arXiv papers from April 2001

S. V. Molkov, S. A. Grebenev, A. A. Lutovinov

Observations of the X-ray burster SLX 1732-304 in the globular cluster Terzan 1 with the PCA/RXTE instrument in April 1997 are presented. The source was in a low state; its flux in the standard X-ray band was half the flux recorded by the ART-P/Granat telescope also during its low state. At the same time, its spectrum was softer than the ART-P spectrum; it w

M. N. Pavlinsky, S. A. Grebenev, A. A. Lutovinov, R. A. Sunyaev

The results of ART-P/Granat observations of the X-ray burster SLX1732-304 in the globular cluster Terzan 1 are presented. The X-ray (3-20 keV) fluxes from the source differed by more than a factor of 4 during the observing sessions on September 8 ($F_{\rm X}\simeq6.95\times10^{-10}$ erg cm$^{-2}$ s$^{-1}$) and October 6, 1990 ($F_{\rm X}\simeq1.64\times10^{-

Alex Kleiner, Sebastian Eggert

The curvature effects in carbon nanotubes are studied analytically as a function of chirality. The pi-orbitals are found to be significantly rehybridized in all tubes, so that they are never normal to the tubes' surface. This results in a curvature induced gap in the electronic band-structure, which turns out to be larger than previous estimates. The tilting

G. Biroli, O. Parcollet

We study the out of equilibrium dynamics of the infinite range quantum Heisenberg spin glass model coupled to a thermal relaxation bath. The SU(2) spin algebra is generalized to SU(N) and we analyse the large-N limit. The model displays a dynamical phase transition between a paramagnetic and a glassy phase. In the latter, the system remains out of equilibriu

E. M. Leitch, C. Pryke, N. W. Halverson, J. Kovac

We describe the instrumentation, experiment design and data reduction for the first season of observations with the Degree Angular Scale Interferometer (DASI), a compact microwave interferometer designed to measure anisotropy in the Cosmic Microwave Background (CMB) on degree and sub-degree scales (l=100--900). The telescope was deployed at the Amundsen-Scot

C. Pryke, N. W. Halverson, E. M. Leitch, J. Kovac

The Degree Angular Scale Interferometer (\dasi) has measured the power spectrum of the Cosmic Microwave Background anisotropy over the range of spherical harmonic multipoles 100<l<900. We compare this data, in combination with the COBE-DMR results, to a seven dimensional grid of adiabatic CDM models. Adopting the priors h>0.45 and 0.0<=tau_c<=0.4, we find th

Z. Chacko, Graham D. Kribs

We establish a correspondence between those Feynman diagrams in the MSSM which give supersymmetric contributions to the muon anomalous magnetic moment and those which contribute to the flavor violating processes $\mu --> e\gamma$ and $\tau --> \mu\gamma$. Using current experimental limits on the branching ratios of these decay modes, combined with the assump

Elso Drigo Filho, Regina Maria Ricotta

A new exact analytically solvable Eckart-type potential is presented, a generalisation of the Hulthen potential. The study through Supersymmetric Quantum Mechanics is presented together with the hierarchy of Hamiltonians and the shape invariance property.

V. A. Lensky, V. A. Gani, A. E. Kudryavtsev

A classical field system of two interacting fields -- a real Higgs field and a complex scalar field -- is considered. It is shown that in such field system a non-trivial solution exists, which is U(1) charged topological kink. Some questions of stability of the obtained solution are discussed. An improved variational procedure for searching of topological U(

N. W. Halverson, E. M. Leitch, C. Pryke, J. Kovac

We present measurements of anisotropy in the Cosmic Microwave Background (CMB) from the first season of observations with the Degree Angular Scale Interferometer (DASI). The instrument was deployed at the South Pole in the austral summer 1999--2000, and made observations throughout the following austral winter. We have measured the angular power spectrum of

D. V. Ahluwalia

For high energy cosmic neutrinos Athar, Jezabek, and Yasuda (AJY) have recently shown that the existing data on neutrino oscillations suggests that cosmic neutrino flux at the AGN/GRB source, F(nu_e):F(nu_mu):F(nu_tau) approx 1:2:0, oscillates to F(nu_e):F(nu_mu):F(nu_tau) approx 1:1:1. These results can be confirmed at AMANDA, Baikal, ANTARES and NESTOR, an

