July 1995 arXiv papers — page 5

E. Calabresu, N. Ferrari, G. Fiorentini, M. Lissia

We find that vacuum oscillations (VO), large-mixing-angle and small-mixing-angle MSW solutions to the solar neutrino problem (SNP) give all very good fits to the most recent results. Measurements of the $^7$Be flux can, in some cases, discriminate between different solutions to the SNP; in particular, VO allow $^7$Be fluxes almost as large as the one predict

Paul H. Frampton

It now appears phenomenologically that the third family may be essentially different from the first two. Particularly the high value of the top quark mass suggests a special role. In the standard model all three families are treated similarly [becoming exactly the same at asymptotically high energies] so I need to extend the model to accommodate the goal of

M. De Francia, H. Falomir, E. M. Santangelo

The total energy in the two-phase chiral bag model is studied, including the contribution due to the bag (Casimir energy plus energy of the valence quarks), as well as the one coming from the Skyrmion in the external sector. A consistent determination of the parameters of the model and the renormalization constants in the energy is performed. The total energ

Anthony L. Spadafora

Recent results on the production of $W$ and $Z$ gauge bosons in $p\bar{p}$ collisions at $\sqrt{s}=1.8$~TeV at the Fermilab Tevatron Collider from the \D0 and CDF experiments are reviewed. Measurements of the inclusive cross sections times leptonic branching ratios in both the electron and muon decay channels are summarized and compared to QCD predictions. U

Claudio M. G. de Sousa, J. L. Tomazelli

In this paper we introduce a current-current type interaction term in the Lagrangian density of gravity coupled to complex scalar fields, in the presence of a degenerated Fermi gas. For low transferred momenta such a term, which might account for the interaction among boson and fermion constituents of compact stellar objects, is subsequently reduced to a qua

K. Musaelian, J. Betouras, A. V. Chubukov, R. Joynt

We consider a 2D isotropic Fermi liquid with attraction in both $s$ and $d$ channels and examine the possibility of a superconducting state with mixed $s$ and $d$ symmetry of the gap function. We show that both in the weak coupling limit and at strong coupling, a mixed $s+id$ symmetry state is realized in a certain range of interaction. Phase transitions bet

A. Furusaki, M. Sigrist, E. Westerberg, P. A. Lee

The one-dimensional quantum Heisenberg model with random $\pm J$ bonds is studied for $S=\frac{1}{2}$ and $S=1$. The specific heat and the zero-field susceptibility are calculated by using high-temperature series expansions and quantum transfer matrix method. The susceptibility shows a Curie-like temperature dependence at low temperatures as well as at high

A. D. Mirlin

Asymptotical behavior of the distribution function of local density of states (LDOS) in disordered metallic samples is studied with making use of the supersymmetric $σ$--model approach, in combination with the saddle--point method. The LDOS distribution is found to have the logarithmically normal asymptotics for quasi--1D and 2D sample geometry. In the case

A. D. Mirlin, E. Altshuler, P. Woelfle

We develop a quasiclassical method based on the path integral formalism, to study the influence of disorder on magnetooscillations of the density of states and conductivity. The treatment is appropriate for electron systems in the presence of a random potential with large correlation length or a random magnetic field, which are characterisitic features of va

Randall D. Kamien, David R. Nelson

Biomolecules are often very long with a definite chirality. DNA, xanthan and poly-gamma-benzyl-glutamate (PBLG) can all form columnar crystalline phases. The chirality, however, competes with the tendency for crystalline order. For chiral polymers, there are two sorts of chirality: the first describes the usual cholesteric-like twist of the local director ar

C. -M. Chen, F. C. MacKintosh, D. R. M. Williams

We consider the swelling kinetics of layered structures. We focus on the case of triblock copolymer mesogels, although our results are applicable to other layered structures including clays. We assume the mesogels are swollen by a solvent that is good for the bridging block but poor for the non-bridging block. At long times the penetration front moves as in

Mario Palumbo, M. J. Graf

We calculate the infrared conductivity tensor of a layered superconductor considering two different order parameter symmetries: strongly anisotropic $s$-wave with line nodes, and pure ($d_{x^2-y^2}$) $d$-wave. The calculations are performed within the quasiclassical theory of superconductivity and include the effects of non-magnetic scattering processes. We

