May 1998 arXiv papers — page 4

J. E. Cieza Montalvo, O. J. P. Eboli, M. B. Magro, P. G. Mercadante

We perform a detailed analysis of the potentiality of the CERN Large Hadron Collider to study the single production of leptoquarks via $pp \to e^\pm q\to$ leptoquark $\to e^\pm q$, with $e^\pm$ generated by the splitting of photons radiated by the protons. Working with the most general $SU(2)_L \otimes U(1)_Y$ invariant effective lagrangian for scalar and ve

Raman Sundrum

A general effective field theory formalism is presented which describes the low-energy dynamics of a 3-brane universe. In this scenario an arbitrary four-dimensional particle theory, such as the Standard Model, is constrained to live on the world-volume of a (3+1)-dimensional hypersurface, or ``3-brane'', which in turn fluctuates in a higher-dimensio

Phillial Oh, Mu-In Park

We derive the Kac-Moody algebra and Virasoro algebra in Chern-Simons theory with boundary by using the symplectic reduction method and the Noether procedures.

R. G. Arendt, N. Odegard, J. L. Weiland, T. J. Sodroski

The Cosmic Infrared Background (CIB) is hidden behind veils of foreground emission from our own solar system and Galaxy. This paper describes procedures for removing the Galactic IR emission from the 1.25 - 240 micron COBE DIRBE maps as steps toward the ultimate goal of detecting the CIB. The Galactic emission models are carefully chosen and constructed so t

Herbert Neuberger

Witten's anomaly for SU(2) with a single I=1/2 Weyl fermion in four dimension is shown to be reproduced by the lattice overlap. The mechanism is based on Berry's phase, and on the analyticity of the matrix $H$ by which the overlap is defined.

M. Davier, A. Hocker

We reevaluate the dispersion integrals of the leading order hadronic contributions to the running of the QED fine structure constant alpha(s) at s=M_Z^2, and to the anomalous magnetic moments of the muon and the electron. Finite-energy QCD sum rule techniques complete the data from e+e- annihilation and tau decays at low energy and at the cc-bar threshold. G

BS Acharya, JM Figueroa-O'Farrill, B Spence, S Stanciu

We complete the classification of supersymmetric configurations of two M5-branes, started by Ohta and Townsend. The novel configurations not considered before are those in which the two branes are moving relative to one another. These configurations are obtained by starting with two coincident branes and Lorentz-transforming one of them while preserving some

Y. B. Ding, V. G. Serbo

Coherent bremsstrahlung (CBS) is a sopecific type of radiation at colliders with short bunches. In the present paper we calculate the main characteristic of CBS for the BEPC collider. At this collider $d N_γ\sim 3\cdot 10^8 dE_γ/E_γ$ photons of CBS will be emitted for a single collision of the beams in the energy range $E_γ$ smaller than 240 eV. It seems tha

Jose D. Edelstein, Marcos Marino, Javier Mas

We study N=2 super Yang-Mills theory with gauge group SU(N) from the point of view of the Whitham hierarchy. We develop a new recursive method to compute the whole instanton expansion of the prepotential using the theta function associated to the root lattice of the group. Explicit results for the one and two-instanton corrections in SU(N) are presented. Int

Martin Fliesser, Robert Graham

We derive a symmetry property for the Fourier-transform of the collisionless sound modes of Bose condensates in anisotropic traps connected with a somewhat hidden conservation law. We discuss its possible observation by dispersive light scattering.

Klaus Fabricius, Barry M. McCoy

We compute, by means of exact diagonalization of systems of N=16 and 18 spins, the correlation function <σ^z_0σ^z_n> at nonzero temperature for the XXZ model with anisotropy Δ. In the gapless ferromagnetic region -1<Δ<0 for fixed separation the temperature can always be made sufficiently low so that the correlation is always negative for n \neq 0. However we

F. V. Gubarev, M. I. Polikarpov, V. I. Zakharov

We consider interaction of a probe monopole-antimonopole pair in the vacuum of the Abelian Higgs model. For simplicity, the mass of the Higgs particle is assumed to be much larger than the mass of the photon (London limit). In case of a massive photon the straightforward application of the Zwanziger formalism to accommodate both magnetic and electric charges