John Singleton, P. A. Goddard, A. Ardavan, N. Harrison

Peaks in the magnetoresistivity of the layered superconductor $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$, measured in fields $\leq 45$ T applied within the layers, show that the Fermi surface is extended in the interlayer direction and enable the interlayer transfer integral ($t_{\perp} \approx 0.04$ meV) to be deduced. However, the quasiparticle scattering rate $\t

E. L. Koschmieder, T. H. Koschmieder

We have determined theoretically the rest mass of the muon neutrino at 50 milli-eV and the rest mass of the electron neutrino at 5 meV, as well as, to 1% accuracy, the ratio of the masses of the stable elementary particles which decay by weak decays. We assume that the particles of the neutrino branch consist of a cubic, isotropic nuclear lattice, held toget

V. M. Loktev, Yu. G. Pogorelov

We consider the interplay between superconducting coupling and dopant impurity scattering of charge carriers in planar square lattice systems and examine physical conditions (doping level, temperature, local symmetry of coupling and scattering potentials) necessary in this model system to obtain a d-wave superconducting order, like that observed in real dope

M. A. Clayton

We show that that vector field-based models of the ether generically do not have a Hamiltonian that is bounded from below in a flat spacetime. We also demonstrate that these models possess multiple light cones in flat or curved spacetime, and that the non-lightlike characteristic is associated with an ether degree of freedom that will tend to form shocks. Si

V. Kartvelishvili, R. Kvatadze

An event weighting method for simulating Bose-Einstein effects in hadronic final states is presented. The weight for an event depends on the momentum distribution of identical bosons in the event. By using a theoretically motivated parametrisation allowing weights below as well as above unity, the necessity of a weight-rescaling procedure is eliminated. A si

C. B. Netterfield, P. A. R. Ade, J. J. Bock, J. R. Bond

This paper presents a measurement of the angular power spectrum of the Cosmic Microwave Background from l=75 to l=1025 (~10' to 5 degrees) from a combined analysis of four 150 GHz channels in the BOOMERANG experiment. The spectrum contains multiple peaks and minima, as predicted by standard adiabatic-inflationary models in which the primordial plasma undergo

V. C. de Andrade, L. C. T. Guillen, J. G. Pereira

A new expression for the spin connection of teleparallel gravity is proposed, given by minus the contorsion tensor plus a zero connection. The corresponding minimal coupling is covariant under local Lorentz transformation, and equivalent to the minimal coupling prescription of general relativity. With this coupling prescription, therefore, teleparallel gravi

Uwe Trittmann

We present a calculation of the correlator <0|T^{++}(r) T^{++}(0) |0> in N=1 SYM theory in 2+1 dimensions. In the calculation, we use supersymmetric discrete light-cone quantization (SDLCQ), which preserves the supersymmetry at every step of the calculation. For small and intermediate r the correlator converges rapidly for all couplings. At small r the corre

Rosalba Perna

By now there is substantial evidence that Gamma-Ray Bursts (GRBs) originate at cosmological distances from very powerful explosions. The interaction between a GRB and its surrounding environment has dramatic consequences on the environment itself. At early times, the strong X-ray UV afterglow flux photoionizes the medium on distance scales on the order of 10

Zoltan Nagy, Zoltan Trocsanyi

We present the perturbative prediction for three-jet production cross section in DIS at the NLO accuracy. We study the dependence on the renormalization and factorization scales of exclusive three-jet cross section. The perturbative prediction for the three-jet differential distribution as a function of the momentum transfer is compared to the corresponding

Rosalba Perna, Jeremy Heyl, Lars Hernquist

We present a simple, unified model which accounts for properties of the X-ray emission from the three middle-aged pulsars PSR 1055-52, PSR 0656+14 and PSR 0630+18 (Geminga). The X-ray radiation from these objects is pulsed more strongly at energies above a transition point around 0.5 keV. In addition, the phase of the pulses shifts by about 80-100 degrees ar

M. Banados, O. Chandia, N. Grandi, F. A. Schaposnik

We formulate noncommutative three-dimensional (3d) gravity by making use of its connection with 3d Chern-Simons theory. In the Euclidean sector, we consider the particular example of topology $T^2 \times R$ and show that the 3d black hole solves the noncommutative equations. We then consider the black hole on a constant U(1) background and show that the blac

Anna Hasenfratz

The topological susceptibility is one of the few physical quantities that directly measure the properties of the QCD vacuum. Chiral perturbation theory predicts that in the small quark mass limit the topological susceptibility depends quadratically on the pion mass, approaching zero in the chiral limit. Lattice calculations have difficulty reproducing this b

