July 1998 arXiv papers — page 2

L. Coraggio, A. Covello, A. Gargano, N. Itaco

The structure of the nuclei 206,205,204Pb is studied interms of shell model employing a realistic effective interaction derived from the Bonn A nucleon-nucleon potential. The energy spectra, binding energies and electromagnetic properties are calculated and compared with experiment. A very good overall agreement is obtained. This evidences the reliability of

Takashi Nakatsukasa, Niels R. Walet

We investigate a description of shape-mixing and shape-transitions using collective coordinates. To that end we apply a theory of adiabatic large-amplitude motion to a simplified nuclear shell-model, where the approximate results can be contrasted with exact diagonalisations. We find excellent agreement for different regimes, and contrast the results with th

Oliver Rudolph

We propose a framework for temporal quantum theories for the purpose of describing states and observables associated with extended regions of space time quantum mechanically. The proposal is motivated by Isham's history theories. We discuss its relation to Isham's history theories and to standard quantum mechanics. We generalize the Isham-Linden info

Susan Tolman, Jonathan Weitsman

Let $M$ be a symplectic manifold, equipped with a Hamiltonian action of a torus $T$. We give an explicit formula for the rational cohomology ring of the symplectic quotient $M//T$ in terms of the cohomology ring of $M$ and fixed point data. Under some restrictions, our formulas apply to integral cohomology. In certain cases these methods enable us to show th

Andrzej Roslanowski, Saharon Shelah

We present a systematic study of the method of "norms on possibilities" of building forcing notions with keeping their properties under full control. This technique allows us to answer several open problems, but on our way to get the solutions we develop various ideas interesting per se.These include a new iterable condition for ``not adding Cohen re

Yuxi Zheng, Tong Zhang

We establish rigorously the existence of a three-parameter family of self-similar,globally bounded, and continuous weak solutions in two space dimensions to the compressible Euler equations with axisymmetry for gamma-law polytropic gases with gamma between 1 and 2, including 1. The initial data of these solutions have constant densities and outward-swirling

Efrain J. Ferrer, Vivian de la Incera

The charged anyon fluid in the presence of an externally applied constant and homogeneous magnetic field is investigated at temperatures larger than the energy gap ($T\gg ω_{c}$). It is shown that the applied magnetic field inhomogeneously penetrates the sample with a spatial periodicity depending on a wavelength that decreases with temperature. The distribu

Sergey A. Cherkis

Various string theory realizations of three-dimensional gauge theories relate them to gravitational instantons, Nahm equations and monopoles. We use this correspondence to model self-dual gravitational instantons of $D_k$-type as moduli spaces of singular monopoles, find their twistor spaces and metrics.

V. Fateev, D. Fradkin, S. Lukyanov, A. Zamolodchikov

We obtain exactly the vacuum expectation values $<(\partialϕ)^2 ({\bar\partial}ϕ) e^{iαϕ}>$ in the sine-Gordon model and $<L_{-2}{\bar L}_{-2} Φ_{l,k}>$ in $Φ_{1,3}$ perturbed minimal CFT. We discuss applications of these results to short-distance expansions of two-point correlation functions.

Michael R. Douglas

We show that discrete torsion is implemented in a D-brane world-volume theory by using a projective representation of the orbifold point group. We study the example of C^3/Z_2 x Z_2 and show that the resolution of singularities agrees with that proposed by Vafa and Witten. A new type of fractional brane appears.

Matthias Doerrzapf, Beatriz Gato-Rivera

Verma modules of superconfomal algebras can have singular vector spaces with dimensions greater than 1. Following a method developed for the Virasoro algebra by Kent, we introduce the concept of adapted orderings on superconformal algebras. We prove several general results on the ordering kernels associated to the adapted orderings and show that the size of

Jiannis Pachos

Within the Electric Schroedinger Representation of the Yang-Mills theory the Hamiltonian eigenstate and eigenvalue, as well as the Coulomb and confining potentials are presented for a special regularization-approximation scheme, which focuses on the ultra-local behavior of the propagator.

G. Handrich, C. Nowak

The quantum algebra of observables postulated in hep-th/9805057 is constructed up to degree five. All independent relations of degree four are given; they involve three as yet undetermined parameters. Definitions and symbols are used as introduced in the above-mentioned article.

