June 1996 arXiv papers — page 3

A. Daehn, W. Huebner, K. H. Bennemann

Using symmetry arguments we show how optical second harmonic generation (SHG) can be used to detect antiferromagnetism at surfaces and in thin films. Based on the group theoretical analysis of the nonlinear electric susceptibility we propose a new nonlinear magneto-optical effect, which allows even in the presence of unit-cell doubling for the unambiguous di

R. E. Prange

The spectral form factor, k(t), is the Fourier transform of the two level correlation function C(x), which is the averaged probability for finding two energy levels spaced x mean level spacings apart. The average is over a piece of the spectrum of width W in the neighborhood of energy E0. An additional ensemble average is traditionally carried out, as in ran

C. Alcock, R. A. Allsman, D. Alves, T. S. Axelrod

The MACHO Project is a search for dark matter in the form of massive compact halo objects (Machos). Photometric monitoring of millions of stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and Galactic bulge is used to search for gravitational microlensing events caused by these otherwise invisible objects. Analysis of the first 2.1 yea

D. Sáez, E. Holtmann, G. F. Smoot

We describe and compare two types of microwave sky simulations which are good for small angular scales. The first type uses expansions in spherical harmonics, and the second one is based on plane waves and the Fast Fourier Transform. The angular power spectrum is extracted from maps corresponding to both types of simulations, and the resulting spectra are ap

Baolian Cheng, Angela V. Olinto, David N. Schramm, James W. Truran

In this paper, we revisit in detail the effects of primordial magnetic fields on big bang nucleosynthesis (BBN) including a discussion of the magnetic field geometry and the anomalous magnetic moment. The presence of magnetic fields affects BBN by (1) increasing the weak reaction rates; (2) increasing the electron density due to changes to the electron phase

John Bahcall

The neutrino fluxes calculated from the 14 standard solar models published recently in refereed journals are inconsistent with the results of the 4 pioneering solar neutrino experiments if nothing happens to the neutrinos after they are created in the solar interior. The calculated fluxes and the experimental results are in good agreement if neutrino oscilla

C. M. Baugh

The null hypothesis that the three dimensional power spectrum measured from the APM Survey is consistent with the one dimensional power spectrum measured from the pencil beams surveys of Broadhurst et al and of Szalay et al is tested. The external estimates of the mean power that we make are sensitive to details of the model for the survey geometry and to th

Alexander Kusenko, Gino Segre

Neutrino oscillations, biased by the magnetic field, alter the shape of the neutrinosphere in a cooling protoneutron star emerging from the supernova collapse. The resulting anisotropy in the momentum of outgoing neutrinos can be the origin of the observed proper motions of pulsars. The connection between the pulsars velocities and neutrino oscillations resu

Francis W. Starr, Stephen T. Harrington, Bruce M. Boghosian, H. Eugene Stanley

Using a hydrodynamic lattice-gas model, we study interface growth in a binary fluid with various concentrations of surfactant. We find that the interface is smoothed by small concentrations of surfactant, while microemulsion droplets form for large surfactant concentrations. To assist in determining the stability limits of the interface, we calculate the cha

Sayan Kar

An analysis of the generalised Raychaudhuri equations for string world sheets is shown to lead to the notion of focusing of timelike worldsheets in the classical Nambu-Goto theory of strings. The conditions under which such effects can occur are obtained . Explicit solutions as well as the Cauchy initial value problem are discussed. The results closely resem

R. Lemus, F. Perez-Bernal, A. Frank, R. Bijker

The stretching and bending vibrations of methane are studied in a local anharmonic model of molecular vibrations. The use of symmetry-adapted operators reduces the eigenvalue problem to block diagonal form. For the 44 observed energies we obtain a fit with a standard deviation of 0.81 cm$^{-1}$ (and a r.m.s. deviation of 1.16 cm$^{-1}$).

Ettore Aldrovandi, Leon A. Takhtajan

We formulate and solve the analog of the universal Conformal Ward Identity for the stress-energy tensor on a compact Riemann surface of genus $g>1$, and present a rigorous invariant formulation of the chiral sector in the induced two-dimensional gravity on higher genus Riemann surfaces. Our construction of the action functional uses various double complexes

Hua-Bin Tang, Paul J. Ellis

It is shown that the off-shell parameters in the interaction Lagrangian of pions, nucleons, and $Δ$-isobars are redundant in the framework of effective field theories. Our results also suggest the necessity of including the $Δ$ as an explicit dynamical degree of freedom.

