November 1999 arXiv papers — page 18

P. Kaaret, J. Grindlay, F. K. Lamb, E. H. Morgan

The great success of the Rossi X-Ray Timing Explorer (RXTE) has given us a new probe to study strong gravitational fields and to measure the physical properties of black holes and neutron stars. Here, we describe a "next-generation" x-ray timing mission, the Relativistic Astrophysics Explorer (RAE), designed to fit within the envelope of a "mediu

A. Gardini, S. A. Bonometto, A. Maccio`

The passage from angular to spatial correlations, in the case of spatial clustering length depending on the average distance between nearby objects is studied. We show that, in a number of cases, the scaling law of angular correlation amplitudes, which holds for constant spatial clustering length, is still true also for a luminosity dependent spatial correla

N. D'Amico

Since the discovery of the original millisecond pulsar, no pulsars with a shorter spin period (P<1.56 ms) were found. However, according to the most popular equations of state, the theoretical limiting spin period of a neutron star can be much shorter. On the other hand, most of the large scale searches for millisecond pulsars carried out so far were strongl

J. J. Kavelaars, W. E. Harris, D. A. Hanes, J. E. Hesser

We have used deep HST/WFPC2 images in V (F606W) and I (F814W) to measure the luminosity distribution of the globular clusters in NGC 4874, the central cD galaxy of the Coma cluster. We find the ``turnover&#39;&#39; point of the globular cluster luminosity function (GCLF) to lie at V = 27.88 +/- 0.12, while the overall GCLF shape matches the standard Gaussian

Sergei Blinnikov, Peter Lundqvist, Oleg Bartunov, Ken&#39;ichi Nomoto

The optical/UV light curves of SN 1987A are analyzed with the multi-energy group radiation hydrodynamics code STELLA. The calculated monochromatic and bolometric light curves are compared with observations shortly after shock breakout, during the early plateau, through the broad second maximum, and during the earliest phase of the radioactive tail. We have c

B. E. J. Pagel

Initial conditions are set by Big bang nucleosynthesis from which we know that 90 per cent of baryons are dark and have essentially unknown chemical composition. In our own Galaxy, there are many clues from individual stars in different populations whereas in elliptical galaxies the data largely come from integrated spectra, but these raise problems enough l

L. Grenacher, Ph. Jetzer, D. Puy

In many clusters of galaxies there is evidence for cooling flow in the central regions. A possibility is that a fraction of the gas forms cold molecular clouds. We investigate the minimum temperature which can be reached by clouds in cooling flows by computing the cooling function due to H2, HD and CO molecules. As an example, we determine the minimum temper

L. Grenacher, Ph. Jetzer, D. Puy

PKS 0745-191 is a powerful radio source with one of the largest known cooling flows (De Grandi, Molendi 1999). A fraction of the cool gas could accumulate into small molecular clouds. We studied the minimum temperature which can be reached by sub-clouds (resulting from the fragmentation of bigger clouds) in the cooling flow region.

L. Grenacher, Ph. Jetzer, D. Puy

In many clusters of galaxies there is evidence for cooling flows which deposit large quantities of cool gas in the central regions. A fraction of this gas might accumulate as dense cool clouds. The aim of this communication is to discuss the minimum temperature achievable by clouds in cooling flows of different cluster of galaxies.

H. -C. Thomas, K. Beuermann, V. Burwitz, K. Reinsch

We report observations of a new AM Herculis binary identified as the optical counterpart of the X-ray source RX J1313.2-3259, detected during the ROSAT All-Sky Survey (RASS). It has an orbital period of 251 min and is strongly modulated at optical wavelengths. The long-term behavior is characterized by a pronounced variation in X-rays between the RASS and tw

L. A. Page

The CMB is perhaps the cleanest cosmological observable. Given a cosmology model, the angular spectrum of the CMB can be computed to percent accuracy. On the observational side, as far as we know, there is little that stands in the way between an accurate measurement and a rigorous confrontation with theory. In this article, we review the state of the data a

Ann A. Esin, Erik Kuulkers, Jeffrey E. McClintock, Ramesh Narayan

We test whether the model proposed by Esin et al. to explain X-ray observations of the black hole soft X-ray transient GRS 1124-68 in outburst can also explain the optical lightcurves of a similar object A0620-00. We show that to reproduce the observed X-ray to optical flux ratio in A0620-00, we need to assume X-ray irradiation of the outer disk that is sign

