approximation for QCD sum-rule channels which are likely to exhibit sensitivity to broad resonance structures. We first discuss how the first two Laplace sum rules are altered when one goes beyond the narrow resonance approximation to include possible subcontinuum resonances with nonzero widths. We then show

Elisabetta Sassaroli

Neutrino flavor mixing is discussed in terms of two-component coupled left-handed flavor fields. This is to take into account the fact that the weak interaction couples only to left-handed fields. The flavor fields are written through a rotation matrix, as a linear combination of left-handed free fields. In order to obtain properly normalized wave functions

Thordur Jonsson, John F. Wheater

The metric of two-dimensional quantum gravity interacting with conformal matter is believed to collapse to a branched polymer metric when the central charge c>1. We show analytically that the spectral dimension of such a branched polymer phase is four thirds. This is in good agreement with numerical simulations for large c.

L. Conti, A. Donini, V. Gimenez, G. Martinelli

We present results on the B-parameters $B_K$, $B^{3/2}_7$ and $B^{3/2}_8$, at $β=6.0$, with the tree-level Clover action. The renormalization of the complete basis of dimension-six four-fermion operators has been performed non-perturbatively. Our results for $B_K$ and $B^{3/2}_7$ are in reasonable agreement with those obtained with the (unimproved) Wilson ac

G. Sardanashvily

The usual formulation of time-dependent mechanics implies a given splitting $Y=R\times M$ of an event space $Y$. This splitting, however, is broken by any time-dependent transformation, including transformations between inertial frames. The goal is the frame-covariant formulation of time-dependent mechanics on a bundle $Y\to R$ whose fibration $Y\to M$ is no

J. J. Rodriguez-Nunez, M. A. de Menezes

We have postulated a single pole for the self-energy, $Σ(\vec{k},ω)$, looking for the consequences on the one-particle Green function, $G(\vec{k},ω)$ in the Hubbard model. We find that $G(\vec{k},ω)$ satisfies the first two sum rules or moments of Nolting (Z. Physik 255, 25 (1972)) for any values of the two unknown $\vec{k}$ parameters of $Σ(\vec{k},ω)$. In

J. J. Rodriguez - Nunez, C. E. Cordeiro, A. Delfino

We use the moment approach of Nolting (exact sum rules) (Z. Physik 255, 25 (1972)) for the attractive Hubbard model in the superconducting phase. Our diagonal and off - diagonal spectral functions are constructed and evaluated with the sum rules. They reduce to the $BCS$ limit for weak interaction. However, the presence of correlations modify the $BCS$ pictu

N. P. Proukakis, K. Burnett

We outline the general features of the conventional mean-field theory for the description of Bose-Einstein condensates at near zero temperatures. This approach, based on a phenomenological model, appears to give excellent agreement with experimental data. We argue, however, that such an approach is not rigorous and cannot contain the full effect of collision

A. Marconi, L. Testi, A. Natta, C. M. Walmsley

We have used the LONGSP spectrometer on the 1.5-m TIRGO telescope to obtain long slit spectra in the J, H, and K wavelength bands towards two positions along the Orion bar. These data have been supplemented with images made using the ARNICA camera mounted on TIRGO as well as with an ESO NTT observation carried out by Dr A. Moorwood. We detect a variety of tr

Alain Blanchard, Simon Prunet

The conditions for structure formation which ultimately lead to galaxies request further ingredients behind the simple collapse criteria. The Jean&#39;s criteria and the cooling criteria are those which are currently used. However in such a simple scheme, a fundamental problem occurs in hierarchical pictures, namely the OVERCOOLING: the predicted fraction of

John C. B. Papaloizou, Caroline Terquem, Doug N. C. Lin

On the global warping of a thin self-gravitating near Keplerian gaseous disk with application to the disk in NGC 4258

F. Yusef-Zadeh, D. A. Roberts, M. Wardle

We present VLA measurements of H92alpha radio recombination line emission from an unusual HII region G0.18--0.04, the ``Sickle&#39;&#39;, with spatial and spectral resolutions of 27&#34; times 24&#34;.9 and 14 km/s, respectively. These observations detected two new kinematic components of ionized gas whose velocities differ greatly from the +25 km/s molecula