S. Nishimoto, Y. Ohta

Based on recent experimental evidences that the electronic charge degrees of freedom plays an essential role in the spin-Peierls--like phase transition of NaV$_2$O$_5$, we first make the mapping of low-energy electronic states of the $d$$-$$p$ model for NaV$_2$O$_5$ to the quarter-filled $t$$-$$J$ ladder with anisotropic parameter values between legs and run

Luca Leuzzi

Ising spin-glass systems with long-range interactions ($J(r)\sim r^{-σ}$) are considered. A numerical study of the critical behaviour is presented in the non-mean-field region together with an analysis of the probability distribution of the overlaps and of the ultrametric structure of the space of the equilibrium configurations in the frozen phase. Also in p

A. L. Larsen, N. Sánchez

It has been known for some time that the SL(2,R) WZWN model reduces to Liouville theory. Here we give a direct and physical derivation of this result based on the classical string equations of motion and the proper string size. This allows us to extract precisely the physical effects of the metric and antisymmetric tensor, respectively, on the {\it exact} st

J. B. Kogut, M. A. Stephanov, C. G. Strouthos

We study a Yukawa theory with spontaneous chiral symmetry breaking and with a large number N of fermions near the finite temperature phase transition. Critical properties in such a system can be described by the mean field theory very close to the transition point. We show that the width of the region where non-trivial critical behavior sets in is suppressed

B. Machet

K -> Pi Pi decays are investigated in the framework of the SU(2)left x U(1) gauge theory of J=0 mesons proposed in ref.[1], to which is added an interaction between mesons respecting the two symmetries generally attributed to strong interactions, flavour symmetry and parity conservation. It is shown that the damping of the K+ -> Pi+ Pi0 amplitude with respec

Valter Moretti

Some general properties of local $ζ$-function procedures to renormalize some quantities in $D$-dimensional (Euclidean) Quantum Field Theory in curved background are rigorously discussed for positive scalar operators $-Δ+ V(x)$ in general closed $D$-manifolds, and a few comments are given for nonclosed manifolds too. A general comparison is carried out with r

Ashoke Sen

A coincident D-brane - anti-D-brane pair has a tachyonic mode. We present an argument showing that at the classical minimum of the tachyonic potential the negative energy density associated with the potential exactly cancels the sum of the tension of the brane and the anti-brane, thereby giving a configuration of zero energy density and restoring space-time

S. Fajfer, S. Prelovsek, P. Singer

The Cabibbo suppressed decays $D\to Vl^+l^-$ (V is light vector meson) present in principle the opportunity to observe the short distance FCNC transition $c\to ul^+l^-$, which is sensitive to physics beyond the Standard Model. We analyze these as well as the Cabibbo allowed $D \to V l^+ l^-$ decays within the Standard Model, where in addition to the short di

Y. Koike, N. Nishiyama, K. Tanaka

We present the one-loop anomalous dimension matrices for the chiral-even twist-3 (nonsinglet) conformal operators, which govern the scale-dependence of the vector meson light-cone wave functions through the conformal expansion. It is clarified that the constraints from the charge-conjugation invariance and the chirality conservation allow only one independen

Ben O&#39;Shaughnessy, Dimitrios Vavylonis

We study the reaction kinetics of end-functionalized polymer chains dispersed in an unreactive polymer melt. Starting from an infinite hierarchy of coupled equations for many-chain correlation functions, a closed equation is derived for the 2nd order rate constant $k$ after postulating simple physical bounds. Our results generalize previous 2-chain treatment

T. Hirayama, N. Ishimura, N. Maekawa

We try to construct a model in which supersymmetry and grand unified gauge symmetry are dynamically broken at the same time. In this model SUSY breaking is mediated mainly by massive vector multiplet, and a new solution for the mu problem is proposed.

Gregory Rudnick, Hans-Walter Rix

We quantify the mean asymmetry of 54 face-on, early type disk galaxies (S0 to Sab) using the amplitude of the m=1 azimuthal Fourier component of the R-band surface brightness. We find that the median lopsidedness, (A_1/A_0)_{mean}, of our sample is 0.11 and that the most lopsided 20% of our galaxies have (A_1/A_0)_{mean} >= 0.19. Asymmetries in early type di

Chao-Shang Huang, Cong-Feng Qiao, Hua-Gang Yan

The $Λ_b \to p$ semileptonic decay is analyzed by using QCD sum rules within the framework of heavy quark effective theory. The Isgur-Wise function of $Λ_b \to p l \barν$ has been calculated. The decay width is given.