Patrick McDonald, Jordi Miralda-Escude, Michael Rauch, Wallace L. W. Sargent

A sample of eight quasars observed at high resolution and signal-to-noise is used to determine the probability distribution function (PDF), the power spectrum, and the correlation function of the transmitted flux in the \lya forest, in three redshift bins centered at z=2.41, 3.00, and 3.89. All the results are presented in tabular form, with full error covar

Paul J. Francis, Matthew T. Whiting, Rachel L. Webster

We present quasi-simultaneous multi-colour optical/near-IR photometry for 157 radio selected quasars, forming an unbiassed sub-sample of the Parkes Flat-Spectrum Sample. Data are also presented for 12 optically selected QSOs, drawn from the Large Bright QSO Survey. The spectral energy distributions of the radio- and optically-selected sources are quite diffe

B. M. Gaensler, R. W. Hunstead

Before and after every 12 hour synthesis observation, the Molonglo Observatory Synthesis Telescope (MOST) measures the flux densities of ~5 compact extragalactic radio sources, chosen from a list of 55 calibrators. From 1984 to 1996, the MOST made some 58 000 such measurements. We have developed an algorithm to process this dataset to produce a light curve f

Laura Ferrarese, N. A. Silbermann, Jeremy R. Mould, Peter B. Stetson

We explore the limits of photometric reductions of crowded stellar fields observed with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope. Two photometric procedures, based on the DoPHOT and DAOPHOT/ALLFRAME programs are tested, and the effects of crowding, complex sky background and cosmic-ray contamination are discussed using an ext

S. R. Heap, G. M. Williger, A. Smette, I. Hubeny

The ultraviolet spectrum (1145--1720A) of the distant quasar Q 0302--003 (z=3.286) was observed at 1.8A resolution with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. A total integration time of 23,280 s was obtained. The spectrum clearly delineates the Gunn-Peterson HeII absorption trough, produced by HeII Lya, along the line of

M. Jahan-Miri

The observed large rates of spinning down after glitches in some radio pulsars has been previously explained in terms of a long-term spin-up behaviour of a superfluid part of the crust of neutron stars. We argue that the suggested mechanism is not viable; being inconsistent with the basic requirements for a superfluid spin-up, in addition to its quantitative

Iosif Bena

Using the known propagator equations for 0,1 and 2 forms in AdS_{d+1}, we find the p-form field propagator equations in dimensions where the forms are Poincare dual. Since the general equation obeyed by the propagators is linear in dimension, this gives us the equation obeyed by the propagators for any d. Furthermore, based on the Poincare duality formulas f

Simon Davis, Hugh Luckock

Several new results regarding the quantum cosmology of the quadratic gravity theory derived from the heterotic string effective action are presented. After describing techniques for solving the Wheeler-De Witt equation with appropriate boundary conditions, it is shown that this quantum cosmological model may be compared with semiclassical theories of inflati

Luciano Rezzolla, Frederick K. Lamb, Stuart L. Shapiro

We show that r-mode oscillations distort the magnetic fields of neutron stars and that their occurrence is likely to be limited by this interaction. If the field is gtrsim 10^{16} (Omega/Omega_B) G, where Omega and Omega_B are the angular velocities of the star and at which mass shedding occurs, r-mode oscillations cannot occur. Much weaker fields will preve

R. Jackiw, So-Young Pi

Projecting a non-Abelian SU(2) vacuum gauge field - a pure gauge constructed from the group element U - onto a fixed (electromagnetic) direction in isospace gives rise to a nontrivial magnetic field, with nonvanishing magnetic helicity, which coincides with the winding number of U. Although the helicity is not conserved under Maxwell (vacuum) evolution, it r

A. S. Kapoyannis, C. N. Ktorides, A. D. Panagiotou

A generalized Strangeness-incorporating Statistical Bootstrap Model (SSBM) is constructed so as to include indepedent fugacities for up and down quarks. Such an extension is crucial for the confrontation of multiparticle data emerging from heavy ion collisions, wherein isospin symmetry is not satisfied. Two constraints, in addition to the presence of a criti

