September 1995 arXiv papers — page 8

S. Bonazzola, J. Frieben, E. Gourgoulhon

We investigate the effects of general relativity upon the non-axisymmetric ``bar'' mode secular instability of rapidly rotating stars, i.e. the relativistic and compressible analog of the transition from Maclaurin spheroids to Jacobi ellipsoids. Our method consists in perturbing a stationary axisymmetric configuration, constructed by a 2-D general re

Ding Chuan Chen, Anupam Garg

Surface superconductivity is studied within Ginzburg-Landau theory for two classes of models for the order parameter of UPt$_{3}$. The first class assumes two independent one-dimensional order parameters ($AB$ models), while the second assumes a single two-dimensional order parameter ($E$ models). $H_{c3}$ is calculated for all cases where the surface normal

R. Golestanian, M. Goulian, M. Kardar

We consider the interaction between two rods embedded in a fluctuating surface which is governed by either surface tension or rigidity. The modification of fluctuations by the rods leads to an attractive long-range interaction that falls off as $1/R^4$ with their separation. The orientational dependence of the resulting interaction is non-trivial and may lea

E. Ben-Naim, G. S. Grest, T. A. Witten, A. R. C. Baljon

We examine entanglements using monomer contacts between pairs of chains in a Brownian-dynamics simulation of a polymer melt. A map of contact positions with respect to the contacting monomer numbers (i,j) shows clustering in small regions of (i,j) which persists in time, as expected for entanglements. Using the ``space''-time correlation function of

C. L. Kane, Matthew P. A. Fisher

We study thermal transport in a one-dimensional (1d) interacting electron gas, employing the Luttinger liquid model. Both thermal conductance and thermopower are analyzed for a pure 1d gas and with impurities. The universal ratio of electrical to thermal conductance in a Fermi-liquid - the Wiedeman-Franz law - is modified, whereas the thermopower is still li

D. G. Shelton, A. M. Tsvelik

We study a one-dimensional model of interacting conduction electrons with a two-fold degenerate band away from half filling. The interaction includes an on-site Coulomb repulsion and Hund's rule coupling. We show that such one-dimensional system has a divergent Cooper pair susceptibility at T = 0, provided the Coulomb interaction $U$ between electrons on

R. Combescot, O. V. Dolgov, D. Rainer, S. V. Shulga

We calculate the optical conductivity of superconductors in the strong-coupling limit. In this anomalous limit the typical energy scale is set by the coupling energy, and other energy scales such as the energy of the bosons mediating the attraction are negligibly small. We find a universal frequency dependence of the optical absorption which is dominated by

Vidar Gudmundsson, Rolf R. Gerhardts

We study, within the Hartree approximation, the effects of the electron-electron interaction on the energy spectrum of a two-dimensional electron gas in a perpendicular homogeneous magnetic field and a lateral superlattice potential with square symmetry. Due to the strong screening effects, the bandwidth of the Landau bands oscillates strongly with their fil

Y. Hatsugai, M. Kohmoto, Y. -S. Wu

The wave functions for two dimensional Bloch electrons in a uniform magnetic field at the mid-band points are studied with the help of the algebraic structure of the quantum group $U_q(sl_2)$. A linear combination of its generators gives the Hamiltonian. We obtain analytical and numerical solutions for the wave functions by solving the Bethe Ansatz equations

A. Yu. Tretyakov, N. Inui, M. Katori, H. Tsukahara

Using Pade approximations and Monte Carlo simulations, we study the phase diagram of the Two-Neighbor Stochastic Cellular Automata, which have two parameters $p_{1}$ and $p_{2}$ and include the mixed site-bond directed percolation (DP) as a special case. The phase transition line $p_{1}=p_{1 {\rm c}}(p_{2})$ has endpoints at $(p_{1}, p_{2})=(1/2,1)$ and at (

Hiroyuki Mori, Minoru Hamada

We studied mesoscopic Hubbard rings with impurities using the renormalization group (RG) technique and the exact diagonalizations. The exact diagonalization calculations showed that the charge stiffness normalized by the value of clean system has a peak as a function of electron-electron interactions. Previous RG analysis has succeeded to show the enhancemen