Paul M. Sheldon

A density operator, $\rho = {P}_{\alpha } |\alpha > <\alpha | + {P}_{\beta } |\beta > <\beta |$, with ${P}_{\alpha }$ and ${P}_{\beta }$ linearly independent normalized wave functions, must be traced normalized, so ${P}_{\beta } = 1 - {P}_{\alpha }$. However, unless $<\alpha |\beta > = 0$, ${P}_{\alpha }$ and ${P}_{\beta }$ cannot be interpreted as probabili

S. Jadach, W. Placzek, M. Skrzypek, B. F. L. Ward

We present the theoretical basis and sample Monte Carlo data for the YFS exponentiated calculation of $e^+e^- \rightarrow W^+ W^- \rightarrow f_1\bar f&#39;_1 + \bar f_2 f&#39;_2$ at and beyond LEP2 energies, where the left-handed parts of $f_i$ and $f&#39;_i$ are the respective upper and lower components of an $SU_{2L}$ doublet, $i=1,2$. The problem of gaug

G. Camici, M. Ciafaloni

By using $\k$-factorization, we derive resummation formulas for the non-abelian $q\bar{q}$ contributions to both heavy flavour production by gluon fusion, and to the next-to-leading BFKL kernel. By combining this result with previous ones by Fadin et al. on the virtual terms, we also compute in closed form the complete $q\bar{q}$ contribution to the gluon an

V. E. Rochev

A new method for non-perturbative calculation of Green functions in quantum mechanics and quantum field theory is proposed. The method is based on an approximation of Schwinger-Dyson equation for the generating functional by exactly soluble equation in functional derivatives. Equations of the leading approximation and the first step are solved for $ϕ^4_d$-mo

P V Landshoff

A first-principles derivation is given of the imaginary part of a Green&#39;s function in real-time thermal field theory. The analysis and its conclusions are simpler than in the usual circled-vertex formalism. The relationship to Cutkosky-like cutting rules is explained.

Hodaka Oda, Norisuke Sakai, Tadakatsu Sakai

Vacuum structures of supersymmetric (SUSY) Yang-Mills theories in $1+1$ dimensions are studied with the spatial direction compactified. SUSY allows only periodic boundary conditions for both fermions and bosons. By using the Born-Oppenheimer approximation for the weak coupling limit, we find that the vacuum energy vanishes, and hence the SUSY is unbroken. Ot

Edi Halyo

We argue that the mass of the inflaton can be much smaller than the Hubble constant in supergravity models in which inflation is driven by D--terms and not F--terms. We investigate a supergravity toy model which leads to hybrid inflation due to an anomalous D--term. We show that the slow--roll condition can be satisfied and the correct magnitude for density

Zhi-zhong Xing

D^0-\bar{D}^0 mixing at the detectable level or significant CP violation in the charm system may strongly signify the existence of new physics. In view of the large discovery potential associated with the fixed target experiments, the B-meson factories and the \tau-charm factories, we make a further study of the phenomenology of D^0-\bar{D}^0 mixing and CP v

Wyn Evans

In a recent Letter (astro-ph/9605001), Cowsik et al. claim that the best fit value of the velocity dispersion of the Galactic dark matter is 600 kms. This result is obtained by a numerical method of solving the coupled self-gravitation equations, assuming Maxwellian velocity distributions. The rotation curve presented in their original paper is not the whole

M. Quinn, S. F. Singer

One fruitful motivating principle of much research on the family of integrable systems known as ``Toda lattices&#39;&#39; has been the heuristic assumption that the periodic Toda lattice in an affine Lie algebra is directly analogous to the nonperiodic Toda lattice in a finite-dimensional Lie algebra. This paper shows that the analogy is not perfect. A discr

Ryszard Horodecki, Michal Horodecki, Pawel Horodecki

Relations between teleportation, Bell&#39;s inequalities and inseparability are investigated. It is shown that any mixed two spin-$1\over2$ state which violates the Bell-CHSH inequality is useful for teleportation. The result is extended to any Bell&#39;s inequalities constructed of the expectation values of products of spin operators. It is also shown that

