April 1995 arXiv papers — page 7

M. Chaichian, P. Chiappetta, J. -M. Gerard, R. Gonzalez Felipe

Severe constraints on parameters of the minimal supersymmetric standard model follow from a dynamical electroweak symmetry breaking mechanism dominated by top and stop loops. In particular, the lightest Higgs boson mass is expected to be smaller than 100 GeV.

F. Franke, H. Fraas

In the Next--To--Minimal Supersymmetric Standard Model (NMSSM), the Higgs and neutralino/chargino sectors are strongly correlated by four common parameters at tree level. Therefore we analyze the experimental data from both the search for Higgs bosons as well as for neutralinos and charginos at LEP 100 in order to constrain the parameter space and the masses

W. Buchmuller, O. Philipsen

We study the phase structure of the abelian Higgs model in three dimensions based on perturbation theory and a set of gauge independent gap equations for Higgs boson and vector boson masses. Contrary to the non-abelian Higgs model, the vector boson mass vanishes in the symmetric phase. In the Higgs phase the gap equations yield masses consistent with perturb

Jechiel Lichtenstadt, Harry J. Lipkin

We apply a model for SU(3) breaking to the analysis of the spin contents of the nucleon from the the latest data on first moments of the spin dependent structure functions and include higher order QCD corrections. The results show that the value of the total quark spin contribution to the nucleon spin $ΔΣ\equiv Δu + Δd +Δs$ remains about 0.3 and is very inse

S. F. Tuan

The efforts of Roy-Sridhar-Close-Cho-Wise-Trivedi to resolve the CDF $ψ'$ anomaly with cascades from above-threshold $χ^\prime_c$ states require well defined signature states require well defined signatures [a small total width and a large branching fraction for $\cp \ra γ+ \pp]$ for the solution to be viable. Here we estimte the production of such state

Martin Luescher, Peter Weisz

Lattice gauge theory with a background gauge field is shown to be renormalizable to all orders of perturbation theory. No additional counterterms are required besides those already needed in the absence of the background field. The argument closely follows the treatment given earlier for the case of dimensional regularization by Kluberg-Stern and Zuber. It i

Krzysztof Piotrzkowski

A precise measurement of the spectrum of the photons from $ep$ bremsstrahlung with the ZEUS luminosity monitor at HERA is reported. The measurement shows a reduced rate compared to the Bethe-Heitler spectrum for photon energies below 5~GeV. This suppression, called the beam-size effect, is explained by the finite transverse size of the beam overlap relative

Anwar Hasmy, Rémi Jullien

The pair-correlation function $g(r,t)$ and its Fourier transform, the structure factor $S(q,t)$, are computed during the gelation process of identical spherical particles using the diffusion-limited cluster-cluster aggregation model in a box. This numerical analysis shows that the time evolution of the characteristic cluster size $ξ$ exhibits a crossover clo

Anwar Hasmy, Isabelle Beurroies, Daniel Bourret, Rémi Jullien

The experimental density dependence of gas (argon and nitrogen) permeability of partially densified silica aerogels in the Knudsen regime is quantitatively accounted for by a computer model. The model simulates both the structure of the sintered material and the random ballistic motion of a point particle inside its voids. The same model is also able to acco

Rémi Jullien, Nathalie Olivi-Tran, Anwar Hasmy, Thierry Woignier

A simple scaling theory for the sintering of fractal aerogels is presented. The densification at small scales is described by an increase of the lower cut-off length $a$ accompanied by a decrease of the upper cut-off length $ξ$, in order to conserve the total mass of the system. Scaling laws are derived which predict how $a$, $ξ$ and the specific pore surfac

R. Jullien, A. Hasmy

The Diffusion-Limited Cluster-Cluster Aggregation (DLCA) model is modified by including cluster deformations using the {\it bond fluctuation} algorithm. From 3$d$ computer simulations, it is shown that, below a given threshold value $c_g$ of the volumic fraction $c$, the realization of all intra-aggregate bonding possibilities prevents the formation of a gel

R. Egger, M. Sassetti, U. Weiss

Transport properties of a single-channel Luttinger liquid impinging on a barrier have been studied for $g=1/2 - ε$, where $g$ is the dimensionless interaction constant and $|ε| \ll 1$. The relevant diagrams contributing to the conductance are identified and evaluated in all orders. Our approach represents a leading-log summation which is valid for sufficient