Micha Berkooz

We suggest a model of the large N limit ${\cal N}=4$ D=4 SU(N) SYM as a gas of 3-branes in a 10 dimensional space. Field theory analysis suggests that this 10 dimensional space does not carry the usual gravity dynamics but rather a contraction of it. Using a non-local transformation some aspects of the dynamics of this system are mapped to the dynamics of st

David A. Lowe

The supermembrane in light-cone gauge gives rise to a supersymmetric quantum mechanics system with SU(N) gauge symmetry when the group of area preserving diffeomorphisms is suitably regulated. de Wit, Marquard and Nicolai showed how eleven-dimensional Lorentz generators can be constructed from these degrees of freedom at the classical level. In this paper, t

A. Opfermann

It is shown that all affine Toda theories admit (1,0) supersymmetric extensions. The construction is based on classical Lie algebras and supersymmetric massive sigma models. The supersymmetrized affine Toda theories have a unique, supersymmetric vacuum, their mass matrix is well defined and their energy functional is positive semi-definite.

Enrique Alvarez, Cesar Gomez

In this paper the whole geometrical set-up giving a conformally invariant holographic projection of a diffeomorphism invariant bulk theory is clarified. By studying the renormalization group flow along null geodesic congruences a holographic version of Zamolodchikov&#39;s c-theorem is proven.

Takayuki Suga, Riuji Mochizuki, Kenji Ikegami

It has been a puzzle that rotating detector may respond even in the appropriate vacuum defined via canonical quantization. We solve this puzzle by taking back reaction of the detector into account. The influence of the back reaction, even in the detector&#39;s mass infinite limit, appears in the response function. It makes the detector possible to respond in

Jian Tang

We explore the possibility of probing the nucleon&#39;s transversity distribution $δq(x)$ through the final state interaction between two mesons ($π^+π^-$, $πK$, or $K\bar K$) produced in transversely polarized nucleon-nucleon collisions. We present a single spin asymmetry and estimate its magnitude under some assumptions for the transversity distribution fu

D. Wackeroth

We present some results of the calculation of MSSM one-loop contributions to strong $t \bar t$ production in hadronic collisions. Here we concentrate on the MSSM electroweak-like O(α) and SQCD O(α_s) corrections to the main production mechanism at the Fermilab Tevatron $p \bar p$ collider, $q\bar q\to g \to t \bar t$. We give results for the total $t \bar t$

M. Plumacher

The baryon asymmetry of the universe can be explained by the out-of-equilibrium decays of heavy right-handed neutrinos. We analyse this mechanism in the framework of a supersymmetric extension of the Standard Model and show that lepton number violating scatterings are indispensable for baryogenesis, even though they may wash-out a generated asymmetry. By ass

George Siopsis

We study the effects of gluon interference in the production and semi-leptonic decay of a t-tbar pair above threshold at the Next Linear Collider (NLC). We calculate all matrix elements to next-to-leading order and use the resulting expressions for the development of a Monte Carlo event generator. Our results show effects at the level of 10% in differential

Stanislaw Mrowczynski

The calculations of the elementary atom (the Coulomb bound state of elementary particles) interaction with the atom of matter, which are performed in the Born approximation, are reviewed. We first discuss the nonrelativistic approach and then its relativistic generalization. The cross section of the elementary atom excitation and ionization as well as the to

Rajiv V. Gavai

A systematic analysis of the L-dependence of the J/psi-suppression in the data of the CERN NA38 and NA50 experiments shows that the anomalous suppression in the 1995 Pb-Pb data is at best a 4$σ$ effect at any of the L-values for the Pb-Pb data, where L is the geometrical mean path length of the J/psi in the colliding nuclei. Possible implications for the 199

M. V. Libanov, V. A. Rubakov, P. G. Tinyakov

We propose a scenario of the beginning of inflation in which the non-vacuum value of the scalar field that drives inflation develops dynamically due to the non-minimal coupling to gravity. In this scenario, inflation emerges as an intermediate stage of the evolution of the Universe, well after the Planck epoch, from a fairly general initial state.

