November 1999 arXiv papers — page 14

Nikolai N. Chugai

It is predicted that H$α$ emission line at the early nebular epoch of type II-P supernovae may display robust observational effects of damping wings. This is illustrated by Monte-Carlo simulations. The strength of damping wing effects may be used to constrain parameters of the line-emitting zone. An anomalous redshift, width and red wing of H$α$ revealed by

Jacco Vink, Jelle S. Kaastra, Johan A. M. Bleeker, Andrea Preite-Martinez

We present BeppoSAX X-ray spectra of the remnant of the supernova of AD 1006, which cover a broad spectral range of 0.1-10 keV. In our analysis we concentrate on the thermal emission from the central region of the remnant. For this purpose we fitted the spectra of the whole remnant using a new version of the spectral program SPEX, which takes into account th

J. Novak, J. M. Ibanez

Tensor-scalar theory of gravity allows the generation of gravitational waves from astrophysical sources, like Supernovæ, even in the spherical case. That motivated us to study the collapse of a degenerate stellar core, within tensor-scalar gravity, leading to the formation of a neutron star through a bounce and the formation of a shock. We discuss in this pa

Karen M. Bekarian, Anahit A. Melkonian

A parametric approach is developed to the method of S-tree diagrams and its generalization for investigation of the hierarchical substructure of $N$-body nonlinearly interacting systems (e.g., clusters of galaxies). The introduction of a parametric function allows us to take into account the individual features of the particles which do not have a direct inf

G. A. Tammann, B. R. Parodi, B. Reindl

Cepheids are the pillar of the extragalactic distance scale, but their reach in distance is not sufficient to calibrate H_0. Yet HST has provided Cepheid distances to eight galaxies which have produced SNe Ia. The latter are used as nearly perfect standard candles to carry the distance scale to 30,000 km/s, giving H_0 = 58 +/- 5. This determination finds sup

Yuri Levin, Greg Ushomirsky

We use a simple physical model to study the nonlinear behaviour of the r-mode instability. We assume that r-modes (Rossby waves) are excited in a thin spherical shell of rotating incompressible fluid. For this case, exact Rossby wave solutions of arbitrary amplitude are known. We find that: (a) These nonlinear Rossby waves carry ZERO physical angular momentu

Charles H. Lineweaver

For the past 15 years most astronomers have assumed that 95% of the Universe was in some mysterious form of cold dark matter. They also assumed that the cosmological constant, Omega_Lambda, was Einstein's biggest blunder and could be ignored. However, recent measurements of the cosmic microwave background combined with other cosmological observations str

S. -J. Xue, Y. -H. Zhang

We present the analysis of archival data from ROSAT and ASCA of a serendipitous source PKS 2316-423. According to its featureless non-thermal radio/optical continuum, the object has been assumed as a BL Lac candidate in the literature. It was evident variable over the multiple X-ray observations. Specially, a variable high-energy tail of the synchrotron radi

M. Machida, MITSURU R. Hayashi, R. Matsumoto

We present the results of three-dimensional global magnetohydrodynamic (MHD) simulations of the Parker-shearing instability in a differentially rotating torus initially threaded by toroidal magnetic fields. An equilibrium model of magnetized torus is adopted as an initial condition. When $β_0 = P_{\rm gas}/P_{\rm mag} \sim 1$ at the initial state, magnetic f

Youjun Lu, Qingjuan Yu

The mass of the central black hole in Seyfert galaxies and QSOs can be determined from the broad emission lines and the reverberation method. Using the measured black hole mass and the bolometric or ionizing luminosity, the accretion rate can be estimated. Compiling a sample of Seyfert 1 galaxies and QSOs with reliable central masses, estimated ionizing lumi

Andrew Gould, S. M. Khairul Alam

If weakly interacting massive particles (WIMPs) in bound solar orbits are systematically driven into the Sun by solar-system resonances (as Farinella et al. have shown is the case for many Earth-crossing asteroids), then the capture of high-mass WIMPs by the Earth would be affected dramatically because high-mass WIMPs are captured primarily from bound orbits