Christian Fronsdal

A large family of &#34;standard&#34; coboundary Hopf algebras is investigated. The existence of a universal R-matrix is demonstrated for the case when the parameters are in general position. Algebraic surfaces in parameter space are characterized by the appearance of certain ideals; in this case the universal R-matrix exists on the associated algebraic quoti

D. Gurevich

We introduce a representation theory of q-Lie algebras defined earlier in \cite{DG1}, \cite{DG2}, formulated in terms of braided modules. We also discuss other ways to define Lie algebra-like objects related to quantum groups, in particular, those based on the so-called reflection equations. We also investigate the truncated tensor product of braided modules

Francesco Mauri, Oleg Zakharov, Stefano de Gironcoli, Steven G. Louie

The phonon dispersion and the electron-phonon interaction for the $β$-Po and the bcc high pressure phases of tellurium are computed with density-functional perturbation theory. Our calculations reproduce and explain the experimentally observed pressure dependence of the superconducting critical temperature (T$_{\rm c}$) and confirm the connection between the

Yutaka Hosotani

Two-dimensional QED with N-flavor fermions serves as a model of quark dynamics in QCD as well as an effective theory of an anti-ferromagnetic spin chain. It is reduced to N-degree quantum mechanics in which a potential is self-consistently determined by the Schrödinger equation itself.

S. K. Kauffmann

A carefully motivated symmetric variant of the Poisson bracket in ordinary (not Grassmann) phase space variables is shown to satisfy identities which are in algebraic correspondence with the anticommutation postulates for quantized Fermion systems. &#34;Symplecticity&#34; in terms of this symmetric Poisson bracket implies generalized Hamilton&#39;s equations

George Jorjadze

A quantization scheme based on the extension of phase space with application of constrained quantization technic is considered. The obtained method is similar to the geometric quantization. For constrained systems the problem of scalar product on the reduced Hilbert space is investigated and possible solution of this problem is done. Generalization of the Gu

A. Love, S. Todd

The modular symmetries of string loop threshold corrections for gauge coupling constants are studied in the presence of discrete Wilson lines for all examples of abelian orbifolds, where the point group is realised by the action of Coxeter elements or generalised Coxeter elements on the root lattices of the Lie groups.

Vincenzo Branchina, Janos Polonyi

The effects of instantons close to the cut-off is studied in four dimensional SU(2) gauge theory with higher order derivative terms in the action. It is found in the framework of the dilute instanton gas approximation that the convergence of the topological observables requires non-universal beta function.

S. A. Apikyan

Liouville field theory on hyperelliptic surface is considered. The partition function of the Liouville field theory on the hyperelliptic surface are expressed as a correlation function of the Liouville vertex operators on a sphere and the twist fields.

Ph. Brax

We study two dimensional freely decaying magnetohydrodynamic turbulence. We investigate the time evolution of the probability law of the gauge field and the stream function. Assuming that this probability law is initially defined by a statistical field theory in the basin of attraction of a renormalisation group fixed point, we show that its time evolution i

A. Harindranath, Rajen Kundu

We investigate the feasibility of analyzing deep inelastic structure functions in Hamiltonian formalism by combining the light-front BJL limit of high energy amplitudes and the Fock space (multi-parton) description of hadrons. This study is motivated by some of the theoretical questions emerging from the ongoing nonperturbative/perturbative studies in light-

G. Dvali, A. Riotto

Usually one expectes the inflaton field to be coupled to some gauge-charged particles allowing for its decay during reheating. Such particles then play a role of the messengers for the gauge-mediated supersymmetry breaking during and (shortly) after the inflation and radiatively induce soft masses to all other $D$-flat directions. We show that during the pre

Thomas Meissner, Michael Frank

A detailed investigation of the low-energy chiral expansion is presented within a model truncation of QCD. The model dependence of the chiral coefficients is tested for several forms of the quark-quark interaction by varying the form of the running coupling in the infrared region. Furthermore we demonstrate how the UA(1)$ anomaly and a mass for the eta&#39;

A. B. Arbuzov, V. S. Fadin, E. A. Kuraev, L. N. Lipatov

We consider small--angle electron--positron scattering in Quantum Electrodynamics. Leading logarithmic contributions to the cross--section are explicitly calculated to three loop. Next--to--leading terms are exactly computed to two loop. All the radiative corrections due to photons as well as pair production are taken into account. The impact of newly evalua

Darwin Chang, Chuan-Hung Chen

The CP properties in hyperon decays are briefly reviewed. We discuss the general phenomenology and define CP odd observables in hyperon decays. With these observables, we discuss the predictions of some models and their observational potential.