Jun-ichi Tanaka

The lifetimes of charmed mesons have been measured using 11.1fb$^{-1} of data collected with the Belle detector at KEKB. Each candidate is fully reconstructed to identify the flavor of the charmed meson. The lifetimes are measured to be $\tau(D^0)=(414.5\pm1.7)$ fs, $\tau(D^+)=(1029\pm12)$ fs and $\tau(D_s^+)=(488.4^{+7.8}_{-7.7})$ fs, where the error is sta

Peter F. Kolb

We review the apparently hydrodynamic behaviour of low transverse momentum particles (p_T < 1.5 GeV/c) produced in central and semicentral (b < 7 fm) heavy ion collisions at RHIC. We investigate the impact parameter dependence of various observables, elaborating on radial and elliptic flow and particle multiplicities. We also discuss possible ambiguities in

P. T. Reuter, K. A. Bugaev

For the statistical multifragmentation model the critical indices $\alpha^\prime, \beta, \gamma^\prime, \delta$ are calculated as functions of the Fisher parameter $\tau$. It is found that these indices have different values than in Fisher's droplet model. Some peculiarities of the scaling relations are discussed. The basic model predicts for the index $\tau

P. K. Aravind

It is shown how a proof of the Bell-Kochen-Specker (BKS) theorem given by Kernaghan and Peres can be experimentally realized using a scheme of measurements derived from a related proof of the same theorem by Mermin. It is also pointed out that if this BKS experiment is carried out independently by two distant observers who repeatedly make measurements on a s

C. B. Yang, X. Cai, Z. M. Zhou

The event mixing method is analyzed for the study of the event-by-event $K/\pi$ ratio distribution. It is shown that there exists some correlation between the kaon and pion multiplicities in the mixed events. The $K/\pi$ ratio distributions in the mixed events for different sets of real events are shown. The dependence of the distributions on the mean $K/\pi

M. López de Haro, S. B. Yuste, A. Santos

A flaw in the comparison between two different theoretical equations of state for a binary mixture of additive hard disks and Monte Carlo results, as recently reported in C. Barrio and J. R. Solana, Phys. Rev. E 63, 011201 (2001), is pointed out. It is found that both proposals, which require the equation of state of the single component system as input, lea

M. B. Altaie

We study the back-reaction effects of the finite-temperature scalar field and the photon field in the background of an Einstein universe. In each case we find a relation between the temperature of the universe and its radius. These relations exhibit a minimum radius below which no self-consistent solution for the Einstein field equation can be found. A maxim

Jesus A. De Loera, Bernd Sturmfels

We study algebraic algorithms for expressing the number of non-negative integer solutions to a unimodular system of linear equations as a function of the right hand side. Our methods include Todd classes of toric varieties via Gr\"obner bases, and rational generating functions as in Barvinok's algorithm. We report polyhedral and computational results for two

Michael Doran, Matthew Lilley

The locations of the peaks of the CMB spectrum are sensitive indicators of cosmological parameters, yet there is no known analytic formula which accurately describes their dependence on them. We parametrize the location of the peaks as l_m = l_A(m - \phi_m), where l_A is the analytically calculable acoustic scale and m labels the peak number. Fitting formula

K. Kotake, S. Nagataki

We present a model explaining the Fe K alpha line and the continuum in the afterglow of GRB000214. We pose the importance to seek the physically natural environment around GRB000214. For the reproduction of the observation, we need the ring-like remnant around the progenitor like that of SN 1987A produced by the mass-loss of the progenitor and the fireball s

A. Surzhenko, S. Schauroth, D. Litzkendorf, M. Zeisberger

We have studied the remanent magnetic flux distribution in bulk melt-textured YBa2Cu3O7 (YBCO) crystals after their magnetization in quasi-static and pulsed magnetic fields up to 6T. It has been shown that, provided that the magnetic pulse is sharp enough and its amplitude much exceeds the twice penetration magnetic field, the pulse magnetization technique b

J. B. Hertzberg, S. R. Bickman, M. T. Hummon, D. Krause

According to the Special Theory of Relativity, a rotating magnetic dielectric cylinder in an axial magnetic field should exhibit a contribution to the radial electric potential that is associated with the motion of the material's magnetic dipoles. In 1913 Wilson and Wilson reported a measurement of the potential difference across a magnetic dielectric constr

Ciprian Acatrinei, Corneliu Sochichiu

We propose an ansatz for the equations of motion of the noncommutative model of a tachyonic scalar field interacting with a gauge field, which allows one to find time-dependent solutions describing decaying solitons. These correspond to the collapse of lower dimensional branes obtained through tachyon condensation of unstable brane systems in string theory.

