March 1999 arXiv papers — page 9

J. Terron

New measurements of the jet shape in ep collisions at HERA using the k_T-cluster jet algorithm are presented.

Manuela Campanelli

The computation of gravitational radiation generated by the coalescence of inspiralling binary black holes is nowdays one of the main goals of numerical relativity. Perturbation theory has emerged as an ubiquitous tool for all those dynamical evolutions where the two black holes start close enough to each other, to be treated as single distorted black hole (

Matthew W. Choptuik, Eric W. Hirschmann, Robert L. Marsa

We extend the investigation of the gravitational collapse of a spherically symmetric Yang-Mills field in Einstein gravity and show that, within the black hole regime, a new kind of critical behavior arises which separates black holes formed via Type I collapse from black holes formed through Type II collapse. Further, we provide evidence that these new attra

Dirk Helbing, Tamas Vicsek

Extremal principles are fundamental in our interpretation of phenomena in nature. One of the best known examples is the second law of thermodynamics, governing most physical and chemical systems and stating the continuous increase of entropy in closed systems. Biological and social systems, however, are usually open and characterised by self-organised struct

Leonard D. Bogarad, Michael W. Deem

Biological diversity has evolved despite the essentially infinite complexity of protein sequence space. We present a hierarchical approach to the efficient searching of this space and quantify the evolutionary potential of our approach with Monte Carlo simulations. These simulations demonstrate that non-homologous juxtaposition of encoded structure is the ra

Mark Lacy, Susan E. Ridgway, Margrethe Wold, Per B. Lilje

We present an optically-based study of the alignment between the radio axes and the optical major axes of eight z~0.7 radio galaxies in a 7C sample. The radio galaxies in this sample are ~20-times less radio luminous than 3C galaxies at the same redshift, and are significantly less radio-luminous than any other well-defined samples studied to date. Using Nor

S. M. Simkin, E. M. Sadler, R. Sault, S. J. Tingay

We present radio and optical imaging and kinematic data for the radio galaxy Pictor A, including HST continuum and [OIII], emission-line images (at a resolution of 25 - 100 mas) and ground-based imaging and spectroscopy (at a resolution of ~ 1.5". The radio data include 3 cm Australia Telescope images of the core, at a resolution comparable to that of th

B. I. Grimberg, E. M. Sadler, S. M. Simkin

PKS0349-27 is a classical FRII radio galaxy with an AGN host which has a spectacular, spiral-like structure in its extended emission line gas (EELG). We have measured the velocity field in this gas and find that it splits into 2 cloud groups separated by radial velocities which at some points approach 400 km/s Measurements of the diagnostic emission line rat

Tristan Hubsch

Chiral superfields have been used, and extensively, almost ever since supersymmetry has been discovered. Complex linear superfields afford an alternate representation of matter, but are widely misbelieved to be 'physically equivalent' to chiral ones. We prove the opposite is true. Curiously, this re-enables a previously thwarted interpretation of the

Masahiko Yoshioka, Masatoshi Shiino

We study associative memory based on temporal coding in which successful retrieval is realized as an entrainment in a network of simple phase oscillators with distributed natural frequencies under the influence of white noise. The memory patterns are assumed to be given by uniformly distributed random numbers on $[0,2π)$ so that the patterns encode the phase

J. M. F. Labastida, Carlos Lozano

We derive the partition function for the Vafa-Witten twist of the $\mathcal{N}=4$ supersymmetric gauge theory with gauge group SU(N) (for prime $N$) and arbitrary values of the 't Hooft fluxes $v\in H^{2}(X,\mathbb{Z}_{N})$ on K\"ahler four-manifolds with $b^{+}_2>1$.

P. Mitra

As in the grand canonical treatment of Reissner - Nordström black holes in anti-de Sitter spacetime, the canonical ensemble formulation also shows that non-extremal black holes tend to have lower action than extremal ones. However, some small non-extremal black holes have higher action, leading to the possibility of transitions between non-extremal and extre

Biswarup Mukhopadhyaya, Sourov Roy

In an R-parity violating supersymmetric scenario, the lightest neutralino $\tilde χ^0_1$ is no longer a stable particle. We calculate the branching ratio for the decay mode $\tilde χ^0_1 \longrightarrow νγ$ which occurs at the one-loop level. Taking into account bilinear as well as trilinear lepton number violating interactions as the sources of R-parity vio