Roger A. Chevalier

Molecular clouds are known to be clumpy, with dense molecular clumps occupying only a few percent of the volume. A supernova remnant then evolves primarily in the interclump medium, and becomes radiative at a radius of about 6 pc, forming a shell that is magnetically supported. When this shell interacts with the dense clumps, the molecular shock fronts are d

D. Jaksch, C. Bruder, J. I. Cirac, C. W. Gardiner

The dynamics of an ultracold dilute gas of bosonic atoms in an optical lattice can be described by a Bose-Hubbard model where the system parameters are controlled by laser light. We study the continuous (zero temperature) quantum phase transition from the superfluid to the Mott insulator phase induced by varying the depth of the optical potential, where the

Andrei P. Kirilyuk

The qualitatively new concept of dynamic complexity in quantum mechanics is based on a new paradigm appearing within a nonperturbational analysis of the Schroedinger equation for a generic Hamiltonian system. The unreduced analysis explicitly provides the complete, consistent solution as a set of many incompatible components (&#39;realisations&#39;) which sh

H. M. Wiseman

Electro-optical feedback can produce an in-loop photocurrent with arbitrarily low noise. This is not regarded as evidence of `real&#39; squeezing because squeezed light cannot be extracted from the loop using a linear beam splitter. Here I show that illuminating an atom (which is a nonlinear optical element) with `in-loop&#39; squeezed light causes line-narr

M. N. Achasov, A. D. Bukin, D. A. Bukin, V. P. Druzhinin

The general purpose spherical nonmagnetic detector (SND) is now taking data at VEPP-2M $e^+e^-$ collider in BINP (Novosibirsk) in the centre of mass energy range of $0.2 ÷1.4$ GeV. The energy calibration of the NaI(Tl) calorimeter of the SND detector with cosmic muons is described. Using this method, the energy resolution of $5.5 % (σ)$ for 500 MeV photons w

B. Echebarria, C. Perez-Garcia

The general form of the amplitude equations for a hexagonal pattern including spatial terms is discussed. At the lowest order we obtain the phase equation for such patterns. The general expression of the diffusion coefficients is given and the contributions of the new spatial terms are analysed in this paper. From these coefficients the phase stability regio

R. Coutinho, B. Fernandez

We study the interfaces&#39; time evolution in one-dimensional bistable extended dynamical systems with discrete time. The dynamics is governed by the competition between a local piece-wise affine bistable mapping and any couplings given by the convolution with a function of bounded variation. We prove the existence of travelling wave interfaces, namely fron

L. E. Marcucci, D. O. Riska, R. Schiavilla

The electromagnetic form factors of the trinucleons 3H and 3He are calculated with wave functions obtained with the Argonne AV18 two-nucleon and Urbana IX three-nucleon interactions. Full account is taken of the two-body currents required by current conservation with the AV18 interaction as well as those associated with N-Delta transition currents and the cu

M. Stoitsov, P. Ring, D. Vretenar, G. A. Lalazissis

The scaled harmonic oscillator basis (SHO) is derived by a local scaling-point transformation of the spherical harmonic oscillator radial wave functions. The unitary scaling transformation produces a basis with improved asymptotic properties. The SHO basis is employed in the solution of the relativistic Hartree-Bogoliubov (RHB) equations in configurational s

Q. H. Zhang, P. Scotto, U. Heinz

The two-pion correlation function can be defined as a ratio of either the measured momentum distributions or the normalized momentum space probabilities. We show that the first alternative avoids certain ambiguities since then the normalization of the two-pion correlator contains important information on the multiplicity distribution of the event ensemble wh

A. A&#39;Campo-Neuen, J. Hausen

We define a quasi--projective reduction of a complex algebraic variety $X$ to be a regular map from $X$ to a quasi--projective variety that is universal with respect to regular maps from $X$ to quasi--projective varieties. A toric quasi--projective reduction is the analogous notion in the category of toric varieties. For a given toric variety $X$ we first co

Matthias Weber, Michael Wolf

We prove the existence of complete minimal surfaces of genus g>1 which minimize the total curvature for their genus. Our method is first to identify this (Weierstrass high dimensional period) problem with the problem of finding a particular type of polygonal arc in the complex domain: the arc alternates between horizontal and vertical segments, and the two c

