February 1999 arXiv papers — page 2

K. Stepanyantz

We discuss the ways of constructing the exact superpotential for N=1 supersymmetric theories and propose a new approach. As a consequence, a new structure of the superpotential is found.

D. de Florian, M. Grazzini, Z. Kunszt

Inclusive associated production of a light Higgs boson (m_H < m_t) with one jet in pp collisions is studied in next-to-leading order QCD. Transverse momentum (p_T < 30 GeV) and rapidity distributions of the Higgs boson are calculated for the LHC in the large top-quark mass limit. It is pointed out that, as much as in the case of inclusive Higgs production, t

Michael Gronau, Dan Pirjol

Three ways are compared of dealing with rescattering effects in $B^{\pm}\to K^0π^{\pm}$, in order to determine the weak phase $γ$ from these processes and $B^{\pm}\to K^{\pm}π^0$. We find that neglecting these contributions altogether may involve sizable errors in $γ$, depending on the rescattering amplitude and on the value of a certain measurable strong ph

N. G. Evanson, J. R. Forshaw

We study the diffractive production of photons in gamma-p and gamma-gamma collisions. We specifically compute the rates for gamma*-p -> gamma-X and for gamma*-gamma* -> gamma-gamma, where X denotes the proton dissociation. We focus on the rates at large momentum transfers, -t >> Lambda^2, where we are most confident in the use of QCD perturbation theory. How

K. G. Chetyrkin, M. Steinhauser

The partial decay rate of the $Z$ boson into bottom quarks constitutes an important decay channel. This is mainly due to the virtual presence of the top quark in the loop diagrams giving rise to correction factors which are quadratic in the top quark mass. At one- and two-loop order it turned out that the leading term in the heavy-top expansion leads to very

G. Calucci, D. Treleani

The observation of double parton collisions by CDF has provided the first direct information on the structure of the proton in transverse space. The actual quantity which has been measured is the `effective cross section&#39; $σ_{eff}$, which is related to the transverse size of the region where hard interactions are localized. The actual value which has bee

M. Bastero-Gil, S. F. King

We propose a model of inflation based on a simple variant of the NMSSM, called $ϕ$NMSSM where the additional singlet $ϕ$ plays the role of the inflaton in hybrid (or inverted hybrid) type models. The $ϕ$NMSSM solves the $μ$ problem of the MSSM via the vacuum expectation value of the gauge singlet N, but also solves the strong CP problem through an approximat

A. T. Davies, C. D. Froggatt, A. Usai

We consider spontaneous CP violation in the Next to Minimal Supersymmetric Standard Model (NMSSM), without the usual $Z_3$ discrete symmetry. CP violation can occur at tree level, raising a potential conflict with the experimental bounds on the electric dipole moments of the electron and neutron. One escape from this is to demand that the CP violating angles

Hoang Ngoc Long, Takeo Inami

The S, T, U parameters in the $ SU(3)_C\times SU(3)_L\times U(1)$ model with right -handed neutrinos are calculated. Explicit expressions for the oblique and Z - Z&#39; mixing contributions are obtained. We show that the bilepton oblique contributions to S and T parameters are bounded : $- 0.085 \stackrel{<}{\sim} S \stackrel{<}{\sim} 0.05$ and $- 0.001 \sta

Chao-Shang Huang, Xiao-Hong Wu, Shou-Hua Zhu

We investigate the flavor changing neutral current bsV(V=$γ$,Z) couplings in the production vertex for the process $e^+e^-\to b\bar s or \bar b s$ in the standard model. The precise calculations keeping all quark masses non-zero are carried out. Production cross sections are found to be the order of $10^{-3}$ fb at LEP II and the order of $10^{-1}$ fb when c

J. J. M. Verbaarschot

In the first part of these lectures we discuss the infrared limit of the spectrum of the QCD Dirac operator. We discuss the global symmetries of the QCD partition function and show that the Dirac spectrum near zero virtuality is determined by the pattern of spontaneous chiral symmetry breaking of a QCD-like partition function with additional bosonic valence

J. Cruz, A. Fabbri, J. Navarro-Salas

We explicitly show that, in the context of a recently proposed 2D dilaton gravity theory, energy conservation requires the ``natural&#39;&#39; Killing vector to have, asymptotically, an unusual normalization. The Hawking temperature $T_H$ is then calculated according to this prescription.

