March 1997 arXiv papers — page 5

Sumit R. Das

It is known that weak coupling calculations of absorption or emission by slightly non-extremal D-brane configurations are in exact agreement with semiclassical results for the black holes they describe at strong couplings. We investigate one open string loop corrections to processes involving single and parallel D-branes and show that a class of relevant ter

M. Dakna, L. Knoll, D. -G. Welsch

We show that conditional output measurement on a beam splitter may be used to produce photon-added states for a large class of signal-mode quantum states, such as thermal states, coherent states, squeezed states, displaced photon-number states, and coherent phase states. Combining a mode prepared in such a state and a mode prepared in a photon-number state,

Yves Brihaye

We analyse the Witten-Woronowicz's type deformations of the Lie superalgebras spl(N,1) and obtain deformations parametrized by N(N-1)/2 independent parameters for N>2 and by three parameters for N=2. For some of these algebras, finite dimensional representations can be constructed in terms of finite difference operators, providing operators that are rele

J. Gratus

An infinite dimensional algebra which is a non-decomposable reducible representation of $su(2)$ is given. This algebra is defined with respect to two real parameters. If one of these parameters is zero the algebra is the commutative algebra of functions on the sphere, otherwise it is a noncommutative analogue. This is an extension of the algebra normally ref

Sergei Kerov, Andrei Okounkov, Grigori Olshanski

Consider the lattice of all Young diagrams ordered by inclusion, and denote by Y its Hasse graph. Using the Pieri formula for Jack symmetric polynomials, we endow the edges of the graph Y with formal multiplicities depending on a real parameter $θ$. The multiplicities determine a potential theory on the graph Y. Our main result identifies the corresponding M

A. C. Voorrips, C. de Valk

A comparison is carried out between two operational wave forecasting/assimilation models for the North Sea, with the emphasis on the assimilation schemes. One model is the WAM model, in combination with an optimal interpolation method (OIP). The other model, DASWAM, consists of the third generation wave model PHIDIAS in combination with an approximate implem

David E. Rosenberg

The baryon overdensity and the matching of the big bang explosion energy with gravitation can be solved by a cyclical baryonic bounce model with correction to the stress-energy tensor. Subtracting accretion energy from the CMBR allows enough baryons in nucleosynthesis to close the universe. Collapse to infinite density states must be prevented by energy loss

C. Elphick, A. Hagberg, B. A. Malomed, E. Meron

The interaction between a pair of Bloch fronts forming a traveling domain in a bistable medium is studied. A parameter range beyond the nonequilibrium Ising-Bloch bifurcation is found where traveling domains collapse. Only beyond a second threshold the repulsive front interactions become strong enough to balance attractive interactions and asymmetries in fro

Nandor Simanyi

We prove that the system of two hard balls in a $ν$-dimensional ($ν\ge2$) rectangular box is ergodic and, therefore, actually it is a Bernoulli flow.

N. Berkovits, W. Siegel

We give a gauge and manifestly SO(2,2) covariant formulation of the field theory of the self-dual string. The string fields are gauge connections that turn the super-Virasoro generators into covariant derivatives.

Yutaka Hosotani

N flavor QED in two dimensions is reduced to a quantum mechanics problem with N degrees of freedom for which the potential is determined by the ground state of the problem itself. The chiral condensate is determined at all values of temperature, fermion masses, and the $θ$ parameter. In the single flavor case, the anomalous mass (m) dependence of the chiral

Alberto Accardi, Andrea Belli, Maurizio Martellini, Mauro Zeni

The first order formalism for 3D Yang-Mills theory is considered and two different formulations are introduced, in which the gauge theory appears to be a deformation of the topological BF theory. We perform the quantization and the algebraic analysis of cohomology and renormalization for both the models, which are found to be anomaly free. We discuss also th

M. Klimek

The general, linear equations with constant coefficients on quantum Minkowski spaces are considered and the explicit formulae for their conserved currents are given. The proposed procedure can be simplified for *-invariant equations. The derived method is then applied to Klein-Gordon, Dirac and wave equations on different classes of Minkowski spaces. In the