Karim Benakli

I review recent results in three topics of the M-world: (i) Scales. (ii) New dark matter candidates. (iii) Cosmological solutions from p-branes. The three topics are discussed in the framework of Hořava-Witten compactifications. Part (iii) includes comments on cosmological solutions in M-theory describing nucleation of universes through instanton effects and

S. M. Klishevich

In the given work we study an interaction of second massive state of an open boson string with the constant electromagnetic field. This state contains massive fields with spins 3 and 1. Using the method of an open string BRST quantization, we receive gauge-invariant lagrangian, describing the electromagnetic interaction of these fields. From the explicit vie

B. Jensen

We construct new bosonic boundary states in the light-cone gauge which describe D(p)-branes moving at the speed of light.

Adel Bilal

In these notes, based on a talk given at the Rencontres de Moriond, I give a simple introduction to the tremendous progress that has been made during the last few years towards the understanding of strong-coupling phenomena in quantum gauge theories and superstring theories.

Mark B. Wise

A review of Heavy Quark Effective Theory and Non Relativistic Quantum Chromondynamics is given. Some applications are discussed.

A. D. Dolgov, S. H. Hansen, D. V. Semikoz

We repeat our previous calculation of the spectrum distortion of massless neutrinos in the early universe with a considerably better accuracy and corrected for a missing numerical factor in one of the two ways of calculations presented in hep-ph/9703315. Now both ways of calculations are in perfect agreement and we essentially reproduce our old results prese

J. Karkowski, Z. Swierczynski

The static vortex solution in Abelian Higgs model with small ratio of vector and Higgs particle masses is considered. Several formulae approximating this solution are discussed. The accuracy of these approximations is tested by numerical computations.

W. L. van Neerven

We analyze the second order QCD corrections to the fragmentation functions F_^H_k(x,Q^2) (k=T,L,A) which are measured in e^+~e^- annihilation From these fragmentation functions one can derive the integrated transverse (sigma_T), longitudinal (sigma_L) and asymmetric (sigma_A) cross sections. The sum sigma_{tot}=sigma_T+sigma_L corrected up to order alpha_s^2

X. Artru, J. Czyzewski

Classical arguments predict that the quark and the antiquark of a pair created during string fragmentation are both transversely polarized in the direction of \hat z \times \vec q_T, where z is the direction of the pull exerted by the string on the antiquark and \vec q_T (-\vec q_T) is the transverse momentum of the quark (antiquark). The existence of this e

Johan Linde, Hakan Snellman

We analyze the axial-vector form factors of the nucleon-hyperon system in a model with SU(3)$_{\text{flavor}}$ symmetry breaking due to mass dependent quark spin polarizations. This mass dependence is deduced from an analysis of magnetic moment data, and implies that the spin contributions from the quarks to a baryon decrease with the mass of the baryon. Whe

D. Hadjimichef, G. Krein, S. Szpigel, J. S. da Veiga

A mapping technique is used to derive in the context of constituent quark models effective Hamiltonians that involve explicit hadron degrees of freedom. The technique is based on the ideas of mapping between physical and ideal Fock spaces and shares similarities with the quasiparticle method of Weinberg. Starting with the Fock-space representation of single-

Myoung-Taek Choi, Jae Kwan Kim

We study the polarization of the J/ψmeson of the B_c -> J/ψmu nu decay process, followed by J/ψ-> mu+ mu-, with the help of the heavy-quark spin symmetry formalism (HQSS). We adapt the ISGW wave function. Due to the clean signature of the decay mode, measurements of the polarization of the J/ψmeson can play a special role in extracting |V_{cb}|, the quark mi

Myoung-Taek Choi, Jae Kwan Kim

Since the degree of polarization of the vector particle in semileptonic decay strongly influences the decay width of the particles, it can be used as a measure of CKM matrix elements. We show that |V_{cb}| can be determined from the measurement of polarization of vector meson in B,B_c --> V l nu decay, where $V$ is vector meson.

Dongsheng Du, Yadong Yang, Guohuai Zhu

Combining three mechanisms, we reanalysis processes of $B \to η^{\prime} K(K^*),ηK(K^*)$ and calculate their branching ratios. The results are compared with other mechanisms in the literature. The striking feature of the gluon fusion mechanism is emphasized and its experimental test is discussed.