G. Viliani, R. Dell'Anna, O. Pilla, M. Montagna

We have employed the method of spectral moments to study the density of vibrational states and the Raman coupling coefficient of large 2- and 3- dimensional percolators at threshold and at higher concentration. We first discuss the over-and under-flow problems of the procedure which arise when -like in the present case- it is necessary to calculate a few tho

Ferenc Igloi, Peter Lajko

The critical temperature of layered Ising models on triangular and honeycomb lattices are calculated in simple, explicit form for arbitrary distribution of the couplings.

Aurel Bulgac, Caio Lewenkopf

We present an analysis of the temperature dependence of the optical response of small sodium clusters in a temperature range bracketing the melting phase transition. When the temperature increases, the mean excitation energy undergoes a red shift and the plasmon is significantly broadened, in agreement with recent experimental data. We show that the single--

Denis Juriev

Stochastic properties of the long-time behaviour of a continuously observed (and interactively controlled) quantum-field top are investigated mathematically. Applications to interactively controlled stochastic computer-graphic dynamic systems are discussed.

Dimitri Kusnezov, Caio H. Lewenkopf

A general formulation of translationally invariant, parametrically correlated random matrix ensembles, is used to classify universality in correlation functions. Surprisingly, the range of possible physical systems is bounded, and can be labeled by a parameter $α\in (0,2]$, in a manner analogous to Lévy diffusion. Universality is obtained after scaling by th

Renu Malhotra

The origin of the highly eccentric, inclined, and resonance-locked orbit of Pluto has long been a puzzle. A possible explanation has been proposed recently [Malhotra, R., {\it Nature} 365:819-21 (1993)] which suggests that these extraordinary orbital properties may be a natural consequence of the formation and early dynamical evolution of the outer Solar sys

Jacek Choloniewski

The new, simple method is proposed for testing the Hubble law using redshifts and magnitude from magnitude-limited sample of galaxies. The power law relation between redshift and distance have been assumed (cz=r^p). The obtained results: p=1.21 \pm 0.04 (for CfA) and p=0.95 \pm 0.04 (for ESO/LV) confirm linear, Hubble expansion. The proposed test does not ta

G. Clementini, M. Tosi, A. Bragaglia, R. Merighi

CCD photometry in the V band is presented for 7 field RR Lyrae stars selected from a sample of eight variables which, according to data collected in the literature, are expected to be {\it ab}-type pulsators, to have short periods and hence high metallicity, and to be located at high {\it z} from the galactic plane. New periods and epochs are derived for the

Shashi M. Kanbur, Martin A. Hendry

In this paper, we derive a physical argument for the existence of Period-luminosity and period-luminosity-colour relations at maximum light. We examine in detail a sample of Cepheids in the Large Magellanic Cloud, and compare the variance of some PL and PLC type distance indicators based on mean and maximum light. We show that a PLC relation based on maximum

D. MacMinn, J. R. Primack

We present models of the extragalactic background light (EBL) based on several scenarios of galaxy formation and evolution. We have treated galaxy formation with the Press-Schecter approximation for both cold dark matter (CDM) and cold+hot dark matter (CHDM) models, representing a moderate ($z_f \sim 3$) and a late ($z_f \sim 1$) era of galaxy formation resp

F. X. Timmes, J. T. Lauroesch, J. W. Truran

Abundance histories for QSO absorption line systems as a function of redshift are presented for all metals lighter than gallium. Coupling various conventional cosmological models with a simple, first--order model for the chemical evolution of the QSO absorption line systems allows transformation of the observed abundance trends in the Galaxy to abundance his

Sean Fleming, Ivan Maksymyk

We examine the oblique correction phenomenology of one-family Technicolor with light pseudo-Goldstone bosons. From loop calculations based on a gauged chiral lagrangian for Technicolor, we are lead to conclude that even though loops with light Goldstone bosons give a negative contribution to $S$ measured at the $Z$-pole, this effect is not sufficiently large