Tomoko Kadoyoshi, Shin'ichi Nojiri

We construct the Lagrangeans of N=3 and N=4 two-form supergravities. The two-form gravity theories are classically equivalent to the Einstein gravity theories and can be formulated as gauge theories. The gauge algebras used here can be identified with the subalgebra of N=3 superconformal algebra and SU(2)\times SU(2)\times U(1)-extended N=4 superconformal al

Philip Candelas, Eugene Perevalov, Govindan Rajesh

We construct, as hypersurfaces in toric varieties, Calabi-Yau manifolds corresponding to F-theory vacua dual to E8*E8 heterotic strings compactified to six dimensions on K3 surfaces with non-semisimple gauge backgrounds. These vacua were studied in the recent work of Aldazabal, Font, Ibanez and Uranga. We extend their results by constructing many more exampl

M. Beneke, V. M. Braun, N. Kivel

Ultraviolet renormalons, contrary to their infrared counterparts, lead to a universal contribution to the large-order behaviour of perturbative expansions in QCD. In this letter, we determine nature of the leading ultraviolet renormalon singularity for the inclusive hadroproduction cross section in $e^+ e^-$ annihilation, for hadronic $τ$ decays and the mome

S. Dawson

We consider the phenomenology of the Standard Model intermediate mass Higgs boson, $71 GeV < M_h < 2 M_W$. The motivation for a Higgs boson in this mass region is emphasized. The branching ratios for the Higgs boson, including electroweak and QCD radiative corrections, are presented, along with production cross sections for $e^+e^-, μ^+μ^-, γγ$, and hadronic

N. S. Amaglobeli, S. M. Esakia, V. R. Garsevanishvili, G. O. Kuratashvili

Scale invariant presentation of inclusive spectra in terms of light front variables is proposed. The variables introduced go over to the well-known scaling variables x_F = 2p_z/sqrt(s) and x_T=2p_T/sqrt{s} in the high p_z and high p_T limits respectively. So Some surface is found in the phase space of produced pi-mesons in the inclusive reaction anti p p ->

B. I. Ermolaev, S. I. Troyan

Nonsinglet structure function g_2(x) for deep inelastic scattering of a lepton on a constituent quark is calculated in the double logarithmic approximation at x<<1. Small-x asymptotics of g_2 is shown to have the same singular behaviour as asymptotics of the nonsinglet structure function g_1.

Johan Linde, Hakan Snellman

The charmonium system is studied in a Salpeter model with a vector plus scalar potential. We use a kinematical formalism based on the one developed by Suttorp, and present general eigenvalue equations and expressions for decay observables in an onium system for such a potential both in the Feynman and Coulomb gauges. Special attention is paid to the problem

G. Domokos, S. Kovesi-Domokos

If massive neutrinos possess magnetic moments, they can undergo spin flip in a magnetic field. The magnetic fields needed for a meaningful measurement of neutrino moments could be very high and may occur in astronomical objects such as some supernovae or active galactic nuclei: they are typically chaotic ones. We develop the general theory of the passage of

Howard E. Haber

The search for the weakly-coupled Higgs sector at future colliders consists of three phases: discovery of a Higgs candidate, verification of the Higgs interpretation of the signal, and precision measurements of Higgs sector properties. The discovery of one Higgs boson with Standard Model properties is not sufficient to expose the underlying structure of the

C. Best, M. Göckeler, R. Horsley, E. -M. Ilgenfritz

We calculate the lower moments of the deep-inelastic structure functions of the pion and the rho meson on the lattice. Of particular interest to us are the spin-dependent structure functions of the rho. The calculations are done with Wilson fermions and for three values of the quark mass, so that we can perform an extrapolation to the chiral limit.

Hideo Nakajima

New partial differential equations for the Wiener-Hermite expansions of the Langevin (stochastic) transitions are formulated. They are solved recursively in full order series solutions with respect to $\sqrt{t}$. A sort of &#39;gauge&#39; degrees of freedom (arbitrariness) involved in the solutions are analyzed and clarified. The Wiener-Hermite expansions pl

A. S. Majumdar

We consider two kinds of higher dimensional models which upon dimensional reduction lead to Jordan-Brans-Dicke type effective actions in four dimensions with the scale factor of the extra dimensions playing the role of the JBD field. These models are characterized by the potential for the JBD field which arises from the process of dimensional reduction, and

