February 1998 arXiv papers — page 8

M. Yu. Konstantinov

Some problems of the space-time causal structure are discussed using models with traversable wormholes. For this purpose the conditions of traversable wormhole matching with the exterior space-time are considered in detail and a mixed boundary problem for the Einstein equations is formulated and analyzed. The influence of these matching conditions on the spa

Y. Enginer, M. Hortacsu, N. Ozdemir

Quantum fluctuations for a massless scalar field in the background metric of spherical impulsive gravitational waves through Minkowski and de Sitter spaces are investigated. It is shown that there exist finite fluctuations for de Sitter space.

A. J. Bray

The coarsening exponents describing the growth of long-range order in systems quenched from a disordered to an ordered phase are discussed in terms of the decay rate, omega(k), for the relaxation of a distortion of wavevector k applied to a topological defect. For systems described by order parameters with Z(2) (`Ising'), and O(2) (`XY') symmetry, th

Julian Shillcock, Udo Seifert

Thermally activated escape of an over-damped particle from a metastable well under the action of a time-ramped force is studied. We express the mean first passage time (MFPT) as the solution to a partial differential equation, which we solve numerically for a model case. We discuss two approximations of the MFPT, one of which works remarkably well over a wid

R. B. Laughlin

I argue that there is a connection between quantum antiferromagnetism and the strong interactions. The underlying idea is that the t-J Hamiltonian and other models commonly studied in the context of cuprate superconductivity are near a quantum critical point at which quark-like objects and gauge fields with which they interact become the true elementary exci

A. Buhot, Mirta B. Gordon

We study the typical learning properties of the recently proposed Support Vectors Machines. The generalization error on linearly separable tasks, the capacity, the typical number of Support Vectors, the margin, and the robustness or noise tolerance of a class of Support Vector Machines are determined in the framework of Statistical Mechanics. The robustness

A. de Padua, Fernando Parisio-Filho, Fernando Moraes

Topological defects in solids, usually described by complicated boundary conditions in elastic theory, may be described more simply as sources of a gravity- like deformation field in the geometric approach of Katanaev and Volovich. This way, the deformation field is described by non-Euclidean metric that incorporates the boundary imposed by the defects. A po

N. F. Johnson, S. Jarvis, R. Jonson, P. Cheung

We present results for the so-called `bar-attendance' model of market behavior: $p$ adaptive agents, each possessing $n$ prediction rules chosen randomly from a pool, attempt to attend a bar whose cut-off is $s$. The global attendance time-series has a mean near, but not equal to, $s$. The variance, or `volatility', can show a minimum with increasing

Osamu Moriyama, Naoya Kuroiwa, Mitsugu Matsushita, Hisao Hayakawa

Density waves of granular material (sand) flowing through a vertical pipe have been investigated. Clear density waves emerge when the cock attached to bottom end of the pipe is closed. The FFT power spectra were found to show a stable power-law form $ P(f) \sim f^{-α}. $ The value of the exponent was evaluated as $α\cong 4/3$. We also introduce a simple one-

R. B. Laughlin, D. Giuliano, R. Caracciolo, O. White

This is a pedagogical introduction to the mathematics of 1-dimensional spin-1/2 antiferromagnets. Topics covered include the Haldane-Shastry Hamiltonian, vector ``supercharges'', conserved spin currents, spinons, the supersymmetric Kuramoto-Yokoyama Hamiltonian, and holons.

Jill Bechtold, Richard Elston, Howard K. C. Yee, Erica Ellingson

Observations of the high redshift Universe, interpreted in the context of a new generation of computer simulated model Universes, are providing new insights into the processes by which galaxies and quasars form and evolve, as well as the relationship between the formation of virialized, star-forming systems and the evolution of the intergalactic medium. We d

David J Jeffery

The gamma-ray transfer in supernovae for the purposes of energy deposition in the ejecta can be approximated as grey radiative transfer using mean opacities. In past work there is a single pure absorption mean opacity which is a free parameter. Accurate results can be obtained by varying this mean opacity to fit the results of more accurate procedures. In th