B. Bunk, S. Elser, R. Frezzotti, K. Jansen

The numerical construction of polynomials in the product representation (as used for instance in variants of the multiboson technique) can become problematic if rounding errors induce an imprecise or even unstable evaluation of the polynomial. We give criteria to quantify the effects of these rounding errors on the computation of polynomials approximating th

P. Butera, M. Comi

For the classical N-vector model, with arbitrary N, we have computed through order β^{17} the high temperature expansions of the second field derivative of the susceptibility χ_4(N,β) on the simple cubic and on the body centered cubic lattices. (The N-vector model is also known as the O(N) symmetric classical spin Heisenberg model or, in quantum field theory

K. Jansen, M. Laine

According to resummed perturbation theory, certain scalar theories have a global symmetry, which is restored in the vacuum but is broken at high temperatures. Recently, this phenomenon has been studied with 4d finite temperature lattice simulations, and it has been suggested that the non-perturbative dynamics thus incorporated would hinder the transition. We

L. Chkhaidze, T. Djobava, L. Kharkhelauri, M. Mosidze

A detailed study of pion production in central Mg-Mg collisions at a momentum of 4.3 GeV/c per incident nucleon was carried out with use of the setup GIBS. The average kinematical characteristics of pions (multiplicity n_, momentum P, transverse momentum P_{T}, emission angle Q, rapidity Y) and corresponding distributions have been obtained. The experimental

A. Dobado, A. L. Maroto

We study the effective action for gravity obtained after the integration of scalar matter fields, using the local momentum representation based on the Riemann normal coordinates expansion. By considering this expansion around different space-time points, we also compute the non-local terms together with the more usual divergent ones. We discuss the applicabi

Mikel Susperregi

Brans-Dicke gravity is remarkable not only in that General Relativity and Mach&#39;s Principle find a common enlarged scenario where they are mutually consistent, but also in that it provides a very interesting quantum cosmological model within the inflationary paradigm. The interplay between the Brans-Dicke scalar $Φ$ and the inflaton field $σ$ plays an imp

A. V. Balatsky, R. Movshovich

We argue that the $d_{x^2-y^2}$-wave superconductor is marginally stable in the presence of external perturbations. Subjected to the external perturbations by magnetic impurities, it develops a secondary component of the gap, complex $d_{xy}$, to maximize the coupling to impurities and lower the total energy. The secondary $d_{xy}$ component exists at high t

M. Mueller, K. Binder

We present a quantitative comparison between extensive Monte Carlo simulations and self-consistent field calculations on the phase diagram and wetting behavior of a symmetric, binary (AB) polymer blend confined into a film. The flat walls attract one component via a short range interaction. The critical point of the confined blend is shifted to lower tempera

Sohrab Ismail-Beigi, T. A. Arias

We present an ab initio exploration of the phenomena which will become important for freestanding structures of silicon as they are realized on the nanoscale. We find that not only surface but also edge effects are important considerations in structures of dimensions on the order of 3 nm. Specifically, for long nanoscale silicon bars, we find two competing l

F. Y. Wu

As a prelude to what might be expected as forthcoming breakthroughs in finding new approaches toward solving three-dimensional lattice models in the twenty-first century, we review the exact solutions of two lattice models in three dimensions obtained using the conventional combinatorial and transfer matrix approaches.

Kun Yang, D. Shahar, R. N. Bhatt, D. C. Tsui

We report in this paper results of experimental and theoretical studies of transitions between different integer quantum Hall phases, as well as transition between the insulating phase and quantum Hall phases at high magnetic fields. We focus mainly on universal properties of the transitions. We demonstrate that properly defined conductivity tensor is univer

Dirk Helbing

A stochastic model for behavioral changes by imitative pair interactions of individuals is developed. `Microscopic&#39; assumptions on the specific form of the imitative processes lead to a stochastic version of the game dynamical equations. That means, the approximate mean value equations of these equations are the game dynamical equations of evolutionary g

G. Reents, R. Urbanczik

Conditions are given under which one may prove that the stochastic dynamics of on-line learning can be described by the deterministic evolution of a finite set of order parameters in the thermodynamic limit. A global constraint on the average magnitude of the increments in the stochastic process is necessary to ensure self-averaging. In the absence of such a