Stefan W. Dieters, Brian A. Vaughan, Erik Kuulkers, Frederick K. Lamb

We have measured the phase-delay and rms amplitude spectra of CygX-2 and ScoX-1. Using EXOSAT data from the normal branch of CygX-2 we confirm earlier (Ginga) results, showing that at an energy near 6keV there is both a minimum in the QPO rms amplitude spectrum and a 150 degree phase jump in the quasi-periodic oscillations (QPO) phase-delay spectrum. Surpris

N. Michael Davies, Valentin V. Khoze

Certain exact results in supersymmetric gauge theories are generated by non-perturbative effects different from instantons. In supersymmetric QCD with N colours and Nf fundamental flavours we examine the Affleck-Dine-Seiberg (ADS) superpotential using controlled semi-classical analysis. We show how for Nf < N-1 the ADS superpotential arises from monopole con

Amihay Hanany, Alberto Zaffaroni

A realization of E_{n+1} monopoles in string theory is given. The NS five brane stuck to an Orientifold eight plane is identified as the &#39;t Hooft Polyakov monopole. Correspondingly, the moduli space of many such NS branes is identified with the moduli space of SU(2) monopoles. These monopoles transform in the spinor representation of an SO(2n) gauge grou

Adam F. Falk, Yosef Nir, Alexey A. Petrov

We argue that there could be large, SU(3) violating resonance contributions to D -> K pi decays which would affect the extraction of the D0-anti-D0 mixing parameters from experiment. Such contributions can induce a large strong phase in the interference between the doubly Cabibbo suppressed and the mixing induced Cabibbo favored contributions to the D0 -> K^

M. Joffre, P. Fischer, J. Frieman, T. McKay

We present two weak lensing reconstructions of the nearby ($z_{cl}=0.055$) merging cluster Abell 3667, based on observations taken $\sim 1$ year apart under different seeing conditions. This is the lowest redshift cluster with a weak lensing mass reconstruction to date. The reproducibility of features in the two mass maps demonstrate that weak lensing studie

Lawrence Hall, Hitoshi Murayama, Neal Weiner

What is the form of the neutrino mass matrix which governs the oscillations of the atmospheric and solar neutrinos? Features of the data have led to a dominant viewpoint where the mass matrix has an ordered, regulated pattern, perhaps dictated by a flavor symmetry. We challenge this viewpoint, and demonstrate that the data are well accounted for by a neutrin

C. M. Zhang

We ascribe the twin kilohertz Quasi Periodic Oscillations (kHz QPOs) of X-ray spectra of Low Mass X-Ray Binaries (LMXBs) to the pseudo-Newtonian Keplerian frequency and the apogee and perigee precession frequency of the same matter in the inner disk, and ascribe 15 - 60 Hz QPO (HBO) to the apogee (or perigee) precession and its second harmonic frequency to b

P. Aurenche, F. Gelis, H. Zaraket

We study the infrared singularities associated to ultra-soft transverse gluons in the calculation of photon production by a quark-gluon plasma. Despite the fact that the KLN theorem works in this context and provides cancellations of infrared singularities, it does not prevent the production rate of low invariant mass dileptons to be sensitive to the magneti

A. Crisanti, F. Ritort

We investigate the inherent structure (IS) dynamics of mean-field {\it finite-size} spin-glass models whose high-temperature dynamics is described in the thermodynamic limit by the schematic Mode Coupling Theory for super-cooled liquids. Near the threshold energy the dynamics is ruled by activated processes which induce a logarithmic slow relaxation. We show

Debajyoti Choudhury, Herbi Dreiner, Peter Richardson, Subir Sarkar

We interpret the KARMEN time anomaly as being due to the production of a (dominantly bino) neutralino with mass 33.9 MeV, which is the lightest supersymmetric particle but decays into 3 leptons through the violation of R-parity. For independent gaugino masses M_1 and M_2 we find regions in the (M_1, M_2, mu, tan beta) parameter space where such a light neutr

Y. J. Ng, H. van Dam

A recent paper (gr-qc/9909017) criticizes our work on the structure of spacetime foam. Its authors argue that the quantum uncertainty limit for the position of the quantum clock in a gedanken timing experiment, obtained by Wigner and used by us, is based on unrealistic assumptions. Here we point out some flaws in their argument. We also discuss their other c