T. Kallman, B. Boroson, S. Vrtilek

Sco X-1 is the brightest extra-solar point source of X-rays, and may serve as a prototype for low mass X-ray binaries as a class. It has been suggested that the UV and optical emission arise as a result of reprocessing of X-rays, and that a likely site for such reprocessing is an accretion disk around the X-ray source. If UV and optical emission are enhanced

John F. Hawley, James M. Stone

We carry out three-dimensional magnetohydrodynamical simulations of the magnetorotational (Balbus-Hawley) instability in weakly-ionized plasmas. We adopt a formulation in which the ions and neutrals each are treated as separate fluids coupled only through a collisional drag term. Ionization and recombination processes are not considered. The linear stability

Charles F. Gammie

We show that radiation dominated accretion discs are likely to suffer from a ``photon bubble'' instability similar to that described by Arons in the context of accretion onto neutron star polar caps. The instability requires a magnetic field for its existence. In an asymptotic regime appropriate to accretion discs, we find that the overstable modes o

A. Shearer, A. Golden, S. Harfst, R. Butler

We present optical data which shows that G", the optical counterpart of the gamma-ray pulsar Geminga, pulses in B with a period of 0.237 seconds. The similarity between the optical pulse shape and the gamma-ray light curve indicates that a large fraction of the optical emission is non-thermal in origin - contrary to recent suggestions based upon the tota

Walter Dehnen

I review recent studies about the gravitational potential and stellar dynamics of M87 in particular, and the dynamics of the stars in the presence of a super-massive central black hole, in general. At large radii, investigations of both the X-ray emitting gas and the velocity distribution of globular clusters indicate the presence of large amounts of non-lum

I. A. Belolaptikov, L. B. Bezrukov, N. M. Budnev, E. V. Bugaev

Supersymmetric models allow for stable non-topological solitons, Q-balls, which can be produced in the early Universe and contribute to dark matter. Experimental signature of electrically neutral Q-balls is, in fact, the same as is expected for superheavy magnetic monopoles catalyzing baryon decay. Here we use the upper limits on monopole flux obtained with

Jochen Greiner

Gamma-ray bursts are sudden releases of energy that for a duration of a few seconds outshine even huge galaxies. 30 years after the first detection of a gamma-ray burst their origin remains a mystery. Here I first review the ``old'' problems which have baffled astronomers over decades, and then report on the ``new'' exciting discoveries of af

Lev Kofman

In inflationary cosmology, the particles constituting the Universe are created after inflation in the process of reheating due to the interaction with the oscillating inflaton field. We briefly review the basics of the slow reheating, and the stage of fast preheating, when the particles are created explosively in the regime of parametric resonance. The non-p

E. Farhi, J. Goldstone, S. Gutmann, M. Sipser

Consider a function f which is defined on the integers from 1 to N and takes the values -1 and +1. The parity of f is the product over all x from 1 to N of f(x). With no further information about f, to classically determine the parity of f requires N calls of the function f. We show that any quantum algorithm capable of determining the parity of f contains a

N. Andruskiewitsch, M. Graña

This is a survey of general aspects of the theory of braided Hopf algebras with emphasis on a special class of braided graded Hopf algebras named tobas. The interest on tobas arises from problems of classification of pointed Hopf algebras. We discuss tobas from different points of view following ideas of Lusztig, Nichols and Schauenburg. We then concentrate

Anatoley T. Zheleznyak, Victor M. Yakovenko

We present a heuristic, semiphenomenological model of the anomalous temperature (T) dependence of resistivity Rxx recently observed experimentally in the quasi-one-dimensional (Q1D) organic conductors of the (TMTSF)2X family in moderately strong magnetic fields. We suggest that a Q1D conductor behaves like an insulator (dRxx/dT<0), when its effective dimensi

Nikolaos Irges, Stephane Lavignac, Pierre Ramond

We present a supersymmetric standard model with three gauged Abelian symmetries, of a type commonly found in superstrings. One is anomalous, the other two are $E_6$ family symmetries. It has a vacuum in which only these symmetries are broken by stringy effects. It reproduces all observed quark and charged lepton Yukawa hierarchies, and the value of the Weinb

E. P. S. Shellard, R. A. Battye

The current cosmological constraints on a dark matter axion are reviewed. We describe the basic mechanisms by which axions are created in the early universe, both in the standard thermal scenario in which axion strings form and in inflationary models. In the thermal scenario, the dominant process for axion production is through the radiative decay of an axio