J. A. Smoller, A. G. Wasserman

In this paper we study a new type of solution of the spherically symmetric, Einstein-Yang/Mills (EYM) equations with SU(2) gauge group. These solutions are well-behaved in the far-field, and have a Reissner-Nordstrom type essential singularity at the origin. These solutions display some novel features which are not present in particle-like, or black-hole sol

M. Banados, M. Henneaux, C. Iannuzzo, C. M. Viallet

The gauge symmetries of pure Chern-Simons theories with p-form gauge fields are analyzed. It is shown that the number of independent gauge symmetries depends crucially on the parity of p. The case where p is odd appears to be a direct generalization of the p=1 case and presents the remarkable feature that the timelike diffeomorphisms can be expressed in term

L. Demopoulos, J. Legare

We consider a simple, physical approach to the problem of marginally trapped surfaces in the Nonsymmetric Gravitational Theory (NGT). We apply this approach to a particular spherically symmetric, Wyman sector gravitational field, consisting of a pulse in the antisymmetric field variable. We demonstrate that marginally trapped surfaces do exist for this choic

M. Welling

We find that the momentum conjugate to the relative distance between two gravitating particles in their center of mass frame is a hyperbolic angle. This fact strongly suggests that momentum space should be taken to be a hyperboloid. We investigate the effect of quantization on this curved momentum space. The coordinates are represented by non commuting, Herm

M. Welling

After a review of multi particle solutions in classical 2+1 dimensional gravity we will construct a one particle Hilbert space. As we will use a curved momentum space, the coordinates $x^μ$ are represented as non commuting Hermitian operators on this Hilbertspace. Finally we will indicate how to construct a Schrodinger equation.

Ichiro Oda

We study an internal structure of (2+1)-dimensional black hole with the neutral scalar matter in the spherically symmetric geometry by using a quantum theory of gravity which holds in the both vicinities of the singularity and the apparent horizon. A special attention is paid to the quantum-mechanical behavior of the singularity in the black hole. We solve a

Ichiro Oda

We discuss an evaporation of (2+1)-dimensional black hole by using quantum gravity holding in the vicinity of the black hole horizon. It is shown that the black hole evaporates at a definite rate by emitting matters through the quantum tunneling effect. A relation of the present formalism to the black hole entropy is briefly commented.

T. Matos

We analyze a new class of static exact solutions of Einstein-Maxwell-Dilaton gravity with arbitrary scalar coupling constant $α$, representing a gravitational body endowed with electromagnetic dipole moment. This class possesses mass, dipole and scalar charge parameters. A discussion of the geodesic motion shows that the scalar field interaction is so weak t

Yuri A. Kordyukov

We study the transversal wave equation on a compact Riemannian foliated manifold. As applications, we get an Egorov&#39;s type theorem for transversally elliptic operators, state a relationship between the singularities of the Fourier transform of the spectrum distribution function of a transversally elliptic operator and the corresponding transversal bichar

Michael Farber

In this paper we study the problem of approximation of the $L^2$-topological invariants by their finite dimensional analogues. We obtain generalizations of the theorem of Lück, dealing with towers of finitely sheeted normal coverings. We prove approximation theorems, establishing relations between the homological invariants, corresponding to infinite dimensi

Emmanuel Trizac, Jean-Pierre Hansen

A concentrated suspension of lamellar colloidal particles (e. g. clay) is modelled by considering a single, uniformly charged, finite platelet confined with co- and counterions to a Wigner-Seitz (WS) cell. The system is treated within Poisson-Boltzmann theory, with appropriate boundary conditions on the surface of the WS cell, supposed to account for the con

F. Mancini, D. Villani, H. Matsumoto

By means of the composite operator method we calculate the specific heat of the 2D Hubbard model. Our results show that the model gives a detailed description of the experimental situation in the normal state of cuprate high Tc superconductors. The observed behavior is consistent with a Fermi liquid picture where the unusual properties are described in terms

J. Häkkinen, M. Lagerholm, C. Peterson, B. Söderberg

A feedback neural network approach to communication routing problems is developed with emphasis on Multiple Shortest Path problems, with several requests for transmissions between distinct start- and endnodes. The basic ingredients are a set of Potts neurons for each request, with interactions designed to minimize path lengths and to prevent overloading of n

Janne Ruostekoski, Dan F. Walls

We study the interaction of light with two Bose condensates as an open quantum system. The two overlapping condensates occupy two different Zeeman sublevels and two driving light beams induce a coherent quantum tunneling between the condensates. We derive the master equation for the system. It is shown that stochastic simulations of the measurements of spont

C. Jarzynski

It is shown that, by applying a principle of information theory, one obtains Berry&#39;s conjecture regarding the high-lying quantal energy eigenstates of classically chaotic systems.