Naoyuki Haba

We suggest a simple composite model that induces the large flavor mixing of neutrino in the supersymmetric theory. This model has only one hyper-color in addition to the standard gauge group, which makes composite states of preons. In this model, {\bf 10} and {\bf 1} representations in SU(5) grand unified theory are composite states and produce the mass hier

Harald Fritzsch

In view of the observed strong hierarchy of the quark and lepton masses and of the flavor mixing angles it is argued that the description of flavor mixing must take this into account. One particular interesting way to describe the flavor mixing, which, however, is not the one used today, emerges, which is particularly suited for models of quark mass matrices

Romuald A. Janik, Maciej A. Nowak, Gabor Papp, Ismail Zahed

If QCD is to undergo a second order phase transition, the light quark return probability is universal for large times at the critical point. We show that this behavior is distinct from the one expected at the mobility edge of a metal-insulator transition or a percolation transition in d$\leq 4$. Our results are accessible to current lattice QCD simulations.

Elisabeth Kraus, Georg Weiglein

We derive the Callan-Symanzik equation of the electroweak Standard Model in the QED-like on-shell parameterization. The various coefficient functions, the $β$-functions and anomalous dimensions, are determined in one-loop order in the most general linear gauge compatible with rigid symmetry. In this way the basic elements for a systematic investigation of hi

A. S. Belyaev, A. V. Gladyshev

The excess of high $Q^2$ events at HERA reported in the early 1997 by H1 and ZEUS collaborations has become the subject of extensive studies in the framework of several models related to new physics. Here we concentrate on the most promising, from our point of view, model describing HERA anomaly. We update our previous analysis and take into account new HERA

B. A. Kniehl, A. Sirlin

The gauge dependence of the Higgs-boson mass and width in the on-shell scheme of renormalization is studied in the heavy-Higgs-boson approximation. The corresponding expansions in the pole scheme are analyzed adopting three frequently employed parametrizations. The convergence properties and other theoretical features of the on-shell and pole expansions, as

A. Rajantie, K. Kajantie, M. Karjalainen, M. Laine

Scalar electrodynamics can be used to investigate the formation of cosmic strings in the early universe. We present the results of lattice Monte Carlo simulations of an effective three-dimensional U(1)+Higgs theory that describes the equilibrium properties of finite-temperature scalar electrodynamics near the transition. A gauge-invariant criterion for the e

E. Bittner, A. Hauke, C. Holm, W. Janke

Standard Regge Calculus provides an interesting method to explore quantum gravity in a non-perturbative fashion but turns out to be a CPU-time demanding enterprise. One therefore seeks for suitable approximations which retain most of its universal features. The $Z_2$-Regge model could be such a desired simplification. Here the quadratic edge lengths $q$ of t

A. A. Slavnov

A new multifermion formulation of lattice QCD is proposed. The model is free of spectrum doubling and preserves all nonanomalous chiral symmetries up to exponentially small corrections. It is argued that a small number of fermion fields may provide a good approximation making computer simulations feasible.

A. Anastassov

We report on a study of exclusive radiative decays of the Upsilon(1S) resonance collected with the CLEO-II detector operating at CESR. We present the first observation of the radiative decays Upsilon(1S)->gamma pi+pi- and Upsilon(1S)->gamma pi0pi0. For the dipion mass regime m(pipi)>1.0 GeV, we obtain Br(Upsilon(1S)->gamma pi+pi-=(6.3+/-1.2+/-1.3) x 10^(-5),

A. Camacho

In this work the possible role that Decoherence Model could play in the emergence of the classical concept of time is analyzed. We take the case of a Mixmaster universe with small anisotropy and construct its Halliwell propagator. Afterwards we introduce in our system terms that comprise the effects of Decoherence Model. This is done by means of the so calle

Eric Baird

Equivalence principles are a major part of modern relativity theory. Gravitational shifts can already be calculated within the time domain as motion shifts, and we examine the consequences of reversing this argument and describing motion shifts outside the time domain, as effects of curvature associated with relative velocity. This unusual &#34;Doppler mass

Hyeong-Chan Kim, Yoonbai Kim, Phillial Oh

We compute the entropy of systems of quantum particles satisfying the fractional exclusion statistics in the space-time of 2+1 dimensional black hole by using the brick-wall method. We show that the entropy of each effective quantum field theory with a Planck scale ultraviolet cutoff obeys the area law, irrespective of the angular momentum of the black hole

Shyan-Ming Perng

There is a well-known short list of asymptotic conserved quantities for a physical system at spatial infinity. We search for new ones.This is carried outwithin the asymptotic framework of Ashtekar and Romano, in which spatial infinity is represented as a smooth boundary of space-time. We first introduce, for physical fields on space-time,a characterization o