Valeri A. Gritsenko, Viacheslav V. Nikulin

We find automorphic form corrections which are generalized Lorentzian Kac--Moody superalgebras without odd real simple roots (see R. Borcherds \cite{Bo1} -- \cite{Bo7}, V. Kac \cite{Ka1} -- \cite{Ka3}, R. Moody \cite{Mo} and §~6 of this paper) for two elliptic Lorentzian Kac--Moody algebras of the rank $3$ with a lattice Weyl vector, and calculate multiplici

Hoang Ngoc Long

We explore some more consequences of the $SU(3)_L\otimes U(1)_N$ electroweak model with right-handed neutrinos. By introducing the $Z - Z'$ mixing angle $\phi$, the {\it exact} physical eigenstates for neutral gauge bosons are obtained. Because of the mixing, there is a modification to the $Z^1$ coupling proportional to $\sin\phi$. The data from the $Z$-deca

Antonio Candiello

A non trivial application of a modern computer language ("C") in a highly structured and object-oriented fashion is presented. The contest is that of Lie algebra representations (irreps), specifically the problem of reducing the products of irreps with the weight tree algorithm. The new WBase V2.0 version with table-generation and Young tableaux disp

R. B. Mann, S. F. Ross

We investigate the pair creation of charged black holes in a background with a positive cosmological constant. We consider $C$ metrics with a cosmological constant, and show that the conical singularities in the metric only disappear when it reduces to the Reissner-Nordström de Sitter metric. We construct an instanton describing the pair production of extrem

Beatriz Gato-Rivera, Jose Ignacio Rosado

We analyze the action of the spectral flows on N=2 twisted topological theories. We show that they provide a useful mapping between the two twisted topological theories associated to a given N=2 superconformal theory. This mapping can also be viewed as a topological algebra automorphism. In particular null vectors are mapped into null vectors, considerably s

A. S. Rinat, M. F. Taragin

We study $eA$ scattering in a model where the total nuclear structure function is a convolution of components $W_N$ for an isolated nucleon and $W_{\NA}$ for a nucleus composed of point-nucleons. $W_N$ is represented by its elastic and lowest-energy inelastic parts, while $W_{\NA}$ is computed from its asymptotic limit, supplemented by final state interactio

G. Esposito, G. Gionti, A. Yu. Kamenshchik, I. V. Mishakov

This paper studies the two-spinor form of the Rarita-Schwinger potentials subject to local boundary conditions compatible with local supersymmetry. The massless Rarita-Schwinger field equations are studied in four-real-dimensional Riemannian backgrounds with boundary. Gauge transformations on the potentials are shown to be compatible with the field equations

D. Comelli, M. Pietroni, A. Riotto

We compute the particle currents induced on a bubble wall background at finite temperature in a model with CP violation in the Higgs sector. Using a field theory approach we show that fermionic currents arise at one loop, so that a suppression factor ${\cal O}(h_t \phi/\pi T)^2$ with respect to previous computations is found. The contributions to the Higgs c

B. Kaulakys, G. Vilutis

A simple theory of the Rydberg atoms ionisation by electromagnetic pulses and microwave field is presented. The analysis is based on the scale transformation which reduces the number of parameters and reveals the functional dependencies of the processes. It is shown that the observed ionisation of Rydberg atoms by subpicosecond electromagnetic pulses scale c

A. Stadler, J. Adam, H. Henning, P. U. Sauer

The Faddeev equations are solved in momentum space for the trinucleon bound state with the new Tucson-Melbourne $π$ and $ρ$ exchange three-nucleon potentials. The three-nucleon potentials are combined with a variety of realistic two-nucleon potentials. The dependence of the triton binding energy on the $πNN$ cut-off parameter in the three-nucleon potentials

Tim Mefford, Rubin H. Landau

Elastic nucleon scattering from the 3He and 3H mirror nuclei is examined as a test of charge symmetry violation. The differential cross-sections are calculated at 500 MeV using a microsopic, momentum-space optical potential including the full coupling of two spin 1/2 particles and an exact treatment of the Coulomb force. The charge-symmetry-breaking effects

Ashok Das, Marcelo Hott

We show, in a simple quantum mechanical model, how a theory can become supersymmetric in the presence of interactions even when the free theory is not. This dynamical generation of supersymmetry relaxes the condition on the equality of masses of the superpartners which would be of phenomenological interest.