ZEUS Collaboration

Deep inelastic charged--current reactions have been studied in $e^+p$ and $e^-p$ collisions at a center of mass energy of about $300\,\gev$ in the kinematic region $Q^2\greater200\,\gev^2$ and $x\greater0.006$ using the ZEUS detector at HERA. The integrated cross sections for $Q^2\greater200\,\gev^2$ are found to be $\sigep=30.3\,{}^{+5.5}_{\mns4.2}\,{}^{+1.

G. Juttner, A. Klumper

The specific heat and the compressibility for the integrable t-J model are calculated showing Luttinger liquid behavior for low temperatures. A Trotter-Suzuki mapping and the quantum transfer matrix approach are utilized. Using an algebraic Bethe ansatz this method permits the exact calculation of the free energy and related quantities. A set of just two non

V. I. Abkevich, A. M. Gutin, E. I. Shakhnovich

In this paper we study the phenomenon of kinetic partitioning when a polypeptide chain has two ground state conformations one of which is more kinetically reachable than the other. This question is relevant to understand the phenomenology of prions, proteins which exist in the cell in non-pathogenic $α$-helical conformation but under certain circumstances ma

T. Fukui, N. Kawakami

We study the Heisenberg spin chain with twisted boundary conditions, focusing on the adiabatic flow of the energy spectrum as a function of the twist angle. In terms of effective field theory for the nearest-neighbor model, we show that the period 2 (in unit $2π$) obtained by Sutherland and Shastry arises from irrelevant perturbations around the massless fix

Jean Desbois, Cyril Furtlehner, Stéphane Ouvry

We consider an electron coupled to a random distribution of point vortices in the plane (magnetic impurities). We analyze the effect of the magnetic impurities on the density of states of the test particle, when the magnetic impurities have a spatial probability distribution governed by Bose or Fermi statistic at a given temperature. Comparison is made with

Vidar Gudmundsson, Arne Brataas, Christoph Steinebach, A. G. Mal&#39;shukov

We investigate the effects of compressible and incompressible states on the FIR-absorption of quantum wires and dots in a homogeneous perpendicular magnetic field. The electron-electron interaction is treated in the Hartree approximation at a finite low temperature. The calculated dispersion of the collective excitations reproduces several experimental resul

D. A. Head, G. J. Rodgers

We introduce a one-dimensional sandpile model which incorporates particle inertia. The inertial dynamics are governed by a new parameter which, as it passes through a threshold value, alters the toppling dynamics in such a way that the system no longer evolves to a self-organized critical state. A range of mean-field theories based on a kinetic equation appr

W. Weller, F. Stefani, M. Souleiman

Following a proposal by Aronov and Ioselevich, we express the Green functions (GF) of a noninteracting disordered Fermi system as a functional integral on a real time/frequency lattice. The normalizing denominator of this functional integral is equal to unity, because of identities satisfied by the GF. The GF can then be simply averaged with respect to the r

I. Vattulainen, J. Merikoski, T. Ala-Nissila, S. C. Ying

In this Letter, we present results of an extensive Monte Carlo study of the O/W(110) system under non-equilibrium conditions. We study the mean square displacements and long wavelength density fluctuations of adatoms. From these quantities, we define effective and time-dependent values for the collective and tracer diffusion mobilities. These mobilities redu

Beat Frischmuth, Stephan Haas, German Sierra, T. M. Rice

An effective low-energy description for multi-leg spin-1/2 Heisenberg ladders with an odd number of legs is proposed. Using a newly developed Monte Carlo loop algorithm and exact diagonalization techniques, the uniform and staggered magnetic susceptibility and the entropy are calculated for ladders with 1, 3, and 5 legs. These systems show a low-temperature