Jason A. Taylor

There is substantial evidence that the initial mass function (IMF) may be a function of the local star formation conditions. In particular, the IMF is predicted to flatten with increasing local luminosity density, with the formation of massive stars being preferentially enhanced in brighter regions. If IMF gradients are general features of galaxies, several

S. S. Gubser, I. R. Klebanov, A. M. Polyakov

We suggest a means of obtaining certain Green&#39;s functions in 3+1-dimensional ${\cal N} = 4$ supersymmetric Yang-Mills theory with a large number of colors via non-critical string theory. The non-critical string theory is related to critical string theory in anti-deSitter background. We introduce a boundary of the anti-deSitter space analogous to a cut-of

Marlon Pierce, Efstratios Manousakis

Using realistic helium-helium and helium-graphite interactions and the path integral Monte Carlo method, we are able to identify the gas, superfluid liquid, commensurate-solid, and incommensurate-solid phases, and the coexistence regions between them, for the second layer of helium on graphite. The phase boundaries and the specific heat that we determine are

F. J. de Urries, J. Julve

We carry out the extension of the Ostrogradski method to relativistic field theories. Higher-derivative Lagrangians reduce to second differential-order with one explicit independent field for each degree of freedom. We consider a higher-derivative relativistic theory of a scalar field and validate a powerful order-reducing covariant procedure by a rigorous p

Jaume Guasch, Joan Sola, Wolfgang Hollik

Heavy squark decays into top and charginos or neutralinos could be an unexpected source of top quarks at hadron colliders. A detailed treatment of these processes is necessary for a reliable calculation of both the top quark production cross-section and the standard top quark branching ratio in the MSSM. Along this line we compute the electroweak corrections

J. Ripoll, M. Nieto-Vesperinas

This paper has been withdrawn by the authors until some changes are made.

S. Falkenberg, B. Geyer

For N=1 Super-Yang-Mills theory we generalize the effective average action Gamma_k in a manifest supersymmetric way using the superspace formalism. The exact evolution equation for Gamma_k is derived and, introducing as an application a simple truncation, the standard one-loop beta-function of N=1 SYM theory is obtained.

S. Barve, T. P. Singh, Cenalo Vaz, Louis Witten

We consider the evaporation of the (shell focusing) naked singularity formed during the self-similar collapse of a marginally bound inhomogeneous dust cloud, in the geometric optics approximation. We show that, neglecting the back reaction of the spacetime, the radiation on $\scrip$ tends to infinity as the Cauchy Horizon is approached. Two consequences can

Alexander Burinskii

A natural combined model of the Kerr spinning particle and superparticle is obtained leading to a non-trivial super black hole solution. By analogue with complex structure of the Kerr solution we perform a supershift on the Kerr geometry, and then select a &#34;body&#34;-submanifold of superspace that yields a non-trivial supergeneralization of the Kerr metr

Rodrigo Ibata, Geraint Lewis

Are dwarf spheroidal galaxies dark matter dominated? We present N-body simulations of the interaction between the Milky Way and its closest companion, the Sagittarius dwarf spheroidal galaxy, constrained by new kinematic, distance and surface density observations detailed in a companion paper. It is shown that there is no possible self-consistent solution to

N. N. Achasov, V. V. Gubin

We perform the analysis of the preliminary data on $e^+e^-\toϕ\toγf_0(980)\toγπ^0π^0$ reaction simultaneously with the data on $ππ$ scattering and reactions $J/ψ\toϕπ^+π^-$ and $K^-p\toπ^+π^-(Λ,Σ)$. It is found that the $f_0(980)$ meson mass $m_{f_0}=950$ MeV and $B(ϕ\toγf_0\toγπ^0π^0)\simeq1\cdot10^{-4}$.

Shinsuke Kawai, Masa-aki Sakagami, Jiro Soda

A stability analysis is made in the context of the previously discovered non-singular cosmological solution from 1-loop corrected superstring effective action. We found that this solution has an instability in graviton mode, which is shown to have a close relation to the avoidance of initial singularity via energy condition. We also estimate the condition fo

Gh. -S. Paraoanu, H. Scutaru

The initial states which minimize the predictability loss for a damped harmonic oscillator are identified as quasi-free states with a symmetry dictated by the environment&#39;s diffusion coefficients. For an isotropic diffusion in phase space, coherent states (or mixtures of coherent states) are selected as the most stable ones.