K. Kifonidis, T. Plewa, H. -Th. Janka, E. Mueller

High-resolution two-dimensional simulations were performed for the first five minutes of the evolution of a core collapse supernova explosion in a 15 solar mass blue supergiant progenitor. The computations start shortly after bounce and include neutrino-matter interactions by using a light-bulb approximation for the neutrinos, and a treatment of the nucleosy

Joachim Kupsch

Continuous and discrete superselection rules induced by the interaction with the environment are investigated for a class of exactly soluble Hamiltonian models. The environment is given by a Boson field. Stable superselection sectors emerge if and only if the low frequences dominate and the ground state of the Boson field disappears due to infrared divergenc

Antony Lewis, Anthony Challinor, Anthony Lasenby

We implement the efficient line of sight method to calculate the anisotropy and polarization of the cosmic microwave background for scalar and tensor modes in almost-Friedmann-Robertson-Walker models with positive spatial curvature. We present new results for the polarization power spectra in such models.

S. A. Smolyansky, V. A. Mizerny, A. V. Prozorkevich, D. V. Vinnik

We investigate the quantum Vlasov equation with a source term describing the spontaneous particle creation in strong fields. The back-reaction problem is treated by solving this kinetic equation together with the Maxwell equation which determines the induced time-dependent electric field in the system. The evolution of distribution functions for bosons and f

P. Dimopoulos, K. Farakos, G. Koutsoumbas

We study the Abelian Higgs Model using an improved form of the action in the scalar sector. The subleading corrections are carefully analysed and the connection between lattice and continuous parameters is worked out. The simulation shows a remarkable improvement of the numerical performance.

Z. Y. Weng, D. N. Sheng, C. S. Ting

Quasiparticle properties are explored in an effective theory of the $t-J$ model which includes two important components: spin-charge separation and unrenormalizable phase shift. We show that the phase shift effect indeed causes the system to be a non-Fermi liquid as conjectured by Anderson on a general ground. But this phase shift also drastically changes a

G. F. Giudice, A. Riotto, I. Tkachev

The excessive production of gravitinos in the early universe destroys the successful predictions of nucleosynthesis. The thermal generation of gravitinos after inflation leads to the bound on the reheating temperature, T_{RH}< 10^9 GeV. However, it has been recently realized that the non-thermal generation of gravitinos in the early universe can be extremely

Alan M. Levine, Saul A. Rappaport, Goce Zojcheski

We report on the results of observations of the binary X-ray pulsar LMC X-4 with the Rossi X-ray Timing Explorer. Our analysis of the Doppler delays of the 13.5-s X-ray pulsations yields the most accurate determination of the LMC X-4 orbital parameters available to date. The epoch of orbital phase zero for the 1.4 day orbit is determined with an uncertainty

Philip R. Page

QCD and QED exhibit an infinite set of three-point Green&#39;s functions that contain only OZI rule violating contributions, and (for QCD) are subleading in the large N_c expansion. The Green&#39;s functions describe the ``decay&#39;&#39; of a J^{PC}={1,3,5 ...}^{-+} exotic hybrid meson current to two J=0 (hybrid) meson currents with identical P and C. We pr

B. Bassetti, M. Cosentino Lagomarsino, P. Jona

We propose a two-dimensional model for the organization of stabilized microtubules driven by molecular motors in an unconfined geometry. In this model two kinds of dynamics are competing. The first one is purely diffusive, with an interaction between the rotational degrees of freedom, the second one is a local drive, dependent on microtubule polarity. As a r

Naoki Kawashima

Global changes of states are of crucial importance in optimization algorithms. We review some heuristic algorithms in which global updates are realized by a sort of real-space renormalization group transformation. Emphasis is on the relationship between the structure of low-energy excitations and ``block-spins&#39;&#39; appearing in the algorithms. We also d

I. Jack, S. Parsons

We show that in a two-dimensional sigma-model whose fields only depend on one target space co-ordinate, the O(d,d) invariance of the conformal invariance conditions observed at one loop is preserved at two loops (in the general case with torsion) and at three loops (in the case without torsion).