Yoji Ohashi, Tsutomu Momoi

We study the Bloch theorem which states absence of the spontaneous current in interacting electron systems. This theorem is shown to be still applicable to the system with the magnetic field induced by the electric current. Application to the spontaneous surface current is also examined in detail. Our result excludes the possibility of the recently proposed

Igor E. Smolyarenko, Boris L. Altshuler

Asymptotic behavior of distribution functions of local quantities in disordered conductors is studied in the weak disorder limit by means of an optimal fluctuation method. It is argued that this method is more appropriate for the study of seldom occurring events than the approaches based on nonlinear $σ$-models because it is capable of correctly handling flu

Günther Görz, Marcus Kesseler, Jörg Spilker, Hans Weber

The German joint research project Verbmobil (VM) aims at the development of a speech to speech translation system. This paper reports on research done in our group which belongs to Verbmobil&#39;s subproject on system architectures (TP15). Our specific research areas are the construction of parsers for spontaneous speech, investigations in the parallelizatio

J F McCann, J T Glass, D S F Crothers

The energy dependence of the nonradiative electron capture cross-section is discussed in the relativistic domain. A simple analytic expression is obtained for inner-shell transitions using second-order perturbation theory. We have confirmed that the leading-order term is found to have the following energy dependence: Q ~ E^{-1}ln^2 E. This is attributed to a

P. Stein

A homogeneous sample of galaxy redshifts in the core regions (R < 0.5 h$^{-1}$ Mpc) of 12 clusters is used to measure the frequency of substructure with different tests. In 50 % of the cases substructure is detected, a frequency which agrees well with previous studies of cluster cores. Magnitude information and rough morphological classes are also available

Eric J. Hooper, Chris D. Impey, Craig B. Foltz, Paul C. Hewett

A sample of 103 quasars from the Large Bright Quasar Survey (LBQS) has been observed with the VLA at 8.4 GHz to study the evolution of the radio luminosity distribution and its dependence on absolute magnitude. Radio data from pointed observations are now available for 359 of the 1055 LBQS quasars. The radio-loud fraction is constant at ~10% over the absolut

M. R. Hayashi, K. Shibata, R. Matsumoto

We propose a model of hard X-ray flares in protostars observed by ASCA satellite. Assuming that the dipole magnetic field of the protostar threads the protostellar disk, we carried out 2.5-dimensional magnetohydrodynamic (MHD) simulations of the disk-star interaction. The closed magnetic loops connecting the central star and the disk are twisted by the rotat

Craig J Copi, Keith A. Olive, David N. Schramm

We consider possible implications if the recent and disconcordant measurements of D/H in quasar absorption systems are real and indicate a dispersion in D/H in these primitive systems. In particular we examine the option that the D/H abundances in these systems, which are separated on cosmological scales, are primordial, implying a large scale inhomogeneity

David A. Cox

This paper will appear in the Proceedings of the 1995 Santa Cruz Summer Institute. The paper is a survey of recent developments in the theory of toric varieties, including new constructions of toric varieties and relations to symplectic geometry, combinatorics and mirror symmetry.

Tsuyoshi Hondou

A new type of dynamical behavior of a multistable system is reported. We found that a simple non-equilibrium system can reduce its effective temperature autonomously at a global minimum if the residual frustration at a global minimum is small enough, which highlights an unexpected feature of non-equilibrium multistable systems.

Stephen E. Zepf, Leonidas A. Moustakas, Marc Davis

We present spectroscopy from the Keck telescope of three sets of objects in the Hubble Deep Field which have lens-like morphologies. In the case of J123641+621204, which is composed of four objects with similar colors and a mean separation of <= 0.8&#34;, we find at least two distinct components at redshifts of z=3.209 and z=3.220 which are separated by 0.5&

Stephen Parke, Yael Shadmi

We show that top-quark pairs are produced in an essentially unique spin configuration in polarized $e^+e^-$ colliders at all energies above the threshold region. Since the directions of the electroweak decay products of polarized top-quarks are strongly correlated to the top-quark spin axis, this unique spin configuration leads to a distinctive topology for

J. A. Cliffe, Adam Frank, T. W. Jones

We present 3-D numerical hydrodynamical simulations of precessing supersonic heavy jets to explore how well they serve as a model for generating molecular outflows from Young Stellar Objects. The dynamics are studied with a number of high resolution simulations on a Cartesian grid (128x128x128 zones) using a high order finite difference method. A range of co