N. A. Batakis

Bianchi-type string cosmology involves generalizations of the FRW backgrounds with three transitive spacelike Killing symmetries, but without any a priori assumption of isotropy in the 3D sections of homogeneity. With emphasis on those cases with diagonal metrics and vanishing cosmological constant which which have not been previously examined in the literat

Bertfried Fauser

We consider Clifford algebras with nonsymmetric bilinear forms, which are isomorphic to the standard symmetric ones, but not equal. Observing, that the content of physical theories is dependent on the injection $\oplus^n\bigwedge \V^{(n)}\to CL({\cal V},Q)$ one has to transform to the standard construction. The injection is of course dependent on the antisym

G. K. Bathas, E. Floratos, G. K. Savvidy, K. G. Savvidy

We perform numerical simulations of the two and three-dimensional spin systems with competing interaction. They describe the model of random surfaces with linear-gonihedric action.The degeneracy of the vacuum state of this spin system is equal to $~~d \cdot 2^{N}~~$ for the lattice of the size $~N^{d}~$. We observe the second order phase transition of the th

Burkhard Kleihaus, Jutta Kunz, Abha Sood

In the SU(3) Einstein-Yang-Mills system sequences of static spherically symmetric regular solutions and black hole solutions exist for both the SU(2) and the SO(3) embedding. We construct the lowest regular solutions of the SO(3) embedding, missed previously, and the corresponding black holes. The SO(3) solutions are classified according to their boundary co

Atsushi Nakayashiki, Yasuhiko Yamada

The quasi-particle structure of the higher spin XXZ model is studied. We obtained a new description of crystals associated with the level $k$ integrable highest weight $U_q(\widehat{sl_2})$ modules in terms of the creation operators at $q=0$ (the crystaline spinon basis). The fermionic character formulas and the Yangian structure of those integrable modules

H. J. de Vega, A. L. Larsen, N. Sánchez

The exact general solution of circular strings in $2+1$ dimensional de Sitter spacetime is described completely in terms of elliptic functions. The novel feature here is that one single world-sheet generically describes {\it infinitely many} (different and independent) strings. This has no analogue in flat spacetime. The circular strings are either oscillati

André Martin, Jean-Marc Richard

The mass of the $Ω^0_c$ baryon with quark content (ssc) is computed in a potential model whose parameters have been determined in 1981 by fitting the spectrum of heavy mesons. It is found in perfect agreement with a recent measurement at the CERN hyperon-beam experiment. The spectroscopy of other charmed baryons in potential models is briefly reviewed.

Yu. A. Simonov, S. Titard, F. J. Yndurain

Bound states of heavy quarks are considered. Using the path integral formalism we are able to rederive, in a gauge invariant way, the Leutwyler-Voloshin short distance analysis as well as a long distance linear potential. At all distances we describe the states in terms of nonperturbative field correlators, and we include radiative corrections at short and i

O. Pène

Lattice QCD is the only non-perturbative method based uniquely on the first principles of QCD. After a very simple introduction to the principles of lattice QCD, I discuss its present limitations and the type of processes it can deal with. Then I present some striking results in the light and heavy quarks sectors. Finally I try to guess the prospects.

A. Le Yaouanc, L. Oliver, O. Pène, J. -C. Raynal

We review mixing and CP violation in $D$ mesons, emphasizing the differences with the other pseudoscalar mesons in the Standard Model, and show that $D$ mesons can be useful to look for physics beyond the Standard Model.

Andrzej J. Buras

We review several aspects of the recent theoretical progress in K and B decays including the impact of the top quark discovery on rare and CP violating decays. In particular we summarize the present status of next-to-leading QCD calculations in this field stressing their importance in the determination of the parameters in the Cabibbo-Kobayashi-Maskawa matri

S. M. Troshin, N. E. Tyurin

On the basis of the mechanism proposed earlier for one-spin asymmetries in inclusive hadron production we consider OZI--suppressed process of $φ$-meson production $pp\rightarrow φX$ and asymmetry $A_N(φ)$ in this process. The main role in generation of this asymmetry belongs to the orbital angular momentum of strange quark-antiquark cloud in internal structu