Michael Gasser

The morphological systems of natural languages are replete with examples of the same devices used for multiple purposes: (1) the same type of morphological process (for example, suffixation for both noun case and verb tense) and (2) identical morphemes (for example, the same suffix for English noun plural and possessive). These sorts of similarity would be e

Gerhard Hummer, Lawrence R. Pratt, Angel E. Garcia

We study the chemical potential of water as a function of charge based on perturbation theory. By calculating the electrostatic-energy fluctuations of two states (fully charged and uncharged) we are able to determine accurate values for the dependence of the chemical potential on charge. We find identical results for the chemical-potential difference of full

S. J. Lilly, L. Tresse, F. Hammer, David Crampton

The cosmic evolution of the field galaxy population has been studied out to a redshift of z ~ 1 using a sample of 730 I-band selected galaxies, of which 591 have secure redshifts with median <z> ~ 0.56. The tri-variate luminosity function phi(M,color,z) shows unambiguously that the population evolves and that this evolution is strongly differential with colo

Martin G. Haehnelt, Max Tegmark

We have investigated the possibility of inferring peculiar velocities for clusters of galaxies from the Doppler shift of scattered cosmic microwave background (CMB) photons. We find that if the core radius of the gas distribution or the beam size of the instrument is larger than 3-7 arcminutes, then the maximum attainable signal-to-noise ratio is determined

B. Fort, Y. Mellier, M. Dantel-Fort, H. Bonnet

We present a first attempt to reveal the possible existence of large foreground mass condensations directly responsible for the gravitational magnification of four distant luminous radiosources and one optical QSO. The technique uses a weak lensing analysis of the distant galaxies in the field of each source. We find a coherent shear map with a large magnifi

Y. Kakigi, T. Okamura, T. Fukuyama

Singularities of caustics appeared in gravitational lensing effect are discussed analytically. Multipole expansion model of lensing object is mainly studied since it is tractable and universal. Our analyses are confirmed by numerical calculations and applied to multiple quasar system of PG1115+080. Consistencies with elliptical lens models are also discussed

The ZEUS Collaboration

Elastic $ρ^0$ photoproduction has been measured using the ZEUS detector at HERA. Untagged photoproduction events from $ep$ interactions were used to measure the reaction $γp \rightarrow ρ^0 p$ ($ρ^0 \rightarrow π^+ π^-$) at photon-proton centre-of-mass energies between 60 and 80~GeV and $|t|<0.5$~GeV$^2$, where $t$ is the square of the four-momentum transfer

S. L. A. de Queiroz, Eytan Domany

We investigate an antiferromagnetic triangular Ising model with anisotropic ferromagnetic interactions between next-nearest neighbours, originally proposed by Kitatani and Oguchi (J. Phys. Soc. Japan {\bf 57}, 1344 (1988)). The phase diagram as a function of temperature and the ratio between first- and second- neighbour interaction strengths is thoroughly ex

J. Kapusta, D. Kharzeev, L. McLerran

We propose that the mass of the $η^\prime$ meson is a particularly sensitive probe of the properties of finite energy density hadronic matter and quark gluon plasma. We argue that the mass of the $η^\prime$ excitation in hot and dense matter should be small, and therefore that the $η^\prime$ production cross section should be much increased relative to that

J. F. van Diejen

Multivariable generalizations of the continuous Hahn and Wilson polynomials are introduced as eigenfunctions of rational Ruijsenaars type difference systems with an external field.

Patrick Gilmer

We consider a cobordism category whose morphisms are punctured connect sums of $S^1 \times S^2$&#39;s (wormhole spaces) with embedded admissibly colored banded trivalent graphs. We define a TQFT on this cobordism category over the field of rational functions in an indeterminant $A.$ For $r$ large, we recover, by specializing $A$ to a primitive 4rth root of u

O. Foda, M. Okado, S. O. Warnaar

We present a proof of polynomial identities related to finite analogues of the branching functions of the coset $\widehat{sl(n)_1} \otimes \widehat{sl(n)_1} / \widehat{sl(n)_2}$.