Tad Hogg, Mehmet Yanik

Local search algorithms use the neighborhood relations among search states and often perform well for a variety of NP-hard combinatorial search problems. This paper shows how quantum computers can also use these neighborhood relations. An example of such a local quantum search is evaluated empirically for the satisfiability (SAT) problem and shown to be part

Alfonso Rueda, Bernhard Haisch

It was proposed by Haisch, Rueda and Puthoff (Phys. Rev. A, 49, 678, 1994) that the inertia of matter could be interpreted at least in part as a reaction force originating in interactions between the electromagnetic zero-point field (ZPF) and the elementary charged consitutents (quarks and electrons) of matter. Within the limited context of that analysis, it

M. Burkardt, G. A. Miller

A light-front treatment for the scalar and vector meson momentum distribution functions is developed using a model in which the nucleus is treated a static source of radius $R$. The limit $R\to \infty$ corresponds to infinite nuclear matter. In this limit, the scalar mesons are shown to carry a vanishing momentum fraction of the nuclear plus momentum $k^+$,

V. R. Pandharipande, A. Akmal, D. G. Ravenhall

We present results obtained for nuclei, nuclear and neutron star matter, and neutron star structure obtained with the recent Argonne v18 two- nucleon and Urbana IX three-nucleon interactions including relativistic boost corrections. These interactions predict that matter will undergo a transition to a spin layered phase with neutral pion condensation. We als

Alfredo Poves, Gabriel Martinez-Pinedo

The influence of the isoscalar and isovector L=0 pairing components of the effective nucleon-nucleon interaction is evaluated for several isobaric chains, in the framework of full pf shell model calculations. We show that the combined effect of both isospin channels of the pairing force is responsible for the appearance of T=1 ground states in N=Z odd-odd nu

J. Sollfrank, F. Becattini, K. Redlich, H. Satz

According to recent experimental data and theoretical developments we discuss three distinct topics related to strangeness enhancement in nuclear reactions. We investigate the compatibility of multi-strange particle ratios measured in a restricted phase space with thermal model parameters extracted recently in 4pi. We study the canonical suppression as a pos

Thomas Jech

We investigate the system TRC of combinatory logic that is equiconsistent with New Foundations. We prove that various unstratified combinators do not exist in TRC.

A. Rittatore

We study the geometry of algebraic monoids. We prove that the group of invertible elements of an irreducible algebraic monoid is an algebraic group, open in the monoid. Moreover, if this group is reductive, then the monoid is affine. We then give a combinatorial classification of reductive monoids by means of the theory of spherical varieties.

J. Chadzynski, T. Krasinski

Let U be a neighbourhood of 0 \in C^n.We show that for a holomorphic mapping F = (f_1,...,f_m) : U -> C^m, F(0) = 0, the Lojasiewicz exponent of F at 0 is attained on the set {z \in U : f_1(z)...f_m(z) = 0}.

Olga Kravchenko

A symplectic fibration is a fibre bundle in the symplectic category. We find the relation between deformation quantization of the base and the fibre, and the total space. We use the weak coupling form of Guillemin, Lerman, Sternberg and find the characteristic class of deformation of symplectic fibration. We also prove that the classical moment map could be

Enrico Meggiolaro

We show how the topological susceptibility in the Minkowskian theory of QCD is related to the corresponding quantity in the Euclidean theory, which is measured on the lattice. We discuss both the zero-temperature case (T = 0) and the finite-temperature case (T > 0). It is shown that the two quantities are equal when T = 0, while the relation between them is

Heinrich Saller

The correlation of the fractionally represented hypercharge group with the isospin and colour group in the standard model determines as faithfully represented internal group the quotient group ${\U(1)\x\SU(2)\x\SU(3)\over\Z_2\x\Z_3}$. The discrete cyclic central abelian-nonabelian internal correlation involved is considered with respect to its consequences f