C. M. Soukoulis, Xiaosha Wang, Qiming Li, M. M. Sigalas

The probability distribution of the conductance Pc(g) at the Anderson critical point is calculated. It is find that Pc(g) has a dip at small g in agreement with epsilon expansion results. The Pc(g) for the 3d system is quite different from the 2d quantum critical point of the integer quantum Hall effect. The universality or not of these distributions is of c

Claudine Lacroix, Benjamin Canals, M. D. Nunez-Regueiro

UNi4B exhibits unusual properties and, in particular, a unique antiferromagnetic arrangement involving only 2/3 of the U sites. Based on the low temperature behavior of this compound, we propose that the remaining 1/3 U sites are nonmagnetic due to the Kondo effect. We derive a model in which the coexistence of magnetic and nonmagnetic U sites is the consequ

Benjamin Canals, Claudine Lacroix

The quantum pyrochlore antiferromagnet is studied by perturbative expansions and exact diagonalization of small clusters. We find that the ground state is a spin-liquid state: The spin-spin correlation functions decay exponentially with distance and the correlation length never exceeds the interatomic distance. The calculated magnetic neutron diffraction cro

B. DeMarco, D. S. Jin

We predict novel phenomena in the behavior of an ultra- cold, trapped gas of fermionic atoms. We find that quantum statistics radically changes the collisional properties, spatial profile, and off-resonant light scattering properties of the atomic fermion system, and we suggest how these effects can be observed.

N. M. Makarov, A. V. Moroz

We calculated the spectrum of normal scalar waves in a planar waveguide with absolutely soft randomly rough boundaries beyond the perturbation theories in the roughness heights and slopes, basing on the exact boundary scattering potential. The spectrum is proved to be a nearly real non-analytic function of the dispersion $ζ^2$ of the roughness heights (with

T. Xiang, C. Panagopoulos, J. R. Cooper

We have reviewed our theoretical and experimental results of the low temperature superfluid response function of high temperature superconductors (HTSC). In clean high-Tc materials the in-plane superfluid density rho_s^{ab} varies linearly with temperature. The slope of this linear T term is found to scale approximately with 1/Tc which, according to the weak

J. M. G. Vilar, A. Corral

We explore systems of pulse-coupled oscillators beyond the mean-field limit [R.E. Mirollo and S.H. Strogatz, {SIAM J. Appl. Math.} {\bf 50}, 1645 (1990)] by means of a manageable description which leads to a great simplification of the dynamics. Sufficient conditions for synchronization are exactly obtained for a ring with nearest-neighbor directed interacti

A. Avella, F. Mancini, D. Villani

The results of G. Su and M. Suzuki [Phys. Rev. B 54, 8291 (1996); ibidem 57, 13367 (1998)] for the spin and pseudo-spin symmetry properties of the Hubbard model are reexamined. We point out that the exact relations they have found are valid down to zero temperature and that their solutions for both spin and pseudo-spin correlation functions are incorrect.

Yu. Holovatch, T. Yavors&#39;kii

Within the massive field theoretical renormalization group approach the expressions for the beta- and gamma-functions of the anisotropic mn-vector model are obtained for general space dimension d in three-loop approximation. Resumming corresponding asymptotic series, critical exponents for the case of the weakly diluted quenched Ising model (m=1, n=0), as we

D. Sornette

We advance the novel hypothesis that water in the presence of finite localized strain within fault gouges may lead to the phase transformation of stable minerals into metastable polymorphs of higher free energy density. Under increasing strain, the transformed minerals eventually become unstable, as shown from an application of Landau theory of structural ph

S. Metens, D. Lima, P. Borckmans, G. Dewel

We investigate within the Gross-Pitaevski (GP) theory the formation of fringe patterns between two Bose condensates stored in a double well potential modelling the forces applied to the experimental systems. In the case of repulsive interactions between the atoms, we report the onset of interference structures similar to those observed in the experiments, af

L. Pitaevskii, S. Stringari

Using hydrodynamic theory of superfluids and the Lee-Huang-Yang equation of state for interacting Bose gases we derive the first correction to the collective frequencies of a trapped gas, due to effects beyond mean field approximation. The corresponding frequency shift, which is calculated at zero temperature and for large N, is compared with other correctio