H. Rosu

Superoscillations can explain the arbitrarily high frequencies&#39; paradox in black hole radiation

Sukanta Bose, Leonard Parker, Yoav Peleg

We combine analytical and numerical techniques to study the collapse of conformally coupled massless scalar fields in semiclassical 2D dilaton gravity, with emphasis on solutions just below criticality when a black hole almost forms. We study classical information and quantum correlations. We show explicitly how recovery of information encoded in the classic

Todd A. Brun

Quantum open systems are described in the Markovian limit by master equations in Lindblad form. I argue that common ``quantum jumps&#39;&#39; techniques, which solve the master equation by unraveling its evolution into stochastic trajectories in Hilbert space, correspond closely to a particular set of decoherent histories. This is illustrated by a simple mod

Jean-Loup Gervais

The characteristic novel features of strongly coupled gravity at the special values ($C_L=7, 13, 19$) are reviewed in a simple manner using pictures as much as possible. (Notes of lectures at the 1995 Cargese Meeting Low dimensional applications of quantum field theory)

P. S. Howe

The superspace formulation of eleven-dimensional supergravity with a seven-form field strength is given.

Hyun Seok Yang, Bum-Hoon Lee, Chanyong Park

We analytically calculate some thermodynamic quantities of an ideal $g$-on gas obeying generalized exclusion statistics. We show that the specific heat of a $g$-on gas ($g \neq 0$) vanishes linearly in any dimension as $T \to 0$ when the particle number is conserved and exhibits an interesting dual symmetry that relates the particle-statistics at $g$ to the

T. R. Hemmert, B. R. Holstein, ; G. Knoechlein, S. Scherer

The spin-independent part of the virtual Compton scattering (VCS) amplitude from the nucleon is calculated within the framework of heavy baryon chiral perturbation theory (HBChPT). The calculation is performed to third order in external momenta according to chiral power counting. The relation of the tree-level amplitudes to what is expected from the low-ener

Micha Berkooz, Michael R. Douglas, Robert G. Leigh

We show that configurations of multiple D-branes related by SU(N) rotations will preserve unbroken supersymmetry. This includes cases in which two D-branes are related by a rotation of arbitrarily small angle, and we discuss some of the physics of this. In particular, we discuss a way of obtaining 4D chiral fermions on the intersection of D-branes. We also r

K. Landsteiner, E. Lopez, D. A. Lowe

Using D-brane techniques, we compute the spectrum of stable BPS states in N=4 supersymmetric gauge theory, and find it is consistent with Montonen-Olive duality.

S. A. Gardiner, J. I. Cirac, P. Zoller

We describe a method to perform a single quantum measurement of an arbitrary observable of a single ion moving in a harmonic potential. We illustrate the measurement procedure with explicit examples, namely the position and phase observables.

Roberto Onofrio, Lorenza Viola

Quantum theory for measurements of energy is introduced and its consequences for the average position of monitored dynamical systems are analyzed. It turns out that energy measurements lead to a localization of the expectation values of other observables. This is manifested, in the case of position, as a damping of the motion without classical analogue. Quan

Alex Kasman, Mitchell Rothstein

This paper considers Darboux transformations of a bispectral operator which preserve its bispectrality. A sufficient condition for this to occur is given, and applied to the case of generalized Airy operators of arbitrary order $r>1$. As a result, the bispectrality of a large family of algebras of rank $r$ is demonstrated. An involution on these algebras is

Dominique Manchon

Nous construisons pour tout corps k de caracteristique zero un foncteur de la categorie des k-espaces vectoriels dans la categorie des k-algebres de Hopf pointees, qui a tout espace vectoriel V associe son algebre de Hopf bitensorielle pointee A(V). Cette algebre de Hopf est graduee, verifie une propriete universelle, et contient une famille remarquable d&#3

John David Crawford, Anandhan Jayaraman

The amplitude equation for an unstable electrostatic wave in a multi-species Vlasov plasma has been derived. The dynamics of the mode amplitude $\rho(t)$ is studied using an expansion in $\rho$; in particular, in the limit $\gamma\rightarrow0^+$, the singularities in the expansion coefficients are analyzed to predict the asymptotic dependence of the electric