Kaori Otsuki, Hideyuki Tagoshi, Toshitaka Kajino, Shin-ya Wanajo

Neutrino-driven wind from young hot neutron star, which is formed by supernova explosion, is the most promising candidate site for r-process nucleosynthesis. We study general relativistic effects on this wind in Schwarzschild geometry in order to look for suitable conditions for a successful r-process nucleosynthesis. It is quantitatively discussed that the

K. Zyablyuk

The spectral density of euclidean Dirac operator is investigated in partially quenched QCD with arbitrary quark masses. A representation of scalar and pseudoscalar correlators in terms of the spectral density is discussed. The spectral density, obtained from the partially quenched chiral perturbation theory is shown to be compatible with low energy sum rules

Marion Flanz, Werner Rodejohann, Kai Zuber

The lepton-number violating process e p \to nu_e l l&#39; X mediated by Majorana neutrinos is studied for the HERA collider for (l l&#39;) = (e tau), (mu tau), (mu mu) and (tau tau). Only the muonic decay of the tau is considered. The direct limit on the effective muon Majorana mass, <m_{mu mu}> is improved significantly to 4.0 times 10^3 GeV and for the fir

Catherine Labruere, Luis Paris

Consider an oriented compact surface F of positive genus, possibly with boundary, and a finite set P of punctures in the interior of F, and define the punctured mapping class group of F relatively to P to be the group of isotopy classes of orientation-preserving homeomorphisms h: F-->F which pointwise fix the boundary of F and such that h(P) = P. In this pap

J. A. Oller, E. Oset, J. R. Pelaez

Starting from the Chiral Perturbation Theory Lagrangian, but keeping different masses for the charged and neutral mesons, and using a previously developed non-perturbative unitary scheme that generates the lightest meson-meson resonances, we construct K Kbar to K Kbar and K Kbar to pi+ pi- in the vector channel. This allows us to obtain the kaon-loop contrib

G. Pinter

A formula describing finite renormalizations is derived in the Epstein-Glaser formalism and an explicit calculation of finite counterterms in $Φ^4$-theory is performed. The Zimmermann identities and the action principle for changes of parameters in the interaction are presented independent of the adiabatic limit.

P. P. Fiziev

We study a new minimal scalar-tensor model of gravity with Brans-Dicke factor $ω(Φ)\equiv 0$ and cosmological factor $Π(Φ)$. The constraints on $Π(Φ)$ from known gravitational experiments are derived. We show that almost any time evolution of the scale factor in a homogeneous isotropic Universe can be obtained via properly chosen $Π(Φ)$ and discuss the gener

S. O. Alexeyev, M. V. Sazhin, M. V. Pomazanov

A lower limit for a neutral black hole size is obtained in the frames of the string gravity model with the second order curvature correction. It is shown that this effect remains when the third order curvature correction is also taken into account and argued that such restriction does exist in all perturbative orders of curvature expansions.

Makoto Natsuume, Takashi Okamura

We propose that Strominger&#39;s method to derive the BTZ black hole entropy is in fact applicable to other asymptotically AdS_3 black holes and gives the correct functional form of entropies. We discuss various solutions in the Einstein-Maxwell theory, dilaton gravity, Einstein-scalar theories, and Einstein-Maxwell-dilaton theory. In some cases, solutions a

A. Gersten

By applying projection operators to state vectors of coordinates we obtain subspaces in which these states are no longer normalized according to Dirac&#39;s delta function but normalized according to what we call &#34;incomplete delta functions&#34;. We show that this class of functions satisfy identities similar to those satisfied by the Dirac delta functio

A. Gersten

One-dimensional particle states are constructed according to orthogonality conditions, without requiring boundary conditions. Free particle states are constructed using Dirac&#39;s delta function orthogonality conditions. The states (doublets) depend on two quantum numbers: energy and parity. With the aid of projection operators the particles are confined to

Marek Zukowski, Dagomir Kaszlikowski

We show that the possibility of distinguishing between single and two photon detection events is not a necessary requirement for the proof that recent operational realization of entanglement swapping cannot find a local realistic description. We propose a simple modification of the experiment, which gives a richer set of interesting phenomena.