Parthasarathi Majumdar, Soumitra SenGupta

The generic observable sector gaugino mass in the weakly-coupled heterotic string compactified to four dimensions by the Scherk-Schwarz scheme (together with hidden sector gaugino condensation inducing the super-Higgs effect with a vanishing cosmological constant) is shown to be non-zero at tree level, being of the order of the gravitino mass, modulo reasona

Kimyeong Lee, Changhai Lu

We investigate the self-dual Yang-Mills gauge configurations on $R^3\times S^1$ when the gauge symmetry SU(2) is broken to U(1) by the Wilson loop. We construct the explicit field configuration for a single instanton by the Nahm method and show that an instanton is composed of two self-dual monopoles of opposite magnetic charge. We normalize the moduli space

S. P. de Alwis

We show that the recent observation that near extremal NS fivebranes decay due to Hawking radiation, can be understood in terms of their coupling to RR states which does not vanish even as the string coupling goes to zero.

R. Jeannerot

A new scenario for baryogenesis is described. The basic idea is that theories beyond the standard model which contain a ${\rm U}(1)_{B-L}$ gauge symmetry, where $B$ and $L$ are respectively baryon and lepton numbers, predict the existence of $B-L$ cosmic strings with right-handed neutrinos trapped as transverse zero modes. Cosmic string loops loose their ene

R. Jeannerot

Inflation arises in supersymmetric grand unified theories (susy GUTs) without fine tuning and cosmic strings usually form at the end of inflation. Hence both strings and inflation contribute to the density perturbations in the very early universe which lead to structure formation and to CMB anisotropies. This may give us a hint as to the $B-L$ breaking scale

Yoshiharu Kawamura, Tatsuo Kobayashi, Manabu Watanabe

We study $μ$ and $B$-parameters in the minimal supersymmetric standard model (MSSM) based on the radiative electroweak symmetry breaking scenario using $\lq\lq$bottom-up&#34; approach and show how useful our approach is to select a phenomenologically viable model beyond the MSSM under the assumption that the underlying theory is a string model or a gauge-Yuk

Kyungsik Kang, Sin Kyu Kang

We discuss a new general class of mass matrix ansatz that respects the fermion mass hierarchy and calculability of the flavor mixing matrix. This is a generalization of the various specific forms of the mass matrix that is obtained by successive breaking of the maximal permutation symmetry. By confronting the experimental data, a large class of the mass matr

Kyungsik Kang, Sin Kyu Kang

We investigate the phenomenological consequences of lepton mass matrices originated from the family permutation symmetry and its suitable breakings. Adopting the recently proposed new mass matrix for the charged lepton mass matrix and the Majorana neutrino mass matrix considered before, we find that the resulting lepton flavor mixing matrix is consistent wit

H. Meyer-Ortmanns, T. Reisz

We propose a new criterion to analyse the order of phase transitions within a finite size scaling analysis. It refers to response functions like order parameter susceptibilities and the specific heat and states different monotony behaviour in volume for first and second order transitions close to the transition point. The criterion applies to analytical and

Dmitri Khokhlov

The model of the homogenous and isotropic universe with two spaces is considered. The background space is a coordinate system of reference and defines the behaviour of the universe. The other space characterizes the gravity of the matter of the universe. In the presented model, the first derivative of the scale factor of the universe with respect to time is

Akihiro Ishibashi, Hideki Ishihara

The equation of motion for a domain wall coupled to gravitational field is derived from the Nambu-Goto action. The domain wall is treated as a source of gravitational field. The perturbed equation is also obtained with gravitational back reaction on the wall motion taken into account. For general spherically symmetric background case, the equation is express

Mikhail V. Altaisky, B. G. Sidharth

We present a rewiew and also new possible applications of $p$-adic numbers to pre-spacetime physics. It is shown that instead of the extension $R^n\to Q_p^n$, which is usually implied in $p$-adic quantum field theory, it is possible to build a model based on the $R^n\to Q_p$, where p=n+2 extension and get rid of loop divergences. It is also shown that the co

Bin Wang, Ru-Keng Su, P. K. N. Yu, E. C. M. Young

By using the gedanken experiments suggested by Bekenstein and Rosenzweig, we have shown that nonextremal Reissner-Nordstrom black hole cannot turn into extremal one by assimilating infalling charged particle and charged spherical shell.