H. Nachbagauer, A. K. Rebhan, D. J. Schwarz

The low-momentum structure of the gravitational polarization tensor of an ultrarelativistic plasma of scalar particles with $λϕ^4$ interactions is evaluated in a two-loop calculation up to and including order $λ^{3/2}$. This turns out to require an improved perturbation theory which resums a local thermal mass term as well as nonlocal hard-thermal-loop verti

M. Bonini, M. D&#39;Attanasio

We study the conditions under which a symmetry is spontaneously broken in the Wilson renormalization group formulation. Both for a global and local symmetry, the result is that in perturbation theory one has to perform a fine tuning of the boundary conditions for the flow of the relevant couplings. We consider in detail the discrete $Z_2$ case and the Abelia

Wolfgang Junker

Quasifree states of a linear Klein-Gordon quantum field on globally hyperbolic spacetime manifolds are considered. Using techniques from the theory of pseudodifferential operators and wavefront sets on manifolds a criterion for a state to be an Hadamard state is developed. It is shown that ground- and KMS-states on certain static spacetimes and adiabatic vac

J. S. Dowker

A simplified direct method is described for obtaining massless scalar functional determinants on the Euclidean ball. The case of odd dimensions is explicitly discussed.

Arlen Anderson

The solution of the classical open-chain n-body Toda problem is derived from an ansatz and is found to have a highly symmetric form. The proof requires an unusual identity involving Vandermonde determinants. The explicit transformation to action-angle variables is exhibited.

Shion Kono, Stephen Naculich

Z-strings in the Weinberg-Salam model including fermions are unstable for all values of the parameters. The cause of this instability is the fermion vacuum energy in the Z-string background. Z-strings with non-zero fermion densities, however, may still be stable.

O. W. Greenberg

Conservation of statistics requires that fermions be coupled to Grassmann external sources. Correspondingly, conservation of statistics requires that parabosons, parafermions and quons be coupled to external sources that are the appropriate generalizations of Grassmann numbers.

Ernest Ma

Naturally light singlet neutrinos which mix with the usual doublet neutrinos are possible if the supersymmetric standard gauge model is extended to include a specific additional U(1) factor derivable from E_6 decomposition. The low-energy particle content of the model is limited to the fundamental 27 representations of E_6.

J. Bellandi, R. J. M. Covolan, A. L. Godoi, J. Montanha

We calculate the average elasticity considering non-diffractive and single diffractive interactions and perform an analysis of the cosmic-ray flux by means of an analytical solution for the nucleonic diffusion equation. We show that the diffractive contribution is important for the adequate description of the nucleonic and hadronic fluxes in the atmosphere.

Eric D. Carlson, Li-Sheng Tseng

We investigate the detection of a pseudoscalar $ϕ$ that couples electromagnetically via an interaction ${1\over4}g ϕF {\tilde F}$. In particular, we focus on the conversion of pseudoscalars produced in the sun&#39;s interior in the presence of the sun&#39;s external magnetic dipole field and sunspot-related magnetic fields. We find that the sunspot approach

Yuval Grossman

In analyzing neutrino oscillation experiments it is often assumed that while new physics contributes to neutrino masses, neutrino interactions are given by the Standard Model. We develop a formalism to study new physics effects in neutrino interactions using oscillation experiments. We argue that the notion of branching ratio is not appropriate in this case.

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

We show that quark models of current matrix-elements based on the Bakamjian-Thomas construction of relativistic states with a fixed number of particles, plus the additivity assumption, are covariant in the heavy-quark limit and satisfy the full set of heavy-quark symmetry relations discovered by Isgur and Wise. We find the lower bound of $ρ^2$ in such models

Sourendu Gupta, D. Indumathi, P. Mathews, V. Ravindran

We study the scattering of hard external particles in a heat bath in a real-time formalism for finite temperature QED. We investigate the distribution of the 4-momentum difference of initial and final hard particles in a fully covariant manner when the scale of the process, $Q$, is much larger than the temperature, $T$. Our computations are valid for all $T$

Dae Sung Hwang, Gwang-Hee Kim

We calculate the ratios of $B$ and $D$ meson decay constants by applying the variational method to the relativistic hamiltonian of the heavy meson. We adopt the Gaussian and hydrogen-type trial wave functions, and use six different potentials of the potential model. We obtain reliable results for the ratios, which are similar for different trial wave functio