J. E. Pask, B. M. Klein, C. Y. Fong, P. A. Sterne

We present an approach to solid-state electronic-structure calculations based on the finite-element method. In this method, the basis functions are strictly local, piecewise polynomials. Because the basis is composed of polynomials, the method is completely general and its convergence can be controlled systematically. Because the basis functions are strictly

B. Pablo-Norman, M. Ruiz-Altaba

Grover's quantum algorithm improves any classical search algorithm. We show how random Gaussian noise at each step of the algorithm can be modelled easily because of the exact recursion formulas available for computing the quantum amplitude in Grover's algorithm. We study the algorithm's intrinsic robustness when no quantum correction codes are u

Michele Mosca, Artur Ekert

A quantum computer can efficiently find the order of an element in a group, factors of composite integers, discrete logarithms, stabilisers in Abelian groups, and `hidden' or `unknown' subgroups of Abelian groups. It is already known how to phrase the first four problems as the estimation of eigenvalues of certain unitary operators. Here we show how

Trevor Pitts

If space, time and mass-energy expand outward from the Big Bang along the time axis equally in the (+) and (-) directions, then time is symmetric by Weyl's definition. In the Feynman-Stueckelberg Interpretation, antimatter is identical to matter but moves backward in time. This paper argues this interpretation is physically real, leading to the universe

H. J. Weber, M. Beyer

Starting from the standard and commonly used relativistic nucleon wave function, we show that residual interactions based on gluon or Goldstone boson exchanges generate additional components leading to configuration mixing. This result suggests that realistic nucleon wave functions can be expected to be far more complex than seemingly successful form factor

R. Vogt

We compare the fractions of the hard and geometric cross sections as a function of impact parameter. For a given definition of central collisions, we calculate the corresponding impact parameter and the fraction of the hard cross section contained within this cut. We use charm quark production as a definite example.

Paula A. A. B. Carvalho, Ian M. Musson

A class of algebras called down-up algebras was introduced by G. Benkart and T. Roby. We classify the finite dimensional simple modules over Noetherian down-up algebras and show that in some cases every finite dimensional module is semisimple. We also study the question of when two down-up algebras are isomorphic.

Muneto Nitta

We have developed N=1 supersymmetric nonlinear realization methods, which realize global symmetry breaking in N=1 supersymmetric theories. The target space of nonlinear sigma models with a linear model origin is a G^C-orbit, which is a non-compact non-homogeneous K"ahler manifold. We show that, if and only if the orbit is open, it includes a compact homo

A. Bonanno, V. Branchina, H. Mohrbach, D. Zappala'

We study the derivative expansion for the effective action in the framework of the Exact Renormalization Group for a single component scalar theory. By truncating the expansion to the first two terms, the potential $U_k$ and the kinetic coefficient $Z_k$, our analysis suggests that a set of coupled differential equations for these two functions can be establ

A. Khodjamirian, R. Rückl, S. Weinzierl, O. Yakovlev

The $B^*Bπ$ and $D^*Dπ$ couplings have previously been derived from a QCD light-cone sum rule in leading order. Here, we describe the calculation of the $O(α_s)$ correction to the twist 2 term of this sum rule. The result is used for a first next-to-leading order analysis. We obtain $g_{B^*Bπ}= 22\pm 7$ and $g_{D^*Dπ}=10.5\pm 3$, where the error indicates th

J. L. Lucio, M. Napsuciale, M. Ruiz-Altaba

We enforce chiral Ward identities on the vertices of the linear sigma model to take into account the width of the scalar sigma, considered as a true physical resonance. We consider pion scattering at very low energies and, from a fit to the measured phase shifts in the various angular momentum and isospin channels, conclude a mass for the sigma of 600+200-10

Herbi Dreiner, Peter Richardson, Michael H. Seymour

We consider the production of resonant sleptons via R-parity Violation followed by gauge decays to a charged lepton and a neutralino which then decays via R-parity Violation. This gives a signature of two like-sign charged leptons. We find a background at run II of 0.14 +/- 0.13 events with an integrated luminosity of 2 fb^-1. This enables us to probe R-pari

Nima Arkani-Hamed, Martin Schmaltz

It is commonly thought that small couplings in a low-energy theory, such as those needed for the fermion mass hierarchy or proton stability, must originate from symmetries in a high-energy theory. We show that this expectation is violated in theories where the Standard Model fields are confined to a thick wall in extra dimensions, with the fermions "stuc