W. Dür, J. I. Cirac

We give a complete, hierarchic classification for arbitrary multi-qubit mixed states based on the separability properties of certain partitions. We introduce a family of N-qubit states to which any arbitrary state can be depolarized. This family can be viewed as the generalization of Werner states to multi-qubit systems. We fully classify those states with r

R Hasson

In an inverse problem, such as the determination of brain activity given magnetic field measurements outside the head, the main quantity of interest is often the power associated with a source. The `standard&#39; way to determine this has been to find the best linear estimate of the source and calculate the power associated with this. This paper proposes an

M. Steinberg, W. Ebeling, J. Ortner

This paper investigates the density expansion of the thermodynamic properties of a two component plasma under the influence of a weak constant uniform magnetic field. We start with the fugacity expansion for the Helmholtz free energy. The leading terms with respect to the density are calculated by a perturbation expansion with respect to the magnetic field.

D. M. Snyder

Certain transformations of isolated physical systems underlying various conservation laws in physics are noted. As regards each of these transformations, there is a theoretical action that is equivalent to a matched physical action on the system. Evidence supporting this thesis is found in experimental psychological research where results of various experime

Chris Plottke, Igor Bray

The S-wave model of electron-hydrogen scattering is evaluated using the convergent close-coupling method with an emphasis on scattering from excited states including an initial state from the target continuum. Convergence is found for discrete excitations and the elastic free-free transition. The latter is particularly interesting given the corresponding pot

M. Agop, C. Gh. Buzea, B. Ciobanu

We show the presence of an electromagnetic field can cause a gravitational Meissner effect and, as a result, a gravitational shielding. With this aim in view we must first unveil the following problems : generalized Maxwell equations, generalized London equations, generalized Meissner effect, generalized shielding, etc.

A. K. Motovilov, W. Sandhas, S. A. Sofianos, E. A. Kolganova

The ^4He_3 bound states and the scattering of a ^4He atom off a ^4He dimer at ultra-low energies are investigated using a hard-core version of the Faddeev differential equations. Various realistic ^4He-^4He interactions were employed, amomg them the LM2M2 potential by Aziz and Slaman and the recent TTY potential by Tang, Toennies and Yiu. The ground state an

Moritz Hoeffe

The diffraction spectrum of the dart-rhombus random tiling of the plane is derived in rigorous terms. Using the theory of dimer models, it is shown that it consists of Bragg peaks and an absolutely continuous diffuse background, but no singular continuous component. The Bragg part is given explicitly.

Andrei G. Bytsko

We study 2x2 matrices A such that the corresponding TBA equations yield c[A] in the form of the effective central charge of a minimal Virasoro model. Certain properties of such matrices and the corresponding solutions of the TBA equations are established. Several continuous families and a discrete set of admissible matrices A are found. The corresponding two

Joel Hass, J. Hyam Rubinstein, Shicheng Wang

This paper presents some finiteness results for the number of boundary slopes of immersed essential surfaces of given genus g in a compact 3-manifold with torus boundary. In the case of hyperbolic 3-manifolds we obtain uniform quadratic bounds in g for the number of possible slopes, independent of the 3-manifold. We also look at some related quantities, such

Eduardo Esteves, Mathieu Gagne, Steven Kleiman

We prove the following autoduality theorem for an integral projective curve C in any characteristic. Given an invertible sheaf L of degree 1, form the corresponding Abel map A_L: C->J, which maps C into its compactified Jacobian, and form its pullback map A_L^*: Pic^0_J to J, which carries the connected component of 0 in the Picard scheme back to the Jacobia

Ludwig Balke

For a smoothing Y of a 2-dimensional cyclic quotient singularity X, we construct a simple handle decomposition of Y by using a particular birational map from Y to the projective plane. The manifold Y is built up from the product of an annulus with a disk by attaching 2-handles in a manner which can be described by means of a plumbing graph. In particular, Y

Viktor Ostrik

Let G be a simple algebraic group over the complex numbers. Let N be the cone of nilpotent elements in the Lie algebra of G. Let K_{G x C^*}(N) denote the Grothendieck group of the category of G x C^*-equivariant coherent sheaves on N. In this note we construct a Kazhdan-Lusztig type canonical basis of K_{G x C^*}(N) over representation ring of C^*. This bas

I. Kh. Musin

The strong dual space of linear continuous functionals on a weighted space G of infinitely differentiable functions defined on the real line is described in terms of their Fourier-Laplace transforms.