T. J. Stocki, D. F. Measday, E. Gete, M. A. Saliba

Many new $\gamma$-rays have been observed, following muon capture on $^{14}$N. One had been reported before, and the low yield is confirmed, indicating that the nuclear structure of $^{14}$N is still not understood. Gamma-rays from $^{13}$C resulting from the reaction $^{14}$N($\mu^{-}$,$\nu$n)$^{13}$C compare favourably with states observed in the reaction

Ruth Gregory, Antonio Padilla

We find the gravitational field of a `nested' domain wall living entirely within a brane-universe, or, a localised vortex within a wall. For a vortex living on a critical Randall-Sundrum brane universe, we show that the induced gravitational field on the brane is identical to that of an (n-1)-dimensional vacuum domain wall. We also describe how to set-up a n

T. Giamarchi, P. Le Doussal, E. Orignac

We study the competition between a random potential and a commensurate potential on interacting fermionic and bosonic systems using a variety of methods. We focus on one dimensional interacting fermionic systems but higher dimensional bosonic and fermionic extensions, as well as classical equivalents are also discussed. Our methods which include bosonization

Rachel Bean

We recently proposed a simple dilaton-derived quintessence model in which the scalar field was non-minimally coupled to cold dark matter, but not to `visible' matter. Such couplings can be attributed to the dilaton in the low energy limit of string theory, beyond tree level. In this paper we discuss the implications of such a model on structure formation, lo

F. Gabbiani

The effective field theory approach is applied to the three-nucleon process of $S=1/2$ neutron-deuteron scattering in the S-wave, including the effective range parameters summed at all orders. This is achieved through a modification of the power counting, following a recent suggestion in the literature. It is shown that with this procedure, while the converg

Slavek M. Rucinski

The distribution of the light-variation amplitudes, A(a), in addition to determining the number of undiscovered contact binary systems falling below photometric detection thresholds and thus lost to statistics, can serve as a tool in determination of the mass-ratio distribution, Q(q), which is very important for understanding of the evolution of contact bina

P. C. Stichel, W. J. Zakrzewski

The gauge model of nonrelativistic particles on a line interacting with nonstandard gravitational fields [5] is supplemented by the addition of a (non)-Abelian gauge interaction. Solving for the gauge fields we obtain equations, in closed form, for a classical two particle system. The corresponding Schr\"{o}dinger equation, obtained by the Moyal quantization

Gabriela Barenboim, G. C. Branco, Andre de Gouvea, M. N. Rebelo

We address the issue of lepton flavour violation and neutrino masses in the ``fat-brane'' paradigm, where flavour changing processes are suppressed by localising different fermion field wave-functions at different positions (in the extra dimensions) in a thick brane. We study the consequences of suppressing lepton number violating charged lepton decays withi

J. Ambjorn, K. N. Anagnostopoulos, W. Bietenholz, F. Hofheinz

In string or M theories, the spontaneous breaking of 10D or 11D Lorentz symmetry is required to describe our space-time. A direct approach to this issue is provided by the IIB matrix model. We study its 4D version, which corresponds to the zero volume limit of 4D super SU(N) Yang-Mills theory. Based on the moment of inertia as a criterion, spontaneous symmet

Bo Feng, Amihay Hanany, Yang-Hui He

Harnessing the unimodular degree of freedom in the definition of any toric diagram, we present a method of constructing inequivalent gauge theories which are world-volume theories of D-branes probing the same toric singularity. These theories are various phases in partial resolution of Abelian orbifolds. As examples, two phases are constructed for both the z

Aristophanes Dimakis, Folkert Muller-Hoissen

A bicomplex is a simple mathematical structure, in particular associated with completely integrable models. The conditions defining a bicomplex are a special form of a parameter-dependent zero curvature condition. We generalize the concept of a Darboux matrix to bicomplexes and use it to derive Backlund transformations for several models. The method also wor

N. Gisin

I am a Quantum Engineer, but on Sundays I have principles, John Bell opened his "underground colloquium" in March 1983, words which I will never forget! What! John Bell, the great John Bell, presented himself as an engineer!?! one of those people who make things work without even understanding how they function?!? whereas I thought of John Bell as one of the

Marco Mackaay, Roger Picken

In this paper we give a short introduction to our results on the holonomy of gerbe-connections and explain our motivation coming from state-sum models.