W. Vincent Liu, William C. Schieve

A dissipative quantum system is treated here by coupling it with a heat bath of harmonic oscillators. Through quantum Langevin equations and Ehrenfest&#39;s theorem, we establish explicitly the quantum Duffing equations with a double-well potential chosen. A quantum noise term appears the only driving force in dynamics. Numerical studies show that the chaoti

P. N. Safier, C. F. McKee, S. W. Stahler

We present an idealized, spherical model of the evolution of a magnetized molecular cloud due to ambipolar diffusion. This model allows us to follow the quasi-static evolution of the cloud&#39;s core prior to collapse and the subsequent evolution of the remaining envelope. By neglecting the thermal pressure gradients in comparison with magnetic stresses and

E. Stengler-Larrea, H. Andernach

We searched for extended radio sources in isolated E/S0 galaxies comparing the FIRST and APM catalogues for a single POSS plate. The 35 most promising candidates were visually inspected on the Digitized Sky Survey (DSS) and on FIRST images: we find several spirals and interacting galaxies and a few E/S0s with very weak, marginally extended radio cores. The o

O. Verkhodanov, H. Andernach, N. Verkhodanova, N. Loiseau

We constructed radio spectra for ~1400 UTR-2 sources and find that 46% of them have concave curvature. Inspection of NVSS maps of 700 UTR sources suggests that half of all UTR sources are either blends of two or more sources or have an ultra-steep spectrum (USS). The fraction of compact USS sources in UTR may be near 10%. Using NVSS and the Digitized Sky Sur

H. Andernach, S. Trushkin

We review the history and present status of radio-source catalogue archiving and on-line retrieval of radio source data. Large efforts were spent by the first author in collecting and restoring electronic versions of new and old source catalogues. Some 67 catalogues with ~520,000 entries were searchable via the &#34;Einstein On-line Service&#34; (EOLS). When

Alessandro Drago, Ubaldo Tambini

We study the equation of state of quark matter at finite temperature, using a confinement model in which chiral symmetry remains broken in the deconfined phase. Implications for type II supernova explosion and for the structure and evolution of the proto-neutron star are discussed.

T. Hamana, M. Hattori, H. Ebeling, J. P. Henry

The amplification of the protogalaxy candidate cB58 due to gravitational lensing by the foreground cluster of galaxies MS1512.4+3647 is quantified based on recent ROSAT and ASCA X-ray observations. It is found that the amplification is at most 25 for any reasonable cosmological model with or without cosmological constant. It is also argued that the system ma

M. Maisack, J. E. Grove, E. Kendziorra, P. Kretschmar

We present pulse phase spectroscopy of A 0535+26 in the energy range 35-200 keV from OSSE observations of its giant outburst in 1994. We discuss the phase dependence of the continuum parameters and the cyclotron resonance feature (CRF) at 110 keV already found in the phase averaged spectrum. We find that a CRF is required at every phase. The behaviour of the

Hien D. Tran, Alexei V. Filippenko, Gary D. Schmidt, Karen S. Bjorkman

We have monitored the polarized radiation of the Type IIb SN 1993J in M81 over a period of 41 days, starting from 7 days after the explosion on 1993 March 27.5 (UT). Our data show clear evidence that the intrinsic continuum polarization of SN 1993J evolved from being essentially negligible on April 3-4, to a peak value of ~ 1% in late April 1993, and started

J. Alexander, A. Hirschowitz

We give a new differential proof of our result on the maximal rank of generic unions of points of multiplicity two in projective space in degrees greater than five. This simplifies somewhat our proof of the Waring conjecture.

J. Alexander, A. Hirschowitz

We show that for any finite generic union of pairs $(x_i,L_i)_i$ where $x_i\in L_i$ is a point of the line $L_i$ in projective $n$-space, the divisors $m_ix_i$ on the $L_i$ have maximal rank with respect to homogeneous $d$ forms for all $d\geq 0$ and all $m_i\geq 0$ modulo the expected numerical restrictions.