Valerio Faraoni

Contrary to common belief, the standard tenet of Brans-Dicke theory reducing to general relativity when omega tends to infinity is false if the trace of the matter energy-momentum tensor vanishes. The issue is clarified in a new approach using conformal transformations. The otherwise unaccountable limiting behavior of Brans-Dicke gravity is easily understood

A. Emperador, M. Barranco, E. Lipparini, M. Pi

We have studied the structure and dipole charge density response of nanorings as a function of the magnetic field using local-spin density functional theory. Two small rings consisting of 12 and 22 electrons confined by a positively charged background are used to represent the cases of a narrow and a wide ring. The results are qualitatively compared with exp

Giovanni Settanni, Cristian Micheletti, Jayanth Banavar, Amos Maritan

An optimization technique is used to determine the pairwise interactions between amino acids in globular proteins. A numerical strategy is applied to a set of proteins for maximizing the native fold stability with respect to alternative structures obtained by gapless threading. The extracted parameters are shown to be very reliable for identifying the native

A. J. Bray, A. J. Briant, D. K. Jervis

The approach to equilibrium, from a nonequilibrium initial state, in a system at its critical point is usually described by a scaling theory with a single growing length scale, $ξ(t) \sim t^{1/z}$, where z is the dynamic exponent that governs the equilibrium dynamics. We show that, for the 2D XY model, the rate of approach to equilibrium depends on the initi

E. K. Kudinov

It is proposed to used, as a basic property specifying the difference between an insulator and a conductor, a static phenomenon, namely the field effect which absent in the former, but present in the latter. The absence or present of the field effect is closely associated with the nature of the homogenious linear response to a static electric field. For an i

D. W. Hess, J. W. Serene

We compare the quasiparticle band structure for a model insulator obtained from the fluctuation exchange approximation (FEA) with the eigenvalues of the corresponding density functional theory (DFT) and local density approximation (LDA). The discontinuity in the exchange-correlation potential for this model is small and the FEA and DFT band structures are in

X. -Z. Yan, C. -R. Hu

The magnetic field effect in the Josephson tunneling between two d-wave superconductors are investigated. When the crystal orientation of one (or each) superconductor relative to the interface normal is such that midgap states exist at the interface, there is a component of the tunneling current due to the midgap states. For a junction with a flat {001}|{110

C. Bennemann, J. Baschnagel, W. Paul, K. Binder

We report results of molecular-dynamics simulations for a glassy polymer melt consisting of short, linear bead-spring chains. It was shown in previous work that this onset of the glassy slowing down is compatible with the predictions of the mode coupling theory. The physical process of `caging&#39; of a monomer by its spatial neighbors leads to a distinct tw

A. Emperador, M. Barranco, E. Lipparini, M. Pi

We have employed time-dependent local-spin density theory to analyze the multipole spin and charge density excitations recently found in GaAs-AlGaAs quatum dots [C. Schüller et al, Phys. Rev. Lett {\bf 80}, 2673 (1998)]. The overall agreement between theory and experiment is good, identifying the angular momentum of the modes observed in the experiment. We h

A. G. Moreira, M. M. Telo da Gama, M. E. Fisher

Criticality in a fluid of dielectric constant D that exhibits Ising-type behavior is studied as additional electrostatic (i.e., ionic) interactions are turned on. An exploratory perturbative calculation is performed for small ionicity as measured by the ratio of the electrostatic energy to the strength of the short-range nonionic (i.e., van der Waals) intera

A. Mourachkine

We use Ni and Zn impurities doped into Bi2212 to test the MS (Magnetic polaron - Spinon) model proposed earlier. We present electron-tunneling spectroscopy of pure, Ni- and Zn-doped Bi2212 single crystals below Tc using a break-junction technique. We show that the magnetic (Ni) and nonmagnetic (Zn) impurities doped into CuO2 planes affect both Tc and the den

V. N. Bogomolov

It is demonstrated that the point of view that metallization of xenon as a result of a band - gap closure has some discrepancies with experimental result. A superconductivity transition as an alternative possibility is examined. At such supposition critical temperature of superconductivity transition T is about 5000 K. A mechanism of inert gas condensation b

T. Fukui

A two dimensional random hopping model with N-species and π-flux is studied. The field theory at the band center is shown to be in the universality class of GL(4m,R)/O(4m) nonlinear sigma model. Vanishing beta function suggests delocalised states at the band center. Contrary to the similar universality class with broken time reversal symmetry, the present cl