Matthew Stone, Christine Doran, Bonnie Webber, Tonia Bleam

The process of microplanning encompasses a range of problems in Natural Language Generation (NLG), such as referring expression generation, lexical choice, and aggregation, problems in which a generator must bridge underlying domain-specific representations and general linguistic representations. In this paper, we describe a uniform approach to microplanning

R. Narevich, Ganpathy Murthy, H. A. Fertig

Experimental results indicating the existence of the high magnetic field Wigner Crystal have been available for a number of years. While variational wavefunctions have demonstrated the instability of the Laughlin liquid to a Wigner Crystal at sufficiently small filling, calculations of the excitation gaps have been hampered by the strong correlations. Recent

K. Sachs

In the Standard Model the process e+e- -> gamma-gamma is fully described by QED. Measurements of the differential cross-sections from the four LEP experiments are compared to the QED expectation and limits are set on parameters describing physics beyond the Standard Model. Three-photon events are used for a direct search for a photonically decaying resonance

Matthew Stone

This paper explores goal-directed proof search in first-order multi-modal logic. The key issue is to design a proof system that respects the modularity and locality of assumptions of many modal logics. By forcing ambiguities to be considered independently, modular disjunctions in particular can be used to construct efficiently executable specifications in re

S. S. Gershtein

It is shown that due to the smallness of the inelastic cross-section of the $d\mu$-atoms scattering in the crystal lattice at sufficiently low temperatures the $dd\mu$-mesomolecules formation from the upper state of the hyperfine structure $d\mu (F=3/2)$ starts earlier than the mesoatoms thermolization. It explains an approximate constancy of the $dd\mu$-mes

E. D. Donets, E. E. Donets, T. Itahashi, N. Kudomi

At low energies, far below Coulumb barrier, fusion nuclear reactions are very sensitive to its shape, which is usually in experiments modified by atomic electrons of targer or both projectile and target particles. This article describes proposal on construction of an installation and measurements of excitation functions for d(d,p)t reaction in the region 1.5

Oktay K. Pashaev, and Jyh-Hao Lee

The classical theory of non-relativistic charged particle interacting with U(1) gauge field is reformulated as the Schr\"odinger wave equation modified by the de-Broglie-Bohm quantum potential nonlinearity. For, (1 - $\hbar^2$) deformed strength of quantum potential the model is gauge equivalent to the standard Schr\"odinger equation with Planck constant $\h

Felix von Oppen, Steven H. Simon, Ady Stern

Motivated by experiments, we study the sign of the Coulomb drag voltage in a double layer system in a strong magnetic field. We show that the commonly used Fermi Golden Rule approach implicitly assumes a linear dependence of intra-layer conductivity on density, and is thus inadequate in strong magnetic fields. Going beyond this approach, we show that the dra

A. Cieply, E. Friedman, A. Gal, J. Mares

The $K^-$ optical potential in the nuclear medium is evaluated self consistently from a free-space $K^-N$ $t$ matrix constructed within a coupled-channel chiral approach to the low-energy $\bar K N$ data. The chiral-model parameters are fitted to a select subset of the low-energy data {\it plus} the $K^-$ atomic data throughout the periodic table. The result

Taekoon Lee

Using the general argument in Borel resummation of perturbation theory that links the divergent perturbation theory to the nonperturbative effect we argue that the nonperturbative effect associated with the perturbation theory should have a branch cut only along the positive real axis in the complex coupling plane. The component in the weak coupling expansio

S. -K. Yip

We here study the collective excitations of a dilute spin-polarized Bose-Fermi mixture at zero temperature, considering in particular the features arising from the interaction between the two species. We show that a propagating zero-sound mode is possible for the fermions even when they do not interact among themselves.

Cong-Feng Qiao

The double J/\psi(DJ) production in direct photon-photon collision is investigated. It is found that the J/\psi production rate in this process is of the same order of magnitude as those of previously discussed ones, which hints the dominant J/\psi inclusive production process in the direct photon-photon collision is still not being touched. As DJ production

M. Guttormsen, M. Hjorth-Jensen, E. Melby, J. Rekstad

A simple model based on the canonical-ensemble theory is outlined for hot nuclei. The properties of the model are discussed with respect to the Fermi gas model and the breaking of Cooper pairs. The model describes well the experimental level density of deformed nuclei in various mass regions. The origin of the so-called S-shape of the heat capacity curve Cv(

Markus Reineke

A class of desingularizations for orbit closures of representations of Dynkin quivers is constructed, which can be viewed as a graded analogue of the Springer resolution. A stratification of the singular fibres is introduced; its geometry and combinatorics are studied. Via the Hall algebra approach, these constructions relate to bases of quantized enveloping

