April 1999 arXiv papers — page 15

A. S. Rinat, M. F. Taragin

We compare recent CEBAF data on inclusive electron scattering on nuclei with predictions, based on a relation between structure functions (SF) of a nucleus, a nucleon and a nucleus of point-nucleons. The latter contains nuclear dynamics, e.g. binary collision contributions in addition to the asymptotic limit. The agreement with the data is good, except in lo

A. S. Rinat, M. F. Taragins

We address the problem of extracting single-nucleon momentum distributions $n(p)$ from inclusice scattering data. A model for these relates nuclear and nucleon structure functions (SF) through an intermediate SF $f^{PN}$ for a nucleus of point-particles. In addition to the asymptotic limit (AL) which depends on $n(p), f^{PN}$ contains, generally $q$-dependen

Henryk Fuks

We present a rigorous derivation of the flow at arbitrary time in a deterministic cellular automaton model of traffic flow. The derivation employs regularities in preimages of blocks of zeros, reducing the problem of preimage enumeration to a well known lattice path counting problem. Assuming infinite lattice size and random initial configuration, the flow c

Yu. I. Manin, P. Zograf

We show that the generating function for the higher Weil-Petersson volumes of the moduli spaces of stable curves with marked points can be obtained from Witten's free energy by a change of variables given by Schur polynomials. Since this generating function has a natural extension to the moduli space of invertible Cohomological Field Theories, this sugge

A. S. Vytheeswaran

We look at and compare two different methods developed earlier for inducing gauge invariances in systems with second class constraints. These two methods, the Batalin-Fradkin method and the Gauge Unfixing method, are applied to a number of systems. We find that the extra field introduced in the Batalin-Fradkin method can actually be found in the original pha

W. Buchmuller, M. Plumacher

The cosmological baryon asymmetry can be explained as remnant of heavy Majorana neutrino decays in the early universe. We study this mechanism for two models of neutrino masses with a large ν_μ-ν_τmixing angle which are based on the symmetries SU(5) x U(1)_F and SU(3)_c x SU(3)_L x SU(3)_R x U(1)_F, respectively. In both cases B-L is broken at the unificatio

S. Shelly Sharma, F. Pisano

We demonstrate that in the process of deducing the constraint on the electroweak mixing angle $θ_{W}$ in our paper, we have indeed been working with three mass scales while implementing (331) model.

A. van Hameren, R. Kleiss, C. G. Papadopoulos

We calculate the 1/N corrections to the probability distributions of quadratic discrepancies for sets of N random points. This is achieved by the introduction of fermionic variables. We give the diagrammatic expansion up to and including the second order in 1/N. For some discrepancies, we give the explicit expansion to first order.

W. R. B. de Araujo, M. Beyer, T. Frederico, H. J. Weber

We compare the Bakamjian-Thomas (BT) formulation of relativistic few-body systems with light front field theories that maintain closer contact with Feynman diagrams. We find that Feynman diagrams distinguish Melosh rotations and other kinematical quantities belonging to various composite subsystem frames that correspond to different loop integrals. The BT fo

C. P. Korthals Altes, Robert D. Pisarski, Annamaria Sinkovics

The contribution of quarks to the effective potential for the phase of the Wilson line is computed at nonzero temperature and quark chemical potential to one and two loop order. At zero temperature, regardless of the value of the quark chemical potential, the effective potential for the phase of the Wilson line vanishes. At nonzero temperature, for special v

S. Groote, J. G. Körner, A. A. Pivovarov

We present a proof that all transcendental numbers that are needed for the calculation of the master integrals for three-loop vacuum Feynman diagrams can be obtained by calculating diagrams with an even simpler topology, the topology of spectacles.

Mohan Narayan, S. Uma Sankar

We consider (ν_μ--> ν_e) oscillations in long baseline experiments within a three flavor framework. A non-zero measurement of this oscillation probability implies that the (13) mixing angle `phi' is non-zero. We consider the effect of neutrino propagation through the matter of earth's crust and show that, given the constraints from solar neutrino and

E. M. Bol'shedvorsky, S. I. Polityko

The polarization properties of the Compton effect in the field of a circularly polarized electromagnetic wave are discussed. In the case of nonlinear Compton effect the behavior of spin is analyzed. The transformation of the longitudinal polarization in the transverse polarization is showed. We obtained the total formulas describing the polarization of the f

A. Halprin, R. R. Volkas

We have examined Lorentz invariance and equivalence principle violations in the neutrino sector as manifested in neutrinoless double beta decay. We conclude that this rare decay cannot provide a useful view of these exotic processes.