J. S. B. Wyithe, R. L. Webster, E. L. Turner

Microlensing in Q2237+0305 between 1985 and 1995 (eg. Irwin et al. 1989; Corrigan et al. 1991; Ostensen et al. 1996) has been interpreted in two different ways; as microlensing by stellar mass objects of a continuum source having dimensions significantly smaller than the microlens Einstein radius (ER) (eg. Wambsganss, Paczynski & Schneider 1990; Rauch & Blan

John A. Gowan

The relationship between the intrinsic motion of gravity, light, and time is explored in terms of the principles of entropy, causality, energy, and symmetry conservation. A conceptual mechanism for gravity and the gravitational connection between quantum mechanics and relativity is explored. A &#34;concept equation&#34; is given for the gravitational annihil

R. V. Jolos, P. von Brentano

An angular momentum dependence of the parity splitting in the alternating parity bands of nuclei with strong octupole correlations is considered basing on the model of the octupole motion in a one-dimensional potential well conserving axial symmetry. A sign reversal of the parity splitting at higher values of the angular momentum is interpreted as a result o

Victor D. Efros, Winfried Leidemann, Giuseppina Orlandini, Edward L. Tomusiak

Total photonuclear absorption cross sections of $^3$H and $^3$He are studied using realistic NN and NNN forces. Final state interactions are fully included. Two NN potential models, the AV14 and the r-space Bonn-A potentials, are considered. For the NNN forces the Urbana-VIII and Tucson-Melbourne models are employed. We find the cross section to be sensitive

Achim Bode, Peter Weisz, Ulli Wolff

We compute the Schroedinger functional (SF) for the case of lattice QCD with Wilson fermions (with and without SW improvement) at two-loop order in lattice perturbation theory. This allows us to extract the three-loop beta-function in the SF-scheme. These results are required to compute the running coupling, the Lambda-parameter and quark masses by finite si

F. W. Stecker

It has been suggested that cosmological gamma-ray bursts (GRBs) can produce the observed flux and spectrum of cosmic rays at the highest energies. However, recent observations indicate that the redshift distribution of GRBs most likely follows that of the star formation rate in the universe, a rate which was much higher at redshifts 1.5-2 than it is today. T

Z. S. Bassi, A. LeClair

We study a two-dimensional disordered system consisting of Dirac fermions coupled to a scalar potential. This model is closely related to a more general disordered system that has been introduced in conjunction with the integer quantum Hall transition. After disorder averaging, the interaction can be written as a marginal osp(2|2) current-current perturbatio

Christophe Chatelain, Bertrand Berche

We report a transfer matrix study of the random bond $q-$state Potts model in the vicinity of the Ising model $q=2$. We draw attention to a precise determination of magnetic scaling dimensions in order to compare with perturbative results. Universality is checked by the computation of the spin-spin correlation function decay exponent obtained with different

A. W. Whinnett

We study spontaneous scalarization in Scalar-Tensor boson stars. We find that scalarization does not occur in stars whose bosons have no self-interaction. We introduce a quartic self-interaction term into the boson Lagrangian and show that when this term is large, scalarization does occur. Strong self-interaction leads to a large value of the compactness (or

S. Mereghetti, G. Barbiellini, G. Budini, P. Caraveo

We describe the AGILE gamma-ray astronomy satellite which has recently been selected as the first Small Scientific Mission of the Italian Space Agency. With a launch in 2002, AGILE will provide a unique tool for high-energy astrophysics in the 30 MeV - 50 GeV range before GLAST. Despite the much smaller weight and dimensions, the scientific performances of A

Zoltan Trocsanyi

We compute power corrections to mean values of hadronic event shapes - the thrust and the C parameter - of tagged b quark events in electron positron annihilation, using the dispersive approach. We find that the leading power corrections are of the same type of 1/Q corrections as for event shapes in the massless case, with the same non-perturbative coefficie

A. Akylas, I. Georgantopoulos, M. Plionis

We have derived the angular correlation function of a sample of 2096 sources detected in the ROSAT All Sky Survey Bright Source Catalogue, in order to investigate the clustering properties of AGN in the local Universe. Our sample is constructed by rejecting all known stars, as well as extended X-ray sources. Areas with |b|<30 deg. and declination <-30 deg. a

Amitabha Lahiri

A proof of renormalizability of the theory of the dynamical non-Abelian two-form is given using the Zinn-Justin equation. Two previously unknown symmetries of the quantum action, different from the BRST symmetry, are needed for the proof. One of these is a gauge fermion dependent nilpotent symmetry, while the other mixes different fields with the same transf