T. Munehisa, P. Aurenche, J. -Ph. Guillet, M. Fontannaz

A new model of QCD parton shower is proposed which is dedicated to two-photon process in $e^+ e^-$ scattering. When hadron jets are produced, the photon may resolve into quark-antiquark pairs so that the structure functions of the photon should be introduced. Based on the Altarelli-Parisi equation for these functions, an algorithm is formulated that allows u

Ghadir Abu Leil, Stefano Moretti

The production of the \mssm\ Higgs bosons $H^0,h^0,A^0$ and $H^\pm$, in the intermediate mass range of the $A^0$, at two different values of $\tanβ$, is studied at the possible CERN LEP$\otimes$LHC $ep$ collider, through $γp$ interactions, by photons generated via Compton back--scattering of laser light. Signatures in which $H^0,h^0,A^0\ar b\bar b$ and $H^\p

U. Baur, T. Han, J. Ohnemus

The process $p\,p\hskip-7pt\hbox{$^{^{(\!-\!)}}$} \rightarrow W^{+} W^{-} + X \rightarrow \ell^+_1 ν_1 \ell^-_2 \bar ν_2 + X$ is calculated to ${\cal O}(α_s)$ for general $C$ and $P$ conserving $WWV$ couplings ($V=γ,\, Z$). The prospects for probing the $WWV$ couplings in this reaction are explored. The impact of ${\cal O}(α_s)$ QCD corrections and various b

Sergei V. Zenkin

We calculate within a mean-field approximation the slopes of the critical lines near the point of appearing the ferrimagnetic phase for the U(1) systems in the weak coupling regime. It is demonstrated that the slope of one of the critical line is continuous, while change of the slope of the other depends strongly on the number of the fermion flavours. We als

Philip Reeves

The results of two methods to extract the strong coupling constant, $α_s$, are reviewed for the LEP experiments. In the first, scaling violations in the scaled momentum distributions of charged particles at LEP and at lower energy experiments are employed. In the second, QCD corrections to $R_τ$, the ratio of hadronic to leptonic decay rates of the tau lepto

Jean-Guy Demers, Rene Lafrance, Robert C. Myers

Using a new regulator, we examine &#39;t Hooft&#39;s approach for evaluating black hole entropy through a statistical-mechanical counting of states for a scalar field propagating outside the event horizon. We find that this calculation yields precisely the one-loop renormalization of the standard Bekenstein-Hawking formula, $S={\Cal A}/(4G)$. Thus our result

Franz Embacher

This talk is devoted to the problem how to compute relative nucleation probabilities of configurations with different topology and dimension in quantum cosmology. Assuming the semiclassical approximation, the usual formula for the nucleation probability induced by the no-boundary wave function is $P_{NB}\approx\exp(-I)$, where $I$ is the Euclidean action, ev

A. M. Tikofsky, S. A. Kivelson

We argue that a new type of quantum Hall state requiring non-perturbative Landau level mixing arises at low electron density. In these states, up and down spin electrons pair to form spinless bosons that condense into a bosonic quantum Hall state. We describe a wavefunction for a paired quantum Hall state at $ν=2$ and argue that it is stabilized by a BCS ins

S. Q. Shen, X. C. Xie

We show that there is pseudospin SU(2) symmetry in the one-dimensional tight-binding model with the inter-molecular electron-phonon interaction. We discuss the relation between the pseudospin symmetry breaking and the charge-density wave (CDW). For a finite lattice at half-filling, the Peierls instability drives the lattice to {\it dimerization} at low tempe

A. Levy Yeyati, M. Buttiker

We present an analysis of the Aharonov-Bohm oscillations for a mesoscopic ring with a quantum dot inserted in one of its arms. It is shown that microreversibility demands that the phase of the Aharonov-Bohm oscillations changes {\it abruptly} when a resonant level crosses the Fermi energy. We use the Friedel sum rule to discuss the conservation of the parity

Jan Lerner, Manfred Pinkal

In this paper, we discuss the question whether phrasal comparatives should be given a direct interpretation, or require an analysis as elliptic constructions, and answer it with Yes and No. The most adequate analysis of wide reading attributive (WRA) comparatives seems to be as cases of ellipsis, while a direct (but asymmetric) analysis fits the data for nar

Charles Walter, Anatoly Klypin

We use N-body simulations to study evolution of galaxy clusters over the redshift interval 0 <= z <= 0.5 in cosmological models with a mixture of cold and hot dark matter (CHDM). Four different techniques are utilized: the cluster-cluster correlation function, axial ratios and quadrupoles of the dark matter distribution in individual clusters, and virial pro