T. Y. Brooke, K. Sellgren, R. G. Smith

New 3.3--3.6~$\mu$m spectra were obtained of nine young stellar objects embedded in molecular clouds. An absorption feature at $\sim$3.47~$\mu$m (2880~cm$^{-1}$) with FWHM$\sim$0.09 $\mu$m (80 cm$^{-1}$), first identified by Allamandola et al. (1992), was definitively detected toward seven objects, and marginally in the other two. The feature is better corre

Tsafrir Kolatt, Avishai Dekel, Galit Ganon, Jeffrey Willick

We describe the construction of an N-body simulation that mimics the true velocity and mass-density fields in a box of side 256\hmpc about the Local Group , and the production of mock catalogs that mimic in detail current catalogs of redshifts and peculiar velocities. Our main purpose is to provide a tool for developing and testing reconstruction methods, bu

Brad K. Gibson

We consider the present-day photometric and chemical properties of elliptical galaxies, adopting the bimodal star formation scenario of Elbaz, Arnaud & Vangioni-Flam (1995). These models utilise an initial mass function (IMF) biased heavily toward massive stars during the early phases of galactic evolution, leading to early Type II supernovae-driven galactic

A. D. Dolgov

The data indicating existence of different forms of dark matter in the universe as well as the role of this matter in structure formation are briefly reviewed. It is argued that vacuum energy gives a dominant contribution into the total energy density of the universe. The model of structure formation with unstable tau-neutrino with MeV-mass and KeV-majoron i

Brian Chaboyer, P. Demarque, Ata Sarajedini

Main sequence turnoff magnitudes from the recent set of Yale isochrones (Chaboyer \ea 1995) have been combined with a variety of relations for the absolute magnitude of RR Lyr stars (\mvrr) to calibrate age as a function of the difference in magnitude between the main sequence turn-off and the horizontal branch (\dv). A best estimate for the calibration of \

M. Catelan, J. A. de Freitas Pacheco, J. E. Horvath

The method developed by Raffelt (1990a,b,c) to estimate a possible increase in the standard values of the helium-core mass at the tip of the red giant branch, $\Mc$, from properties of the color-magnitude diagrams of Galactic globular clusters is employed. In the present study, we revise and update Raffelt's database, including also constraints from RR L

V. M. Belyaev, A. V. Radyushkin

The purely nonperturbative soft contribution to the $γ^* p \to Δ^+$ transition form factors is estimated using the local quark-hadron duality approach. Our results show that the soft contribution is dominated by the magnetic transition: the ratio $G_E^*(Q^2)/G_M^*(Q^2)$ is small for all accessible $Q^2$, in contrast to pQCD expectations that $G_E^*(Q^2) \to

C. Wengel, C. L. Henley, A. Zippelius

We report on a Monte Carlo study of a diluted Ising antiferromagnet on a fcc lattice. This is a typical model example of a highly frustrated antiferromagnet, and we ask, whether sufficient random dilution of spins does produce a spin glass phase. Our data strongly indicate the existence of a spin glass transition for spin--concentration $p<0.75$: We find a d

A. P. Heinson, A. S. Belyaev, E. E. Boos

Top quarks can be produced from the electroweak Wtb coupling, leading to a single top or antitop in the final state. We examine single top quark production at the Fermilab Tevatron and calculate the cross section as a function of top quark mass, for each of three separate production processes. We give details of the interferences between Feynman diagrams in

L. Ya. Glozman, D. O. Riska

The spectrum of the C=1 hyperons is well described by the constituent quark model, if the fine structure interaction between the light and strange quarks is mediated by the $SU(3)_F$ octet of light pseudoscalar mesons, which are the Goldstone bosons of the hidden approximate chiral symmetry of QCD. With the addition of a phenomenological flavor exchange inte

Tanmay Vachaspati

We construct a model in which stable magnetic monopoles have magnetic charges that are identical to the electric charges on leptons and quarks and the colored monopoles are confined by strings in color singlets.