A. Alavi-Harati et al, KTeV Collaboration

We report on two null searches, one for the spontaneous appearance of $π^+π^-$ pairs, another for a single $π^0$, consistent with the decay of a long-lived neutral particle into hadrons and an unseen neutral particle. For the lowest level gluon-gluino bound state, known as the $R^0$, we exclude the decays $R^0\to π^+π^-\tildeγ$ and $R^0\to π^0\tildeγ$ for th

Giovanni Amelino-Camelia

The interferometry-based experimental tests of quantum properties of space-time which the author sketched out in a recent short Letter [Nature 398 (1999) 216] are here discussed in self-contained fashion. Besides providing detailed derivations of the results already announced in the previous Letter, some new results are also derived; in particular, the analy

L. P. Grishchuk

The expected amplitudes and spectral slopes of relic gravitational waves, plus their specific correlation properties associated with the phenomenon of squeezing, may allow the registration of relic (squeezed) gravitational waves by the first generation of sensitive gravity-wave detectors.

Naresh Dadhich, L. K. Patel

We obtain an exact simple solution of the Einstein equation describing a spherically symmetric cosmological model without the big-bang or any other kind of singularity. The matter content of the model is shear free isotropic fluid with radial heat flux and it satisfies the weak and strong energy conditions. It is pressure gradient combined with heat flux tha

A. H. MacDonald, R. Rajaraman, T. Jungwirth

We report on a study of a bilayer two-dimensional electron gas at Landau level filling factor $ν=2$. The system exhibits both magnetic and spontaneous interlayer phase coherence broken symmetries. We propose a 3-parameter Slater determinant variational wavefunction which describes the ground state over the full range of bias potential ($Δ_V$) Zeeman coupling

C. Kusko, R. S. Markiewicz

Recent experiments have introduced a new concept for analyzing the photoemission spectra of correlated electrons -- the remnant Fermi surface (rFs), which can be measured even in systems which lack a conventional Fermi surface. Here, we analyze the rFs in a number of interacting electron models, and find that the results fall into two classes. For systems wi

Paolo De Los Rios

We study KPZ surfaces on Euclidean lattices and directed polymers on hierarchical lattices subject to different distributions of disorder, showing that universality holds, at odds with recent results on Euclidean lattices. Moreover, we find the presence of a slow (power-law) crossover toward the universal values of the exponents and verify that the exponent

E. V. Kuz'min, S. G. Ovchinnikov

To compare the superconductivity in strongly correlated electron systems with the antiferromagnetic fluctuations in the copper oxides and with the ferromagnetic fluctuations in Sr_2RuO_4 a t-J-I model is proposed. The antiferromagnetic coupling J results in the superconducting state of d_{x^2-y^2} symmetry and the ferromagnetic coupling constant I results in

Igor F. Lyuksyutov, Valery Pokrovsky

We discuss a new class of phenomena based on strong interaction between magnetic superstructures and vortices in superconductors in combined heterogeneous structures. An inhomogeneous magnetization can pin vortices or create them spontaneously changing drastically properties of the superconductor. On the other hand, the interaction between magnetic moments m

Mikito Koga, Gergely Zarand, Daniel L. Cox

A model for crystal field triplet ground states on rare earth or actinide ions with dipolar and quadrupolar couplings to conduction electrons is studied for the first time with renormalization group methods. The quadrupolar coupling leads to a new nontrivial, non-Fermi liquid fixed point, which survives in an intermediate valence Anderson model. The calculat

Adolfo G. Eguiluz, Wei Ku, James M. Sullivan

We present results of ab initio theoretical investigations of the excitation spectra of correlated electrons in metals (Al, K, and Li) and their interplay with inelastic scattering experiments. We resolve various anomalies contained in the data, which were originally viewed as signatures of strong dynamical electronic correlations; we show that, instead, the

M. Henriksen

An 8.3 hour observation of the Abell 2256 galaxy cluster using the Rossi X-ray Timing Explorer proportional counter array produced a high quality spectrum in the 2 - 30 keV range. Joint fitting with the 0.7 - 11 keV spectrum obtained with the Advanced Satellite for Astrophysics and Cosmology gas imaging spectrometer gives an upperlimit of 2.3x10^-7 photons/c

J. Papaloizou, C. Terquem

We study a solid protoplanetary core of 1-10 earth masses migrating through a disk. We suppose the core luminosity is generated as a result of planetesimal accretion and calculate the structure of the gaseous envelope assuming equilibrium. This is a good approximation when the core mass is less than the critical value, M_{crit}, above which rapid gas accreti