J. E. Horvath

A large class of gamma-ray burst (GRB) models (overwhelming until recently) involve the release of energy in a neutron star quake. Even though the extreme isotropy of the GRB sky established by the BATSE experiment has now shifted the interest to cosmological models, the former starquake scenarios are still attractive and may naturally produce a gravitationa

Stephan Endrass

The estimate for the maximal number of ordinary double points of a projective surface of degree eight is improved to $168\leqμ(8)\leq 174$ by constructing a projective surface of degree eight with 168 nodes.

M. G. Higgins, R. N. Henriksen

The motions of comets and neutron stars have been integrated over five billion years in the Galactic potential to determine a gamma-ray burst distribution, presuming that bursts are the result of interactions between these two families of objects. The comets originate in two distinct populations - one from ejection by stars in the Galactic disk, and the othe

J. A. Nieto, O. Obregón, V. M. Villanueva

A non-minimal coupling for spin $3/2$ fields is obtained. We use the fact that the Rarita-Schwinger field equations are the square root of the full linearized Einstein field equations in order to investigate the form of the interaction for the spin $3/2$ field with gauge fields. We deduce the form of the interaction terms for the electromagnetic and non-Abel

C. Alvarez, R. B. Mann

The Einstein Equivalence Principle has as one of its implications that the non-gravitational laws of physics are those of special relativity in any local freely-falling frame. We consider possible tests of this hypothesis for systems whose energies are due to radiative corrections, i.e. which arise purely as a consequence of quantum field theoretic loop effe

Andrew Gould

The paper previously submitted under this title is incorrect in that it drastically overestimates the cumulative deflection due to a gravitational wave (GW) background. Avi Loeb gives a simple argument that there can be no $(Dω)^{1/2}$ enhancement: since the problem is linear in $h$, one can decompose the GWs into plane waves and for each of these there is n

Mirjam Cvetic, Donam Youm

Within effective heterotic superstring theory compactified on a six-torus we derive minimum energy (supersymmetric), static, spherically symmetric solutions, which are manifestly invariant under the target space $O(6,22)$ and the strong-weak coupling $SL(2)$ duality symmetries with 28 electric and 28 magnetic charges subject to one constraint. The class of s

C. Nappi, G. Filatrella, S. Pagano

We show that a 2N junction SQUID (Superconducting QUantum Interference Device) made of 2N overdamped, shunted, identical junctions may be described as a system having only 6 degrees of freedom for any N > 2. This is achieved by means of the reduction introduced by Watanabe and Strogatz (Physica D, Vol. 74, (1994) p. 197) for series biased arrays. In our case

Douglas Ridgway, Herb Levine, Yuhai Tu

We present calculations of the stability of planar fronts in two mean field models of diffusion limited growth. The steady state solution for the front can exist for a continuous family of velocities, we show that the selected velocity is given by marginal stability theory. We find that naive mean field theory has no instability to transverse perturbations,

Georg Wagner, Alfons J. Buchmann, Amand Faessler

In quark potential models, two--body current contributions to baryon magnetic moments arise necessarily to satisfy the continuity equation for the electromagnetic current. On the other hand, the naive additive quark model predicts the experimental octet magnetic moments to within 5$\%$. We demonstrate that consistently derived two--body current contributions

Menachem Kojman

For every uncountable cardinal $λ$, suitable negations of the Generalized Continuum Hypothesis imply: - For all infinite $α$ and $β$, there is no universal $K_{α,β}$-free graphs in $λ$ - For all $α\ge 3$, there is no universal $K_α$-free graph in $λ$ The instance $K_{ω,ω_1}$ for $λ=\aleph_1$ was settled by Komjath and Pach from the principle $\diamondsuit(ω_

Joseph Polchinski

Is string theory relevant to the black hole information problem? This is an attempt to clarify some of the issues involved. Presented at Strings &#39;95.

J. Adams, J. Berges, S. Bornholdt, F. Freire

Non-perturbative exact flow equations describe the scale dependence of the effective average action. We present a numerical solution for an approximate form of the flow equation for the potential in a three-dimensional N-component scalar field theory. The critical behaviour, with associated critical exponents, can be inferred with good accuracy.