J. F. Poyatos, J. I. Cirac, R. Blatt, P. Zoller

The interaction of a trapped ion with a laser beam in the strong excitation regime is analyzed. In this regime, a variety of non--classical states of motion can be prepared either by using laser pulses of well defined area, or by an adiabatic passage scheme based on the variation of the laser frequency. We show how these states can be used to investigate fun

Tsuneo Suzuki

If the dual Meissner effect due to abelian monopole condensation is the quark confinement mechanism of QCD as suggested in recent Monte-Carlo simulations of lattice QCD, new axial-vector and scalar bosons with the mass of O(1GeV) would appear as physical states which are different from ordinary hadrons and glueballs. The axial-vector boson can not decay into

C. Ahn, W. M. Koo

Using the boundary Yang-Baxter equations and exact results on the bulk $S$-matrices, we compute exact boundary scattering amplitudes of the supersymmetric sine-Gordon model with integrable boundary potentials.

Saul Youssef

Recent results suggest that quantum mechanical phenomena may be interpreted as a failure of standard probability theory and may be described by a Bayesian complex probability theory.

M. A. Olshanetsky, V. -B. K. Rogov

We define a q-analog of the modified Bessel and Bessel-Macdonald functions. As for the q-Bessel functions of Jackson there is a couple of functions of the both kind. They are arisen in the Harmonic analysis on quantum symmetric spaces similarly to their classical counterpart. Their definition is based on the power expansions. We derive the recurrence relatio

J. Katriel, B. Abdesselam, A. Chakrabarti

The fundumental invariant of the Hecke algebra $H_{n}(q)$ is the $q$-deformed class-sum of transpositions of the symmetric group $S_{n}$. Irreducible representations of $H_{n}(q)$, for generic $q$, are shown to be completely characterized by the corresponding eigenvalues of $C_{n}$ alone. For $S_{n}$ more and more invariants are necessary as $n$ inereases. I

B. Abdesselam, D. Arnaudon, A. Chakrabarti

Non--minimal $q$-deformations are defined. Their role in the explicit construction of the matrix elements of the generators of ${\cal U}_{q}(SO(5))$ on suitably parametrized bases are exhibited. The implications are discussed.

A. Atalmi, M. Baldo, G. F. Burgio, A. Rapisarda

In this work we discuss the most recent results concerning the Vlasov dynamics inside the spinodal region. The chaotic behaviour which follows an initial regular evolution is characterized through the calculation of the fractal dimension of the distribution of the final modes excited. The ambiguous role of the largest Lyapunov exponent for unstable systems i

Jie Wu

The homology with coefficients in a field of the configuration spaces $C(M\times \bold R ^n,M_o\times \bold R ^n;X)$ is determined in this paper.

Robert Gilman

This article presents a combinatorial result on indexed languages which was inspired by an attempt to understand the structure of groups with indexed language word problem. We show that a sufficiently long word in an indexed language can be written as a product of a uniformly bounded number of terms in such a way that some proper subproduct belongs to the la

Robert Gilman

This article is an introduction to formal languages from the point of view of combinatorial group theory. Group theoretic applications are included and language classes are defined algebraically.

A. V. Ramallo, S. Roy, J. M. Sanchez de Santos

We obtain a bosonization prescription that allows to represent the energy-momentum tensor and supersymmetry generators of non-critical superstring theories with minimal matter as those of topological supergravity. Superstrings with $N=1$ and $N=2$ world-sheet supersymmetry are considered. The topological symmetry associated with the topological supergravity

G. Bimonte, G. Lozano

We reexamine a recently proposed non-inflationary solution to the monopole problem, based on the possibility that spontaneously broken Grand-Unified symmetries do not get restored at high temperature. We go beyond leading order by studying the self-consistent one-loop equations of the model. We find large next-to-leading corrections that reverse the lowest o

Stefano De Leo, Pietro Rotelli

We discuss the use of the variational principle within quaternionic quantum mechanics. This is non-trivial because of the non commutative nature of quaternions. We derive the Dirac Lagrangian density corresponding to the two-component Dirac equation. This Lagrangian is complex projected as anticipated in previous articles and this feature is necessary even f

Stefano De Leo

We show that the Klein-Gordon equation on the quaternion field is equivalent to a pair of DKP equations. We shall also prove that this pair of DKP equations can be taken back to a pair of new KG equations. We shall emphasize the important difference between the standard and the new KG equations. We also present some qualitative arguments, concerning the poss