Christian Y. Cardall, Daniel J. H. Chung

We show in detail the general relationship between the Schrödinger equation approach to calculating the MSW effect and the quantum field theoretical S-matrix approach. We show the precise form a generic neutrino propagator must have to allow a physically meaningful ``oscillation probability'' to be decoupled from neutrino production fluxes and detect

Jiri Chyla

Factorization scheme analysis of $F_2^γ(x,Q^2)$ in the next-to-leading order QCD is revisited. It is emphasized that the presence of the inhomogeneous term in the evolution equations for quark distribution functions of the photon implies subtle but important difference in the way factorization mechanism works in photon-hadron and photon-photon collisions as

Michael Creutz

Lattice gauge theory is now well into its third decade as a major subfield of theoretical particle physics. I open these lattice sessions with a brief review of the motivations for this formulation of quantum field theory. I then comment on the recent drive of lattice theorists to include a fictitious ``fifth'' dimension to treat issues of chiral sym

L. Nodulman

Progress continues on many fronts of experimental testing of electroweak symmetry breaking. Updates were presented on LEP, SLC, Brookhaven g-2 ring, Tevatron Collider, HERA, CESR and Tevatron neutrino experiments. Perhaps most exciting is the Higgs search at LEP2, complementing the indirect constraints. However, the standard model with one Higgs doublet rema

Sacha E. Kopp

Future asymmetric e+e- --> Upsilon(4S) B factories are being constructed to search for CP violation in B0 decays. It is hoped that a CP asymmetry may be observed in B0-B0bar mixing in analogy with that found in neutral kaons. In this mixing measurement, B0 decays to CP eigenstates, such as the rare decay B0 psi Kshort, may provide information on the CKM angl

G. Rizzi, A. Tartaglia

The paper shows that, conceptually and operationally, the speed of light as measured locally in the inertial comoving frame of a point on the rim of a rotating disk, is different from the one measured globally for a round trip along the rim, obtained dividing the length of the rim (as measured in the ''relative space'' of the disk) by the tim

E Alfinito, R Manka, G Vitiello

We consider gravitational wave modes in the FRW metrics in a de Sitter phase and show that the state space splits into many unitarily inequivalent representations of the canonical commutation relations. Non-unitary time evolution is described as a trajectory in the space of the representations. The generator of time evolution is related to the entropy operat

Mark Lee, John Barnden

Mixed metaphors have been neglected in recent metaphor research. This paper suggests that such neglect is short-sighted. Though mixing is a more complex phenomenon than straight metaphors, the same kinds of reasoning and knowledge structures are required. This paper provides an analysis of both parallel and serial mixed metaphors within the framework of an A

J. J. Mazo, E. Trias, T. P. Orlando

We propose a method to excite and detect a rotor localized mode (rotobreather) in a Josephson-junction array biased by dc currents. In our numerical studies of the dynamics we have used experimentally realizable parameters and included self-inductances. We have uncovered two families of rotobreathers. Both types are stable under thermal fluctuations and exis

Clare C. Yu

We show that the time development of the Coulomb gap in a Coulomb glass can involve very long relaxation times due to electron rearrangement and hopping. We find that an applied magnetic field reduces the rate of electron hopping and, hence, Coulomb gap formation. These results are consistent with recent conductance experiments on thin semiconducting and met

Gabriele Ferrari

We propose a method to study the degeneracy of a trapped atomic gas of fermions through the relaxation of the motion of a test particle. In the degenerate regime, and for an energy of the test particle well below the Fermi energy, we show that the Fermi-Dirac statistics is responsible for a strong decrease of the relaxation rate. This method can be used to d

Jafferson Kamphorst Leal da Silva, Ronald Dickman

We study the stationary properties of the two-dimensional pair contact process, a nonequilibrium lattice model exhibiting a phase transition to an absorbing state with an infinite number of configurations. The critical probability and static critical exponents are determined via Monte Carlo simulations, as well as order-parameter moment ratios and the scalin

N. P. Ong, K. Krishana, Y. Zhang, Z. A. Xu

In underdoped YBa_2Cu_3O_x (x=6.63), the low-T thermal conductivity Kappa_xx varies steeply with field B at small B, and saturates to a nearly field-independent value at high fields. The simple expression [1+p(T)|B|]^(-1) provides an excellent fit to Kappa_xx(B) over a wide range of fields. From the fit, we extract the zero-field mean-free-path, and the low