A. Azhari, T. T. Truong

Following Sutherland&#39;s work on one-dimensional integrable systems we formulate and study its two-dimensional version. Physically it expresses the absence of true 3-body forces among an assembly of N particles leaving exclusively effective 2-body interactions. This criterion may be a suitable candidate for an integrability condition.

V. M. Belyaev, A. V. Radyushkin

We use local quark-hadron duality to estimate the purely nonperturbative soft contribution to the $γ^*p\to Δ$ form factors. Our results are in agreement with existing experimental data. We predict that the ratio $G_E^*(Q^2)/G_M^*(Q^2)$ is small for all accessible $Q^2$, in contrast to the pQCD expectations that $G_E^*(Q^2)\to -G_M^*(Q^2)$.

C. J. A. P. Martins, E. P. S. Shellard

We study the effects of friction on the scaling evolution of string networks in condensed matter and cosmological contexts. We derive a generalized `one-scale&#39; model with the string correlation length $L$ and velocity $v$ as dynamical variables. In non-relativistic systems, we obtain a well-known $L\propto t^{1/2}$ law, showing that loop production is im

Wojciech Slominski, Jerzy Szwed

The influence of the QCD structure of the weak bosons on the Higgs boson production in $e$-$p$ scattering is studied. The energy and Higgs boson mass dependence of the cross-section, following from the new contributions, is calculated.

S. A. Abel, S. Sarkar, P. L. White

We discuss the domain wall problem in the Next-to-Minimal Supersymmetric Standard Model, with particular attention to the usual solution of explicit breaking of the discrete symmetry by non-renormalisable operators. This ``solution&#39;&#39; leads to a contradiction between the requirements of cosmology and those of avoiding the destabilisation of the hierar

T. Gehrmann, W. J. Stirling

The $Q^2$ evolution of polarised parton distributions at small $x$ is studied. Various analytic approximations are critically discussed. We compare the full evolution with that obtained from the leading-pole approximation to the splitting functions, and show that the validity of this approximation depends critically on the $x \to 0$ behaviour of the starting

C. Adam

We derive a systematic procedure to compute Green functions for the massive Schwinger model via a perturbation expansion in the fermion mass. The known exact solution of the massless Schwinger model is used as a starting point. We compute the corrections to the Schwinger mass up to second order.

Y. Srivastava, A. Widom, E. Sassaroli

Following notions of quantum mechanics as interpreted by the Copenhagen School, we make a distinction between measurements involving one or two virtual K mesons. New predictions result for the period of K oscillations at the Phi Factory.

G. Kramer, W. Palmer

We calculate CP-violating rates and asymmetry parameters in charged and neutral $B\to ππ, πK$ and $\bar K K$ decays arising from the interference of tree and penguin (strong and electroweak) amplitudes with different strong and CKM phases. The perturbative strong (electroweak) phases develop at order $α_s$ ($α_{em}$) from absorptive parts of one-loop matrix

Norberto N. Scoccola, Thomas D. Cohen

The full Hamiltonian of the soliton models contains no electric seagull terms. Here it is shown that if one restricts the fields to the collective subspace then electric seagull terms are induced in the effective Hamiltonian. These effective seagull contributions are consistent with gauge invariance. They also reproduce the leading nonanalytic behavior of a

E. Accomando, A. Ballestrero, E. Maina

Six--jet events via WW pairs, $e^+e^- \ar W^+W^- \ar q_1 \overline{q_1} q_2 \overline{q_2} g g$ are studied at tree level using helicity amplitudes. This is the dominant production mechanism for six--jet final states at Lep II energy. ISR effects are taken into account. Total production rates as a function of $y_{cut}$ are given. The relevance of these proce

Claude Amsler, Frank Close

Following the discovery of two new scalar mesons, $f_0(1370)$ and $f_0(1500)$ at the Low Energy Antiproton Ring at CERN, we argue that the observed properties of this pair are incompatible with them both being $\qqbar$ mesons. We show instead that $f_0(1500)$ is compatible with the ground state glueball expected around 1500 MeV mixed with the nearby states o

R. C. Verma

We study charm D - meson decays to two pseudoscalar mesons in Cabibbo favored mode employing SU(3)-flavor for the nonfactorizable matrix elements. Using $D\rightarrow \bar K π$ and $D_{s} \rightarrow \bar K K$ to fix the reduced matrix elements, we obtain a consistent fit for $ η$ and $ η&#39;$ emitting decays of $D$ and $ D_{s}$ mesons.