Tahl Nowik

Let F be a closed orientable surface. We give an explicit formula for the number mod 2 of quadruple points occurring in any generic regular homotopy between any two regularly homotopic embeddings e,e&#39;:F -> R^3. The formula is in terms of homological data extracted from the two embeddings.

Mirjana Borisavljevic, Kosta Dosen, Zoran Petric

The paper presents a cut-elimination procedure for intuitionistic propositional logic in which cut is eliminated directly, without introducing the multiple-cut rule mix, and in which pushing cut above contraction is one of the reduction steps. The presentation of this procedure is preceded by an analysis of Gentzen&#39;s mix-elimination procedure, made in th

Petar J. Topalov, Vladimir S. Matveev

We suggest a construction that, given a trajectorial diffeomorphism between two Hamiltonian systems, produces integrals of them. As the main example we treat geodesic equivalence of metrics. We show that the existence of a non-trivially geodesically equivalent metric leads to Liouville integrability, and present explicit formulae for integrals.

Michael Baake

Toral automorphisms are widely used (discrete) dynamical systems, the perhaps most prominent example (in 2D) being Arnold&#39;s cat map. Given such an automorphism M, its symmetries (i.e. all automorphisms that commute with M) and reversing symmetries (i.e. all automorphisms that conjugate M into its inverse) can be determined by means of number theoretic to

J. M. Isidro

We prove that if $D\subset C^n$ is a bounded domain with real analytic boundary and D is pseudoconvex then the compact open topology in the group of holomorphic automorphisms of D is the topology of uniform convergence on D.

Kosta Dosen, Zoran Petric

It is proved that equalities between arrows assumed for cartesian categories are maximal in the sense that extending them with any new equality in the language of free cartesian categories collapses a cartesian category into a preorder. An analogous result holds for categories with binary products, which may lack a terminal object. The proof is based on a co

Yao-Zhong Zhang, Mark D. Gould

Bosonized q-vertex operators related to the 4-dimensional evaluation modules of the quantum affine superalgebra $U_q[\hat{sl(2|1)}]$ are constructed for arbitrary level $k=α$, where $α\neq 0, -1$ is a complex parameter appearing in the 4-dimensional evaluation representations. They are intertwiners among the level-$α$ highest weight Fock-Wakimoto modules. Sc

Bernhard Lamel

We define a new local invariant (called degeneracy) associated to a triple (M,M&#39;,H), where M and M&#39; are real submanifolds of C^N and C^N&#39;, respectively, and H: M->M&#39; is either a holomorphic map, a formal holomorphic map, or a smooth CR-map. We use this invariant to find sufficient conditions under which finite jet dependence, convergence and

R. Jackiw

A lesson for the new millennium from quantum field theory: Not all field-theoretic infinities are bad. Some give rise to finite, symmetry-breaking effects, whose consequences are observed in Nature.

Sukanta Bose, Thant Zin Naing

We explore the (non)-universality of Martinez&#39;s conjecture, originally proposed for Kerr black holes, within and beyond general relativity. The conjecture states that the Brown-York quasilocal energy at the outer horizon of such a black hole reduces to twice its irreducible mass, or equivalently, to \sqrt{A} /(2\sqrt{pi}), where `A&#39; is its area. We f

Sukanta Bose, Naresh Dadhich, Sayan Kar

The electrogravity transformation is applied to the three-dimensional Einstein field equations to obtain new multi-parameter families of black hole solutions. The Bañados-Teitelboim-Zanelli black hole is shown to be a special case of one of these families. The causal structure, associated matter, as well as the mechanical and thermodynamical properties of so

Tom Banks

This is a series of lectures on M Theory for cosmologists. After summarizing some of the main properties of M Theory and its dualities I show how it can be used to address various fundamental and phenomenological issues in cosmology.

Prasanta K. Tripathy, Fidel A. Schaposnik

We study static spherically symmetric monopole solutions in non-Abelian Einstein-Born-Infeld-Higgs model with normal trace structure. These monopoles are similar to the corresponding solution with symmetrised trace structure and are existing only up to some critical value of the strength of the gravitational interaction. In addition, similar to their flat sp

V. P. Nair

Recent progress in understanding (2+1)-dimensional Yang-Mills (YM_{2+1}) theory via the use of gauge-invariant variables is reviewed. Among other things, we discuss the vacuum wavefunction, an analytic calculation of the string tension and the propagator mass for gluons and its relation to the magnetic mass for YM_{3+1} at nonzero temperature.