Maciej M. Maska

When electron correlations are important it is often necessary to use numerical methods to solve the Hamiltonian for a finite system (cluster) &#34;exactly&#34;. Unfortunately, such methods are restricted to small systems. We propose to combine the &#34;exact&#34; numerical diagonalization for small clusters with the perturbative calculations to take into ac

V. Tripathi, D. E. Khmelnitskii

We calculate the energy level statistics in a two-dimensional disc with diffusive boundary scattering by the means of the recently proposed ballistic nonlinear sigma-model.

Ya. M. Blanter, A. D. Mirlin, B. A. Muzykantskii

Statistical properties of energy levels and eigenfunctions in a ballistic system with diffusive surface scattering are investigated. The two-level correlation function, the level number variance, the correlation function of wavefunction intensities, and the inverse participation ratio are calculated.

Ch. Waldtmann, H. -U. Everts, B. Bernu, P. Sindzingre

We study the exact low energy spectra of the spin 1/2 Heisenberg antiferromagnet on small samples of the kagomé lattice of up to N=36 sites. In agreement with the conclusions of previous authors, we find that these low energy spectra contradict the hypothesis of Néel type long range order. Certainly, the ground state of this system is a spin liquid, but its

Antonio Pérez-Garrido, M. A. Moore

We have simulated a system of classical particles confined on the surface of a sphere interacting with a repulsive $r^{-12}$ potential. The same system simulated on a plane with periodic boundary conditions has van der Waals loops in pressure-density plots which are usually interpreted as evidence for a first order melting transition, but on the sphere such

Matteo Marsili, Angelo Valleriani

We introduce a simple model which shows non-trivial self organized critical properties. The model describes a system of interacting units, modelled by Polya urns, subject to perturbations and which occasionally break down. Three equivalent formulations - stochastic, quenched and deterministic - are shown to reproduce the same dynamics. Among the novel featur

Graeme Honner, Miklos Gulacsi

We describe the transition from a ferromagnetic phase, to a disordered para- magnetic phase, which occurs in one-dimensional Kondo lattice models with partial conduction band filling. The transition is the quantum order-disorder transition of the transverse-field Ising chain, and reflects double-exchange ordered regions of localized spins being gradually des

Steven D. Kawaler

Although it a very narrow angle survey, the depth of the HDF results in its sampling a significant volume of the halo of our galaxy. Thus it is useful for the purposes of detecting (or placing upper limits on the distribution of) intrinsically faint stars, such as white dwarfs. White dwarfs could provide a significant fraction of the total mass of the halo o

A. Del Popolo, M. Gambera

We study the effect of tidal torques on the collapse of density peaks through the equations of motion of a shell of barionic matter falling into the central regions of a cluster of galaxies. We calculate the time of collapse of the perturbation taking into account the gravitational interaction of the quadrupole moment of the system with the tidal field of th

Stephen Serjeant, Steve Rawlings, Mark Lacy, Richard G. McMahon

The z=2.286 IRAS galaxy F10214+4724 remains one of the most luminous galaxies in the Universe, despite its gravitational lens magnification. We present optical and near-infrared spectra of F10214+4724, with clear evidence for three distinct components: lines of width ~1000 km/s from a Seyfert-II nucleus; <~200 km/s lines which are likely to be associated wit

Martin White

It is common practice to estimate the errors on the angular power spectrum which could be obtained by an experiment with a given angular resolution and noise level. Several authors have also addressed the question of foreground subtraction using multi-frequency observations. In such observations the angular resolution of the different frequency channels is r

R. A. Koopmann, J. D. P. Kenney

Quantitative measures of central light concentration and star formation activity are derived from R and Halpha surface photometry of 84 bright S0-Scd Virgo Cluster and isolated spiral galaxies. For isolated spirals, there is a good correlation between these two parameters and assigned Hubble types. In the Virgo Cluster, the correlation between central light

R. Kantowski

Analytic expressions for distance-redshift relations which have been corrected for the effects of inhomogeneities in the Friedmann-Lemaître-Robertson-Walker (FLRW) mass density are given in terms of Heun functions and are used to illustrate the significance of inhomogeneities on a determination of the mass parameter $Ω_m$ and the cosmological constant $Λ$. T

M. Dugic

We briefly summarize the main recently obtained results concerning existence of the (effective) necessary conditions for the occurrence of the &#34;environment-induced superselection rules&#34; (decoherence).