R. R. Volkas

Two models incorporating different forms of spontaneously broken quark-lepton symmetry are discussed. Both models are constructed so that quark-lepton symmetry can be broken at as low an energy scale as phenomenology allows, thus maximising their testability. The first model uses the Pati-Salam gauge group SU(4)$\otimes$SU(2)$_L\otimes$SU(2)$_R$. The main an

J. F. Gunion, Douglas W. McKay, H. Pois

We investigate the phenomenology of minimal four-family MSSM supergravity theories containing an additional generation of heavy fermions along with their superpartners. We demand: gauge coupling constant unification at high energy scales; perturbative values for all Yukawa couplings for energy scales $\leq \mgut$; radiative electroweak symmetry breaking via

A. Patrascioiu, E. Seiler

We discuss some aspects of the continuum limit of some lattice models, in particular the $2D$ $O(N)$ models. The continuum limit is taken either in an infinite volume or in a box whose size is a fixed fraction of the infinite volume correlation length. We point out that in this limit the fluctuations of the lattice variables must be $O(1)$ and thus restore t

Timothy Striker

A lattice version of the Dirac-Kaehler equation (DKE) describing fermions was discussed in articles by Becher and Joos. The decomposition of lattice Dirac-Kaehler fields (inhomogeneous cochains) to lattice Dirac fields remained as an open problem. I show that it is possible to extract Dirac fields from the DKE and discuss the resulting lattice Dirac equation

Arlen Anderson

A general definition of a clock is proposed, and the role of clocks in establishing temporal pre-conditions in quantum mechanical questions is critically discussed. The different status of clocks as used by theorists external to a system and as used by participant-observers within a system is emphasized. It is shown that the foliation of spacetime into insta

Arlen Anderson

A critical presentation of Rovelli&#39;s ``evolving constants of motion&#39;&#39; is given. Previous criticisms by Kuchař concerning the role of factor ordering and the non-existence of observables are dealt with and shown to be unfounded. Kuchař&#39;s criticisms that this approach does not solve the global, multiple choice or Hilbert space problems of time

Robin Horan

We investigate the cohomology of a certain elliptic complex defined on a compact quaternionic-Kähler manifold with negative scalar curvature. We show that this particular complex is exact, with the possible exception of one term.

Georgios Varelogiannis

We comment on a letter publised in PRL by: D. Coffey and L. Coffey, Phys. Rev. Lett. {\bf 70}, 1529 (1993) where it is claimed that the dip structure above the gap is evidence for d-wave pairing. We show that the analysis in this letter is completely contradictory to all ARPES experiments (including those which are considered to be evidence for d-wave), sinc

G. Varelogiannis, L. Pietronero

We consider the Eliashberg theory in the coupling region where some fundamental qualitative deviations from the conventional BCS-like behaviour begin to appear. These deviations are identified as the onset of a cross-over from BCS superconductivity to Bose condensation. We point out that the beginning of this cross-over occurs when the gap $Δ_g$ becomes comp

J. L. Alonso, A. Tarancon, H. G. Ballesteros, L. A. Fernandez

We study three antiferromagnetic formulations of the O(3) spin model in three dimensions by means of Monte Carlo simulations: 1. a two parameter $σ$ model with nearest and next to nearest neighbors couplings in a cubic lattice; 2. a face centered cubic lattice with nearest neighbors interaction; 3. a cubic lattice with a set of fully frustrating couplings. W

M. Fabrizio, C. Castellani, C. Di Castro

We consider a one-dimensional system of electrons interacting via a short-range repulsion and coupled to phonons close to the metal-insulator transition at half filling. We argue that the metal-insulator transition can be described as a standard one dimensional incommensurate to commensurate transition, even if the electronic system is coupled to the lattice

E. H. Aifer, B. B. Goldberg, D. A. Broido

We observe a dramatic reduction in the degree of spin-polarization of a two-dimensional electron gas in a magnetic field when the Fermi energy moves off the mid-point of the spin-gap of the lowest Landau level, $ν=1$. This rapid decay of spin alignment to an unpolarized state occurs over small changes to both higher and lower magnetic field. The degree of el