Weiping Zhang, C. A. Sackett, R. G. Hulet

Light scattering from a spin-polarized degenerate Fermi gas of trapped ultracold Li-6 atoms is studied. We find that the scattered light contains information which directly reflects the quantum pair correlation due to the formation of atomic Cooper pairs resulting from a BCS phase transition to a superfluid state. Evidence for pairing can be observed in both

V. V. Makhro

We propose a novel approach to the problem of a transition from quantum to classical behavior in mesoscopic spin systems. This paper is intended to demonstrate that main cause of such transitions is quantum decoherence which appear as a result of a thermal interaction between spin system and its environment.

Alexei Vazquez, Oscar Sotolongo-Costa

The dynamics of a domain wall in magnetostrictive materials is investigated. The domain wall is modeled by a d-dimensional interface moving in a d+1-dimensional environment. Long-range demagnetization effects and quenched disorder are considered, while the external magnetic field is increased at constant rate. Exact expressions for the average interface velo

Shauna Sallmen, D. C. Backer, T. H. Hankins, D. Moffett

Simultaneous measurements of giant pulses from the Crab pulsar were taken at two widely spaced frequencies using the real-time detection of a giant pulse at 1.4 GHz at the Very Large Array to trigger the observation of that same pulse at 0.6 GHz at a 25-m telescope in Green Bank, WV. Interstellar dispersion of the signals provided the necessary time to commu

Jason D. Fiege, Ralph E. Pudritz

In Paper I (Fiege & Pudritz, 1999), we constructed models of filamentary molecular clouds that are truncated by a realistic external pressure and contain a rather general helical magnetic field. We address the stability of our models to gravitational fragmentation and axisymmetric MHD-driven instabilities. By calculating the dominant modes of axisymmetric in

A Meiksin

Prior to the epoch of full reionization, the intergalactic medium and gravitationally collapsed systems will be detectable in 21-cm radiation. Physical mechanisms that would produce a 21-cm signature are discussed. These include Lya coupling of the hydrogen spin temperature to the kinetic temperature of the gas resulting from the radiation by an early genera

Sofia Feltzing, Gerard Gilmore, Rosemary F. G. Wyse

Analyses of their internal stellar kinematics imply that the dwarf spheroidal (dSph) companion galaxies to the Milky Way are among the most dark-matter dominated systems known. Should there be significant dark matter in the form of faint stars in these systems, the stellar luminosity function must be very different from that of a similar metallicity globular

M. R. de Garcia Maia, J. C. Carvalho, C. S. da Câmara Neto

Some cosmological consequences of first order quantum corrections to Maxwell electrodynamics are investigated in the context of a spatially flat homogeneous and isotropic universe driven by a magnetic field plus a cosmological term $Λ$. For a vanishing $Λ$, we derive the general solution corresponding to the particular one recently found by Novello et al. [g

B. T. Draine, F. Bertoldi

ISO has provided us with a new perspective on gas temperatures in photodissociation regions through measurements of line emission from rotationally-excited levels of the H_2 molecule. The H_2 rotational level populations provide a thermal probe, showing that gas temperatures T_gas approx 500-1000 K prevail in a portion of the PDR where significant quantities

G. Risaliti, R. Maiolino, M. Salvati

We use hard X-ray data for an &#34;optimal&#34; sample of Seyfert 2 galaxies to derive the distribution of the gaseous absorbing column densities among obscured active nuclei in the local Universe. Of all Seyfert 2 galaxies in the sample, 75% are heavily obscured (N_H > 10^23 cm^-2) and about half are Compton thick (N_H > 10^24 cm^-2). Intermediate type 1.8-

M. Villar-Martin, C. Tadhunter, R. Morganti, D. Axon

We present high resolution, long-slit spectra of the jet-cloud interaction in the powerful southern radio galaxy PKS2250-41. We have resolved the emission lines into two main kinematic components: a broad component (FWHM \geq 900 km/s) and a narrow component (FWHM \leq 150 km/s). While the broad component is characterized by a low ionization level (with part

Dan Kiselman

NLTE effects - the errors caused by assuming local thermodynamic equilibrium (LTE) - on LiBeB abundance determinations for cool stars are discussed. These NLTE effects are significant in many cases for B I and Li I lines. The Be II 313 nm lines are not formed under LTE circumstances, but the NLTE effects on equivalent widths seem to be rather small. Reasons

S. Capozziello, G. Lambiase, G. Papini, G. Scarpetta

We show that, in cosmological microlensing, corrections of order $v/c \sim Δλ/λ$, to the deflection angle of light beams from a distant source are not negligible and that all microlensing quantities should be corrected up to this order independently of the cosmological model used.