Federico Finkel, Artemio Gonzalez-Lopez, Miguel A. Rodriguez

The algebraic structures underlying quasi-exact solvability for spin 1/2 Hamiltonians in one dimension are studied in detail. Necessary and sufficient conditions for a matrix second-order differential operator preserving a space of wave functions with polynomial components to be equivalent to a \sch\ operator are found. Systematic simplifications of these co

Kazuo Ghoroku, Kazunari Kaneko

We investigate 2d gravity quantized in the ADM formulation, where only the loop length $l(z)$ is retained as a dynamical variable of the gravitation, in order to get an intuitive physical insight of the theory. The effective action of $l(z)$ is calculated by adding scalar fields of conformal coupling, and the problems of the critical dimension and the time d

Leszek Roszkowski

I present a way of reconciling gauge coupling unification in minimal supersymmetry with small $α_s(m_Z) \approx 0.11$ and discuss the ensuing consequences.

B. Holdom, M. V. Ramana

A new $U(1)$ gauge boson coupling predominantly to the third family has been considered in connection with recent LEP data. We consider another likely consequence of such a gauge boson, a greatly enhanced $b$ quark decay mode, $b \to s \nnbar$.

Tom Appelquist, Nick Evans

We present a one-doublet extended technicolor model, with all fermions in fundamental representations. The bare lagrangian has no explicit mass terms but generates masses through gauge symmetry breaking by purely QCD-like dynamics. The model generates three families of quarks and leptons and can accommodate the observed third family mass spectrum (including

D. Melikhov

A formalism for the relativistic description of hadron decays within the constituent quark model is presented. First, hadron amplitudes of the light--cone constituent quark model, in particular the weak transition form factors at spacelike momentum transfers, $q^2\le 0$, are represented in the form of the dispersion integrals over the hadron mass. Second, th

N. V. Krasnikov

We discuss the phenomenology of many Higgs doublet model - the model where each Higgs isodoublet couples with each own quark and lepton with relatively big Yukawa coupling constants. Namely, we discuss the discovery potential of the Higgs bosons at LHC and find lower mass limits on nonstandard Higgs bosons from FNAL data.

Torbjorn Sjostrand, Gerhard A. Schuler

Four new parton distributions of the photon are presented, with a description of theory choices, properties and applications.

Claude Bernard, Maarten Golterman

We study, in the quenched approximation, Luescher&#39;s relation between pion scattering lengths and the finite-volume energy of two pions at rest. The quenched relation is drastically different from the full theory one; in particular, ``enhanced finite-volume corrections&#34; of order $L^0=1$ and $L^{-2}$ occur at one loop ($L$ is the linear size of the box

Attilio Cucchieri, Tereza Mendes, Andrea Pelissetto, Alan D. Sokal

We solve exactly the general one-dimensional $O(N)$-invariant spin model taking values in the sphere $S^{N-1}$, with nearest-neighbor interactions, in finite volume with periodic boundary conditions, by an expansion in hyperspherical harmonics. The possible continuum limits are discussed for a general one-parameter family of interactions, and an infinite num

Pietro Menotti, Pier Paolo Peirano

By restricting the functional integration to the Regge geometries, we give the discretized version of the well known path integral formulation of 2--dimensional quantum gravity in the conformal gauge. We analyze the role played by diffeomorphisms in the Regge framework and we give an exact expression for the Faddeev--Popov determinant related to a Regge surf

Bas van den Heuvel

For SU(2) gauge theory on the three-sphere we implement the influence of the boundary of the fundamental domain, and in particular the $θ$-dependence, on a subspace of low-energy modes of the gauge field. We construct a basis of functions that respect these boundary conditions and use these in a variational approximation of the spectrum of the lowest order e

Karl Jansen

I review the status of non-perturbative investigations of the finite temperature electroweak phase transition by means of lattice simulations.