Boris V. Karpov, Dmitri Yu. Nogin

We study complete exceptional collections of coherent sheaves over Del Pezzo surfaces, which consist of three blocks such that inside each block all Ext groups between the sheaves are zero. We show that the ranks of all sheaves in such a block are the same and the three ranks corresponding to a complete 3-block exceptional collection satisfy a Markov-type Di

William Oxbury, Christian Pauly

If C is a curve of genus 4 without vanishing theta-nulls then there exists a unique (irreducible) Heisenberg-invariant quartic Q_C in |2Θ| = P^{15} such that Sing Q_C contains the image of SU_C(2), the moduli space of rank 2 vector bundles with trivial determinant. Moreover, in each eigen-P^7 of the Heisenberg action on |2Θ|, Q_C restricts to the classical C

Ann E. Nelson

The most severe constraints on quark-lepton four-fermion contact interactions come from the agreement of atomic parity violation measurements with the Standard Model. In this letter I note that for contact interactions which arise in theories of composite quarks and leptons, other approximate global symmetries than parity can eliminate the contribution of co

U. A. Wiedemann, P. Foka, H. Kalechofsky, M. Martin

For a set of N identical massive boson wavepackets with optimal initial quantum mechanical localization, we calculate the Hanbury-Brown/Twiss (HBT) two-particle correlation function. Our result provides an algorithm for calculating one-particle spectra and two-particle correlations from an arbitrary phase space occupation (q_i,p_i,t_i)_{i=1,N} as e.g. return

Nora Brambilla, Antonio Vairo

We write the 4-point Green function in QCD in the Feynman-Schwinger representation and show that all the dynamical information are contained in the Wilson loop average. We work out the QED case in order to obtain the usual Bethe-Salpeter kernel. Finally we discuss the QCD case in the non-perturbative regime giving some insight in the nature of the interactio

Nora Brambilla, Antonio Vairo

Starting from the relativistic gauge-invariant quark-antiquark Green function we obtain the relevant interaction in the one-body limit, which can be interpreted as the kernel of a non-perturbative Dirac equation. We study this kernel in different kinematic regions, reproducing, in particular, for heavy quark the potential case and sum rules results. We discu

S. F. Hewson, N. D. Lambert

We discuss the application of T-duality to massive supersymmetric sigma models. In particular (1,1) supersymmetric models with off-shell central charges reveal an interesting structure. The T-duality transformations of the BPS states of these theories are also discussed and an explicit example of Q-kinks is given.

Nicola Di Bartolomeo, Marco Fabbrichesi

We discuss the possibility of explaining the excess in the cross section at high-Q^2 recently found at HERA in terms of four-fermion effective interactions. To avoid the constraints from low-energy data, we select three special cases in which the contact interaction is a product of vector-vector, axial-axial and vector-axial currents. For these a satisfactor

Tae-Hyoung Gimm, Seung-Pyo Hong, Sung-Ho Suck Salk

By allowing the spin degrees of freedom, we present a generalized spin allowed $U(1)\times U(1)$ Chern-Simons theory of fractional quantum Hall effects for odd and even denominator filling factors in single layers. This theory is shown to reproduce all possible odd denominator filling factors corresponding to spin-unpolarized, partially polarized, and fully

B. Rusakov

An exactly soluble non-perturbative model of the pure gauge QCD is derived as a weak coupling limit of the lattice theory in plaquette formulation. The model represents QCD as a theory of the weakly interacting field strength fluxes. The area law behavior of the Wilson loop average is a direct result of this representation: the total flux through macroscopic

D. Diakonov, V. Petrov, M. Polyakov

We predict an exotic Z^+ baryon (having spin 1/2, isospin 0 and strangeness +1) with a relatively low mass of about 1530 MeV and total width of less than 15 MeV. It seems that this region of masses has avoided thorough searches in the past.

Peter F. Arndt, Thomas Heinzel, Vladimir Rittenberg

The stationary state of a stochastic process on a ring can be expressed using traces of monomials of an associative algebra defined by quadratic relations. If one considers only exclusion processes one can restrict the type of algebras and obtain recurrence relations for the traces. This is possible only if the rates satisfy certain compatibility conditions.