Christopher W. Churchill, Donald P. Schneider, Maarten Schmidt, James E. Gunn

The z=4.591 quasar PC 1415+3408 exhibits very strong associated metal-line absorption from the N V (1238,1242), Si IV (1393,1402), and C IV (1548,1550) doublets spanning the velocity interval -1700 < v < 0 km/s. Also present, are detached absorption troughs in N V and C IV spanning -5000 < v < -3000 km/s; this is characteristic of broad absorption line (BAL)

Joseph M. Hahn, Renu Malhotra

The existence of the Oort Comet Cloud, the Kuiper Belt, and plausible inefficiencies in planetary core formation, all suggest that there was once a residual planetesimal disk of mass 10-100 Earth-masses in the vicinity of the giant planets following their formation. Since removal of this disk requires an exchange of orbital energy and angular momentum with t

Simon Portegies Zwart, Junichiro Makino, Stephen L. W. McMillan, Piet Hut

The evolution of young compact star clusters is studied using N-body simulations in which both stellar evolution and physical collisions between stars are taken into account. The initial conditions are chosen to represent R136, a compact star cluster in the 30 Doradus region of the Large Magellanic Cloud. The present runs do not include the effects of primor

James P. Crutchfield, Erik van Nimwegen

We analyze the population dynamics of a broad class of fitness functions that exhibit epochal evolution---a dynamical behavior, commonly observed in both natural and artificial evolutionary processes, in which long periods of stasis in an evolving population are punctuated by sudden bursts of change. Our approach---statistical dynamics---combines methods fro

Leor Barack, Amos Ori

We present an analytic method for calculating the late-time tails of a linear scalar field outside a Kerr black hole. We give the asymptotic behavior at timelike infinity (for fixed $r$), at future null infinity, and along the event horizon (EH). In all three asymptotic regions we find a power-law decay. We show that the power indices describing the decay of

Manuel Masip, Alex Pomarol

The presence of an extra dimension of size R \approx TeV^{-1} introduces a tower of Kaluza-Klein gauge boson excitations that affects the standard model (SM) relations between electroweak observables. The mixing of the W and Z bosons with their excitations changes their masses and couplings to fermions. This effect depends on the Higgs field, which may live

Gregory Gabadadze

The theta dependence of the vacuum energy in large N Yang-Mills theory has been studied some time ago by Witten using a duality of large N gauge theories with string theory compactified on a certain space-time. We show that within the field theory context vacuum fluctuations of the topological charge give rise to the vacuum energy consistent with the string

J. Teschner

A deformation of the wave equation on a two-dimensional black hole is considered as a toy-model for possible gravitational or stringy nonlocal effects. The deformed wave-equation allows for an initial-value problem despite being nonlocal. The classical singularity present in the classical geometry is resolved by the deformation, so that propagation of a wave

V. M. Kendon, J-C. Desplat, P. Bladon, M. E. Cates

We simulate late-stage coarsening of a 3D symmetric binary fluid using a lattice Boltzmann method. With reduced lengths and times l and t respectively (scales set by viscosity, density and surface tension) our data sets cover 1 < l < 10^5, 10 < t < 10^8. We achieve Reynolds numbers approaching 350. At Re > 100 we find clear evidence of Furukawa&#39;s inertia

Jesus A. Alvarez Lopez, Yuri A. Kordyukov

For general Riemannian foliations, spectral asymptotics of the Laplacian is studied when the metric on the ambient manifold is blown up in directions normal to the leaves (adiabatic limit). The number of ``small'' eigenvalues is given in terms of the differentiable spectral sequence of the foliation. The asymptotics of the corresponding eigenforms also leads

A. Wacker, A. -P. Jauho, S. Rott, A. Markus

Electrical transport in semiconductor superlattices is studied within a fully self-consistent quantum transport model based on nonequilibrium Green functions, including phonon and impurity scattering. We compute both the drift velocity-field relation and the momentum distribution function covering the whole field range from linear response to negative differ