Emilio Artacho, Daniel Sanchez-Portal, Pablo Ordejon, Alberto Garcia

A brief review of the SIESTA project is presented in the context of linear-scaling density-functional methods for electronic-structure calculations and molecular-dynamics simulations of systems with a large number of atoms. Applications of the method to different systems are reviewed, including carbon nanotubes, gold nanostructures, adsorbates on silicon sur

D. G. Salinas, S. Guéron, D. C. Ralph, C. T. Black

The presence of spin-orbit scattering within an aluminum nanoparticle affects measurements of the discrete energy levels within the particle by (1) reducing the effective g-factor below the free-electron value of 2, (2) causing avoided crossings as a function of magnetic field between predominantly-spin-up and predominantly-spin-down levels, and (3) introduc

Holger Frahm

A family of exactly solvable models describing a spin-S Heisenberg chain doped with mobile spin-(S-1/2) carriers is constructed from gl(2|1)-invariant solutions of the Yang-Baxter equation. The models are generalizations of the supersymmetric t-J model which is obtained for S=1/2. We solve the model by means of the algebraic Bethe Ansatz and present results

Fernando Falo, Pedro J. Martinez, Juan J. Mazo, Sofia Cilla

We propose a simple configuration of a one-dimensional parallel array of Josephson junctions in which the pinning potential for trapped fluxons lacks inversion symmetry (ratchet potential). This sytem can be modelised by a set of non-linear pendula with alternating lengths and harmonic couplings. We show, by molecular dynamics simulations, that fluxons behav

J. A. Chervenak, J. M. Valles,

We report results of transport measurements in the quantum critical regime of the disorder tuned, 2D superconductor-insulator transition (SIT) in homogeneously disordered films. We show that, as the superconducting transition temperature decreases, the transition width grows, appearing to diverge at the SIT. In addition, structure develops in the DC current-

Andrea Parmeggiani, Frank Jülicher, Armand Ajdari, Jacques Prost

We study the energetics of isothermal ratchets which are driven by a chemical reaction between two states and operate in contact with a single heat bath of constant temperature. We discuss generic aspects of energy transduction such as Onsager relations in the linear response regime as well as the efficiency and dissipation close to and far from equilibrium.

Markus Porto, Armin Bunde, Shlomo Havlin

We study numerically and by scaling arguments the probability P(M)dM that a given dangling end of the incipient percolation cluster has a mass between M and M + dM. We find by scaling arguments that P(M) decays with a power law, P(M)~M^(-(1+k)), with an exponent k=dBf/df, where df and dBf are the fractal dimensions of the cluster and its backbone, respective

Michael Brunner, Fakher F. Assaad, Alejandro Muramatsu

We present a new finite-temperature quantum Monte Carlo algorithm to compute imaginary-time Green functions for a single hole in the t-J model on non-frustrated lattices. Spectral functions are then obtained with the Maximum Entropy method. Simulations of the one-dimensional case show that a simple charge-spin separation Ansatz is able to describe the overal

C. Weiss, W. Zwerger

Motivated by recent experiments, we calculate both the average current and the current fluctuations for a metallic island which oscillates between two symmetric electrodes. Electrons can only tunnel on or off the island when it is close to one of the electrodes. Using a Master equation we investigate the accuracy of such an electron shuttle both analytically

Itzhak Webman, Jose Luis Gruver, Shlomo Havlin

We study the motion of elastic networks driven over a random substrate. Our model which includes local friction forces leads to complex dynamical behavior. We find a transition to a sliding state which belongs to a new universality class. The phase diagram comprises of a pinned state, a stick-slip motion phase, and a free motion phase.