Sergei Sergeenkov

Zero-temperature field-induced polarization, supercurrent density, and the related electrostriction (ES) of a granular superconductor are calculated within a model of 3D Josephson junction arrays. Both the &#34;bulk-modulus-driven ES&#34; (the change of the sample&#39;s volume in the free energy upon the applied stress) and the &#34;change-of-phase ES&#34; (

D. Meyer, W. Nolting, G. G. Reddy, A. Ramakanth

We introduce a new approach to the periodic Anderson model (PAM) that allows a detailed investigation of the magnetic properties in the Kondo as well as the intermediate valence regime. Our method is based on an exact mapping of the PAM onto an effective medium strong-coupling Hubbard model. For the latter, the so-called spectral density approach (SDA) is ra

D. R. Leadley, R. J. Nicholas, J. J. Harris, C. T. Foxon

The critical filling factor v_c where Shubnikov-de Haas oscillations become spin split is investigated for a set of GaAs-GaAlAs heterojunctions. Finite temperature magnetoresistance measurements are used to extract the value of v_c at zero temperature. The critically point is where the disorder potential has the same magnitude as the exchange energy, leading

P. J. Forrester, T. Nagao

The circular Dyson Brownian motion model refers to the stochastic dynamics of the log-gas on a circle. It also specifies the eigenvalues of certain parameter-dependent ensembles of unitary random matrices. This model is considered with the initial condition that the particles are non-interacting (Poisson statistics). Jack polynomial theory is used to derive

F. Y. Wu

A new duality relation is derived for the Potts model in one dimension. It is shown that the partition function is self-dual with the nearest-neighbor interaction and the external field appearing as dual parameters. Zeroes of the partition function are analyzed. Particularly, we show that the new duality relation implies a circle theorem in the complex tempe

Chigak Itoi

Employing a simple calculation method obtained by M.-H. Kato, we calculate the three loop renormalization group in the $su(2)$ coset conformal field theory with a slightly relevant perturbation and the $su(2)$ Wess-Zumino-Witten model with a particular invariant marginal perturbation. Zamolodchikov&#39;s $c$-theorem, exact data of the perturbation operator a

R. Erichsen, G. I. de Oliveira, F. B. Rizzato

In this work we analyze the interaction of isolated solitary structures and ion-acoustic radiation. If the radiation amplitude is small solitary structures persists, but when the amplitude grows energy transfer towards small spatial scales occurs. We show that transfer is particularly fast when a fixed point of a low dimensional model is destroyed.

T. Schreiber, H. Kantz

We discuss applications of nonlinear filtering of time series by locally linear phase space projections. Noise can be reduced whenever the error due to the manifold approximation is smaller than the noise in the system. Examples include the real time extraction of the fetal electrocardiogram from abdominal recordings.

H. Kantz, T. Schreiber

We derive a locally projective noise reduction scheme for nonlinear time series using concepts from deterministic dynamical systems, or chaos theory. We will demonstrate its effectiveness with an example with known deterministic dynamics and discuss methods for the verification of the results in the case of an unknown deterministic system.

Stuart D. Ryder, Yin-Sheng Sun, Michael C. B. Ashley, Michael G. Burton

We describe the specifications, characteristics, calibration, and analysis of data from the University of New South Wales Infrared Fabry-Perot (UNSWIRF) etalon. UNSWIRF is a near-infrared tunable imaging spectrometer, used primarily in conjunction with IRIS on the AAT, but suitable for use as a visitor instrument at other telescopes. The etalon delivers a re

Nicolas Cretton, Frank C. van den Bosch

We present axisymmetric dynamical models of the edge-on S0 galaxy NGC 4342. A combination of observations from the ground and with the Hubble Space Telescope (HST) has shown that NGC 4342 rotates rapidly and has a strong central increase in velocity dispersion. We construct simple two-integral Jeans models as well as fully general, three-integral models. The

Ravi K. Sheth, Gerard Lemson

We describe a simple efficient algorithm that allows one to construct Monte-Carlo realizations of merger histories of dark matter halos. The algorithm is motivated by the excursion set model (Bond et al. 1991) for the conditional and unconditional halo mass functions. The forest of trees constructed using this algorithm depends on the underlying power spectr

J. A. de Freitas Pacheco

Soft gamma repeaters are identified as highly magnetized (B$\approx 10^{14}$ Gauss) neutron stars. Magnetic stresses induce tectonic activity, and field annihilation in faults is the ultimate energy source for the observed $γ$-ray emission. As a consequence of the crustal cracking, the stored elastic energy is converted into high frequency (kHz) shear waves,