Maxim Nazarov

Take the matrix Lie superalgebra $gl_{N|N}$ with the standard generators $E_{ij}$ where $i,j=-N,...,-1,1,...,N$. Define an involutive automorphism of $gl_{N|N}$ by sending $E_{ij}$ to $E_{-i,-j}$. Then the corresponding twisted subalgebra $g$ in the polynomial current Lie superalgebra $gl_{N|N}[u]$, has a natural Lie co-superalgebra structure. Here we quanti

W. M. Alberico, A. Lavagno, P. Quarati

Starting from the experimental evidence that high-energy nucleus-nucleus collisions cannot be described in terms of superpositions of elementary nucleon-nucleon interactions, we analyze the possibility that memory effects and long-range forces imply a nonextensive statistical regime during high energy heavy ion collisions. The relevance of these statistical

S. M. Bilenky, C. Giunti, C. W. Kim

The present status of the problem of neutrino mass, mixing and neutrino oscillations is briefly summarized. The evidence for oscillations of atmospheric neutrinos found recently in the Super-Kamiokande experiment is discussed. Indications in favor of neutrino oscillations obtained in solar neutrino experiments and in the accelerator LSND experiment are also

Cecile Monthus

To study the localization of random heteropolymers at an interface separating two selective solvents within the model of Garel, Huse, Leibler and Orland, Europhys. Lett. {\bf 8} 9 (1989), we propose an approach based on a disorder-dependent real space renormalization procedure. This approach allows to recover that a chain with a symmetric distribution in hyd

Filipe Bonjour, Christos Charmousis, Ruth Gregory

We investigate the spacetime of a thick gravitating domain wall for a general potential $V(Φ)$. Using general analytical arguments we show that all nontrivial solutions fall into two categories: those interpretable as an isolated domain wall with a cosmological event horizon, and those which are pure false vacuum de Sitter solutions. Although this latter sol

Denis Bernard, Nicolas Regnault

We apply algebraic and vertex operator techniques to solve two dimensional reduced vacuum Einstein&#39;s equations. This leads to explicit expressions for the coefficients of metrics solutions of the vacuum equations as ratios of determinants. No quadratures are left. These formulas rely on the identification of dual pairs of vertex operators corresponding t

P. Ao, X. -M. Zhu

Vortex dynamics in fermionic superfluids is carefully considered from the microscopic point of view. Finite temperatures, as well as impurities, are explicitly incorporated. To enable readers understand the physical implications, macroscopic demonstrations based on thermodynamics and fluctuations- dissipation theorems are constructed. For the first time a cl

Raphael Bousso

I study the global structure of de Sitter space in the semi-classical and one-loop approximations to quantum gravity. The creation and evaporation of neutral black holes causes the fragmentation of de Sitter space into disconnected daughter universes. If the black holes are stabilized by a charge, I find that the decay leads to a necklace of de Sitter univer

Li-Xin Li

A toy model for the Blandford-Znajek mechanism is investigated: a Kerr black hole with a toroidal electric current residing in a thin disk around the black hole. The toroidal electric current generates a poloidal magnetic field threading the black hole and disk. Due to the interaction of the magnetic field with remote charged particles, the rotation of the b

Yasushi Suto, Tetsu Kitayama, Eiichiro Komatsu, Makoto Hattori

Cosmological implications of clusters of galaxies are discussed with particular attention to their importance in probing the cosmological parameters. More specifically we compute the number counts of clusters of galaxies, Log $N$ -- Log $S$ relation, in X-ray and submm bands on the basis of the Press--Schechter theory. As an important step toward breaking th

Jeff P. Barnes, Warren S. Warren

An examination of the concept of using classical degrees of freedom to drive the evolution of quantum computers is given. Specifically, when externally generated, coherent states of the electromagnetic field are used to drive transitions within the qubit system, a decoherence results due to the back reaction from the qubits onto the quantum field. We derive

Francesco De Martini, Mauro Fortunato, Paolo Tombesi, David Vitali

We suggest a variant of the recently proposed experiment for the generation of a new kind of Schroedinger-cat states, using two coupled parametric down-converter nonlinear crystals [F. De Martini, Phys. Rev. Lett. 81, 2842 (1998)]. We study the parametric oscillator case and find that an entangled Schroedinger-cat type state of two cavities, whose mirrors ar

A. F. Kracklauer

It is shown that EPR correlations are the angular analogue to the Hanbury-Brown--Twiss effect. As insight provided by this model, it is seen that, analysis of the EPR experiment requires conditional probabilities which do not admit the derivation of Bell inequalities.