C. de C. Chamon, D. E. Freed, X. G. Wen

We study non-equilibrium noise in Chiral Luttinger Liquids using the Landauer-Buttiker Scattering approach, obtaining the current/voltage noise spectrum for a four-terminal measurement scheme. Experimental consequences of the tunneling of charges are present in the four-terminal measurement of both the low-frequency shot noise ($ω$ near 0), and the high-freq

Antonio Moreno, José M. Goñi

A model for the full treatment of Spanish inflection for verbs, nouns and adjectives is presented. This model is based on feature unification and it relies upon a lexicon of allomorphs both for stems and morphemes. Word forms are built by the concatenation of allomorphs by means of special contextual features. We make use of standard Definite Clause Grammars

Martin D. Weinberg

Previous attempts at disturbing the galactic disk by the Magellanic Clouds relied on direct tidal forcing. However, by allowing the halo to actively respond rather than remain a rigid contributor to the rotation curve, the Clouds may produce a wake in the halo which then distorts the disk. Recent work reported here suggests that the Magellanic Clouds use thi

J. E. Dyson, R. J. R. Williams, M. P. Redman

We propose that a significant fraction of the ultracompact HII regions found in massive star-forming clouds are the result of the interaction of the wind and ionizing radiation from a young massive star with the clumpy molecular cloud gas in its neighbourhood. Distributed mass loading in the flow allows the compact nebulae to be long-lived. In this paper, we

Erik M. Rauch, Mark M. Millonas, Dante R. Chialvo

We explore a simplified class of models we call swarms, which are inspired by the collective behavior of social insects. We perform a mean-field stability analysis and perform numerical simulations of the model. Several interesting types of behavior emerge in the vicinity of a second-order phase transition in the model, including the formation of stable line

Junwu Gan, Per Hedegard

Numerical studies, from variational calculation to exact diagonalization, all indicate that the quasiparticle generated by introducing one hole into a two-dimensional quantum antiferromagnet has the same nature as a string state in the $t-J_{z}$ model. Based on this observation, we attempt to visualize the quasiparticle formation and subsequent coherent prop

Fernando Lund

Elastic singularities such as crack tips, when in motion through a medium that is itself vibrating, are subject to forces orthogonal to the direction of motion and thus impossible to determine by energy considerations alone. This fact is used to propose a universal scenario, in which three dimensionality is essential, for the dynamic instability of fast crac

Teruaki Watabe, Hyun-Chul Kim, Klaus Goeke

We investigate the effects of mesonic clouds on neutron electric and nucleon strange form factors in the framework of the chiral quark soliton model. We present a mechanism to identify the mesonic clouds and their Yukawa tail in the polarized Dirac sea. We find that, assuming hedgehog structures and semiclassical quantization, the neutron electric and the nu

Hideo Kodama

In this paper a new formulation of quantum dynamics of totally constrained systems is developed, in which physical quantities representing time are included as observables. In this formulation the hamiltonian constraints are imposed on a relative probability amplitude functional $Ψ$ which determines the relative probability for each state to be observed, ins

Alexander Moroz

A new summability method was tested to calculate the critical exponent $ν$ of the localization length for the symplectic case derived from the non-linear $σ$-model. Although we used the same series as Hikami and others, unlike them we were able to resum the series in two-dimensions (2D) and obtain the result $ν\sim 1$. Values of $ν$ in $2+\varepsilon$ dimens

R. Albrecht, WA80-Collaboration

Minimum Bias production cross sections of $η$ mesons have been measured in 200 AGeV/c S+Au and S+S collisions at the CERN SPS by reconstructing the $η\to γγ$ decay. The measurements have been made over the rapidity range $2.1 \leq y \leq 2.9$ using the leadglass spectrometer of WA80. Within the statistical and systematical uncertainties the spectral shapes o

F. Fusi Pecci, M. Bellazzini, C. Cacciari, F. R. Ferraro

The small group of Galactic Globular Clusters (GGC) (Pal 12, Terzan 7, Ruprecht 106, Arp 2) recently discovered to be significantly younger (by ~3-4 Gyr) than the average cluster population of the Galaxy are shown to lie near planes passing in the vicinity of some satellite galaxies of the Milky Way and through the Galactic Centre itself. Assuming that these