A. Le Yaouanc, L. Oliver, O. Pène, J. -C. Raynal

We underline the general features of the constituent quark model and its success in the description of the spectrum and transitions of hadrons made up of light or heavy quarks, briefly compared to first principles of QCD. To show the present usefulness of the techniques and intuitive insight of the model we present a semirelativistic quark model of meson for

T. S. Evans

The thermal expectation values of all possible bosonic generalised retarded functions evaluated at zero energy are studied. The relationship of such functions to calculational schemes, technical problems and physical applications is outlined. It is then shown that all generalised retarded functions constructed from any one set of bosonic fields are equal at

M. Faber, O. Borisenko, G. Zinovjev

Discrete symmetries in grand canonical ensembles and in ensembles canonical with respect to triality are investigated. We speculate about the general phase structure of finite temperature gauge theories with discrete $Z(N)$ symmetry. Low and high temperature phases turn out to be different in both ensembles even for infinite systems. It is argued that gauge

J. P. Ma

We calculate the functions of parton fragmentation into $^3P_J$ quarkonium at order $α_s ^2$, where the parton can be a heavy or light quark. The obtained functions explicitly satisfy the Altarelli-Parisi equation and they are divergent, behaving as $z^{-1}$ near $z=0$. However, if one choses the renormalization scale as twice of the heavy quark mass, the fr

A. Le Yaouanc, L. Oliver, O. Pène, J. -C. Raynal

We study in a quark model the contradiction between factorization and duality found in nonleptonic decays at next to leading order in $1/N_c$, concentrating on quark exchange mechanism. The contradiction originates in the fact that the standard factorization assumption approximates the asymptotic final states by a non-orthogonal set of states, thus leading t

Masahisa MATSUDA, Morimitsu TANIMOTO

We study the explicit $CP$ violation of the Higgs sector in the minimal supersymmetric standard model with a gauge singlet Higgs field. The magnitude of $CP$ violation is discussed in the limiting cases of $x\gg v_1,\ v_2$ and $x\ll v_1,\ v_2$, where $x$ and $v_{1,2}$ denote VEV of singlet and doublet Higgs scalars, respectively. Our numerical predictions of

Peter Peldan

By choosing an unconventional polarization of the connection phase space in (2+1)-gravity on the torus, a modular invariant quantum theory is constructed. Unitary equivalence to the ADM-quantization is shown.

Gregory A. Burnett

A globally hyperbolic asymptotically flat spacetime is presented (having non-negative energy density and pressures) that shows that not all K(pi,1) prime factors of the Cauchy surface topology are passively censored according to asymptotic observers in contradiction to an argument of Friedman, Schleich, and Witt.

R. Mélin

We investigate the presence of quantum chaos in the spectrum of the bidimensional Fermi liquid by means of analytical and numerical methods. This model is integrable in a certain limit by bosonization of the Fermi surface. We study the effect on the level statisticsof the momentum cutoff $Λ$ present in the bidimensional bosonization procedure. We first analy

M. A. Moore, T. J. Newman

We present a functional renormalization group (FRG) analysis of a Landau-Ginzburg model of type-II superconductors (generalized to $n/2$ complex fields) in a magnetic field, both for a pure system, and in the presence of quenched random impurities. Our analysis is based on a previous FRG treatment of the pure case [E.Brézin et. al., Phys. Rev. B, {\bf 31}, 7

Simon C. Benjamin, Neil F. Johnson

We present an analytically solvable model of $P$ colinear, two-dimensional quantum dots, each containing two electrons. Inter-dot coupling via the electron-electron interaction gives rise to sets of entangled ground states. These ground states have crystal-like inter-plane correlations and arise discontinously with increasing magnetic field. Their ranges and

Neil F. Johnson, Luis Quiroga

The $2N$-dimensional quantum problem of $N$ particles (e.g. electrons) with interaction $β/r^2$ in a two-dimensional parabolic potential $ω_0$ (e.g. quantum dot) and magnetic field $B$, reduces exactly to solving a $(2N-4)$-dimensional problem which is independent of $B$ and $ω_0$. An exact, infinite set of relative mode excitations are obtained for any $N$.