F. Pisano, J. L. Tomazelli

A class of boson-fermion stars, whose spin-0 and spin-1/2 constituents interact through a U(1) current-current term in the Lagrangian density, is analysed. It is shown that it describes the low-energy behavior of a system of weakly interacting massive particles (WIMPs) from the leptonic sector of the minimal supersymmetric standard model. In this case the ef

A. M. Jayannavar, Mangal C. Mahato

The dynamical evolution of a Brownian particle in an inhomogeneous medium with spatially varying friction and temperature field is important to understand conceptually. It requires to address the basic problem of relative stability of states in nonequilibrium systems which has been a subject of debate for over several decades. The theoretical treatments adop

Mangal C. Mahato, A. M. Jayannavar

We perform Langevin dynamic numerical simulation on a double-well potential system subjected to an asymmetric saw-tooth type external time varying field and white noise forces. The hysteresis loss calculated from the first-passage time distribution obtained shows asymmetric behaviour with respect to the asymmetry in the field sweep. The hysteresis loss, in o

Jonathan Miller, Jane Wang

We study the two-dimensional localization problem for (i) a classical diffusing particle advected by a quenched random mean-zero vorticity field, and (ii) a quantum particle in a quenched random mean-zero magnetic field. Through a combination of numerical and analytic techniques we argue that both systems have extended eigenstates at a special point in the s

Miguel A. Martin-Delgado, German Sierra

We show that the failure of the real-space RG method in the 1D tight-binding model is not intrinsic to the method as considered so far but depends on the choice of boundary conditions. For fixed BC&#39;s the failure does happen. For free BC&#39;s we present a new analytical block RG-method which gives the exact ground state of the model and the correct $1/N^

Christopher Mudry, Claudio Chamon, Xiao-Gang Wen

Using a Kac-Moody current algebra with $U(1/1)\times U(1/1)$ graded symmetry, we describe a class of (possibly disordered) critical points in two spatial dimensions. The critical points are labelled by the triplets $(l,m,k^{\ }_j)$, where $l$ is an odd integer, $m$ is an integer, and $k^{\ }_j$ is real. For most such critical points, we show that there are i

Daniel Sanchez-Portal, Emilio Artacho, Jose M. Soler

The projection of the eigenfunctions obtained in standard plane-wave first-principle calculations is used for analyzing atomic-orbital basis sets. The &#34;spilling&#34; defining the error in such a projection allows the evaluation of the quality of an atomic-orbital basis set for a given system and its systematic variational optimization. The same projectio

A. K. Kanyuka, V. S. Glukhov

Geometrical approach to the phenomenological theory of phase transitions of the second kind at constant pressure $P$ and variable temperature $T$ is proposed. Equilibrium states of a system at zero external field and fixed $P$ and $T$ are described by points in three-dimensional space with coordinates $η$, the order parameter, $T$, the temperature and $ϕ$, t

J. Timmer

The method of surrogate data is a tool to test whether data were generated by some class of model. Tests based on the periodogram have been proposed to decide if linear systems driven by Gaussian noise could have generated a sample time series. We show that this procedure based on the periodogram, in general, misspecifies the test statistic. Based on the the

S. Sello

A general method for testing nonlinearity in time series is described and applied to measurements of different pressure data inside the draft tube surge of a real Francis turbine. Comparing the current original time series to an ensemble of surrogates time series, suitably constructed to mimic the linear properties of the original one, we was able to disting

L. R. Jones, C. A. Scharf, H. Ebeling, E. Perlman

We have searched for extended X-ray sources in the ROSAT PSPC archive using the Voronoi Tesslation and Percolation algorithm (VTP). This algorithm detects all significant sources regardless of shape or size, and is particularly suited to finding low surface brightness extended sources which could be missed or wrongly interpreted by other algorithms. In an in

M. Rozas, J. E. Beckman, J. H. Knapen

We present new high quality continuum-subtracted H alpha images of the grand-design galaxies NGC 157, NGC 3631, NGC 6764 and NGC 6951. We have determined the positions, angular sizes, and fluxes of their individual HII regions, and describe statistical properties of the HII region samples. We construct luminosity functions for all the HII regions in the disc

Shigeru Ida, Y-h. Taguchi

Non-Gaussian velocity distribution in star forming region is reproduced by inelastic clump collision model. We numerically calculated the evolution of inelastic hard spheres in sheared flow, which corresponds to cloud clumps in differential galactic rotation. This system fluctuates largely around equilibrium state, creating clusters with inelastic collisions