Costas G. Papadopoulos

A study of the production and the decay of scalar and vector leptoquarks at high-energy e+ e- colliders is presented. All tree-order contributions to single leptoquark production have been calculated and incorporated in the Monte Carlo event generator ERATO-LQ.

Ian I. Kogan, John F. Wheater

We consider new objects in bosonic open string theory -- ND tadpoles, which have N(euman) boundary conditions at one end of the world-sheet and D(irichlet) at the other, must exist due to s-t duality in a string theory with both NN strings and D-branes. We demonstrate how to interpolate between N and D boundary conditions. In the case of mixed boundary condi

Yuri Bespalov, Bernhard Drabant

Braided non-commutative differential geometry is studied. In particular we investigate the theory of (bicovariant) differential calculi in braided abelian categories. Previous results on crossed modules and Hopf bimodules in braided categories are used to construct higher order bicovariant differential calculi over braided Hopf algebras out of first order on

Michael Danos, Tien D Kieu

The conceptual problems in quantum mechanics -- related to the collapse of the wave function, the particle-wave duality, the meaning of measurement -- arise from the need to ascribe particle character to the wave function. As will be shown, all these problems dissolve when working instead with quantum fields, which have both wave and particle character. Othe

P. K. Mohanty, A. Taraphder

Intense experimental and theoretical efforts have recently been brought to bear on the determination of the symmetry of superconducting order parameter in high T$_c$ Cuprates as this would shed light on the nature of microscopic interactions that are responsible for superconductivity in these unusual systems. We use a two band model that reproduces the Fermi

Andres Gomberoff, Sergio A. Hojman

Examples of the construction of Hamiltonian structures for dynamical systems in field theory (including one reputedly non-Hamiltonian problem) without using Lagrangians, are presented. The recently developed method used requires the knowledge of one constant of the motion of the system under consideration and one solution of the symmetry equation.

I. G. Korepanov

This paper continues the series begun with works solv-int/9701016 and solv-int/9702004. Here we show how to construct eigenstates for a model based on tetrahedron equation using the tetrahedral Zamolodchikov algebras. This yields, in particular, new eigenstates for the model on infinite lattice -- `perturbed&#39;, or `broken&#39;, strings.

B. Bagchi, C. Quesne

Quasi-exactly solvable rational potentials with known zero-energy solutions of the Schro\&#34; odinger equation are constructed by starting from exactly solvable potentials for which the Schr\&#34; odinger equation admits an so(2,1) potential algebra. For some of them, the zero-energy wave function is shown to be normalizable and to describe a bound state.

Lu-Ming Duan, Guang-Can Guo

We consider decoherence of quantum registers, which consist of the qubits sited approximately periodically in space. The sites of the qubits are permitted to have a small random variance. We derive the explicit conditions under which the qubits can be assumed decohering independently. In other circumstances, the qubits are decohered cooperatively. We describ

G. G. Athanasiu, E. G. Floratos, G. K. Savvidy

We analyze the structure of the periodic trajectories of the K-system generator of pseudorandom numbers on rational sublattice which coincides with the Galois field. The period of the trajectories increases as a function of lattice size and the dimension of the K-matrix. We emphasize the connection of this approach with the one which is based on primitive ma

M. V. Stoitsov, S. S. Dimitrova, S. Pittel, P. Van Isacker

Slater determinants built from the single-particle wave functions of the analytically solvable Ginocchio potential are used to approximate the self-consistent Hartree-Fock solutions for the ground states of nuclei. The results indicate that the Ginocchio potential provides a good parametrization of the nuclear mean field for a wide range of nuclei, including

J. Brachmann, A. Dumitru, M. Bleicher, J. A. Maruhn

We study transverse expansion and directed flow in Au(11AGeV)Au reactions within a multi-fluid dynamical model. Although we do not employ an equation of state (EoS) with a first order phase transition, we find a slow increase of the transverse velocities of the nucleons with time. A similar behaviour can be observed for the directed nucleon flow. This is due

Victor A. Vassiliev

Finite-order invariants of knots in arbitrary 3-manifolds (including non-orientable ones) are constructed and studied by methods of the topology of discriminant sets. Obstructions to the integrability of admissible weight systems to well-defined knot invariants are identified as 1-dimensional cohomology classes of generalized loop spaces of the manifold. Unl

A. Mironov

This is a short review of the results on the associativity algebras and WDVV equations found recently for the Seiberg-Witten solutions of N=2 4d SUSY gauge theories. The presentation is mostly based on the integrable treatment of these solutions.