Limin Lu, Blair D. Savage, Kenneth R. Sembach, Bart P. Wakker

We estimate the abundances of S and Fe in the high velocity cloud HVC 287.5+22.5+240, which has a velocity of +240 km/s with respect to the local standard of rest and is in the Galactic direction l~287, b~23. The measurements are based on UV absorption lines of these elements in the Hubble Space Telescope spectrum of NGC 3783, a background Seyfert galaxy, as

E. Sharpe

In this technical note we describe a pair of results on heterotic compactifications. First, we give an example demonstrating that the usual statement of the anomaly-freedom constraint for perturbative heterotic compactifications (meaning, matching second Chern characters) is incorrect for compactifications involving torsion-free sheaves. Secondly, we correct

J. J. Palacios

We show how to calculate semi-analytically the dense vortex state in strong type-II superconducting nanostructures. For the specific case of a strip, we find vortex lattice solutions which also incorporate surface superconductivity. We calculate the energy cost to displace individual vortex rows parallel to the surfaces and find that this energy oscillates w

Luis A. Anchordoqui, Diego F. Torres, Marta L. Trobo, Santiago E. Perez Bergliaffa

We present here analytical solutions of General Relativity that describe evolving wormholes with a non-constant redshift function. We show that the matter that threads these wormholes is not necessarily exotic. Finally, we investigate some issues concerning WEC violation and human traversability in these time-dependent geometries.

P. S. Howe, N. D. Lambert, P. C. West

We obtain the complete quantum Seiberg-Witten effective action for N=2 supersymmetric SU(N) Yang-Mills theory from the classical M-fivebrane equations of motion with N threebranes moving in its worldvolume.

Shinya Kanemura

The non-decoupling effects of heavy Higgs bosons as well as fermions on the loop-induced $H^\pm W^\mp Z^0$ vertex are discussed in the general two Higgs doublet model. The decay width of the process $H^+ \to W^+ Z^0$ is calculated at one-loop level and the possibility of its enhancement is explored both analytically and numerically. We find that the novel en

A. Pautz, G. Shaw

Rho photoproduction on complex nuclei is re-examined using a generalised vector dominance model which succesfully predicts the observed nuclear shadowing in real photoabsorption and deep inelastic scattering. This model is shown to give a good fit to rho photoproduction data on both nucleons and complex nuclei, in which the well-known disagreement between th

B. Alles, C. Christou, A. Feo, H. Panagopoulos

We calculate the third coefficient of the lattice beta function in QCD with Wilson fermions, extending the pure gauge results of Luescher and Weisz; we show how this coefficient modifies the scaling function on the lattice. We also calculate the three-loop average plaquette in the presence of Wilson fermions. This allows us to compute the lattice scaling fun

N. Gurappa, Prasanta. K. Panigrahi

A similarity transformation is constructed through which a system of particles interacting with inverse-square two-body and harmonic potentials in one dimension, can be mapped identically, to a set of free harmonic oscillators. This equivalence provides a straightforward method to find the complete set of eigenfunctions, the exact constants of motion and a l

Kei Ito, Nobuhito Maru

Configurations of fivebranes, twobranes and fourbranes in type IIA string theory, which give (1+1) dimensional supersymmetric gauge theories in the low energy limit, are constructed. It is shown that these brane configurations are equivalent to a certain class of matrix string theories. This opens up an avenue for the investigation of matrix string dynamics

Victor P. Debattista, J. A. Sellwood

We use fully self-consistent N-body simulations of barred galaxies to show that dynamical friction from a dense dark matter halo dramatically slows the rotation rate of bars. Our result supports previous theoretical predictions for a bar rotating within a massive halo. On the other hand, low density halos, such as those required for maximum disks, allow the

Anjan Kundu

A strongly correlated electron system with controlled hopping, in the line of the recently proposed generalized Hubbard models as candidates for high T_c-superconductors, is considered. The model along with a whole class of such systems are shown to be completely integrable with explicit quantum R-matrices and the Lax operators. Inspite of novelties in the B

Tomohiro Matsuda

Domain wall solution for $N_{c}=N_{f}$ supersymmetric QCD is constructed. Astrophysical implications of the domain wall configuration is also discussed.