Karin A. Dahmen, David R. Nelson, Nadav M. Shnerb

We propose a simple experiment to study delocalization and extinction in inhomogeneous biological systems. The nonlinear steady state for, say, a bacteria colony living on and near a patch of nutrient or favorable illumination (``oasis&#39;&#39;) in the presence of a drift term (``wind&#39;&#39;) is computed. The bacteria, described by a simple generalizatio

Kirill N. Alekseev, Gennady P. Berman

We consider the chaotic dynamics of the interaction between an ensemble of two-level atoms in a high-Q Fabry-Perot cavity with a single mode of self-consistent field and with an external amplitude-modulated field. It is shown that in the case of an exact atom-field resonance and at the initial population of the atomic ground state, the Hamiltonian chaos in t

Ricardo P. Schiavon, Beatriz Barbuy

We have computed a grid of high resolution synthetic spectra for cool stars (2500<Teff<6000 K) in the wavelength range 6000 -- 10200A, by employing an updated line list of atomic and molecular lines, together with state-of-the-art model atmospheres. As a by-product, by fitting TiO bandheads in spectra of well-known M giants, we have derived the electronic os

Jing Wang, Timothy M. Heckman, Matthew D. Lehnert

We analyze H$α$ images and long-slit spectra of samples of normal and starburst galaxies to better understand the nature of the diffuse, low-surface-brightness gas in these galaxies. We find that in both samples there is a strong inverse correlation between the H$α$ surface-brightness ($Σ_{Hα}$) and the [SII]/H$α$ line ratio at a given location in the galaxy

J. P. Norris, J. T. Bonnell, K. Watanabe

We explore the hypothesis, similar to one recently suggested by Bloom and colleagues, that some nearby supernovae are associated with smooth, single-pulse gamma-ray bursts, possibly having no emission above ~ 300 keV. We examine BATSE bursts with durations longer than 2 s, fitting those which can be visually characterized as single-pulse events with a lognor

Volker Springel, Simon D. M. White

We study the formation of tidal tails in pairs of merging disk galaxies with structural properties motivated by current theories of cold dark matter (CDM) cosmologies. In a recent study, Dubinski, Mihos & Hernquist (1996) showed that the formation of prominent tidal tails can be strongly suppressed by massive and extended dark haloes. For the large halo-to-d

R. R. Caldwell, Marc Kamionkowski, Leven Wadley

Gravitational waves provide a laboratory for general relativity and a window to energetic astrophysical phenomena invisible with electromagnetic radiation. Several terrestrial detectors are currently under construction, and a space-based interferometer is envisioned for launch early next century to detect test-mass motions induced by waves of relatively shor

A. P. Reynolds, A. N. Parmar, P. J. Hakala, A. M. T. Pollock

We present a catalog of X-ray sources observed during slew maneuvers by the Medium Energy Detector Array onboard the EXOSAT Observatory. The EXOSAT Medium Energy slew-survey catalog (EXMS) provides a unique record of the 1--8 keV X-ray sky between 1983 and 1986. 98% of the sky was observed, with 85% receiving an exposure of >60 s. 1210 sources were detected.

G. Ghisellini, A. Celotti, G. Fossati, L. Maraschi

The phenomenology of gamma-ray bright blazars can be accounted for by a sequence in the source power and intensity of the diffuse radiation field surrounding the relativistic jet. Correspondingly, the equilibrium particle distribution peaks at different energies. This leads to a trend in the observed properties: an increase of the observed power corresponds

G. S. Bisnovatyi-Kogan, A. V. Dorodnitsyn

Approximate approach based on the Galerkin method is suggested for the investigation of equilibrium stellar models, a relativistic collapse problem and black hole formation. Some results of its simplified version - energetic method- are reviewed, and equations for general Gelerkin method are presented.