P. Duffy, J. G. Kirk, Y. A. Gallant, R. O. Dendy

The theory of first order Fermi acceleration at shocks assumes that particles diffuse due to scattering off slow-moving magnetic irregularities. However, cosmic rays are closely tied to magnetic field lines, and the transport process, particularly across the direction of the field, is likely to be more complicated. To describe cross field transport we employ

Sanatan Digal, Ajit M. Srivastava

We demonstrate a novel mechanism for the formation of topological defects in a first order phase transition for theories in the presence of small explicit symmetry breaking terms. We carry out numerical simulations of collisions of two bubbles in 2+1 dimensions for a field theory where U(1) global symmetry is spontaneously as well as explicitly broken. In th

Ahmed Hindawi, Burt A. Ovrut, Daniel Waldram

A discussion of the number of degrees of freedom, and their dynamical properties, in higher derivative gravitational theories is presented. The complete non-linear sigma model for these degrees of freedom is exhibited using the method of auxiliary fields. As a by-product we present a consistent non-linear coupling of a spin-2 tensor to gravitation. It is sho

Ryoen Shirasaki

In this paper we analytically study the effects of the lattice discreteness on the electron band in the SSH model. We propose a modified version of the TLM model which is derived from the SSH model using a continuum approximation. When a soliton is induced in the electron-lattice system, the electron scattering states both at the bottom of the valence band a

Yuri A. Abramovich, Mikhail Zaidenberg

The following theorem is the main result of this note. Theorem 1. Let $(E, \|\cdot\|_E) $ be a rearrangement invariant Banach function space on the interval $[0, 1]$. If $E$ is isometric to $Ł_p [0, 1]$ for some $1\le p<\infty$, then $E$ coincides with $Ł_p [0, 1]$ and furthermore $\|\cdot\|_E = λ\|\cdot\|_{Ł_p}$, where $λ= \|{\bf 1}\|_E$.

Douglas Singleton, Atsushi Yoshida

An exact solution for an SU(2) Yang-Mills field coupled to a scalar field is given. This solution has potentials with a linear and Coulomb part. This may have some physical importance since many phenomenological QCD studies assume a linear plus Coulomb potential. Usually the linear potential is motivated with lattice gauge theory arguments. Here the linear p

Paolo Pasti, Dmitrij Sorokin, Mario Tonin

A way of covariantizing duality symmetric actions is proposed. As examples considered are a manifestly space-time invariant duality--symmetric action for abelian gauge fields coupled to axion-dilaton fields and gravity in D=4, and a Lorentz-invariant action for chiral bosons in D=2. The latter is shown to admit a manifestly supersymmetric generalization for

Yuhsuke Yoshida

An analysis is given of the dynamical symmetry breaking of semi-simple gauge groups. We construct a class of renormalizable gauge theories for the dynamically broken topcolor and technicolor interactions. It is shown that a four-Fermi interaction in the strong coupling phase emerges by the tumbling of semi-simple gauge groups in the low energy region. In our

A. M. Jayannavar

We have investigated the recently proposed self-consistent theory of fluctuation - induced transport. In this framework the subsystem under study is coupled to two independent baths at different temperatures. In this non-equilibrium system one can extract energy at the expense of increased entropy. This is a simple model of Maxwell&#39;s demon engine that ex

Ryoen Shirasaki

The formation energy of a soliton was derived in the TLM model to be 2Δ_{0}/πwhich is independent of the masses of the polymer atoms. We estimate effects of the electron-phonon coupling on the soliton formation energy, particularly, through modifications of the harmonic oscillations of (CH) groups. A model based on the amplitude mode formalism is used and th

A. D. Dolgov

These lectures have been given to particle physicists, mostly experimentalists and very briefly and at a pedestrian level review the problems of dark matter. The content of the lectures is the following: 1. Introduction. 2. Cosmological background. 3. Luminous matter. 4. Primordial nucleosynthesis and the total amount of baryons. 5. Gravitating invisible mat

Steven Kleiman, Bernd Ulrich

Inspired by recent work in the theory of central projections onto hypersurfaces, we characterize self-linked perfect ideals of grade 2 as those with a Hilbert--Burch matrix that has a maximal symmetric subblock. We also prove that every Gorenstein perfect algebra of grade 1 can be presented, as a module, by a symmetric matrix. Both results are derived from t

Yu Shi

We investigate correlations among pitches in several songs and pieces of piano music by mapping them to one-dimensional walks. Two kinds of correlations are studied, one is related to the real values of frequencies while they are treated only as different symbols for another. Long-range power law behavior is found in both kinds. The first is more meaningful.