J. Cisternas, M. C. Depassier

In a recent paper Goriely considers the one--dimensional scalar reaction--diffusion equation $u_t = u_{xx} + f(u)$ with a polynomial reaction term $f(u)$ and conjectures the existence of a relation between a global resonance of the hamiltonian system $ u_{xx} + f(u) = 0$ and the asymptotic speed of propagation of fronts of the reaction diffusion equation. Ba

Charles W. Johnson, George Fai, Michael R. Frank

We use a lattice of nonlocal confining solitons to describe nuclear matter in the Wigner-Seitz approximation. The average density is varied by changing the size of the Wigner-Seitz cell. At sufficiently large density quark energy bands develop. The intersection of the filled valence band with the next empty band at a few times standard nuclear density signal

Greg Keaton, Ron Workman

Ambiguities in pseudoscalar-meson photoproduction, arising from incomplete experimental data, have analogs in pion-nucleon scattering. Amplitude ambiguities have important implications for the problems of amplitude extraction and resonance identification in partial-wave analysis. The effect of these ambiguities on observables is described. We compare our res

S. Boffi, Ye. Golubeva, L. A. Kondratyuk, M. I. Krivoruchenko

Medium effects as a function of the mass number $A$ are studied in the total photonuclear cross section from the $Δ$-resonance region up to the region where shadowing effects are known to exist. A consistent picture is obtained by simply assuming a density dependence of the different mechanisms of resonance broadening and shadowing. The $Δ$-mass shift is fou

Robert Myers

Suppose $M$ is a closed, connected, orientable, \irr\ \3m\ such that $G=π_1(M)$ is infinite. One consequence of Thurston&#39;s geometrization conjecture is that the universal covering space $\widetilde{M}$ of $M$ must be \homeo\ to $\RRR$. This has been verified directly under several different additional assumptions on $G$. (See, for example, \cite{2}, \cit

Vered Rom-Kedar

When an integrable two-degrees-of-freedom Hamiltonian system possessing a circle of parabolic fixed points is perturbed, a parabolic resonance occurs. It is proved that its occurrence is generic for one parameter families (co-dimension one phenomenon) of near-integrable, t.d.o. systems. Numerical experiments indicate that the motion near a parabolic resonanc

Alexei G. Poltoratski

We use Rokhlin&#39;s Theorem on the uniqueness of canonical systems to find a new way to establish connections between Function Theory in the unit disk and rank one perturbations of self-adjoint or unitary operators. In the n-dimensional case, we prove that for any cyclic self-adjoint operator $A$, operator $A_λ= A + Σ_{k=1}^n λ_k(\cdot,ϕ_k)ϕ_k$ is pure poin

M. R. Rahimi Tabar, S. Rouhani

We consider the correlation functions of two-dimensional turbulence in the presence and absence of a three-dimensional perturbation, by means of conformal field theory. In the persence of three dimensional perturbation, we show that in the strong coupling limit of a small scale random force, there is some logarithmic factor in the correlation functions of ve

Barton Zwiebach

The main limitations of string field theory arise because its present formulation requires a background representing a classical solution, a background defined by a strictly conformally invariant theory. Here we sketch a construction for a gauge-invariant string field action around non-conformal backgrounds. The construction makes no reference to any conform

Paolo Cea

I investigate three dimensional abelian and non-abelian gauge theories interacting with Dirac fermions. Using a variational method I evaluate the vacuum energy density in the one-loop approximation. It turns out that the states with a constant magnetic condensate lie below the perturbative ground state only in the case of three dimensional quantum electrodyn

I. Brunner, R. Schimmrigk

We discuss some aspects of F-theory in four dimensions on elliptically fibered Calabi-Yau fourfolds which are Calabi-Yau threefold fibrations. A particularly simple class of such manifolds emerges for fourfolds in which the generic Calabi-Yau threefold fiber is itself an elliptic fibration and is K3 fibered. Duality between F-theory compactified on Calabi-Ya

Dmitri Sorokin

By use of geometrical methods of surface theory we demonstrate links of Green-Schwarz superstring dynamics with supersymmetric exactly-solvable nonlinear systems and super-WZNW models reduced in an appropriate way.