M. Veillette, Ya. B. Bazaliy, A. J. Berlinsky, C. Kallin

We study the formation of stripe order within the SO(5) theory of high T_c superconductivity. We show that spin and charge modulations arise as a result of the competition between a local tendency to phase separate and the long-range Coulomb interaction. This frustrated phase separation leads to hole-rich and hole-poor regions which are respectively supercon

B. Kaulakys, G. Vilutis

We present a consecutive derivation of mapping equations of motion for the one-dimensional classical hydrogenic atom in a monochromatic field of any frequency. We analyze this map in the case of high and low relative frequency of the field and transition from regular to chaotic behavior. We show that the map at aphelion is suitable for investigation of trans

Andrei Goryachev, Hugues Chate', Raymond Kapral

The transition from complex-periodic to chaotic behavior is investigated in oscillatory media supporting spiral waves. We find turbulent regimes characterized by the spontaneous nucleation, proliferation and erratic motion of synchronization defect lines which separate domains of different oscillation phases. The line defect dynamics is controlled by the com

Robert P. Kraft, Ruth C. Peterson, Puragra Guhathakurta, Christopher Sneden

We have serendipitously discovered an extremely lithium-rich star on the red giant branch of the globular cluster M3 (NGC 5272). An echelle spectrum obtained with the Keck I HIRES reveals a Li I 6707 Angstrom resonance doublet of 520 milli-Angstrom equivalent width, and our analysis places the star among the most Li-rich giants known: log[epsilon(Li)] ~= +3.

Ian Waddington

The results of an optical and infrared investigation of a complete sub-sample of the Leiden-Berkeley Deep Survey (flux > 1 mJy at 1.4 GHz) are presented. Optical counterparts have been identified for 69 of the 73 sources in the two Hercules fields, and redshifts obtained for 49 of them. Photometric redshifts are computed from the g,r,i,K data for the remaini

S. Veilleux, D. -C. Kim, D. B. Sanders

This paper discusses the optical spectroscopic properties of the IRAS 1-Jy sample of ultraluminous infrared galaxies (ULIGs). One hundred and eight of the 118 1-Jy ULIGs have been observed at dlambda = 8.3 AA resolution over the wavelength range ~4500 A -- 8900 A. These data are combined with large, previously published sets of optical spectroscopic data of

S. Veilleux, D. B. Sanders, D. -C. Kim

This paper reports the latest results from a near-infrared search for hidden broad-line regions (BLRs: FWHM >~ 2,000 km/s) in ultraluminous infrared galaxies (ULIGs). The new sample contains thirty-nine ULIGs from the 1-Jy sample selected for their lack of BLRs at optical wavelengths. The results from this new study are combined with those from our previous

M. J. Claussen, W. M. Goss, D. A. Frail, K. Desai

We have used the NRAO Very Long Baseline Array (VLBA) to image OH(1720 MHz) masers in the supernova remnants W28 and W44 at a resolution of 40 mas. We also used MERLIN to observe the same OH(1720 MHz) masers in W44 at a resolution of 290 x 165 mas. All the masers are resolved by these VLBA and MERLIN observations. The measured sizes range from 50 to 180 mas

F. Yusef-Zadeh, D. Choate, W. Cotton

The absolute position of the compact radio source at the dynamical center of the Galaxy, Sgr A$^*$, was known only to an accuracy of $0.2''$ in spite of its accurate location with respect to near-IR stellar sources to within 30 milliarcsecond (mas). To remedy this poor positional accuracy, we have selected 15 high-resolution, high-frequency VLA obser

M. D. Lehnert

I discuss the observational evidence that starburst galaxies are able to drive galactic-scale outflows ("superwinds") and then argue generally that superwinds must have had an important role in galaxy evolution. To explore the role of feedback from massive stars, I review results suggesting that starbursts seem to obey a limiting IR surface brightnes

Ennio Poretti

The Fourier decomposition was applied to the light curves of the short period variable stars discovered by the OGLE team in Omega Cen. The phi_21 parameters are confined in a narrow strip for periods between 0.042 d and 0.07 d. Toward longer periods, there is an overlapping with the values obtained in the case of galactic stars. Toward shorter periods, the t

I. Berentzen, C. H. Heller, E. Athanassoula, K. J. Fricke

Using an N-body+SPH code we have performed numerical simulations to investigate the dynamical effects of an interaction between an initially barred galaxy and a small spherical companion. In the models described here the small companion passes through the disk of the larger galaxy perpendicular to its plane. The impact positions and times are varied with res

V. G. Klochkova, R. Szczerba, V. E. Panchuk, K. Volk

The optical spectrum of the infrared source IRAS 04296+3429 (optical counterpart-G0 Ia star, V=14.2) was obtained with the echelle spectrometer PFES at the prime focus of the 6 m telescope. We discover emission bands (0,0) and (0,1) of the Swan system of the C2 molecule in the optical spectrum of IRAS 04296+3429. Comparison with the spectrum of the Hale-Bopp