Marcelo De Francia, Klaus Kirsten

We study the effect of a background flux string on the vacuum energy of massive Dirac fermions in 3+1 dimensions confined to a finite spatial region through MIT boundary conditions. We treat two admissible self-adjoint extensions of the Hamiltonian. The external sector is also studied and unambiguous results for the Casimir energy of massive fermions in the

Michihiro Hori

In Next Linear Colliders at TeV scale, electroweak double logarithmic corrections, which come from the infrared behaviors of theory can not be neglected. It is well known that in QED and QCD, double logarithmic corrections are resummed to all orders, and these corrections can be exponentiated, resulting in the Sudakov form factor. However it is never trivial

H. D. Yang, J. -Y. Lin, H. H. Li, F. H. Hsu

We have measured the low-temperature specific heat C(T) for polycrystalline MgB_2 prepared by high pressure synthesis. C(T) below 10 K vanishes exponentially, which unambiguously indicates a fully opened superconducting energy gap. However, this gap is found to be too small to account for Tc of MgB_2. Together with the small specific heat jump DeltaC/gamma_n

Hideyuki Kamaya, Joseph Silk

We study the prospects for observing H$_2$ emission during the assembly of primordial molecular cloud kernels. The primordial molecular cloud cores, which resemble those at the present epoch, can emerge around $1+z=20$ according to recent numerical simulations. The kernels form inside the cores, and the first stars will appear inside the kernels. A kernel ty

Chongxing Yue, Guoli Liu, Qingjun Xu

We calculate the contributions of the top-Higgs $h_{t}^{0}$ predicted by topcolor assisted technicolor(TC2) models to $e^{+}e^{-}\longrightarrow \overline{t}c\overline{\nu}_{e}\nu_{e}$ and compare the results with the contributions of $h^{0}_{t}$ to the processes $e^{+}e^{-}\longrightarrow Z h^{0}_{t}\longrightarrow Z\overline{t}c$ and $e^+e^-\longrightarrow

Hideyuki Kamaya, Hiroyuki Hirashita

A possible formation mechanism of hydrogen molecules on a galactic scale is examined. We are interested especially in the role of hydrogen molecules for formation and evolution of primordial galaxies. Then, formation process of hydrogen molecules in a very low-metallicity galaxy (I Zw 18; the most typical metal-deficient galaxy) is studied. Adopting a recent

Hagen Kleinert, Flavio S. Nogueira

We present a semi-perturbative approach which yields an infrared-stable fixed point in the Ginzburg-Landau for N=2, where $N/2$ is the number of complex components. The calculations are done in $d=3$ dimensions and below $T_c$, where the renormalization group functions can be expressed directly as functions of the Ginzburg parameter $\kappa$ which is the rat

D. A. Head, A. V. Tkachenko, T. A. Witten

By employing the adaptive network simulation method, we demonstrate that the ensemble-averaged stress caused by a local force for packings of frictionless rigid beads is concentrated along rays whose slope is consistent with unity: forces propagate along lines at 45 degrees to the horizontal or vertical. This slope is shown to be independent of polydispersit

H. Gopalkrishna Gadiyar

Bohr and Rosenfeld carried out an analysis of the consequences of field theory commutation relations. In this note the analysis is sharpened. A conjecture of Heisenberg that volume is quantized is shown to be a consequence of the second quantization of gauge fields. A way to generalize the equations of physics to include the Planck length is indicated.

J. Gomez-Torrecillas, F. J. Lobillo

In this paper we use refiltering methods to prove that certain types of multi-filtered algebras are Auslander-regular and Cohen-Macaulay. This is applied to obtain that the quantized enveloping algebra associated to a Cartan matrix is Auslander-regular and Cohen-Macaulay.