John M. Porter

The theory of radiatively-induced warps in accretion discs is applied to the discs of Be stars. It is found that these discs may develop warps in their inner regions, although once the warp amplitude is large enough then the interaction between the disc and fast radiatively-driven wind will determine its evolution. The warping is shown to be more important f

Ravi K. Sheth

A model of the gravitationally evolved dark matter distribution, in the Eulerian space, is developed. It is a simple extension of the excursion set model that is commonly used to estimate the mass function of collapsed dark matter haloes. In addition to describing the evolution of the dark matter itself, the model allows one to describe the evolution of the

O. K. Sil&#39;chenko, A. N. Burenkov, V. V. Vlasyuk

The results of a spectroscopic and photometric investigation of the central region of M 31 are presented. An analysis of absorption-index radial profiles involving magnesium, calcium, and iron lines has shown that the unresolved nucleus of M 31 is distinct by its increased metallicity; unexpectedly, among two nuclei of M 31, it is the faintest one located ex

Samar Abbas, Afsar Abbas, Shukadev Mohanty

Recent evidence quite convincingly indicates that the Late Permian biotic crisis was in fact a binary extinction with a distinct end-Guadalupian extinction pulse preceding the major terminal end-Permian Tartarian event by 5 million years. In addition anoxia appears to be closely associated with each of these end-Paleozoic binary extinctions. Most leading mod

Bruce Margon

The Sloan Digital Sky Survey is an ambitious, multi-institutional project to create a huge digital imaging and spectroscopic data bank of 25% of the celestial sphere, approximately 10,000 deg^2 centred on the north galactic polar cap. The photometric atlas will be in 5 specially-chosen colours, covering the pi ster of the Survey area to a limiting magnitude

Julio H. Toloza, Francisco A. Tamarit, Sergio A. Cannas

Aging in a two-dimensional Ising spin model with both ferromagnetic exchange and antiferromagnetic dipolar interactions is established and investigated via Monte Carlo simulations. The behaviour of the autocorrelation function $C(t,t_w)$ is analyzed for different values of the temperature, the waiting time $t_w$ and the quotient $δ=J_0/J_d$, $J_0$ and $J_d$

P. Hansen, D. Augier, J. Riera, D. Poilblanc

The effects of magnetic and non-magnetic impurities in spin-Peierls systems are investigated allowing for lattice relaxation and quantum fluctuations. We show that, in isolated chains, strong bonds form next to impurities, leading to the appearance of magneto-elastic solitons. Generically, these solitonic excitations do not bind to impurities. However, inter

T. Asaka, Masahiro Yamaguchi

A simple hadronic axion model is proposed in the framework of gauge-mediated supersymmetry breaking. Dynamics of Peccei-Quinn symmetry breaking is governed by supersymmetry breaking effects and the Peccei-Quinn breaking scale $f_{PQ}$ is inversely proportional to the gravitino mass. The gravitino mass range which corresponds to the axion window $f_{PQ} \sime

Gi-Chol Cho, Kaoru Hagiwara, Yoshiaki Umeda

We study constraints on additional $Z&#39;$ bosons predicted in the supersymmetric (SUSY) $E_6$ models by using the updated results of electroweak experiments -- $Z$-pole experiments, $m_W$ measurements and low-energy neutral current (LENC) experiments. We find that the effects of $Z$-$Z&#39;$ mixing are parametrized by (i) a tree-level contribution to the $

Yoshiaki Umeda, Gi-Chol Cho, Kaoru Hagiwara

We study the constraints from updated electroweak data on the three leptophobic Z&#39; models, the $η$ model with an appropriate $U(1)&#39;-U(1)_Y$ kinetic mixing, a Z&#39; model motivated by the flipped SU(5) \times U(1) unification, and the phenomenological Z&#39; model of Agashe, Graesser, and Hinchliffe. The $Z-Z&#39;$ mixing effects are parametrized in

Jae-weon Lee, Seoktae Koh, Chul H. Lee

The open inflation model recently proposed by Hawking and Turok is investigated in scalar-tensor gravity context. If the dilaton-like field has no potential, the instanton of our model is singular but has a finite action. The Gibbons-Hawking surface term vanishes and hence, can not be used to make $Ω_0$ nonzero. To obtain a successful open inflation one shou