Alexander Molev, Maxim Nazarov

We extend the Capelli identities (1890) from the Lie algebra $gl_N$ to the other two classical Lie algebras $so_N$ and $sp_N$. We employ the theory of reductive dual pairs due to Howe. Our technique comes from the representation theory of Yangians.

Tom Ostoma, Mike Trushyk

We provide a quantum field theoretic derivation of Einstein&#39;s Weak Equivalence Principle of general relativity using a new quantum gravity theory proposed by the authors called Electro-Magnetic Quantum Gravity or EMQG (ref. 1). EMQG is based on a new theory of inertia (ref. 5) proposed by R. Haisch, A. Rueda, and H. Puthoff (which we modified and called

F. Doenau, D. Almehed, R. G. Nazmitdinov

Using the spectral function F&#39;(z)/F(z) the RPA correlation energy and other properties of a finite system can be written as a contour integral in a compact way. This yields a transparent expression and reduces drastically the numerical efforts for obtaining reliable values. The method applied to pairing vibrations in rotating nuclei as an illustrative ex

J. E. Amaro, G. Co&#39;, A. M. Lallena

The validity of the approximations done in the mean field description of the quasi-elastic excitation of medium-heavy nuclei is discussed. A test of the reliability of the plane wave Born approximation is presented. The uncertainty related to the choice of the electromagnetic nucleon form factors is discussed. The effects produced by the meson exchange curre

J. C. Nacher, E. Oset, H. Toki, A. Ramos

We have carried a theoretical study of the K^- p\to M B γreaction with M B = K^-p, \bar{K}^0 n, π^- Σ^+, π^+ Σ^-, π^0 Σ^0, π^0 Λ, for K^- lab. momenta between 200 and 500 MeV/c, using a chiral unitary approach for the strong K^-p interaction with its coupled channels. The Λ(1405) resonance, which is generated dynamically in this approach, shows up clearly in

C. G. Bao

It was found in this paper that the dominant component of the wave function of the second 0^+ state of 4^He and the corresponding component of the 3^H+p channel have different spatial permutation symmetries. This fact will hinder the wave function to extend from the interior region to the outgoing channel and will lead to a narrower width.

Indranil Biswas, Leticia Brambila-Paz

Let $\cMx$ be the moduli space of stable vector bundles of rank $n\geq 3$ and determinant $ξ$ over a connected Riemann surface $X$, with $n$ and $d(ξ)$ coprime. Let $D$ be a Calabi-Yau hypersurface of $\cMx$. Denote by $U_D$ the restriction of the universal bundle to $X\times D$. It is shown that the restriction $(U_D)_x$ to $x\times D$ is stable, for any $x

Xufeng Liu

An polynomial identity is derived from the representation V_m(x)\otimes V_n(y) of U_q(\hat {sl_2}) and a new basis of V_m(x)\otimes V_n(y) is established under some condition.

Mark Gross

We continue the study of the Strominger-Yau-Zaslow mirror symmetry conjecture. Roughly put, this states that if two Calabi-Yau manifolds X and Y are mirror partners, then X and Y have special Lagrangian torus fibrations which are dual to each other. Much work on this conjecture is necessarily of a speculative nature, as in dimension 3 it is still a very diff

Allen Knutson, Terence Tao

We introduce the honeycomb model of BZ polytopes, which calculate Littlewood-Richardson coefficients, the tensor product rule for GL(n). Our main result is the existence of a particularly well-behaved honeycomb with given boundary conditions (choice of triple of representations to be tensored together). This honeycomb is necessarily integral, which proves th

Mirjam Cvetic, Steven S. Gubser

We study the thermodynamic stability of charged black holes in gauged supergravity theories in D=5, D=4 and D=7. We find explicitly the location of the Hawking-Page phase transition between charged black holes and the pure anti-de Sitter space-time, both in the grand-canonical ensemble, where electric potentials are held fixed, and in the canonical ensemble,

Ioannis Giannakis

In this paper we present a method of deforming to first order the stress-tensor and the supercurrent of the superstring corresponding to turning on NS-NS bosonic fields. Furthermore we discuss the difficulties associated with turning on spacetime fermions and R-R bosons. We also derive the gauge symmetries of the massless spacetime fields.