Jeffrey M. Rabin

Conformal mapping techniques are used to determine analytically the geodesics on the Seiberg-Witten Riemann surface which correspond to the BPS dyon states in N=2 SUSY QCD with gauge group SU(2) and up to three flavors of massless fundamental matter. The results are exact for zero and two flavors, and approximate in the weak-coupling limit for one and three

Yi Cheng, Lin Zhang

The V-algebras are the non-local matrix generalization of the well-known W-algebras. Their classical realizations are given by the second Poisson brackets associated with the matrix pseudodifferential operators. In this paper, by using the general Miura transformation, we give the decomposition theorems for the second Poisson brackets, from which we are able

M. D. Scadron

We review the theoretical predictions for ρ^0-ωmixing and conclude in many ways that <ρ^0 H_{em} ω>~ -5000 MeV^2, more in line with earlier analyses of charge symmetry violation and with present data.

A. Dedes, K. Tamvakis

We make a complete analysis of the Yukawa coupling unification in SU(5) extensions of the MSSM in the framework of the radiative symmetry breaking scenario. Both logarithmic and finite threshold corrections of sparticles have been included in the determination of the gauge and Yukawa couplings at M_Z. The effect of the heavy masses of each model in the renor

Shi-lin Zhu, Zhenping Li

The isospin symmetry breakings of q{\bar q} are investigated in the QCD sum rule method. The electromagnetic effects are evaluated following the procedure requiring that the electromagnetic effects for charged meson be gauge invariant. We find that the electromagnetic effects are also dominant in the isospin violations of rho meson, which have been shown to

Sourendu Gupta, Prakash Mathews

We study the hadro- and photo-production of $\bar cc$ and $\bar bb$ mesons at low transverse momentum to high orders in the relative velocity of the pair, v, in non-relativistic QCD. We evaluate cross sections to order v^7 for $η_c$, sufficient for studies of photo-production in the almost-elastic region. For all other charmonium states we find the cross sec

C. Adloff

The results of a measurement of the proton structure function F_2(x,Q^2)and the virtual photon-proton cross section are reported for momentum transfers squared Q^2 between 0.35 GeV^2 and 3.5 GeV^2 and for Bjorken-x values down to 6 10^{-6} using data collected by the HERA experiment H1 in 1995. The data represent an increase in kinematic reach to lower x and

D. Yu. Akimov, A. A Burenkov, D. L. Churakov, V. F. Kuzichev

Characteristics of a scintillation proportional counter with WLS fiber optics readout is described. The possibility of detection of the proportional scintillation signal produced by the single electron of primary ionization is shown. The counter can be applied for the experiments in &#34;low--background&#34; physics which require a low energy threshold.

CDF Collaboration

We report the first observation of diffractively produced W bosons. In a sample of W -> e nu events produced in p-barp collisions at sqrt{s}=1.8 TeV, we find an excess of events with a forward rapidity gap, which is attributed to diffraction. The probability that this excess is consistent with non-diffractive production is 1.1 10^{-4} (3.8 sigma). The relati

M. A. Clayton, L. Demopoulos, J. Legare

We cast the four-dimensional field equations of the Nonsymmetric Gravitational Theory (NGT) into a form appropriate for numerical study. In doing so, we have restricted ourselves to spherically symmetric spacetimes, and we have kept only the Wyman sector of the theory. We investigate the well-posedness of the initial-value problem of NGT for a particular dat

Philippe Jetzer, David Scialom

We study the time evolution of small classical perturbations in a gauge invariant way for a complex scalar field in the early zero curvature Friedmann-Lema\^ıtre universe. We, thus, generalize the analysis which has been done so far for a real scalar field. We give also a derivation of the Jeans wavenumber in the Newtonian regime starting from the general re

Eleny-Nicoleta Ionel, Thomas H. Parker

Given a symplectomorphism f of a symplectic manifold X, one can form the `symplectic mapping cylinder&#39; $X_f = (X \times R \times S^1)/Z$ where the Z action is generated by $(x,s,t)\mapsto (f(x),s+1,t)$. In this paper we compute the Gromov invariants of the manifolds $X_f$ and of fiber sums of the $X_f$ with other symplectic manifolds. This is done by exp