Shin-ichi Sasa

We present a simple mathematical model in which a time averaged pattern emerges out of spatio-temporal chaos as a result of the collective action of chaotic fluctuations. Our evolution equation possesses spatial translational symmetry under a periodic boundary condition. Thus the spatial inhomogeneity of the statistical state arises through a spontaneous sym

Martin Krockenberger, J. Grindlay

We present the results of a search for diffuse x-ray sources in a 65 ksec ROSAT PSPC exposure of 47 Tuc. There is faint, soft emission on the NE side of the cluster at a distance of 6 arcmin from the core. The location of this emission along the direction of proper motion of the cluster suggests that it might be due to a bow shock. We show that a simple shoc

F. Lucchin, S. Colafrancesco, G. de Gasperis, S. Matarrese

Recently, there has been growing interest on primordial ``blue" ($n>1$) perturbation spectra, motivated both by a composite set of observational data on large scales and from the point of view of theoretical model building. After reviewing the theoretical (inflationary) motivations for these blue spectra, we consider various observational constraints, wi

K. W. Smith, I. A. Bonnell, G. F. Lewis

A general model of magnetically controlled accretion onto T Tauri stars is presented. In this model the magnetic field is oriented arbitrarily in relation to the star's rotation axis. The resultant interplay between the magnetic field and accretion disc causes a variable accretion rate. The dominant timescale of this variability is the beat frequency bet

Steen Rasmussen, Christopher Barrett

Unlike computation or the numerical analysis of differential equations, simulation does not have a well established conceptual and mathematical foundation. Simulation is an arguable unique union of modeling and computation. However, simulation also qualifies as a separate species of system representation with its own motivations, characteristics, and implica

Eizo Akiyama, Kunihiko Kaneko

A non-zero-sum 3-person coalition game is presented, to study the evolution of complexity and diversity in cooperation, where the population dynamics of players with strategies is given according to their scores in the iterated game and mutations. Two types of differentiations emerge initially; biased one to classes and temporal one to change their roles for

D. Foerster, H. Kachkachi

Warning: We have recently discovered a technical error in the paper cond-mat/9504032 and entitled here above, that invalidates part but not all of our conclusions. A corrected version will be soon put in.

Damiano Anselmi

Topological Yang-Mills theory with the Belavin-Polyakov-Schwarz-Tyupkin $SU(2)$ instanton is solved completely, revealing an underlying multi-link intersection theory. Link invariants are also shown to survive the coupling to a certain kind of matter (hyperinstantons). The physical relevance of topological field theory and its invariants is discovered. By em

Bruce W. Roberts, Eberhard Bodenschatz, James P. Sethna

Motivated by the idea of developing a ``hydrodynamic'' description of spatiotemporal chaos, we have investigated the defect--defect correlation functions in the defect turbulence regime of the two--dimensional, anisotropic complex Ginzburg--Landau equation. We compare our results with the predictions of generic scale invariance. Using the topological

Luca Amendola

We generalize the maximum likelihood method to non-Gaussian distribution functions by means of the multivariate Edgeworth expansion. We stress the potential interest of this technique in all those cosmological problems in which the determination of a non-Gaussian signature is relevant, e.g. in the analysis of large scale structure and cosmic microwave backgr

J. A. Harvey, A. Strominger

It is shown that the Type IIA superstring compactified on $K3$ has a smooth string soliton with the same zero mode structure as the heterotic string compactified on a four torus, thus providing new evidence for a conjectured exact duality between the two six-dimensional string theories. The chiral worldsheet bosons arise as zero modes of Ramond-Ramond fields

R. Karrlein, H. Kleinert

We systematically improve the recent variational calculation of the imaginary part of the ground state energy of the quartic anharmonic oscillator. The results are extremely accurate as demonstrated by deriving, from the calculated imaginary part, all perturbation coefficients via a dispersion relation and reproducing the exact values with a relative error o

Masahiro Tanaka

We calculate the induced Einstein action from supersymmetric models in general space-time. Supersymmetric models consist of two kinds of supermultiplets, called scalar supermultiplets and vector supermultiplets, respectively. We show that the vector multiplets generate a negative Newton constant, while the scalar multiplets a positive one. Then we find that

Stefan Sint

In a previous publication, we have constructed the Schrödinger functional in Wilson's lattice QCD. It was found that the naive continuum limit leads to a well-defined classical continuum theory. Starting from the latter, a formal continuum definition of the Schrödinger functional is given and its saddle point expansion is carried out to one-loop order of