S. M. de Souza, O. Rojas Santos, M. T. Thomaz

Charret et. al. applied the properties of the Grassmann generators to develop a new method to calculate the coefficients of the high temperature expansion of the grand canonical partition function of self-interacting fermionic models in any d-dimensions (d>=1). The method explores the anti-commuting nature of fermionic fields and avoids the calculation of th

Silvio Pallua, Predrag Prester

We consider here XXZ spin chain perturbed by the operator sigma^x (``in transverse field&#39;&#39;) which is a lattice regularization of the sine-Gordon model. This can be shown using conformal perturbation theory. We calculated mass ratios of particles which lie in a discrete part of the spectrum and obtained results in accord with the DHN formula and in di

John Ellis, A. Ghosh, N. E. Mavromatos

We discuss the thermodynamics of a gas of black holes in five-dimensional anti-de-Sitter (AdS) space, showing that they are described by a van der Waals equation of state. Motivated by the Maldacena conjecture, we relate the energy density and pressure of this non-ideal AdS black-hole gas to those of four-dimensional gauge theory in the unconfined phase. We

J. Wirstam

Using the low energy effective action of the N=2 supersymmetric SU(2) Yang-Mills theory we calculate the free energy at finite temperature, both in the semiclassical region and in the dual monopole/dyon theory. In all regions the free energy depends on both the temperature T and the appropriate moduli parameter, and is thus minimized only for specific values

Fedele Lizzi

We describe how the presence of the antisymmetric tensor (torsion) on the world sheet action of string theory renders the size of the target space a gauge non invariant quantity. This generalizes the R <--> 1/R symmetry in which momenta and windings are exchanged, to the whole O(d,d,Z). The crucial point is that, with a transformation, it is possible always

Arjan Keurentjes

We continue the construction of non-trivial vacua for gauge theories on the 3-torus, started in hep-th/9901154. Application of constructions based on twist in SU(N) with N > 2 produce more extra vacua in theories with exceptional groups. We calculate the relevant unbroken subgroups, and their contribution to the Witten index. We show that the extra vacua we

M. N. Stoilov

We show that the regularization of the Standard Model proposed by Frolov and Slavnov describes a nonlocal theory with quite simple Lagrangian.

I. Brevik, S. D. Odintsov

We consider quantum \cal{N} = 4 super Yang-Mills theory interacting in a covariant way with \cal{N} = 4 conformal supergravity. The induced large N effective action for such a theory is calculated on a dilaton-gravitational background using the conformal anomaly found via AdS/CFT correspondence. Considering such an effective action as a quantum correction to

Borut Bajc

The status of internal symmetry breaking at high temperature in supersymmetric models is reviewed. This phenomenon could solve some well known cosmological problems, such as the domain wall, monopole and false vacuum problems.

T. M. Aliev, M. Savci

The strong coupling constants g_{K LAMBDA N} and g_{K SIGMA N} for the structure (sigma_{mu,nu} gamma_5) are calculated within light cone QCD sum rules. A comparison of our results on these couplings with predictions from traditional QCD sum rules is presented.

Ernest Ma

If a family symmetry exists so that all three neutrinos have equal Majorana masses (via the seesaw mechanism), then the breaking of this symmetry from charged-lepton masses (via two-loop double $W$ exchange) implies $Δm$ less than about $10^{-9}m_0$. With the common mass $m_0 \sim$ eV for hot dark matter, $Δm^2 \sim 10^{-10}$ eV$^2$ is natural for vacuum sol

Guy D. Moore

I review what we know about the ``sphaleron rate&#39;&#39;, which is the efficiency of baryon number violation at high temperatures of order 100 GeV in the Standard Model. The leading behavior at weak coupling in the symmetric phase is known accurately; Gamma = (10.7 +- .7) (g^2 T^2 / m_D^2) log(m_D/g^2T)α_w^5 T^4. At realistic values of the coupling our acc

Gabriel Amoros, Johan Bijnens

We discuss various models and Chiral Perturbation Theory results for the $K_{l4}$ form factors $F$ and $G$. We check in how much a simple parametrization with a few parameters can be used to extract information from experiment.