Y. S. Myung, H. W. Lee

We propose the two formalisms for obtaining the noncommutative spacetime in a magnetic field. One is the first-order formalism and the other is the second-order formalism. Although the noncommutative spacetime is realized manifestly in the first-order formalism, the second-order formalism would be more useful for calculating the physical quantities in the no

S. A. Paston, E. V. Prokhvatilov, V. A. Franke

Light-Front (LF) Hamiltonian for QED in (1+1)-dimensions is constructed using the boson form of this model with additional Pauli-Villars type ultraviolet regularization. Perturbation theory, generated by this LF Hamiltonian, is proved to be equivalent to usual covariant chiral perturbation theory. The obtained LF Hamiltonian depends explicitly on chiral cond

A. Brandhuber, K. Sfetsos

Within the AdS/CFT correspondence we use multicentre D3-brane metrics to investigate Wilson loops and compute the associated heavy quark-antiquark potentials for the strongly coupled SU(N) super-Yang-Mills gauge theory, when the gauge symmetry is broken by the expectation values of the scalar fields. For the case of a uniform distribution of D3-branes over a

V. A. Rubakov

We suggest that the cosmological constant has been relaxed to its present, very small value during the inflationary stage of the evolution of the Universe. This requires relatively low scale, very long duration and unconventional source of inflation. We present a concrete mechanism of the cosmological constant relaxation at the inflationary epoch.

Tobias Hurth

We discuss the gluino-induced contribution to rare B decays in supersymmetric frameworks with generic sources of flavour change.

M. Jack

After 10 years of steadily increasing the experimental precision at LEP/SLC, there is a strong demand on an update of existing programs for fermion pair production. We present a rederivation of the O(alpha) Bremsstrahlung corrections to e+e- --> f+f- for the semi-analytic program ZFITTER. We focus on observables like total cross section and forward-backward

P. Osland, P. N. Pandita

An elementary Higgs boson, which is the remnant of the spontaneous symmetry breaking mechanism in the Standard Model, remains one of the most elusive particles. If a Higgs boson candidate is found at future accelerators, it becomes necessary to determine its properties, beyond the mass, production cross section and decay rates. The other crucial properties r

Alex Pomarol

We consider the possibility of gauge bosons living in the recently proposed five-dimensional theory with localized gravity. We study the mass spectrum of the Kaluza-Klein (KK) excitations of the gauge fields and calculate their couplings to the boundaries of the fifth dimension. We find a different behaviour from the case of the graviton. In particular, we f

D. Elazzar Kaplan, Graham D. Kribs, Martin Schmaltz

We propose a new framework for mediating supersymmetry breaking through an extra dimension. It predicts positive scalar masses and solves the supersymmetric flavor problem. Supersymmetry breaks on a ``source&#39;&#39; brane that is spatially separated from a parallel brane on which the standard model matter fields and their superpartners live. The gauge and

Lior M. Burko

We study the self forces acting on static scalar and electric test charges in the spacetime of a Schwarzschild black hole. The analysis is based on a direct, local calculation of the self forces via mode decomposition, and on two independent regularization procedures: A spatially-extended particle model method, and on a mode-sum regularization prescription.

Jose M. Pozo, Josep M. Parra

Senovilla has recently defined an algebraic construction of a superenergy tensor T{A} from any arbitrary tensor A, by structuring it as an r-fold form. This superenergy tensor satisfies automatically the dominant superenergy property. We present a more compact definition using the r-direct product Clifford algebra r-Cl(p,q). This form for the superenergy ten

S. A. Pavluchenko, A. V. Toporensky

The chaotic behavior in FRW cosmology with a scalar field is studied for scalar field potentials less steep than quadratic. We describe a transition to much stronger chaos for appropriate parameters of such potentials. The range of parameters which allows this transition is specified. The influence of ordinary matter on the chaotic properties of this model i