A. Fuente, J. Martin-Pintado, N. J. Rodrıguez-Fernández, A. Rodriguez-Franco

We have observed the S(0), S(1), S(2), S(3), S(4) and S(5) rotational lines of molecular hydrogen (H2) towards the peak of the photodissociation region (PDR) associated with the reflection nebula NGC 7023. The observed H2 line ratios show that they arise in warm gas with kinetic temperatures ~300 - 700 K. However, the data cannot be fitted by an ortho- to pa

P. Martin, D. Friedli

The nebular properties (electronic density, extinction, age, O/H abundances) of HII regions found along the bars of the sample of barred spiral galaxies studied by Martin & Friedli (1997) are examined. From line ratio diagnostic diagrams, it is showed that regions located along the major axis of the bars have a normal photoionization spectrum, that is, line

F. Combes

Can the present dynamics of spiral galaxies tell us something about the merging history, the formation and evolution of disks? Galaxy interactions thicken or destroy disks; the simultaneous presence of thick and thin disks is a tracer of past accretion, and also of recent disk re-formation. Observation of a large number of counter-rotating disks is also evid

R. D'hulst, G. J. Rodgers

We introduce two three sided adaptative systems as toy models to mimic the exchange of commodities between buyers and sellers. These models are simple extensions of the minority game, exhibiting similar behaviour as well as some new features. The main difference between our two models is that in the first the three sides are equivalent while in the second, o

Alan D. Sokal

I show that there exist universal constants $C(r) < \infty$ such that, for all loopless graphs $G$ of maximum degree $\le r$, the zeros (real or complex) of the chromatic polynomial $P_G(q)$ lie in the disc $|q| < C(r)$. Furthermore, $C(r) \le 7.963906... r$. This result is a corollary of a more general result on the zeros of the Potts-model partition functi

T. M. Aliev, M. Savci

We calculate the &#34;pi Sigma Lambda&#34; and &#34;pi Sigma Sigma&#34; coupling constants in light cone QCD sum rules for the structure &#34;sigma_{alpha beta} gamma_5 p^alpha q^beta&#34;. A comparison of our results on these coupling constants with prediction of the SU(3) symmetry is presented.

W. Chen, W. Wang, T. Zhong

The structure of weighting coefficient matrices of Harmonic Differential Quadrature (HDQ) is found to be either centrosymmetric or skew centrosymmetric depending on the order of the corresponding derivatives. The properties of both matrices are briefly discussed in this paper. It is noted that the computational effort of the harmonic quadrature for some prob

Brett D. Altschul

Comparing the Dirac Hamiltonians for a neutron subjected to either a Schwartzchild gravitational field or a uniform acceleration, we observe that the difference between the two is precisely the sort that might be eliminated by the introduction of a new quantum number. The origin of this quantum number lies in the noncommutation of an acceleration with the qu

Asher Peres

Two observers (Alice and Bob) independently prepare two sets of singlets. They test one particle of each singlet along an arbitrarily chosen direction and send the other particle to a third observer, Eve. At a later time, Eve performs joint tests on pairs of particles (one from Alice and one from Bob). According to Eve&#39;s choice of test and to her results

Eric Baird

Coule&#39;s primary objection to the Alcubierre &#34;warpdrive&#34; is that the material producing the warp field needs to be superluminal. This difficulty is solved by placing the drive material inside its own warp field (making the drive system part of the payload), but we then have to deal with Low&#39;s related objection, that there is then a restricted

W. M. Alberico, A. Molinari

A short review of the present knowledge of the nucleons distribution in nuclei is given. A proposal is made about a possible measurements of the neutron distribution through polarized electron scattering off nuclei.

Wanda M. Alberico

We report here theoretical investigations on the complexity of nuclear structure, which have been carried out in the framework of different many-body approaches, typically applied to nuclear matter and quark matter studies. The variational, functional and perturbative scheme are illustrated in their latest developments. The effect of various nucleon-nucleon

Andrei Tyurin

Geometric Quantization links holomorphic geometry with real geometry, a relation that is a prototype for the modern development of mirror symmetry. We show how to use this treatment to construct a special basis in every space of conformal blocks. This is a direct generalization of the basis of theta functions with characteristics in every complete linear sys

R. M. Green, J. Losonczy

We establish the existence of an IC basis for the generalized Temperley--Lieb algebra associated to a Coxeter system of arbitrary type. We determine this basis explicitly in the case where the Coxeter system is simply laced and the algebra is finite dimensional.