A. Doliwa, M. Nieszporski, P. M. Santini

We review recent results on asymptotic lattices and their integrable reductions. We present the theory of general asymptotic lattices in R^3 together with the corresponding theory of their Darboux-type transformations. Then we study the discrete analogues of the Bianchi surfaces and their transformations. Finally, we present the corresponding theory of the d

Juan Nieves, Enrique Ruiz Arriola

The $s-$wave meson-baryon scattering is analyzed for the strangeness S=0 sector in a Bethe-Salpeter coupled channel formalism incorporating Chiral Symmetry. Four channels have been considered: $\pi N$, $\eta N$, $K \Lambda$, $K \Sigma$. The needed two particle irreducible matrix amplitude is taken from lowest order Chiral Perturbation Theory in a relativisti

Y. R. Fernandez, D. C. Jewitt, S. S. Sheppard

We present radiometric effective radii and visual geometric albedos for six asteroids in comet-like orbits. Our sample has three of the four known retrograde asteroids (1999 LE31, 2000 DG8, and 2000 HE46) and three objects ((18916) 2000 OG44, 2000 PG3, and 2000 SB1) on prograde but highly elliptical orbits. These measurements more than double the number of k

M. Bonini, E. Tricarico

A cutoff regularization for a pure Yang-Mills theory is implemented within the background field method keeping explicit the gauge invariance of the effective action. The method has been applied to compute the beta function at one loop order.

Namiko Mitarai, Hiizu Nakanishi

We study numerically the stability of granular flow on a rough slope in collisional flow regime in the two-dimension. We examine the density dependence of the flowing behavior in low density region, and demonstrate that the particle collisions stabilize the flow above a certain density in the parameter region where a single particle shows an accelerated beha

L. E. Campusano, R. Pello, J. -P. Kneib, J. -F. Le Borgne

We present the first results of a spectroscopic survey of faint lensed galaxie s in the core of the galaxy cluster AC114 (z=0.312) obtained from observations w ith the FORS1 spectrograph mounted on the VLT-Antu. The galaxies were chose n in areas close to the high-z critical lines predicted by the gravitational lens model of Natarajan et al (NKSE, 1998) for

M. D. Reid, W. J. Munro, F. De Martini

We show how polarisation measurements on the output fields generated by parametric down conversion will reveal a violation of multi-particle Bell inequalities, in the regime of both low and high output intensity. In this case each spatially separated system, upon which a measurement is performed, is comprised of more than one particle. In view of the formal

B. Saghai

Using a chiral constituent quark approach based on the broken SU(6) \otimes O(3) symmetry, we focus on the spectroscopy of isospin-1/2 nucleonic resonances. A model for the eta photoproduction, embodying all known nucleonic resonances, shows clear need for a yet undiscovered S11 resonance, for which we determine the mass (1.730 GeV) and the total width (180

M. Takahashi

We have detected pulsed X-ray emission from the fastest millisecond pulsar known, PSR B1937+21 (P=1.558 msec), with ASCA. The pulsar is detected as a point source above $\sim 1.7$ keV, with no indication of nebulosity. The source flux in the 2--10 keV band is found to be $f = (3.7\pm 0.6) \times 10^{-13}$ erg s$^{-1}$ cm$^{-2}$, which implies an isotropic lu

Serge F. Mingaleev, Yuri S. Kivshar

We overview our recent results on the nonlinear localized modes in two-dimensional (2D) photonic crystals and photonic-crystal waveguides. Employing the technique based on the Green function, we describe the existence domains for nonlinear guided modes in photonic crystal waveguides and study their unique properties including bistability. We also show that l

José Antonio Belinchón

In this paper we study how all the physical "constants" vary in the framework described by a model in which we have taken into account the generalize conservation principle for its stress-energy tensor. This possibility enable us to take into account the adiabatic matter creation in order to get rid of the entropy problem. We try to generalize this situation

M. Hilke, D. C. Tsui, M. Grayson, L. N. Pfeiffer

We present experimental results on the tunneling into the edge of a two dimensional electron gas (2DEG) obtained with a GaAs/AlGaAs cleaved edge overgrown structure in a strong perpendicular magnetic field. While the 2DEG exhibits typical fractional quantum Hall features of a very high mobility sample, we observe the onset of a non-linear current-voltage cha

N. Murray, M. Paskowitz, M. Holman

We examine the eccentricity evolution of a system of two planets locked in a mean motion resonance, in which the outer planet loses energy and angular momentum. The sink of energy and angular momentum could be either a gas or planetesimal disk. We show that the eccentricity of both planetary bodies can grow to large values, particularly if the inner body doe

K. Zarembo

Thermal pion fluctuations, in principle, can completely disorder the phase of the quark condensate and thus restore chiral symmetry. If this happens before the quark condensate melts, strongly-interacting matter will be in the pseudogap state just above the chiral phase transition. The quark condensate does not vanish locally and quarks acquire constituent m