Iouri Chepelev, Radu Roiban

A noncommutative Feynman graph is a ribbon graph and can be drawn on a genus $g$ 2-surface with a boundary. We formulate a general convergence theorem for the noncommutative Feynman graphs in topological terms and prove it for some classes of diagrams in the scalar field theories. We propose a noncommutative analog of Bogoliubov-Parasiuk's recursive subtract

Stefano Mancini, David Vitali, Paolo Tombesi

We show that by using a feedback loop it is possible to reduce the fluctuations in one quadrature of the vibrational degree of freedom of a trapped ion below the quantum limit. The stationary state is not a proper squeezed state, but rather a ``squashed&#39;&#39; state, since the uncertainty in the orthogonal quadrature, which is larger than the standard qua

Z. Hradil, J. Summhammer, G. Badurek, H. Rauch

System of 1/2 spin particles is observed repeatedly using Stern-Gerlach apparatuses with rotated orientations. Synthesis of such non-commuting observables is analyzed using maximum likelihood estimation as an example of quantum state reconstruction. Repeated incompatible observations represent a new generalized measurement. This idealized scheme will serve f

Z. Hradil, J. Summhammer

Maximum likelihood principle is shown to be the best measure for relating the experimental data with the predictions of quantum theory.

Klaus Morawetz, Václav Špička, Pavel Lipavský

The short time behavior of a disturbed system is influenced by off-shell motion and best characterized by the reduced density matrix possessing high energetic tails. We present analytically the formation of correlations due to collisions in an interacting Fermionic system with and without initial correlation. After this short time regime the time evolution i

V. V. Flambaum

Highly excited many-particle states in quantum systems (nuclei, atoms, quantum dots, spin systems, quantum computers) can be ``chaotic&#39;&#39; superpositions of mean-field basis states (Slater determinants, products of spin or qubit states). This is a result of the very high energy level density of many-body states which can be easily mixed by a residual i

Marek Zukowski, Dagomir Kaszlikowski

Motivated by pedagogical reasons we pinpoint the mistake in the recent claim, in quant-ph/9911016, that faster than light communication is possible.

K. A. Valiev, A. A. Kokin

Here we made an analysis of the principles of a semiconductor NMR quantum computer and its developments. The known variant of an individual-access computer (B. Kane) and alternative solid-state bulk-ensemble approach versions allowing to avoid some difficulties in implementing the first variant are considered.

Michael J. York

We examine historic formulations of the spin-statistics theorem from a point of view that distinguishes between the observable consequences and the ``symmetrization postulate&#39;&#39;. In particular, we make a critical analysis of concepts of particle identity, state distinguishability and permutation, and particle ``labels&#39;&#39;. We discuss how to cons

Barbara A. Cohen, Robert F. Coker

We have constructed an asteroid model with the intent of tracking the radial and temporal dependence of temperature and composition throughout a 100-km diameter CM-type parent body, with emphasis on constraining the temperature and duration of a liquid water phase. We produce a non-uniform distribution where liquid water persists longest and is hottest in th

Yong-Hoon Kim, In-Ho Lee, Richard M. Martin

We describe the object-oriented implementation of a higher-order finite-difference density-functional code in Fortran 90. Object-oriented models of grid and related objects are constructed and employed for the implementation of an efficient one-way multigrid method we have recently proposed for the density-functional electronic-structure calculations. Detail

In-Ho Lee, Yong-Hoon Kim, Richard Martin

We propose a simple and efficient one-way multigrid method for self-consistent electronic structure calculations based on iterative diagonalization. Total energy calculations are performed on several different levels of grids starting from the coarsest grid, with wave functions transferred to each finer level. The only changes compared to a single grid calcu

Kelly A. Shorlin, John R. de Bruyn, Malcolm Graham, Stephen W. Morris

We have studied shrinkage crack patterns which form when a thin layer of an alumina/water slurry dries. Both isotropic and directional drying were studied. The dynamics of the pattern formation process and the geometric properties of the isotropic crack patterns are similar to what is expected from recent models, assuming weak disorder. There is some evidenc