J. S. Bloom, S. G. Djorgovski, S. R. Kulkarni, D. A. Frail

We present late-time imaging and spectroscopic observations of the optical transient (OT) of gamma-ray burst (GRB) 970508. Imaging observations roughly 200 and 300 days after the burst provide unambiguous evidence for the flattening of the light-curve. The spectroscopic observations reveal two persistent features which we identify with [O II] 3727 Angstrom a

J. J. M. in &#39;t Zand, L. Amati, L. A. Antonelli, R. C. Butler

GRB 980329 is the brightest gamma-ray burst detected so far with the Wide Field Cameras aboard BeppoSAX, both in gamma-rays and X-rays. With respect to its fluence (2.6 X 10**-5 erg/s/cm**2 in 50 to 300 keV) it would be in the top 4% of gamma-ray bursts in the 4B catalog (Meegan et al. 1998). The time-averaged burst spectrum from 2 to 20 and 70 to 650 keV ca

Chris Simpson, Vikki Meadows

We present near-infrared spectra of the nuclear disk in the nearby radio galaxy NGC 5128 (Centaurus A). On the basis of the observed strengths of the [S III] 0.9532um and [Fe II] 1.2567um lines, we classify NGC 5128 as a LINER. Modeling of the strengths of these and additional lines suggests that the nuclear region is powered by shocks rather than photoioniz

A. R. R. Casti, P. J. Morrison, E. A. Spiegel

We study the longitudinal instabilities of two interpenetrating fluids interacting only through gravity. When one of the constituents is of relatively low density, it is possible to have a band of unstable wave numbers well separated from those involved in the usual Jeans instability. If the initial streaming is large enough, and there is no linear instabili

J. Velkovska, R. L. McGrath

A method for plasma delay and pulse-height defect corrections for Si surface barrier detectors (SBD) is presented. Based on known empirical formulae, simple approximations involving the measured time-of-flight (TOF) and energy of the ions were found and a mass reconstruction procedure was developed. The procedure was applied for obtaining the fission fragmen

Ian. I. Kogan, O. A. Soloviev

We propose a world-sheet realization of the zigzag-invariant bosonic and fermionic strings as a perturbed Wess-Zumino-Novikov-Witten model at large negative level $k$ on a group manifold $G$ coupled to 2D gravity. In the large $k$ limit the zigzag symmetry can be obtained as a result of a self-consistent solution of the gravitationally dressed RG equation. T

John Bahcall, Plamen Krastev

If the low energy cross section for 3He + p goes to 4He + e + nu_e, the `hep&#39; reaction, is > 20 times larger than the best (but uncertain) theoretical estimates, then this reaction could significantly influence the electron energy spectrum produced by solar neutrino interactions and measured in the SuperKamiokande, SNO, and ICARUS experiments. We compare

Lutfi Ozyuzer, John F. Zasadzinski, Chris Kendziora, Kenneth E. Gray

The point contact tunneling technique is used to examine quasiparticle and Josephson currents in overdoped Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+δ}$ (Bi-2212) single crystals with bulk T$_{c}$ values near 62 K. High quality superconductor-insulator-normal metal (SIN) tunnel junctions are formed between Bi-2212 crystals and a Au tip, which display well-resolved qua

R. F. Alvarez-Estrada, J. L. Sanchez-Gomez

We study the time evolution of decaying particles in renormalizable models of Relativistic Quantum Field Theory. Significant differences between the latter and Non Relativistic Quantum Mechanics are found -in particular, the Zeno effect seems to be absent in such RQFT models. Conventional renormalization yields finite time behavior in some cases but fails to

B. G. Zakharov

A new rigorous light-cone path integral approach to the Landau-Pomeranchuk-Migdal effect in QED and QCD is discussed. The rate of photon (gluon) radiation by an electron (quark) in a medium is expressed through the Green&#39;s function of a two-dimensional Schrodinger equation with an imaginary potential. In QED this potential is proportional to the dipole c

L. L. Salcedo

The temperature dependence of the anomalous sector of the effective action of fermions coupled to external gauge and pseudo-scalar fields is computed at leading order in an expansion in the number of Lorentz indices in two and four dimensions. The calculation preserves chiral symmetry and confirms that a temperature dependence is compatible with axial anomal

A. Lima-Santos

The nineteen-vertex models of Zamolodchikov-Fateev, Izergin-Korepin and the supersymmetric osp(1|2) with periodic boundary conditions are studied. We find the spectrum of these quantum spin chains using the Coordinate Bethe Ansatz. The approche is a suitable parametrization of their wavefunctions. We also applied the Algebraic Bethe Ansatz in order to obtain