D. Zanchi, H. J. Schulz

We study the weakly interacting Hubbard model on the square lattice using a one-loop renormalization group approach. The transition temperature T_c between the metallic and (nearly) ordered states is found. In the parquet regime, (T_c >> |mu|), the dominant correlations at temperatures below T_c are antiferromagnetic while in the BCS regime (T_c << |mu|) at

Shi-Jie Xiong, S. N. Evangelou

We investigate the random matrix configurations for two or three interacting electrons in one-dimensional disordered systems. In a suitable non-interacting localized electron basis we obtain a sparse random matrix with very long tails which is different from a superimposed random band matrix usually thought to be valid. The number of non-zero off-diagonal ma

Robert Shrock, Shan-Ho Tsai

We study the dependence of complex-temperature phase diagrams on details of the Hamiltonian, focusing on the effect of non-nearest-neighbor spin-spin couplings. For this purpose, we consider a simple exactly solvable model, the 1D Ising model with nearest-neighbor (NN) and next-to-nearest-neighbor (NNN) couplings. We work out the exact phase diagrams for var

J. van den Brink, Olle Gunnarsson, V. Eyert

We study the optical conductivity in A3C60 (A =K, Rb). The effects of the electron-phonon interaction is included to lowest order in the coupling strength lambda. It is shown that this leads to a narrowing of the Drude peak by a factor 1+lambda and a transfer of weight to a mid-infrared peak at somewhat larger energies than the phonon energy. Although this g

B. J. Feenstra, F. C. Klaassen, D. van der Marel, Z. H. Barber

Using mm-wave transmission we obtain information about both the real and imaginary part of the dielectric function of superconducting thin films. This is done by fitting the Fabry-Perot resonance spectrum for the film plus substrate over a broad frequency range (110-180 GHz) using the full Fresnel equations and a two-fluid description for the dielectric func

A. Buhot, J. -M. Torres Moreno, M. B. Gordon

We study numerically the properties of the bayesian perceptron through a gradient descent on the optimal cost function. The theoretical distribution of stabilities is deduced. It predicts that the optimal generalizer lies close to the boundary of the space of (error-free) solutions. The numerical simulations are in good agreement with the theoretical distrib

Pierre Deltour, Jean-Louis Barrat, Pablo Jensen

We present a Molecular Dynamics study of large Lennard-Jones clusters evolving on a crystalline surface. The static and the dynamic properties of the cluster are described. We find that large clusters can diffuse rapidly, as experimentally observed. The role of the mismatch between the lattice parameters of the cluster and the substrate is emphasized to expl

J. I. Katz, T. Piran, R. Sari

The gamma-ray burst source GRB970228 has been observed after a delay of 8--12 hours in X-rays and after one day in visible and near infrared light. This marks the first detection of emission at lower frequencies following the gamma-ray observation of a GRB and the first detection of any visible counterpart to a GRB. We consider possible delayed visible and X

D. L. Band, L. A. Ford, J. L. Matteson, M. S. Briggs

The physical importance of the apparent discrepancy between the detections by pre-BATSE missions of absorption lines in gamma-ray burst spectra and the absence of a BATSE line detection necessitates a statistical analysis of this discrepancy. This analysis requires a calculation of the probability that a line, if present, will be detected in a given burst. H

R. de la Reza, N. A. Drake, L. da Silva, C. A. O. Torres

A model scenario has recently been introduced to explain the presence of very strong Li lines in the spectra of some low mass K giant stars (de la Reza et al. 1996). In this scenario all ordinary, Li poor, K giants become Li rich during a short time ($\sim 10^5 yr$) when compared to the red giant phase of 5 10^7 yr. In this ``Li period&#39;&#39;, a large par

J. M. Kommers, D. W. Fox, W. H. G. Lewin, R. E. Rutledge

The repetitive X-ray bursts from the accretion-powered pulsar GRO J1744-28 show similarities to the type II X-ray bursts from the Rapid Burster. Several authors (notably Lewin et al.) have suggested that the bursts from GRO J1744-28 are type II bursts (which arise from the sudden release of gravitational potential energy). In this paper, we present another s