B. Bruegmann, E. Marinari

Dynamical triangulations of four-dimensional Euclidean quantum gravity give rise to an interesting, numerically accessible model of quantum gravity. We give a simple introduction to the model and discuss two particularly important issues. One is that contrary to recent claims there is strong analytical and numerical evidence for the existence of an exponenti

Leo Radzihovsky

I show that in Bose Glass superconductor with high $j_c$ and at low $T$ the magnetization relaxation (S), dominated by quantum tunneling, is $\propto{\sqrt j_c}$, which crosses over to the conventional classical rate $\propto T/j_c$ at higher $T$ and lower $j_c$, with the crossover $T^*\sim j_c^{3/2}$. I argue that due to interactions between flux lines ther

D. Horn, G. C. Ball, D. R. Bowman, A. Galindo-Uribarri

The partition of decay energy between the kinetic energy of reaction products and their Q-value of formation is obtained in a statistical derivation appropriate to highly excited nuclei, and is shown to be in a constant ratio. We measure the kinetic energy fraction, $R = ΣE_{kin}/(ΣE_{kin} + ΣQ_0)$, over a wide range of excitation energy for well-defined sys

Moustafa Awada

Recently we have shown that a phase transition occurs in the leading approximation of the large N limit in rigid strings coupled to long range Kalb-Ramond interactions. The disordered phase is essentially the Nambu-Goto-Polyakov string theory while the ordered phase is a new theory. In this part II letter we study the first sub-leading quantum corrections we

Moustafa Awada

Recently we have shown that a phase transition occurs in the leading approximation of the large N limit in rigid strings coupled to long range Kalb-Ramond interactions. The disordered phase is essentially the Nambu-Goto-Polyakov string theory while The ordered phase is a new theory. In this part I letter we study the first sub-leading quantum corrections of

M. Awada, D. Zoller, J. F. Clark

Rigid QED is a renormalizable generalization of Feynman's space-time action characterized by the addition of the curvature of the world line (rigidity). We have recently shown that a phase transition occurs in the leading approximation of the large N limit. The disordered phase essentially coincides with ordinary QED, while the ordered phase is a new the

Moustafa Awada

Recently we have shown that a phase transition occurs in the leading and sub-leading approximation of the large N limit in rigid strings coupled to long range Kalb-Ramond interactions. The disordered phase is essentially the Nambu-Goto-Polyakov string theory while the ordered phase is a new theory. In this letter we compute the free energy per unit length of

Jose W. Maluf, Andreas Kneip

In the teleparallel equivalent of general relativity the energy density of asymptoticaly flat gravitational fields can be naturally defined as a scalar density restricted to a three dimensional spacelike hypersurface. The scalar density has simple expression in terms of the trace of the torsion tensor. Here we obtain the formal expression of the localized en

M. Zyskin

We construct quantum operators solving the quantum versions of the Sturm-Liouville equation and the resolvent equation, and show the existence of conserved currents. The construction depends on the following input data: the basic quantum field $O(k)$ and the regularization .

Geunbae Lee, Jong-Hyeok Lee

Spoken language processing requires speech and natural language integration. Moreover, spoken Korean calls for unique processing methodology due to its linguistic characteristics. This paper presents SKOPE, a connectionist/symbolic spoken Korean processing engine, which emphasizes that: 1) connectionist and symbolic techniques must be selectively applied acc

B. K. Agrawal, P. K. Sahu

Using an exactly solvable pairing model Hamiltonian in the static path approximation together with small-amplitude quantal fluctuation corrections in random phase approximation (SPA+RPA), we have analyzed the behaviour of canonical (number projected) and grandcanonical treatments of nuclear level densities as a function of temperature and number of particles

Ilinski, G. V. Kalinin, V. S. Kapitonov

We show that the exchange statistics have consequences in 1D systems with compact topology, contrary to the common opinion that exchange statistics is arbitrary in 1D. As examples of non-trivial statistical behavior we exactly calculate the partition function and correlators for systems of free q-particles on compactified chains using functional integral tec