Edmond L. Berger, Harry Contopanagos

We summarize calculations of the cross section for top quark production at hadron colliders within the context of perturbative quantum chromodynamics, including resummation of the effects of initial-state soft gluon radiation to all orders in the strong coupling strength. In our approach we resum the universal leading-logarithm contributions, and we restrict

Darwin Chang

Using a simple analytic expression for $q \bar{q}, g g \rightarrow t \bar{t} \rightarrow b W^+ \bar{b} W^- \rightarrow b \bar{l} ν_l \bar{b} l&#39; \bar{ν_{l&#39;}}$ with the interference effects due to the polarizations of the $t$ and $\bar{t}$, we demonstrate how the effects can be measured at Tevatron at $3σ$ level.

Mar Bastero-Gil, Biswajoy Brahmachari

Renormalization effects of large baryon-nonconserving Yukawa couplings $λ^{\prime\prime}_{ijk} \overline{U_i} \overline{D_j} \overline{D_k}$ lower the right handed squark masses keeping the left-handed squark masses virtually untouched at the lowest order. At low energy they enhance the mass-splitting between left and right handed squarks of the same generat

V. Barger, M. S. Berger, J. F. Gunion, T. Han

We discuss the excellent prospects for a detailed study of a strongly interacting electroweak sector at a muon collider with c.m. energy $\rts\sim 4\tev$. For expected luminosity of $L=200-1000\fbi$ per year, $\mup\mum$ and $\mup\mup$ (or $\mum\mum$) collisions can be used to study longitudinal $\wp\wm$ and $\wp\wp$ (or $\wm\wm$) scattering with considerable

Alexander Gromov

The rules of calculating three undetermined functions which defined a solution in the LTB model are used to study the class of exact nonhomogene\-ous models with $f^2(μ) = 1$, $Λ= 0$. The parameter $ν(μ)$ defined the difference between LTB and FRW models is found out and the limit transformation to the FRW model is shown. The initial conditions are present t

F. Schein, P. C. Aichelburg

We construct a static axisymmetric wormhole from the gravitational field of two charged shells which are kept in equilibrium by their electromagnetic repulsion. For large separations the exterior tends to the Majumdar-Papapetrou spacetime of two charged particles. The interior of the wormhole is a Reissner-Nordström black hole matching to the two shells. The

Alexander Gromov

The Caushy problem in the LTB model is formulated. The rules of calculating three undetermined functions which defined a solution in the LTB model are presented. One example of exact nonhomogeneous model is studied. The limit transformation to the FRW model is shown.

J. A. S. Lima, L. R. W. Abramo

A nonsingular deflationary cosmology driven by adiabatic matter creation is proposed. In this scenario there is no preinflationary stage as happens in conventional inflationary models. Deflation starts from a de Sitter spacetime characterized by an arbitrary time scale $H_{I}^{-1}$, which also pins down an initial value for the temperature of the universe. T

George Ganchev, Stefan Ivanov

On a Hermitian manifold we construct a symmetric $(1,1)$- tensor $H$ using the torsion and the curvature of the Chern connection. On a compact balanced Hermitian manifold we find necessary and sufficient conditions in terms of the tensor $H$ for a harmonic $1$-form to be analytic and for an analytic $1$-form to be harmonic. We prove that if $H$ is positive d

A. M. Gutin, V. I. Abkevich, E. I. Shakhnovich

Folding of protein-like heteropolymers into unique 3D structures is investigated using Monte Carlo simulations on a cubic lattice. We found that folding time of chains of length $N$ scales as $N^λ$ at temperature of fastest folding. For chains with random sequences of monomers $λ\approx 6$, and for chains with sequences designed to provide a pronounced minim

Safi R. Bahcall

The properties of a conventional type-II superconductor near the upper critical field are usually calculated using a perturbative expansion in the strength of the order parameter. Here we show that perturbation theory breaks down near the upper critical field and that this breakdown leads to unusual behavior near the phase transition.

Sergei F. Burlatsky, Valeriy V. Ginzburg, Noel A. Clark

We propose the general scaling model for the diffusio n-annihilation reaction $A_{+} + A_{-} \longrightarrow \emptyset$ with long-range power-law i nteractions. The presented scaling arguments lead to the finding of three different regimes, dep ending on the space dimensionality d and the long-range force power e xponent n. The obtained kinetic phase diagram