Joseph Kouneiher

I describe our understanding of physics near the planck length, in particular the great progress of the last four years in string theory. Superstring theory, and a recent extension called M theory, are leading candidates for a quantum theory that unifies gravity with the other forces. As such, they are certainly not ordinary quantum field theories. However,

P. F. Harrison, D. H. Perkins, W. G. Scott

We re-fit for the neutrino mass-squared difference $Δm^2$ in the threefold maximal (ie. tri-maximal) mixing scenario using recent CHOOZ and SUPER-K data, taking account of matter effects in the Earth. While matter effects have little influence on reactor experiments and proposed long-baseline accelerator experiments with $L \simlt 1000 km$, they are highly s

J. A. Casas, V. Di Clemente, A. Ibarra, M. Quiros

If neutrino masses are produced by a see-saw mechanism the Standard Model prediction for the Higgs mass window (defined by upper (perturbativity) and lower (stability) bounds) can be substantially affected. Actually the Higgs mass window can close completely, which settles an upper bound on the Majorana mass for the right-handed neutrinos, $M$, ranging from

Efrat Shimshoni

In attempt to settle the apparent disagreements between different experimental results, transport data near quantum Hall transitions are interpreted by identifying two distinct conduction regimes. The ``classical&#39;&#39; regime, dominated by nearest neighbor hopping between localized conducting puddles, manifests an activated-like resistivity formula, and

Benjamin J. Weiner, J. A. Sellwood

Longitude-velocity (l-V) diagrams of H I and CO gas in the inner Milky Way have long been known to be inconsistent with circular motion in an axisymmetric potential. Several lines of evidence suggest that the Galaxy is barred, and gas flow in a barred potential could be consistent with the observed ``forbidden&#39;&#39; velocities and other features in the d

Volker Bromm, Bradley E. Schaefer

We have constructed a broad-band spectrum for GRB 930131 (the ``Superbowl Burst&#39;&#39;), ranging from 20 keV to 200 MeV, by combining spectral information from the Gamma Ray Observatory&#39;s BATSE, COMPTEL and EGRET instruments. We present general methods for combining spectra from different time intervals obtained by the same instrument as well as for c

Amand Faessler, C. Fuchs, M. I. Krivoruchenko

The invariant mass spectrum of the $e^{+}e^{-}$ and $μ^{+}μ^{-}$ pairs from decays of light unflavored mesons with masses below the $ϕ(1020)$-meson mass to final states containing along with a dilepton pair one photon, one meson, and two mesons are calculated within the framework of the effective meson theory. The results can be used for simulations of the d

D. Ghilencea

We apply the Renormalisation Group Evolution (RGE) to analyze the phenomenological implications of an extended supersymmetric model, for the value of the unification scale and the strong coupling at the electroweak scale. The model we consider is predicted to exist in Calabi-Yau string compactifications with Wilson line mechanism for $E_6$ symmetry breaking,

Shou-Cheng Zhang, Jiang-Ping Hu, Enrico Arrigoni, Werner Hanke

We construct a class of projected SO(5) models where the Gutzwiller constraint of no-double-occupancy is implemented exactly. We introduce the concept of projected SO(5) symmetry where all static correlation functions are exactly SO(5) symmetric and discuss the signature of the projected SO(5) symmetry in dynamical correlation functions. We show that this cl

Renyue Cen

It is shown that differential Doppler shift of different patches of the blastwave front in the fireball model at varying angles to the line of sight could provide an intrinsic smoothing mechanism for the spectra of gamma-ray bursts (GRBs) and the associated afterglows at lower energy bands. For the model parameters of interest, it is illustrated that a monoc

James V. Steele

The origin of the breakdown scale in an effective field theory treatment of nuclear forces is investigated. Different organizational schemes used in the nonperturbative calculation of nucleon-nucleon scattering seem to break down for different physical reasons. It is argued that the same physics is actually responsible, namely strong two-pion exchange as als

Elena Gubankova, Gabor Papp

The effective Hamiltonian, as obtained from applying the Hamiltonian flow equations to front form QED, are solved numerically for positronium. Both the exchange and the annihilation channels are included. The impact of different similarity functions is explicitly studied. Perfect numerical agreement with other methods is found.