Y. N. Srivastava, A. Widom, E. Sassaroli

A simple but general proof is presented to show that Lorents covariance and 4-momentum conservation alone are sufficient to obtain muon oscillations in the pion decay if the recoiling neutrinos oscillate.

R. Arnowitt, Pran Nath

A detailed analysis of dark matter event rates in minimal supergravity models (MSGM) is given. It is shown analytically that the lightest neutralino the ${{\tilde {Z}_{1}}}$ is the LSP over almost all of the parameter space, and hence the natural candidate for cold dark matter (CDM). The radiative breaking of $SU(2)\times U(1)$ constraints are shown to be cr

Tsuneo Suzuki, Shun-ichi Kitahara, Tsuyoshi Okude, Fumiyoshi Shoji

We report the preliminary results of the studies of hadron spectrum under the background of abelian and monopole gauge fields in quenched Wilson SU(3) QCD. Abelian gauge fields alone reproduce the same chiral limit as in the full case. Critical hopping parameter $κ_c$ and $m_ρ$ are the same in both cases. We need more time to get a definite result in the cas

Tsuneo Suzuki, Yoshimi Matsubara, Shinji Ejiri, Kazuya Yamada

To find a perfect lattice action in terms of monopole action on the dual lattice, we performed simulations of a monopole effective action obtained numerically from vacuum configurations in SU(2) QCD. Although the Polyakov loop behavior near $T_c$ is well reproduced by the action, a small but repulsive term is needed in addition to get the string tension corr

Shinji Ejiri

We investigated a behavior of monopole currents in the high temperature phase of abelian projected finite temperature SU(2) QCD in maximally abelian gauge. Wrapped monopole currents which are closed by periodic boundary play an important role for the spatial string tension. And the wrapped monopole current density seems to be non-vanishing in the continuum l

Shinji Ejiri, Shun-ichi Kitahara, Yoshimi Matsubara, Tsuyoshi Okude

We investigated the gauge (in)dependence of the confinement mechanism due to monopole condensation in SU(2) lattice QCD by various abelian projections. We found (1) the string tension can be reproduced by monopoles alone also in Polyakov gauge and (2) the behaviors of the Polyakov loop at the critical temperature seem to be explained by the uniformity breaki

Ti-ming Chiang, Brian R. Greene

We review the geometrical framework required for understanding the moduli space of $(2,2)$ superconformal-field theories, highlighting various aspects of its phase structure. In particular, we indicate the types of phase diagrams that emerge for ``generic&#39;&#39; Calabi-Yau theories and review an efficient method for their determination. We then focus on s

Craig A. Tracy, Harold Widom

We prove that the solution to a pair of nonlinear integral equations arising in the thermodynamic Bethe Ansatz can be expressed in terms of the resolvent kernel of the linear integral operator with kernel exp(-u(theta)-u(theta&#39;))/cosh[(1/2)(theta-theta&#39;)]

Shi-shyr Roan

We study the differential equations governing mirror symmetry of elliptic curves, and obtain a characterization of the ODEs which give rise to the integral ${\bf q}$-expansion of mirror maps. Through theta function representation of the defining equation, we express the mirror correspondence in terms of theta constants. By investigating the elliptic curves i

A. Ali Khan, S. Collins, C. Davies, J. Shigemitsu

We present results on the spectrum of B mesons and heavy baryons, using a non-relativistic formulation for the heavy and a clover action for the light quark. We also discuss B meson decay constants and their dependency upon the heavy meson mass.