Eddy Timmermans, Paolo Tommasini, Robin Cote, Mahir Hussein

Recently, effects of Feshbach resonances in atom-atom interactions were observed by varying the external magnetic field of an atomic Bose-Einstein condensate (BEC). We point out that the quasi-bound molecules created in the intermediate state of the resonance can form a second, molecular condensate. The many-body state of the system is then a hybrid atomic/m

B. J. Schroers, F. A. Bais

It is observed that the magnetic charges of classical monopole solutions in Yang-Mills-Higgs theory with non-abelian unbroken gauge group $H$ are in one-to-one correspondence with coherent states of a dual or magnetic group $\tilde H$. In the spirit of the Goddard-Nuyts-Olive conjecture this observation is interpreted as evidence for a hidden magnetic symmet

Yupeng Wang, U. Eckern

To study the impurity potential effect to the Kondo problem in a Luttinger liquid, we propose an integrable model of two interacting half-chains coupled with a single magnetic impurity ferromagnetically. It is shown that the scalar potential effectively reconciles the spin dynamics at low temperatures. Generally, there is a competition between the Kondo coup

Maximo Banados, Karin Bautier, Olivier Coussaert, Marc Henneaux

Anti-de Sitter supergravity models are considered in three dimensions. Precise asymptotic conditions involving a chiral projection are given on the Rarita-Schwinger fields. Together with the known boundary conditions on the bosonic fields, these ensure that the asymptotic symmetry algebra is the superconformal algebra. The classical central charge is compute

S. Peris, M. Perrottet, E. de Rafael

It is shown, with the example of the experimentally known Adler function, that there is no matching in the intermediate region between the two asymptotic regimes described by perturbative QCD (for the very short-distances) and by chiral perturbation theory (for the very long-distances). We then propose to consider an approximation of large-Nc QCD which consi

A. M. Ghezelbash, K. Kaviani, S. Parvizi, A. H. Fatollahi

By taking the interacting spinor-scalar theory on the $AdS_{d+1}$ space we calculate the boundary CFT correlation functions using AdS/CFT correspondence.

A. Pelissetto, E. Vicari

We study the low-temperature effective potential of the Ising model. We evaluate the three-point and four-point zero-momentum renormalized coupling constants that parametrize the expansion of the effective potential near the coexistence curve. These results are obtained by a constrained analysis of the $ε$-expansion that uses accurate estimates for the two-d

J. M. Camino, A. V. Ramallo, J. M. Sanchez de Santos

A graded generalization of the Z_k parafermionic current osp(1|2)/U(1) coset conformal field theory. The structure of the parafermionic highest-weight modules is analyzed and the dimensions of the fields of the theory are determined. A free field realization of the graded parafermionic system is obtained and the structure constants of the current algebra are

Karl Landsteiner, Esperanza Lopez, David A. Lowe

We study brane configurations in the presence of orientifold six-planes. After deriving the curves for N=2 supersymmetric SU(Nc) gauge theories with one flavor in the symmetric or antisymmetric representation and Nf fundamental flavors, we rotate the brane configuration, reducing the supersymmetry to N=1. For the case of an antisymmetric flavor and less than

J. E. Avron, A. Elgart

We prove the adiabatic theorem for quantum evolution without the traditional gap condition. All that this adiabatic theorem needs is a (piecewise) twice differentiable finite dimensional spectral projection. The result implies that the adiabatic theorem holds for the ground state of atoms in quantized radiation field. The general result we prove gives no inf

Th. Maier, M. B. Zoelfl, Th. Pruschke, J. Keller

We present magnetic properties of the three-band Hubbard model in the para- and antiferromagnetic phase on a hypercubic lattice calculated with the Dynamical Mean-Field Theory (DMFT). To allow for solutions with broken spin-symmetry we extended the approach to lattices with AB-like structure. Above a critical sublattice magnetization m_d=0.5 one can observe

H. Kleinert

We point out a possible mechanism by which smooth surfaces can become spiky as the constant of curvature stiffness $κ$ falls below certain critical values. This happens either in a single first-order transition, or in a sequence of two Kosterlitz-Thouless-like transitions. There may also be additional phases in which the spikes form a hexagonal solid-like ar