David J. Reiss, Lisa M. Germany, Brian P. Schmidt, C. W. Stubbs

We have initiated a three-year project to find supernovae (SNe) in a well-defined sample of high-density southern Abell clusters with redshifts $z\leq0.08$. These observations will provide a volume-limited sample of SNe Ia to more than a magnitude below their peak brightness, and will enable us to: (1) measure the luminosity function of SNe, (2) further expl

M. Daoud, Y. Hassouni, M. Kibler

Operators, refered to as k-fermion operators, that interpolate between boson and fermion operators are introduced through the consideration of two noncommuting quon algebras. The deformation parameters for these quon algebras are roots of unity connected to an integer k. The case k=2 corresponds to fermions and the limiting case k going to infinity to bosons

P. Garbaczewski, G. Kondrat, R. Olkiewicz

We discuss a connection (and a proper place in this framework) of the unforced and deterministically forced Burgers equation for local velocity fields of certain flows, with probabilistic solutions of the so-called Schrödinger interpolation problem. The latter allows to reconstruct the microscopic dynamics of the system from the available probability density

Lu-Ming Duan, Guang-Can Guo

In the comment, Zanardi and Rasetti argue that several claims in our recent letter (Phys. Rev. Lett. 79, 1953, 1997) are questionable. The reply shows these claims remain true.

O. Foda, B. Leclerc, M. Okado, J. -Y. Thibon

We study the restrictions of simple modules of Ariki-Koike algebras $\H_m(\v)$ with set of parameters $\v= (ζ;ζ^{v_0},... ,ζ^{v_{l-1}})$, where $ζ$ is an $n$th root of unity, to their subalgebras $\H_{m-j}(\v)$. Using a theorem of Ariki and the crystal basis theory of Kashiwara, we relate this problem to the calculation of tensor product multiplicities of hi

J. R. Mureika

The 100m world rankings of the 1997 outdoor track and field competition season are reviewed, subject to corrections for wind effects and atmospheric drag. The rankings and times are compared with those of 1996, and the improvements of each athlete over the course of a year are discussed. Additionally, the athletes&#39; wind-corrected 50m and 60m splits from

V. Aldaya, J. Guerrero, G. Marmo

Contents * Introduction -- Why $S^1$-extended phase space? -- Why central extensions of classical symmetries? * Central extension \Gt of a group $G$ -- Group cohomology -- Cohomology and contractions: Pseudo-cohomology -- Principal bundle with connection $(\Gtm,Θ)$ * Group Approach to Quantization -- $U(1)$-quantization -- Non-horizontal polarizations * Simp

Aric Hagberg, Ehud Meron

We study a mechanism of pulse propagation failure in excitable media where stable traveling pulse solutions appear via a subcritical pitchfork bifurcation. The bifurcation plays a key role in that mechanism. Small perturbations, externally applied or from internal instabilities, may cause pulse propagation failure (wave breakup) provided the system is close

S. Donev, M. Tashkova

This paper aims to consider the general properties of the non-linear solutions to the vacuum equations of Extended Electrodynamics. The *-invariance and the conformal invariance of the equations are mentioned. It is also proved that all non-linear solutions have zero invariants: F_{μν}F^{μν} = (*F)_{μν}F^{μν} = 0. The three invariant characteristics of the n

P. S. Howe, N. D. Lambert, P. C. West

We discuss the supersymmetry algebra of the M theory fivebrane and obtain a new threebrane soliton preserving half of the six-dimensional supersymmetry. This solution is dimensionally reduced to various D-p-branes.