M. Viviani, A. Kievsky, L. E. Marcucci, S. Rosati

The present work reports results for: pd radiative capture observables measured at center-of-mass (c.m.) energies in the range 0--100 keV and at 2 MeV by the TUNL and Wisconsin groups, respectively; contributions to the Gerasimov-Drell-Hearn (GDH) integral in 3He from the two- up to the three-body breakup thresholds, compared to experimental determinations b

R. V. Jolos, P. von Brentano

A nuclear physics example of the U(6/2) supersymmetry group is considered. It is shown that this group contains a supersymmetric subgroup with a structure similar to the SUSY model of the quantum field theory (QFT). A comparison of two models help to clarify the relation between the supersymmetry schemes of QFT and of nuclear physics. Using this similarity a

Michael C. Birse, Judith A. McGovern, Keith G. Richardson

A Wilsonian renormalisation group is used to study nonrelativistic two-body scattering by a short-ranged potential. We identify two fixed points: a trivial one and one describing systems with a bound state at zero energy. The eigenvalues of the linearised renormalisation group are used to assign a systematic power-counting to terms in the potential near each

Dinesh Kumar Srivastava

We discuss the recent developments in the study of single photon production in relativistic heavy ion collisions. In particular their production at SPS, RHIC, and LHC energies is re-examined in view of the results of Aurenche et al which show that the rate of photon production from quark gluon plasma, evaluated at the order of two loops far exceeds the rates

H. Shen, H. Toki

We study nuclear matter and finite nuclei in terms of the quark mean field (QMF) model, in which we describe the nucleon using the constituent quark model. The meson mean fields, in particular the sigma meson, created by other nucleons act on quarks inside a nucleon and change the nucleon properties in nuclear medium. The QMF model predicts an increasing siz

I. N. Mishustin

In this talk I discuss three main topics concerning the theoretical description and observable signatures of possible phase transitions in nuclear collisions. The first one is related to the multifragmentation of thermalized sources and its connection to a liquid-gas phase transition in finite systems. The second one is dealing with the Coulomb excitation of

M. Tanifuji, S. Ishikawa, Y. Iseri, T. Uesaka

For backward elastic scattering of deuterons by ^3He, cross sections σand tensor analyzing power T_{20} are measured at E_d=140-270 MeV. The data are analyzed by the PWIA and by the general formula which includes virtual excitations of other channels, with the assumption of the proton transfer from ^3He to the deuteron. Using ^3He wave functions calculated b

Bas Edixhoven

We prove, assuming the generalized Riemann hypothesis, the Andre-Oort conjecture for Hilbert modular surfaces. More precisely, let K be a real quadratic field and let S be the coarse moduli space of complex abelian surfaces with multiplications by the ring of integers of K. Let C be an irreducible closed curve in S, and suppose that C contains infinitely man

M. V. Movshev

We introduce and study elementary properties of graph homology of algebras. This new homology theory shares many features of cyclic and Hochschild homology. We also define a graph K-theory together with an analog of Chern character.

A. Arias, Haskell P. Rosenthal

This work introduces the concept of an M-complete approximate identity (M-cai) for a given operator subspace X of an operator space Y. M-cai&#39;s generalize central approximate identities in ideals in $C^*$-algebras, for it is proved that if X admits an M-cai in Y, then X is a complete M-ideal in Y. It is proved, using ``special&#39;&#39; M-cai&#39;s, that

T. Bodineau, D. Ioffe, Y. Velenik

The rigorous microscopic theory of equilibrium crystal shapes has made enormous progress during the last decade. We review here the main results which have been obtained, both in two and higher dimensions. In particular, we describe how the phenomenological Wulff and Winterbottom constructions can be derived from the microscopic description provided by the e

K. Oguiso

We show the density of the jumping loci of the Picard number of a hyperkähler manifold under small deformation and provide several applications. In particular, we apply this to reveal the structure of hierarchy among all the narrow Mordell-Weil lattices of Jacobian K3 surfaces.