Gunnar Pruessner, Henrik Jeldtoft Jensen

We present the first solvable non-conservative sandpile-like critical model of Self-Organized Criticality (SOC), and thereby substantiate the suggestion by Vespignani and Zapperi [A. Vespignani and S. Zapperi, Phys. Rev. E 57, 6345 (1998)] that a lack of conservation in the microscopic dynamics of an SOC-model can be compensated by introducing an external dr

F. Jegerlehner

I review recent evaluations of the hadronic contribution to the shift in the fine structure constant and to the anomalous magnetic moment of the muon. Substantial progress in a precise determination of these important observables is a consequence of substantially improved total cross section measurement by the CMD-2 and BES II collaborations and an improved

Max Pettini, David V. Bowen

From the analysis of the near-UV spectrum of the QSO 2206-199, obtained with a long series of exposures with STIS on the HST, we deduce a value (D/H) = (1.65 +/- 0.35) x 10(-5) (1 sigma error) for the abundance of deuterium in the z(abs) = 2.0762 damped Lyman alpha system (DLA) along this sight-line. The velocity structure of this absorber is very simple and

M. D. Girardeau, E. M. Wright

Several experimental groups are currently working towards realizing quasi-one-dimensional (1D) atom waveguides and loading them with ultracold atoms. The dynamics becomes truly 1D in a regime (Tonks gas) of low temperatures and densities and large positive scattering lengths for which the transverse mode becomes frozen, in which case the many-body Schrodinge

Paolo Carra, Andres Jerez, Ivan Marri

We present a theoretical analysis of photo-absorption spectroscopies in noncentrosymmetric systems, covering both x-ray and optical regions. Integrated dichroic spectra are interpreted using microscopic effective operators, which are obtained by coupling the orbital angular momentum to the orbital anapole. Symmetry arguments afford a classification of valenc

Prabhakar P. Singh

We present a comparison of electronic structure of MgB2 and TaB2, the two new superconductors, as well as VB2, calculated using full-potential, density- functional-based methods in P6/mmm crystal structure. Our results, described in terms of (i) density of states (DOS), (ii) band-structure, and (iii) the DOS and the electronic charge density in a small energ

Keshav N. Shrivastava

We report that the rate of field sweep is important for the observation of the zeroes in the transverse resistivity in the quantum Hall effect. The resistivity also shows resonances at the nuclear magnetic resonance (NMR) frequencies when the r.f. coil is placed along the x direction. The relationship of the eigen values with the resistivity is pointed out w

J. L. O&#39;Brien, S. R. Schofield, M. Y. Simmons, R. G. Clark

The quest to build a quantum computer has been inspired by the recognition of the formidable computational power such a device could offer. In particular silicon-based proposals, using the nuclear or electron spin of dopants as qubits, are attractive due to the long spin relaxation times involved, their scalability, and the ease of integration with existing

Y. Moritomo, Sh. Xu

Effects of chemical substitution of the divalent transition metals has been systematically investigated in Mg$_{1-x}M_x$B$_2$ (x=0.03; M=Mn, Fe, Co, Ni and Zn). Substitution of magnetic ions, i.e., Mn$^{2+}$, Fe$^{2+}$, Co$^{2+}$ and Ni$^{2+}$, for the Mg$^{2+}$ ion suppresses $T_{\rm c}$: d$T_{\rm c}$/d$x$ is the largest (= - 159 K) in the Mn-doped sample.

F. Chevy, K. Madison, V. Bretin, J. Dalibard

Using a focused laser beam we stir a Bose-Einstein condensate confined in a magnetic trap. When the stirring frequency lies near the transverse quadrupolar mode resonance we observe the nucleation of vortices. When several vortices are nucleated, they arrange themselves in regular Abrikosov arrays, and in the limit of large quantum number the lattice structu

Tod E. Strohmayer

We report the discovery with the proportional counter array (PCA) onboard the Rossi X-ray Timing Explorer (RXTE) of a 450 Hz quasiperiodic oscillation (QPO) in the hard X-ray flux from the galactic microquasar GRO J1655-40. This is the highest frequency QPO modulation seen to date from a black hole. The QPO is detected only in the hard X-ray band above 13 ke

K. Motohara, T. Yamada, F. Iwamuro, R. Hata

We present low-resolution, near-IR JHK spectra of the weak z=2.39 radio galaxy 53W002, obtained with the OH-airglow Suppressor spectrograph (OHS) and Cooled Infrared Spectrograph and Camera for OHS (CISCO) on the Subaru Telescope. They cover rest-frame wavelengths of 3400-7200 A, and the emission lines of [O II]3727, Hb, [O III]4959, 5007, Ha, [N II]6548, 65