G. I Poulis, P. J. Mulders

We revisit the Dirac quantization condition for string-like and string-less (but multi-valued) magnetic monopole potentials. In doing so we allow for an {\it a priori} different coupling ${\tilde e}$ associated with the longitudinal components of the gauge potential. By imposing physical criteria in the choice of the longitudinal--transverse decomposition we

Alexander O. Gogolin

Impurity ions with orbitally degenerate ground electronic configuration embedded in metals are subjects to both the Kondo effect and the Jahn-Teller instability. While increasing the Jahn-Teller coupling, one passes, from the region of parameters where the perturbation theory is applicable, through a complicated intermediate region, to a region where phonons

A. E. Kaloshin, V. M. Persikov, V. V. Serebryakov

We analyze the existing data on the angular distributions of the $γγ\to π^+ π^- ,π^0 π^0$ reactions with using of the unitary model for helicity 2 amplitude. The purpose is to obtain the D--wave parameters and S--wave cross section. We obtain from experiment in the first time the values of $α+ β$ for sum of the electric and magnetic pion's polarizabiliti

I. Antoniadis, S. Ferrara, E. Gava, K. S. Narain

We discuss the prepotential describing the effective field theory of N=2 heterotic superstring models. At the one loop-level the prepotential develops logarithmic singularities due to the appearance of charged massless states at particular surfaces in the moduli space of vector multiplets. These singularities modify the classical duality symmetry group which

Asher Peres

Necessary and sufficient conditions are given for the existence of extended Schmidt decompositions, with more than two subspaces.

B. Leclerc, J. -Y. Thibon

We show that the quantum straightening algorithm for Young tableaux and Young bitableaux reduces in the crystal limit $q \mapsto 0$ to the Robinson-Schensted algorithm.

E. D. Izquierdo, G. Barenboim, A. O. Gattone

We study the contribution of two-body meson-exchange processes to axial charge transitions for nuclei in the lead, tin and oxygen regions. We conduct calculations in the Dirac-Hartree (the Walecka model) and the relativistic Hartree (where the full one-nucleon-loop effects are included) approximations. We present results indicating that one- and two-body pro

A. Stadler, J. A. Tjon

In a recent paper [Phys.\ Rev.\ C{\bf 49}, 2142 (1994)], Haberzettl presented cluster N-body equations for arbitrarily large systems of nucleons and mesons. Application to the three-nucleon system is claimed to yield a new kind of three-nucleon force. We demonstrate that these three-nucleon equations contain double counting.

Kim Maltman, Mikhail Shmatikov

We compute the modified factorization contributions to the $Λ\rightarrow Nρ$ and $Σ\rightarrow Nρ$ couplings and demonstrate that these contributions naturally include $ΔI=3/2$ terms which are comparable ($\simeq 0.4$ to $-0.8$ times) in magnitude to the corresponding $ΔI=1/2$ terms. As a consequence, we conclude that models which treat vector meson exchange

F. W. Gehring, G. J. Martin

The Margulis constant for Kleinian groups is the smallest constant $c$ such that for each discrete group $G$ and each point $x$ in the upper half space ${\bold H}^3$, the group generated by the elements in $G$ which move $x$ less than distance c is elementary. We take a first step towards determining this constant by proving that if $\langle f,g \rangle$ is

F. W. Gehring, C. Maclachlan, G. J. Martin, A. W. Reid

We give an arithmetic criterion which is sufficient to imply the discreteness of various two-generator subgroups of $PSL(2,{\bold C})$. We then examine certain two-generator groups which arise as extremals in various geometric problems in the theory of Kleinian groups, in particular those encountered in efforts to determine the smallest co-volume, the Margul

Noel Brady, Benson Farb

In this paper we construct and study isoperimetric functions at infinity for Hadamard manifolds. These quasi-isometry invariants give a measure of the spread of geodesics in such a manifold.

A. S. Fokas, I. M. Gelfand, M. V. Zyskin

In the paper we study nonlocal functionals whose kernels are homogeneous generalized functions. We also use such functionals to solve the Korteweg-de Vries , the nonlinear Schrödinger and the Davey-Stewartson equations.

Geoffrey Dixon

The Leech lattice, $Λ_{24}$, is represented on the space of octonionic 3-vectors. It is built from two octonionic representations of $E_{8}$, and is reached via $Λ_{16}$. It is invariant under the octonion index cycling and doubling maps.