L. E. Sinclair

A search for photoproduction events which contain a rapidity gap between the two highest transverse energy jets has been conducted at HERA using the ZEUS detector. The jets have transverse energies greater than 6~GeV, and are separated by pseudorapidity intervals of up to four units. The fraction of events containing a gap is measured as a function of the ga

Dmitri V. Vasilevich

We study the problem of gauge-invariance and gauge-dependence in one-loop quantum cosmology. We formulate some requirements which should be satisfied by boundary conditions in order to give gauge-independent path integral. The case of QED is studied in some detail. We outline difficulties in gauge-invariant quantization of gravitational field in a bounded re

A. M. Abrahams, R. H. Price

The Misner initial value solution for two momentarily stationary black holes has been the focus of much numerical study. We report here analytic results for an astrophysically similar initial solution, that of Brill and Lindquist (BL). Results are given from perturbation theory for initially close holes and are compared with available numerical results. A co

Dexin Zhong, Daniel ben-Avraham

We analyze a two-offspring Branching Annihilating Random Walk ($n=2$ BAW) model, with finite annihilation rate. The finite annihilation rate allows for a dynamical phase transition between a vacuum, absorbing state and a non-empty, active steady state. We find numerically that this transition belongs to the same universality class as BAW&#39;s with an even n

P. B. Sunil Kumar, Debnarayan Jana

We report an imbibition experiment in 2D random porous media in which height - height correlation function grows with a nonuniversal exponent. We find the exponent to depend on evaporation. A cellular automaton model for imbibition based on first principles is presented. A numerical study of the model gives results which are consistent with the experiment. T

John D. Lafferty, Bernhard Suhm

The maximum entropy method has recently been successfully introduced to a variety of natural language applications. In each of these applications, however, the power of the maximum entropy method is achieved at the cost of a considerable increase in computational requirements. In this paper we present a technique, closely related to the classical cluster exp

P. Rosati

We present a deep X-ray selected sample of galaxy clusters which has been created from a serendipitous search in ROSAT-PSPC deep pointed observations at high galactic latitude. This survey, hereafter known as the ROSAT Deep Cluster Survey (RDCS), is being carried out utilizing a wavelet-based detection algorithm which, unlike other detection methods, is not

Roeland P. van der Marel

Massive nuclear black holes of 10^6 - 10^9 solar masses are believed to be responsible for the the energy production in quasars and active galaxies, and are thought to be present in many quiescent galaxies as well. Dynamical evidence for this can be sought by studying the dynamics of gas and stars in galactic nuclei at high spatial resolution. This paper rev

Rafael A. Vera

The theoretical properties of the black holes (BHs) and of the universe were derived from a unified relativistic theory based on a generalization of local relativity for nonlocal cases in gravitational fields and a quantized standing wave particle model that accounts for relativity, quantum mechanics and the gravitational tests (See gr-qc/9509014). They fix

M. Carvalho, L. C. Q. Vilar, C. A. G. Sasaki, S. P. Sorella

The Yang-Mills type theories and their BRS cohomology are analysed within the zero curvature formalism.

M. Carvalho, L. C. Q. Vilar, C. A. G. Sasaki, S. P. Sorella

We present here the zero curvature formulation for a wide class of field theory models. This formalism, which relies on the existence of an operator $\d$ which decomposes the exterior space-time derivative as a BRS commutator, turns out to be particularly useful in order to solve the Wess-Zumino consistency condition. The examples of the topological theories

Arjun Berera, John C. Collins

We treat hadron-hadron collisions where the final state is kinematically of the kind associated with double-pomeron-exchange (DPE) and has large transverse momentum jets. We show that in addition to the conventional factorized (FDPE) contribution, there is a non-factorized (NDPE) contribution which has no pomeron beam jet. Within a simple model we compute DP

Luis Anchordoqui, Graciela Birman, Santiago Perez Bergliaffa, Héctor Vucetich

Cosmological solutions of Einstein equation for a \mbox{5-dimensional} space-time, in the case of a dust-filled universe, are presented. With these solutions we are able to test a hypothetical relation between the rest mass of a particle and the $5^{\rm th}$ dimension. Comparison with experiment strongly refutes the implied dependence of the rest mass on the

Luis A. Anchordoqui, Graciela S. Birman, Jose D. Edelstein, Carlos Núñez

Solutions of Einstein vacuum equations, for a static pseudospherically symmetric system, are presented. They describe a naked singularity and a singular solution with many resemblances to the Schwartzschild solution but with two major differences: its static region, lying inside the null horizon, sees the singularity, and its effective gravitational field is