Walter D. Neumann, Penelope G. Wightwick

Vladimir Shpilrain and Jie-Tai Yu have asked for an effective algorithm to decide if two elements of C[x,y] are related by an automorphism of C[x,y]. We describe here an efficient algorithm that decides this question and finds the automorphism if it exists. The algorithm is due to the second author, who described it in terms of Newton polygons, with C replac

Matilde Marcolli, Varghese Mathai

This paper is the continuation of Part I, expanding previous results of math.DG/9803051. This paper uses techniques in noncommutative geometry as developed by Alain Connes in order to study the twisted higher index theory of elliptic operators on orbifold covering spaces of compact good orbifolds, which are invariant under a projective action of the orbifold

Matilde Marcolli, Varghese Mathai

This paper, together with Part II, expands the results of math.DG/9803051. In Part I we study the twisted index theory of elliptic operators on orbifold covering spaces of compact good orbifolds, which are invariant under a projective action of the orbifold fundamental group. We apply these results to obtain qualitative results on real and complex hyperbolic

Jose Gaite

The relative entropy of the massive free bosonic field theory is studied on various compact Riemann surfaces as a universal quantity with physical significance, in particular, for gravitational phenomena. The exact expression for the sphere is obtained, as well as its asymptotic series for large mass and its Taylor series for small mass. One can also derive

G. Sardanashvily

A field model on fibre bundles can be extended in a standard way to the BRS-invariant SUSY field model which possesses the Lie supergroup ISp(2) of symmetries.

M. Banados, A. Chamblin, G. W. Gibbons

We consider travelling waves propagating on the anti-de Sitter (AdS) background. It is pointed out that for any dimension d, this space of solutions has a Virasoro symmetry with a non-zero central charge. This result is a natural generalization to higher dimensions of the three-dimensional Brown-Henneaux symmetry.

Antti Sorri

We consider the indeterminacy in the sign of the neutrino asymmetry generated by active-sterile neutrino oscillations in the early universe. The dynamics of asymmetry growth is discussed in detail and the indeterminacy in the final sign of the asymmetry is shown to be a real physical phenomenon. Recently published contradicting results are carefully consider

E. Kh. Akhmedov, G. C. Branco, M. N. Rebelo

We consider the seesaw mechanism of neutrino mass generation in the light of our present knowledge of the neutrino masses and mixing. We analyse the seesaw mechanism constrained by the following assumptions: (1) minimal seesaw with no Higgs triplets, (2) hierarchical Dirac masses of neutrinos, (3) large lepton mixing primarily or solely due to the mixing in

G. Domokos, S. Kovesi-Domokos

Ultrahigh energy protons in magnetic fields produce pions and thus lose energy. The mean free path of such a process is worked out for Gaussian random fields. Two cases are considered: an isotropic and a cylindrically symmetric distribution. The energy loss is proportional to E^3 <B^2>; it becomes significant for protons of energies larger than about 10^19 e

K. Zuber

The current status of direct terrestrial neutrino mass searches is presented. This includes direct kinematical searches, double beta decay and the search for a magnetic moment.

A. Gutiérrez-Rodríguez, O. A. Sampayo

We study the possibility of detecting the charged Higgs bosons predicted in the Minimal Supersymmetric Standard Model $(H^\pm)$, with the reactions $e^{+}e^{-}\to τ^-\bar ν_τH^+, τ^+ν_τH^-$, using the helicity formalism. We analyze the region of parameter space $(m_{A^0}-\tanβ)$ where $H^\pm$ could be detected in the limit when $\tanβ$ is large. The numerica

Sandro Ambrosanio, Grahame A. Blair

Assuming gauge-mediated supersymmetry breaking, we simulate precision measurements of fundamental parameters at a 500 GeV e+e- linear collider in the scenario where a neutralino is the next-to-lightest supersymmetric particle. Information on the supersymmetry breaking and the messenger sectors of the theory is extracted from realistic fits to the measured ma

Matteo Beccaria, Fernand M. Renard, Stefania Spagnolo, Claudio Verzegnassi

We discuss New Physics effects in fermion pair production at LC in the framework of the ``Z-peak subtracted approach&#39;&#39;, a theoretical scheme that exploits the experimental measurements at LEP1 and SLC as input parameters. In particular, we discuss the role of the longitudinal polarization asymmetry $A_{LR,μ}$ which turns out to be a very sensitive pr

A. Del Fabbro, D. Treleani

The experimental capability of recognizing the presence of b quarks in complex hadronic final states has addressed the attention towards final states with b\bar{b} pairs for observing the production of the Higgs boson at the LHC, in the intermediate Higgs mass range.We point out that double parton scattering processes are going to represent a sizeable backgr