B. Ananthanarayan, P. Büttiker

Chiral perturbation theory, the low energy effective theory of the strong interactions for the light pseudoscalar degrees of freedom, is based on effective Lagrangian techniques and is an expansion in the powers of the external momenta and the powers of the quark masses, which correct the soft-pion theorems. Our primary emphasis will be on the problem of $ππ

Hisakazu Minakata, Hiroshi Nunokawa

We perform an updated model-independent analysis using all the latest solar neutrino data, including the one coming from remarkably high statistics SuperKamiokande experiment. We confirm that the astrophysical solutions to the solar neutrino problem are extremely disfavored. We also present a new way of illuminating the suppression pattern of various solar n

Simon Hands, John B. Kogut, Maria-Paola Lombardo, Susan E. Morrison

We study SU(2) Lattice Gauge Theory with dynamical fermions at non-zero chemical potential $μ$. The symmetries special to SU(2) for staggered fermions on the lattice are discussed explicitly and their relevance to spectroscopy and condensates at non-zero chemical potential are considered. Using the molecular dynamics algorithm on small lattices we find quali

Ian Barbour, Simon Hands, John B. Kogut, Maria-Paola Lombardo

We simulate the Gross-Neveu model in 2+1 dimensions at nonzero baryon density (chemical potential mu =/= 0). It is possible to formulate this model with a real action and therefore to perform standard hybrid Monte Carlo simulations with mu =/= 0 in the functional measure. We compare the physical observables from these simulations with simulations using the G

John W. Negele

Evidence from lattice QCD calculations is presented showing that instantons and their associated zero modes play a major role in the physics of light hadrons and the propagation of light quarks in the QCD vacuum.

Yorick Wilks

This paper compares the tasks of part-of-speech (POS) tagging and word-sense-tagging or disambiguation (WSD), and argues that the tasks are not related by fineness of grain or anything like that, but are quite different kinds of task, particularly becuase there is nothing in POS corresponding to sense novelty. The paper also argues for the reintegration of s

Yorick Wilks

The paper argues that Fodor and Lepore are misguided in their attack on Pustejovsky&#39;s Generative Lexicon, largely because their argument rests on a traditional, but implausible and discredited, view of the lexicon on which it is effectively empty of content, a view that stands in the long line of explaining word meaning (a) by ostension and then (b) expl

Donald Byrd

We are interested in questions of improving user control in best-match text-retrieval systems, specifically questions as to whether simple visualizations that nonetheless go beyond the minimal ones generally available can significantly help users. Recently, we have been investigating ways to help users decide-given a set of documents retrieved by a query-whi

R. Jay Mashl, Niels Grønbech-Jensen, M. R. Fitzsimmons, M. Lütt

Using self-assembly techniques, x-ray reflectivity measurements, and computer simulations, we study the effective interaction between charged polymer rods and surfaces. Long-time Brownian dynamics simulations are used to measure the effective adhesion force acting on the rods in a model consisting of a planar array of uniformly positively charged, stiff rods

R. Jay Mashl, Niels Grønbech-Jensen

We study the effective interaction between a planar array of uniformly negatively charged, stiff rods parallel to a negatively charged planar substrate in the absence of salt in a continuous, isotropic dielectric medium. Using Brownian dynamics simulations, we examine the general effects of counterion valence, rod spacing, macroion charge densities, and the

D. R. Bowler, I. J. Bush, M. J. Gillan

We describe recent progress in developing practical ab initio methods for which the computer effort is proportional to the number of atoms: linear scaling or O(N) methods. It is shown that the locality property of the density matrix gives a general framework for constructing such methods. We then describe our scheme, which operates within density functional

Avraham Cohen, Klaus Richter, Richard Berkovits

We study the effect of electronic interactions on the addition spectra and on the energy level distributions of two-dimensional quantum dots with weak disorder using the self-consistent Hartree-Fock approximation for spinless electrons. We show that the distribution of the conductance peak spacings is Gaussian with large fluctuations that exceed, in agreemen

William Bialek, Naftali Tishby

Observations on the past provide some hints about what will happen in the future, and this can be quantified using information theory. The ``predictive information&#39;&#39; defined in this way has connections to measures of complexity that have been proposed both in the study of dynamical systems and in mathematical statistics. In particular, the predictive