Mark D. Roberts

A generalization of scalar electrodynamics called fluid electrodynamics is presented. In this theory a fluid replaces the Higgs scalar field. Fluid electrodynamics might have application to the theory of low temperature Helium superfluids, but here it is argued that it provides an alternative method of approaching symmetry breaking in particle physics. The m

A. Bohm, H. Kaldass, S. Wickramasekara, P. Kielanowski

Gamow vectors in non-relativistic quantum mechanics are generalized eigenvectors (kets) of self-adjoint Hamiltonians with complex eigenvalues. Like the Dirac kets, they are mathematically well defined in the Rigged Hilbert Space. Gamow kets are derived from the resonance poles of the S-matrix. They have a Breit-Wigner energy distribution, an exponential deca

R. J. M. Covolan, A. V. Kisselev

The recent data from H1 Collaboration on hadron multiplicity in diffractive DIS has been studied in the framework of perturbative QCD as a function of invariant diffractive mass. The formulas obtained explain the observed excess of particle production in diffractive DIS relative to that in DIS and $e^+e^-$ annihilation. It is shown that the results are sensi

N. Haba, Y. Matsui, N. Okamura, M. Sugiura

We study an energy-scale dependence of the lepton-flavor-mixing matrix in the minimal supersymmetric standard model with the effective dimension-five operators which give the masses of neutrinos. We analyze the renormalization group equations of kappa_{ij}s which are coefficients of these effective operators under the approximation to neglect the corrections

E. Trias, J. J. Mazo, T. P. Orlando

We present an experimental study of discrete breathers in an underdamped Josephson-junction array. Breathers exist under a range of dc current biases and temperatures, and are detected by measuring dc voltages. We find the maximum allowable bias current for the breather is proportional to the array depinning current while the minimum current seems to be rela

Tatsuo Komori, Hajime Yoshino, Hajime Takayama

Using Monte Carlo simulations, we have studied the relaxation of energy of the three-dimensional Ising spin-glass model in aging process. Our finite-size-scaling analysis on the isothermal energy decay after the quench suggests strongly that the energy relaxes by coarsening of domain walls in agreement with the droplet theory. We have also evaluated relaxati

L. L. Kiss, K. Szatmary, R. R. Cadmus, J. A. Mattei

We present a detailed period analysis for 93 red semiregular variables by means of Fourier and wavelet analyses of long-term visual observations carried out by amateur astronomers. The results of this analysis yield insights into the mode structure of semiregular variables and help to clarify the relationship between them and Mira variables. After collecting

Christoph Schaab, Armen Sedrakian, Fridolin Weber, Manfred K. Weigel

The impact of various competing heating processes on the thermal evolution of neutron stars is investigated. We show that internal heating leads to significantly enhanced surface temperatures for pulsars of middle and old age. The heating due to thermal creep of pinned vortices and due to outward motion of proton vortices in the interior of the star leads to

A. J. Barger, L. L. Cowie, D. B. Sanders

Recent deep blank field submillimeter surveys have revealed a population of luminous high redshift galaxies that emit most of their energy in the submillimeter. The results suggest that much of the star formation at high redshift may be hidden to optical observations. In this paper we present wide-area 850-micron SCUBA data on the Hawaii Survey Fields SSA13,

Z. L. Xiao, E. Y. Andrei, M. J. Higgins

We report on experiments probing the evolution of a vortex state in response to a driving current in 2H-NbSe$_2$ crystals. By following the vortex motion with fast transport measurements we find that the current enables the system to reorganize and access new configurations. During this process the system exhibits a long-term memory: if the current is turned

Craig A. Tracy, Harold Widom

We consider the distributions of the lengths of the longest weakly increasing and strongly decreasing subsequences in words of length N from an alphabet of k letters. We find Toeplitz determinant representations for the exponential generating functions (on N) of these distribution functions and show that they are expressible in terms of solutions of Painlevé

K. Krishana, N. P. Ong, Y. Zhang, Z. A. Xu

We present a way to extract the quasiparticle (qp) thermal conductivity Kappa_e and mean-free-path in YBa_2Cu_3O_x, using the thermal Hall effect and the magnetoconductance of Kappa_e. The results are very consistent with heat capacity experiments. Moreover, we find a simple relation between the thermal Hall angle Theta_Q and the H-dependence of Kappa_e, as