V. I. Yukalov, E. P. Yukalova

A method is suggested for treating those complicated physical problems for which exact solutions are not known but a few approximation terms of a calculational algorithm can be derived. The method permits one to answer the following rather delicate questions: What can be said about the convergence of the calculational procedure when only a few its terms are

I. Scimemi

First non-trivial chiral corrections to the magnetic moments of triplet (T) and sextet ($S^{(*)}$) heavy baryons are presented using Heavy Hadron Chiral Perturbation Theory. The contributions are calculated up to order ${\cal O}(1/(m_Q Λ_χ^2))$ for T-baryons and up to order ${\cal O}(1/Λ_χ^2)$ for $S^{(*)}$-baryons. The renormalization of the chiral loops is

I. Scimemi

Recently the semileptonic decays $B\to X_s e^+ e^-$, $B\to X_s μ^+ μ^-$ in generic supersymmetric extensions of the Standard Model have been studied in ref.~\cite{noi}. In this talk I review the main points of this analysis. SUSY effects are parameterized using the mass insertion approximation formalism and differences with MSSM results are pointed out. Cons

P. Eden

Benefiting from the high statistics from $e^+e^-$ experiments at the $Z^0$ resonance, it is possible to impose strong two-jet cuts on the data without losing the statistical significance. In these events perturbative activity is suppressed and hadronization effects can be more prominent. I give two examples of observables that can be important tools for a mo

P. Eden

The properties of quark and gluon jets depend on jet definitions and event selection. I discuss how these can be included in calculations and present jet definitions designed to give unbiased jets.

P. Eden

I discuss event cuts in DIS which improve the similarity between the current Breit hemisphere and hemispheres in $e^+e^-$ annihilation. I also present a method to study the scale evolution in quark hemispheres using data from fixed energy $e^+e^-$ experiments. This method can benefit from the high statistics and flavour tagging at LEP1, also at scales releva

K. J. Eskola

Highlights of the results from ultrarelativistic heavy ion collisions at CERN-SPS are reviewed. In particular, I discuss how the experimental results indicate that a collective strongly interacting system has been produced, and what are the implications towards the Quark Gluon Plasma. The physical ideas behind measuring certain observables are introduced. Th

P. N. Burrows

The status of the design of a detector for the TESLA collider is presented.

M. Angeles Serrano, J. Alberto Lobo

We discuss the capabilities of spherical antennæas single multifrequency detectors of gravitational waves. A first order theory allows us to evaluate the coupled spectrum and the resonators readouts when the first and the second quadrupole bare sphere frequencies are simultaneously selected for layout tuning. We stress the existence of non-tuning influences

J. Ellis, N. E. Mavromatos, D. V. Nanopoulos, G. Volkov

Motivated by the possible experimental opportunities to test quantum gravity via its effects on high-energy neutrinos propagating through space-time foam, we discuss how to incorporate spin structures in our D-brane description of gravitational recoil effects in vacuo. We also point to an interesting analogous condensed-matter system. We use a suitable super

Giampiero Esposito

An attempt is made of giving a self-contained introduction to holomorphic ideas in general relativity, following work over the last thirty years by several authors. The main topics are complex manifolds, spinor and twistor methods, heaven spaces.

A. Beygelzimer, L. A. Hemaspaandra, C. M. Homan, J. Rothe

We survey recent developments in the study of (worst-case) one-way functions having strong algebraic and security properties. According to [RS93], this line of research was initiated in 1984 by Rivest and Sherman who designed two-party secret-key agreement protocols that use strongly noninvertible, total, associative one-way functions as their key building b

M. Murata, M. Utiyama, H. Isahara

Question answering task is now being done in TREC8 using English documents. We examined question answering task in Japanese sentences. Our method selects the answer by matching the question sentence with knowledge-based data written in natural language. We use syntactic information to obtain highly accurate answers.