J. Terasaki, R. Wyss, P. -H. Heenen

The yrast line of the N=Z nucleus 48Cr is studied up to high spins by means of the cranked Hartree-Fock-Bogoliubov method including the T=0 and T=1 isospin pairing channels. A Skyrme force is used in the mean-field channel together with a zero-range density-dependent interaction in the pairing channels. The extensions of the method needed to incorporate the

Saharon Shelah, Otmar Spinas

We introduce a large cardinal property which is consistent with L and show that for every superatomic Boolean algebra B and every cardinal lambda with the large cardinal property, if tightness^+(B) >= lambda^+, then depth (B) >= lambda. This improves a theorem of Dow and Monk.

Saharon Shelah

This is a slightly corrected version of an old work. For a cardinal $μ$ we give a sufficient condition $\oplus_μ$ (involving ranks measuring existence of independent sets) for: $\otimes_μ$ if a Borel set $B\subseteq \mathbb{R} \times \mathbb{R}$ contains a $μ$-square (i.e. a set of the form $A \times A$, with $|A| =μ)$ then it contains a $2^{\aleph_0}$-squar

Charles Livingston, Swatee Naik

We prove that if the order of the first homology of the 2-fold branched cover of a knot K in the 3-sphere is given by pm where p is a prime congruent to 3 mod 4 and gcd(p,m) =1, then K is of infinite order in the knot concordance group. This provides an obstruction to classical knots being of order 4. In particular, there are 11 prime knots with 10 or fewer

E. G. Floratos, A. Kehagias

We discuss higher-dimensional gravitational instantons by studying appropriate self-duality equations for the spin connection. In seven and in eight dimensions, the corresponding spaces admit a covariantly constant spinor and have holonomies in G_2 and Spin(7), respectively. We find a non-compact solution to the self-duality equations in eight dimensions in

G. Salesi, E. Recami, H. Hernandez F., L. C. Kretly

In this note, we first obtain the decomposition of the non-relativistic field velocity into the classical part (i.e., the velocity w=p/m OF the center-of-mass (CM), and the so-called quantum part (i.e., the velocity V of the motion IN the CM frame (namely, the internal spin-motion or Zitterbewegung), these two parts being orthogonal. Our starting point is th

Ashoke Sen

In this review I discuss some basic aspects of non-perturbative string theory. The topics include test of duality symmetries based on the analysis of the low energy effective action and the spectrum of BPS states, relationship between different duality symmetries, an introduction to M- and F-theories, black hole entropy in string theory, and Matrix theory.

Fayyazuddin, Riazuddin

The two body non-leptonic $Λ_b$ decays are analyzed in factorization approximation, using quark model, $ξ= 1 / N_c$ as a free parameter. It is shown that the experimental branching ratio for $Λ_b \longrightarrow Λ{J/ψ}$ restricts $ξ$ and this ratio can be understood for a value of $ξ$ which lies in the range $ 0 \leq ξ\leq 0.5 $ suggested by two body B meson

E. Polizzi, F. Mila, E. S. Sorensen

The $s=1/2$ chain-boundary excitations occurring in the Haldane phaseof $s=1$ antiferromagnetic spin chains are investigated. The bilinear-biquadratic hamiltonian is used to study these excitations as a function of the strength of the biquadratic term, $β$, between $-1\leβ\le1$. At the AKLT point, $β=-1/3$, we show explicitly that these excitations are local

Vladislav S. Olkhovsky, Erasmo Recami

In the First Part of this paper [that was submitted for pub. in 1991 and appeared in print in Phys. Reports 214 (1992) 339] we critically review the main theoretical definitions and calculations of the sub-barrier tunnelling and reflection times. Moreover, within conventional QM, we propose a new definition of such durations, on the basis of a recent general

Edmund J. Copeland, Ian J. Grivell, Edward W. Kolb, Andrew R. Liddle

If primordial scalar and tensor perturbation spectra can be inferred from observations of the cosmic background radiation and large-scale structure, then one might hope to reconstruct a unique single-field inflaton potential capable of generating the observed spectra. In this paper we examine conditions under which such a potential can be reliably reconstruc