M. Benayoun, H. B. O&#39;Connell, A. G. Williams

We discuss the properties of vector mesons, in particular the rho^0, in the context of the Hidden Local Symmetry (HLS) model. This provides a unified framework to study several aspects of the low energy QCD sector. Firstly, we show that in the HLS model the physical photon is massless, without requiring off field diagonalization. We then demonstrate the equi

Steen Hannestad

We investigate the possible effect of the residual annihilations of heavy particles after freeze-out from equilibrium in the early universe. An error in previous work on this subject is pointed out and the correct method of solving the Boltzmann equation for this case is developed. For Majorana particles there are significant differences relative to previous

M. O. Katanaev, T. Kloesch, W. Kummer

Assuming the four-dimensional space-time to be a general warped product of two surfaces we reduce the four-dimensional Einstein equations to a two-dimensional problem which can be solved. All global vacuum solutions are explicitly constructed and analysed. The classification of the solutions includes the Schwarzschild, the (anti-)de Sitter, and other well-kn

Yunkyu Bang

We show that the Migdal theorem is obviously violated in the high Tc cuprates and the vertex correction should be included, in particular, in the gap equation, in order to be consistent with the anomalously strong inelastic scattering in the ``hot spots&#39;&#39;, which is observed from the various normal state experiments. The vertex correction is obtained

Pasi Huovinen, P. V. Ruuskanen, Josef Sollfrank

We study Pb+Pb collisions at 158 A GeV/c using a hydrodynamical approach. We test different equations of state (EoSs) and different initial conditions and show that there are more than one initial state for each EoS which reproduce the observed hadronic spectra. We also find that different equations of state favour different freeze-out temperature. Simultane

S. V. Goloskokov, P. Kroll

We study $pp$ scattering at high energies and moderately large momentum transfer, using a model in which the proton is viewed as being composed of a quark and a diquark. We show that this model leads to single and double spin transverse asymmetries which are neither small nor vanish at high energies.

Reinaldo Gleiser, Carlos Nicasio, Richard Price, Jorge Pullin

The perturbation theory of black holes has been useful recently for providing estimates of gravitational radiation from black hole collisions. Second order perturbation theory, relatively undeveloped until recently, has proved to be important both for providing refined estimates and for indicating the range of validity of perturbation theory. Here we present

Blake Mellor

Bar-Natan used Chinese characters to show that finite type invariants classify string links up to homotopy. In this paper, I construct the correct spaces of chord diagrams and Chinese characters for links up to homotopy. I use these spaces to show that the only rational finite type invariants of link homotopy are the pairwise linking numbers of the component

T. Shigehara, M. Yokoyama, H. Mizoguchi, T. Mishima

In order to give some insight into a role of small impurities on the electron motion in microscopic devices, we examine from a general viewpoint, the effect of small obstacles on a particle motion at low energy inside microscopic bounded regions. It will be shown that the obstacles disturb the electron motion only if they are weakly attractive.

Heinz-Peter Breuer, Bernd Kappler, Francesco Petruccione

A stochastic simulation algorithm for the computation of multitime correlation functions which is based on the quantum state diffusion model of open systems is developed. The crucial point of the proposed scheme is a suitable extension of the quantum master equation to a doubled Hilbert space which is then unraveled by a stochastic differential equation.

Georg Junker, Pinaki Roy

Recently, based on a supersymmetric approach, new classes of conditionally exactly solvable problems have been found, which exhibit a symmetry structure characterized by non-linear algebras. In this paper the associated ``non-linear&#39;&#39; coherent states are constructed and some of their properties are discussed in detail.

Iosif Pinelis

It is demonstrated that any two reference frames (RFs), which are uniformly and rectilinearly moving relative to each other, can be adjusted via (possibly anisotropic) rescaling and re-synchronization so that the resulting pair of RFs is Lorentzian; this statement remains true if the word &#34;Lorentzian&#34; is replaced by &#34;Galilean&#34; or &#34;Riemann

Josif Frenkel, R B Santos

We discuss, in the context of classical electrodynamics with a Lorentz invariant cut-off at short distances, the self-force acting on a point charged particle. It follows that the electromagnetic mass of the point charge occurs in the equation of motion in a form consistent with special relativity. We find that the exact equation of motion does not exhibit r

A. G. Kulikovskii, N. V. Pogorelov, A. Yu Semenov

A number of physical phenomena are described by nonlinear hyperbolic equations. Presence of discontinuous solutions motivates the necessity of development of reliable numerical methods based on the fundamental mathematical properties of hyperbolic systems. Construction of such methods for systems more complicated that the Euler gas dynamic systems requires t