H. Perez, L. Villegas

We discuss the occurrence of Bose-Einstein condensation in systems of noninteracting charged particles in three in one dimensions and in presence of an external magnetic field. In the one dimensional, as well as in the magnetic field cases, although not a critical temperature, a characteristic temperature can be found, corresponding to the case in which the

B. Jouault, G. Santoro, A. Tagliacozzo

We have calculated the linear magnetoconductance across a vertical parabolic Quantum Dot with a magnetic field in the direction of the current. Gate voltage and magnetic field are tuned at the degeneracy point between the occupancies N=2 and N=3, close to the Singlet-Triplet transition for N=2. We find that the conductance is enhanced prior to the transition

R. Chitra, G. Kotliar

We construct a new functional for the single particle Green&#39;s function, which is a variant of the standard Baym Kadanoff functional. The stability of the stationary solutions to the new functional is directly related to aspects of the irreducible particle hole interaction through the Bethe Salpeter equation. A startling aspect of this functional is that

P. Leboeuf

It is well known that the joint probability density of the eigenvalues of Gaussian ensembles of random matrices may be interpreted as a Coulomb gas. We review these classical results for hermitian and complex random matrices, with special attention devoted to electrostatic analogies. We also discuss the joint probability density of the zeros of polynomials w

L. A. Abramyan, A. P. Protogenov, V. A. Verbus

We have computed the contribution of zero modes to the value of the number of particles in the model of discrete (2+1)-dimensional nonlinear Schrödinger equation. It is shown for the first time that in the region of small values of the Chern-Simons coefficient k there exists a universal attraction between field configurations. For k=2 this phenomenon may be

X. F. Wang, I. C. da Cunha Lima, A. Troper

The optic vibrational (confined and interface) modes and the electron-phonon and hole-phonon interactions are obtained, in the dielectric continuum model, for two diluted magnetic semiconductor structures: a single well of Cd1-xMnxTe/Cd1-yMgyTe with the magnetic ions in the well, and a double well of CdTe/Cd1-xMnxTe, in which a thin layer of the magnetic mat

H. Fehske, J. Loos, G. Wellein

We explore the quasiparticle properties of lattice polarons on the basis of a quite general electron-phonon Hamiltonian with a long-range displacement-type of interaction. To treat the dynamical quantum phonons without significant loss of accuracy we adapt an exact Lanczos diagonalization method and compute various static and dynamical quantities, such as th

J. Vanacken, L. Trappeniers, G. Teniers, P. Wagner

Recently, the normal state resistivity of high temperature superconductors (in particular in La2-xSrxCuO4 single crystals) has been studied extensively in the region below Tc by suppressing the superconducting state in high magnetic fields. In the present work we report on the normal state resistance of underdoped La2-xSrxCuO4 thin films under epitaxial stra

J. Vanacken, L. Trappeniers, K. Rosseel, I. N. Goncharov

The understanding of flux jumps in the high temperature superconductors is of importance since the occurrence of these jumps may limit the perspectives of the practical use of these materials. In this work we present the experimental study of the role of heavy ion irradiation in stabilizing the HTSC against flux jumps by comparing un-irradiated and 7.5 10^10

P. Abbamonte, C. A. Burns, E. D. Isaacs, P. M. Platzman

We demonstrate the utility of point group representation theory for symmetry analysis in resonant inelastic x-ray scattering. From its polarization-dependence, we show that a 5 eV inelastic feature in Sr2CuO2Cl2 has pure B1g symmetry and assign it to a transition in the cell-perturbation calculations of Simon, et. al. [Phys. Rev. B., 54, R3780 (1996)]. We di

Atsushi Kaneko, Tomi Ohtsuki

We study the metal-insulator transition on a three dimensional quantum percolation model by analyzing energy level statistics. The quantum percolation threshold $\pq$, which is larger than the classical percolation threshold $\pc$, becomes smaller when the time reversal symmetry (TRS) is broken, i.e. $\pq({\rm with TRS})>\pq({\rm without TRS})>\pc$. It is sh

Tomi Ohtsuki, Keith Slevin, Tohru Kawarabayashi

A review of recent progress in numerical studies of the Anderson transition in three dimensional systems is presented. From high precision calculations the critical exponent $ν$ for the divergence of the localization length is estimated to be $ν=1.57\pm 0.02$ for the orthogonal universality class, which is clearly distinguished from $ν=1.43\pm 0.03$ for the

Niels Asger Mortensen, Kristinn Johnsen, Antti-Pekka Jauho, Karsten Flensberg

We consider the conductance of a quantum tube connected to a metallic contact. The number of angular momentum states that the tube can support depends on the strength of the radial confinement. We calculate the transmission coefficients which yield the conductance via the Landauer formula. We relate our results to armchair carbon nanotubes embedded in a meta