Andrei Shelankov

The problem of the scattering of a charge by the Aharonov-Bohm (AB) flux line is reconsidered in terms of finite width beams. It is shown that despite the left-right symmetry in the AB scattering cross-section, the charge is scattered asymmetrically. The asymmetry (i.e. magnetic force) originates from almost forward scattering within the angular size of the

A. V. Thampan, D. Bhattacharya, B. Datta

Kilohertz quasi-periodic oscillations (QPOs) in low-mass X-ray binaries (LMXBs) may represent the orbital frequencies of the innermost Keplerian orbits around accreting neutron stars. Attempts have recently been made to derive constraints on the mass and the equation of state of the neutron star, by identifying the highest observed QPO frequency with the Kep

T. Takaishi, Ph. de Forcrand

We study truncation effects in the SU(3) gauge actions obtained by the Monte Carlo renormalization group method. By measuring the heavy quark potential we find that the truncation effects in the actions coarsen the lattice by 40-50 % from the original blocked lattice. On the other hand, we find that rotational symmetry of the heavy quark potentials is well r

E. E. Fenimore, C. Cooper, E. Ramirez-Ruiz, M. C. Sumner

The variability observed in many complex gamma-ray bursts (GRBs) is inconsistent with causally connected variations in a single, symmetric, relativistic shell interacting with the ambient material (&#34;external shocks&#34;). Rather, the symmetry of the shell must be broken on an angular scale much smaller than Gamma^{-1} where Gamma is the bulk Lorentz fact

Jonathan Arons

I summarize the theory of acceleration of non-neutral particle beams by starvation electric fields along the polar magnetic field lines of rotation powered pulsars, including the effect of dragging of inertial frames which dominates the acceleration of a space charge limited beam. I apply these acceleration results to a new calculation of the radio pulsar de

I. G. Korepanov, S. M. Sergeev

In this paper we reformulate free field theory models defined on the rectangular $D+1$ dimensional lattices as $D+1$ evolution models. This evolution is in part a simple linear evolution on free (``creation&#39;&#39; and ``annihilation&#39;&#39;) operators. Formal eigenvectors of this linear evolution can be directly constructed, and them play the role of th

V. A. Dzuba, V. V. Flambaum, J. K. Webb.

Detection of high-redshift absorption in the optical spectra of quasars have provided a powerful tool to measure spatial and temporal variations of physical ``constants&#39;&#39; in the Universe. It is demonstrated that high sensitivity to the variation of the fine structure constant alpha can be obtained from a comparison of the spectra of heavy and light a

Andrew DeBenedictis

This paper presents a brief but comprehensive introduction to certain mathematical techniques in General Relativity. Familiar mathematical procedures are investigated taking into account the complications of introducing a non trivial space-time geometry. This transcript should be of use to the beginning student and assumes only very basic familiarity with te

Shi-lin Zhu, W. -Y. P. Hwang, Ze-sen Yang

We apply the method of QCD sum rules in the presence of external electromagnetic fields $F_{μν}$ to the problem of the electromagnetic decays of various vector mesons, such as $ρ\toπγ$, $K^\ast\to Kγ$ and $η&#39;\toργ$. The induced condensates obtained previously from the study of baryon magnetic moments are adopted, thereby ensuring the parameter-free natur

Shi-Lin Zhu, Zhi-ning Zhou, Ze-sen Yang

We use a solvable model to perform modified dyson mapping and reveal the unphysical-state effects in the original Random Phase Approximation (RPA). We then propose a method to introduce the RPA and improve it based on a Boson mapping.

Anatoly N. Kochubei

We study p-adic counterparts of stable distributions, that is limit distributions for sequences of normalized sums of independent identically distributed p-adic-valued random variables. In contrast to the classical case, non-degenerate limit distributions can be obtained only under certain assumptions on the asymptotic behaviour of the number of summands in

Tsuyoshi Kajiwara, Claudia Pinzari, Yasuo Watatani

Pimsner introduced the C*-algebra O_X generated by a Hilbert bimodule X over a C*-algebra A. We look for additional conditions that X should satisfy in order to study simplicity and, more generally, the ideal structure of O_X when X is finite projective. We introduce two conditions: `(I)-freeness&#39; and `(II)-freeness&#39;, stronger than the former, in ana