Franz E. Schunck, Diego F. Torres

We study boson star configurations with generic, but not non-topological, self-interaction terms, i.e. we do not restrict ourselves just to consider the standard $λ|ψ|^4$ interaction but more general U(1)-symmetry-preserving profiles. We find that when compared with the usual potential, similar results for masses and number of particles appear. However, chan

Wolfgang Slany

We consider combinatorial avoidance and achievement games based on graph Ramsey theory: The players take turns in coloring still uncolored edges of a graph G, each player being assigned a distinct color, choosing one edge per move. In avoidance games, completing a monochromatic subgraph isomorphic to another graph A leads to immediate defeat or is forbidden

Sergio Curilef, Constantino Tsallis

Molecular dynamic simulations for systems with $D=2,3$ Lennard-Jones-like interactions are studied. In the model, we assume that, at long distances, the two-body attractive potential decays as $r^{-α}$. Thermodynamic extensivity (nonextensivity) is observed for $α> D$ ($0\leq α\leq D$). Particular attention is payed to the liquid-gas critical point located,

E. J. Mele, P. Kral, D. Tomanek

Coherent one photon ($2 ω$) and two photon ($ ω$) electronic excitations are studied for graphene sheets and for carbon nanotubes using a long wavelength theory for the low energy electronic states. For graphene sheets we find that coherent superposition of these excitations produces a polar asymmetry in the momentum space distribution of the excited carrier

Markus Holzmann, Franck Laloë

The Bogoliubov transformation is generally derived in the context of identical bosons with the use of ``second quantized&#39;&#39; a and $a^{\dagger}$ operators (or, equivalently, in field theory). Here, we show that the transformation, together with its characteristic energy spectrum, can also be derived within the Hilbert space of distinguishable particles

N. D. Whelan, J. P. Carbotte

Among high T_c materials, the YBCO (YBa_2Cu_3O_{7-x}) compounds are special since they have superconducting chains as well as planes. We show that a discontinuity in the density of states as a function of magnetic field may appear at a new energy scale, characteristic of the chain and distinct from that set by the d wave gap. This is observable in experiment

Felix Ritort

We propose damage spreading (DS) as a tool to investigate the topological features related to the ruggedness of the free energy landscape. We argue that DS measures the positiveness of the largest Lyapunov exponent associated to the basins of attraction visited by the system during its dynamical evolution. We discuss recent results obtained in the framework

S. Brazovski, N. Kirova

The rich order parameter of Spin Density Waves allows for an unusual object of a complex topological nature: a half-integer dislocation combined with a semi-vortex of the staggered magnetization. It becomes energetically preferable to ordinary dislocation due to enhanced Coulomb interactions in the semiconducting regime. Generation of these objects changes t

Yue Yu, Huan-Xiong Yang, Yong-Shi Wu

We develop a bosonization approach for one-dimensional models based on Bethe ansatz equations. The operator formalism of the exact soluble models in the low energy limit provides a systematic method to calculate the asymptotic correlation functions. As examples with and without internal degrees of freedom, the Calogero-Sutherland (C-S) model and the repulsiv

M. Steinberg, J. Ortner

The high-density electron gas in a strong magnetic field B and at zero temperature is investigated. The quantum strong-field limit is considered in which only the lowest Landau level is occupied. It is shown that the perturbation series of the ground-state energy can be represented in analogy to the Gell-Mann Brueckner expression of the ground-state energy o

H. J. Hilhorst

We consider the d-dimensional diffusion equation for a field phi(x,t) with random initial condition, and observe that, when appropriately scaled, phi(0,t) is Gaussian and Markovian in the limit d->0. This leads via the Majumdar-Sire perturbation theory to a small-d expansion for the persistence exponent theta(d). We find theta(d) = d/4 - 0.12065...d^{3/2} +

Masaki Oshikawa

Combined with Laughlin&#39;s argument on the quantized Hall conductivity, Lieb-Schultz-Mattis argument is extended to quantum many-particle systems (including quantum spin systems) with a conserved particle number, on a periodic lattice in arbitrary dimensions. Regardless of dimensionality, interaction strength and particle statistics (bose/fermi), a finite

Gunnar Palsson, Gabriel Kotliar

We investigate the thermoelectric response of correlated electron systems near the density driven Mott transition using the dynamical mean field theory.