I. Ennes, S. Naculich, H. Rhedin, H. Schnitzer

The one-instanton contribution to the prepotential for N=2 supersymmetric gauge theories with classical groups exhibits a universality of form. We extrapolate the observed regularity to SU(N) gauge theory with two antisymmetric hypermultiplets and N_f \leq 3 hypermultiplets in the defining representation. Using methods developed for the instanton expansion o

John W. Barrett, Louis Crane

We give a relativistic spin network model for quantum gravity based on the Lorentz group and its q-deformation, the Quantum Lorentz Algebra. We propose a combinatorial model for the path integral given by an integral over suitable representations of this algebra. This generalises the state sum models for the case of the four-dimensional rotation group previo

A. Corichi, G. Cruz-Pacheco, A. Minzoni, P. Padilla

In the present work the evolution of a coherent field structure of the Sine-Gordon equation under quantum fluctuations is studied. The basic equations are derived from the coherent state approximation to the functional Schrödinger equation for the field. These equations are solved asymptotically and numerically for three physical situations. The first is the

Emiliano Papa, Alexei M. Tsvelik

Using the recently obtained exact results for the expectation values of operators in the sine- and sinh-Gordon models [A. B. Zamolodchikov and S. Lukyanov, Nucl. Phys. B{\bf 493}, 571 (1997), V. Fateev, S. Lukyanov, A. B. Zamolodchikov and Al. B. Zamolodchikov, Phys. Lett. B{\bf 406}, 83 (1997)] we calculate the specific heat of the corresponding two dimensi

D. L. Sisson, S. G. Doettinger, A. Kapitulnik, R. Liang

The magnetic field dependence of the specific heat of Zn-doped single crystals of YBa_{2}Cu_3O_{6.95} was measured between 2 and 10 K and up to 8 Tesla. Doping levels of 0, 0.15%, 0.31%, and 1% were studied and compared. In particular we searched for the Schottky anomaly associated with the Zn-induced magnetic moments.

A. Szczurek, V. Uleshchenko

We construct a simple two-phase model of the nucleon structure functions valid for both small and large Q^2 and in the broad range of Bjorken x. The model incorporates hadron dominance at small x and Q^2 and parton model at large Q^2. The VDM contribution is modified for small fluctuation times of the hadronic state of the photon. With two free parameters we

Harald Fritzsch, Zhi-zhong Xing

In view of the observed strong hierarchy of quark masses, we propose a new description of flavor mixing which is particularly suited for models of quark mass matrices based on flavor symmetries. The necessary and sufficient conditions for CP violation are clarified. The emergence of CP violation is primarily linked to a large phase difference (near 90^{\circ

C. Panagiotakopoulos

In the presence of fields without superpotential but with large vevs through D-terms the mass-squared of the inflaton in the context of supergravity hybrid inflation receives positive contributions which could cancel the possibly negative K$\ddot{a}$hler potential ones. The mechanism is demonstrated using K$\ddot{a}$hler potentials associated with products o

Chen-Ping Zhu, Shi-Jie Xiong, Tao Chen

We prove that the hierarchical fractal model recently proposed for describing the stretched polymers [A. N. Samukhin et al, Phys. Rev. Lett.{\bf 78}, 326(1997)] is equivalent to a one-dimensional chain with hierarchical aperiodic structure. By use of the transfer matrix technique we calculate the electronic transmission and the dc conductance. We find that t

Vadim M. Loktev, Rachel M. Quick, Sergei G. Sharapov

The presence of nonmagnetic impurities in a 2D ``bad metal&#39;&#39; depresses the superconducting Berezinskii-Kosterlitz-Thouless transition temperature, while leaving the pairing energy scale unchanged. Thus the region of the pseudogap non-superconducting phase, where the modulus of the order parameter is non-zero but its phase is random, and which opens a

B. Coluzzi, G. Parisi, P. Verrocchio

We study the liquid-glass transition of the Lennard-Jones binary mixture introduced by Kob and Andersen from a thermodynamic point of view. By means of the replica approach, translating the problem in the study of a molecular liquid, we study the phase transition due to the entropy crisis and we find that the Kauzmann&#39;s temperature $\tk$ is $\sim 0.32$.

Helen Johnston, Rob Fender, Kinwah Wu

We present new optical and infrared (IR) observations of Cir X-1 taken near apastron. Both sets of spectra show asymmetric emission lines. Archival optical observations show that an asymmetric H-alpha emission line has been in evidence for the past twenty years, although the shape of the line has changed significantly. We present an eccentric (e ~ 0.7-0.9) l