A. Yu. Illarionov, G. I. Lykasov

A detailed analysis of the processes of the type NN -> Dπis presented taking into account the exchange graphs of a nucleon and a pion. A large sensitivity of polarization observables to the off-mass shell effects of nucleons inside the deuteron is shown. The influence of the inclusion of the P-wave in the Deuteron Wave Function (DWF) is studied. We have anal

D. H. Lu, K. Tsushima, A. W. Thomas, A. G. Williams

We calculate electromagnetic form factors of the proton bound in specified orbits for several closed shell nuclei. The quark structure of the nucleon and the shell structure of the finite nuclei are given by the QMC model. We find that orbital electromagnetic form factors of the bound nucleon deviate significantly from those of the free nucleon.

Gregory G. Smith

Let X be a projective scheme; let M and N be two coherent O_X-modules. Given an integer m, we present an algorithm for computing the global extension module Ext^m(X;M,N). In particular, this allows one to compute the sheaf cohomology H^m(X,N) and to construct the sheaf corresponding to an element of the module Ext^1(X;M,N). This algorithm can be implemented

Deane Yang

An complete exposition of Matthias Gunther&#39;s elementary proof of Nash&#39;s isometric embedding theorem.

Chongying Dong, Kiyokazu Nagatomo

We classify the irreducible modules for the fixed point vertex operator subalgebra V_L^+ of the vertex operator algebra V_L associated to a positive definite even lattice of rank 1 under the automorphism lifted from the -1 isometry of L.

A. Cossidente, G. Korchmaros, F. Torres

We classify, up to isomorphism, maximal curves covered by the Hermitian curve \mathcal H by a prime degree Galois covering. We also compute the genus of maximal curves obtained by the quotient of \mathcal H by several automorphisms groups. Finally we discuss the value for the third largest genus that a maximal curve can have.

In-Jen Lin, Malay K. Sen, Douglas B. West

The leafage of a digraph is the minimum number of leaves in a host tree in which it has a subtree intersection representation. We discuss bounds on the leafage in terms of other parameters (including Ferrers dimension), obtaining a string of sharp inequalities.

Finnur Larusson, Ragnar Sigurdsson

We introduce a new type of pluricomplex Green function which has a logarithmic pole along a complex subspace A of a complex manifold X. It is the largest negative plurisubharmonic function on X whose Lelong number is at least the Lelong number of log max{|f_1|,...,|f_m|}, where f_1,...,f_m are local generators for the ideal sheaf of A. The pluricomplex Green

Terence Tao, Ana Vargas, Luis Vega

Bilinear restriction estimates have been appeared in work of Bourgain, Klainerman, and Machedon. In this paper we develop the theory of these estimates (together with the analogues for Kakeya estimates). As a consequence we improve the $(L^p,L^p)$ spherical restriction theorem of Wolff from $p > 42/11$ to $p > 34/9$, and also obtain a sharp $(L^p,L^q)$ spher

Theodore B. Stanford

Brunnian links have been known for a long time in knot theory, whereas the idea of n-triviality is a recent innovation. We illustrate the relationship between the two concepts with four short theorems.

Dan Burghelea

Witten- Helffer-Sjöstrand theory is a considerable addition to the De Rham- Hodge theory for Riemannian manifolds and can serve as a general tool to prove results about comparison of numerical invariants associated to compact manifolds analytically, i.e. by using a Riemannian metric, or combinatorially, i.e by using a triangulation. In this presentation a tr

Dan Burghelea

Ray Singer torsion is a numerical invariant associated with a compact Riemannian manifold equipped with a flat bundle and a Hermitian structure on this bundle. In this note we show how one can remove the dependence on the Riemannian metric and on the Hermitian structure with the help of a base point and of an Euler structure, in order to obtain a topological

A. Johansen

The relation between the trace and R-current anomalies in 4D supersymmetric theories implies that the U(1)$_R$F$^2$, U(1)$_R$ and U(1)$^3_R$ anomalies which matched in studies of N=1 Seiberg duality satisfy positivity constraints. These constraints are tested in a large number of N=1 supersymmetric gauge theories in the non-Abelian Coulomb phase, and they ar