Ichiro Oda

Starting with topological field theory, we derive space-time uncertainty relation proposed by Yoneya through breakdown of topological symmetry in the large $N$ matrix model. Next, on the basis of only two basic principles, those are, generalized space-time uncertainty principle containing spinor field and topological symmetry, we construct a new matrix model

B. Chakraborty, A. S. Majumdar

We couple the Hopf term to the relativistic $CP^1$ model and carry out the Hamiltonian analysis at the classical level. The symplectic structure of the model given by the set of Dirac Brackets among the phase space variables is found to be the same as that of the pure $CP^1$ model. This symplectic structure is shown to be inherited from the global SU(2) inva

R. Arnowitt

The effect of non-universal SUSY soft breaking on predictions of dark matter detector event rates are surveyed for supergravity models with gravity mediated soft breaking. For universal soft breaking in the first two generations and tan(beta)<=20, non-universal effects can be characterized by four parameters (two for Higgs and two for third generation squark

R. A. Bertlmann, W. Grimus

Considering semileptonic decays of the entangled B^0 \bar B^0 state which is generated in the decay of Upsilon(4S), we simply multiply the quantum-mechanical interference term by a factor (1-ζ) and use the ``decoherence parameter&#39;&#39; ζas a measure for deviations from quantum mechanics. We investigate several consequences of this modification of semilep

M. Giovannini, M. E. Shaposhnikov

The high-temperature plasma above the electroweak scale $\sim 100$ GeV may have contained a primordial hypercharge magnetic field whose anomalous coupling to the fermions induces a transformation of the hypermagnetic energy density into fermionic number. In order to describe this process, we generalize the ordinary magnetohydrodynamical equations to the anom

Marco Aurelio Diaz

The simplest way of studying systematically R-parity violating phenomena is by introducing a bilinear term in the superpotential of the type $ε\hat L\hat H_2$, which violates R-parity and lepton number but keep barion number conserved. In its simplest version, this ``$ε$--model&#39;&#39; is a two parameter extension of the MSSM and a one parameter extension

H. Walliser

Masses of the SU(3) chiral soliton in tree approximation turn out at much too high energies typically around 2 GeV. It is shown that 1-loop corrections reduce this value drastically with results in the region of the empirical nucleon mass.

S. Umisedo, H. Suganuma, H. Toki

We study the correlation between confinement and dynamical chiral-symmetry breaking (D$χ$SB) in the dual Ginzburg-Landau (DGL) theory using the effective potential formalism. The DGL theory is an infrared effective theory based on the dual Higgs mechanism, and provides the nonperturbative gluon propagator, which leads to the linear quark potential. The scree

Maarten Golterman, Ka Chun Leung

We use one-loop chiral perturbation theory (ChPT) to compare lattice results for the K+ to pi+ pi0 decay amplitude with the experimental value. Three systematic effects: quenching, finite-volume effects, and the use of unphysical values of quark masses and pion external momenta can be investigated. We find that the corrections help in explaining the discrepa

Sara Collins, Robert G. Edwards, Urs. M. Heller, John Sloan

We compare light hadron spectroscopy using the Wilson and Clover fermionic actions. We show that a Clover coefficient chosen using tadpole-improved tree-level perturbation theory effectively eliminates the O(a) discretization errors present in the Wilson action. We find that discretization errors in light spectroscopy for both the Wilson and Clover actions a

W. Bardeen, A. Duncan, E. Eichten, H. Thacker

Lattice QED2 with the Wilson formulation of fermions is used as a convenient model system to study artifacts of the quenched approximation on a finite lattice. The quenched functional integral is shown to be ill-defined in this system as a consequence of the appearance of exactly real modes for physical values of the fermion mass. The location and frequency

Stephan Elser, Burkhard Bunk

We study quenched and dynamical pion correlators in the two-flavour Schwinger model (2D QED) both within topological charge sectors and averaged. The results show that a clean-cut definition of a pion mass is no longer possible if tunneling between sectors does not occur. PACS numbers: 11.15.Ha, 12.20.-m, 11.10.Kk