Ramchander R. Sastry

The infinite dimensional generalization of the quantum mechanics of extended objects, namely, the quantum field theory of extended objects is presented. The paradigm example studied in this paper is the Euclidean scalar field with a $λ(ϕ^{6})/6!$ interaction in four spacetime dimensions. The theory is found to be finite when the virtual particle intermediate

M. G. Revnivtsev, S. P. Trudolyubov, K. N. Borozdin

We present an analysis of the RXTE observations of the recently discovered Galactic microquasar XTE J1748--288 during its 1998 outburst. The spectral evolution of the source during the outburst can be considered a sequence of qualitatively distinct states. During the first observations, corresponding to the maximum of X-ray flux, the spectrum of the source c

D. Nagai, M. E. Sulkanen, A. E. Evrard

Constraints on the clustered mass density Ω_m of the universe derived from the mean intracluster gas fraction of X-ray clusters may be biased by a single-phase assumption for the thermodynamic structure of the intracluster medium (ICM). We propose a descriptive model for multiphase structure in which a spherically symmetric ICM contains isobaric density pert

T. Boeker, D. Calzetti, W. Sparks

We present ``snapshot'' observations with the NearInfrared Camera and MultiObject Spectrometer (NICMOS) on board the Hubble Space Telescope (HST) of 94 nearby galaxies from the Revised Shapley Ames Catalog. Images with 0.2 as resolution were obtained in two filters, a broad-band continuum filter (F160W, roughly equivalent to the H-band) and a narrow

A. P. Kharel, K. H. Soon, J. R. Powell, A. Porch

We have carried out non-linear microwave (8 GHz) surface impedance measurements of three YBaCuO thin films in dc magnetic fields $H_{dc}$ (parallel to c axis) up to 12 mT using a coplanar resonator technique. In zero dc field the three films, deposited by the same method, show a spread of low-power residual surface resistance, $R_{res}$ and penetration depth

Anton V. Velichko, Adrian Porch

The nonlinear response of a short Josephson Junction (JJ), being irradiated simultaneously with two high-frequency signals, has been studied in the framework of the nonlinear Resistively-Shunted Junction (RSJ) Model. One of the signals, hereafter referred to as "probe signal", has a small amplitude $I_{pr}<I_c$ ($I_c$ is the critical current of the JJ) and f

N. V. Mikheev, A. Ya. Parkhomenko, L. A. Vassilevskaya

We investigate the effective interaction of a pseudoscalar particle with two photons in an external electromagnetic field in the general case of all external particles being off the mass shell. This interaction is used to study the radiative decay $a \to γγ$ of the axion, a pseudoscalar particle associated with the Peccei-Quinn symmetry, and the crossing cha

S. Groote, J. G. Körner, A. A. Pivovarov

We derive recurrence relations for the calculation of multiloop sunset-type diagrams with large powers of massive propagators. The technique is formulated in configuration space and exploits the explicit form of the massive propagator raised to a given power. We write down and evaluate a convenient set of basis integrals. The method is well suited for a nume

Lee Smolin

A class of background independent membrane field theories are studied, and several properties are discovered which suggest that they may play a role in a background independent form of M theory. The bulk kinematics of these theories are described in terms of the conformal blocks of an algebra G on all oriented, finite genus, two-surfaces. The bulk dynamics i

H. Kachkachi, W. T. Coffey, D. S. F. Crothers, A. Ezzir

The effect of an applied magnetic field on the temperature at the maximum of the ZFC magnetization, $M_{ZFC}$, is studied using the recently obtained analytic results of Coffey et al. (Phys. Rev. Lett. {\bf 80}(1998) 5655) for the prefactor of the Néel relaxation time which allow one to precisely calculate the prefactor in the Néel-Brown model and thus the b

Y. Nakaoka, M. Ichimura

We calculate the two-step contribution to (p,p&#39;) and (p,n) reactions at intermediate energy. We describe the motion of the incident nucleon with plane wave and compare the contribution from the two-step processes with that from the one-step processes. To describe the two-step processes, we extende the response functions into the nondiagonal ones with res

A. Habig

Upward-going muons observed by the Super-Kamiokande detector are produced by high-energy atmospheric neutrinos which interact in rock around the detector. Those which pass completely through the detector have a mean parent neutrino energy of ~100 GeV, while those which range out inside the detector come from neutrinos of mean energy ~10 GeV. The neutrino bas

P. G. Silvestrov, Y. Imry

For a quantum dot (QD) in the intermediate regime between integrable and fully chaotic, the widths of single-particle levels naturally differ by orders of magnitude. In particular, the width of one strongly coupled level may be larger than the spacing between other, very narrow, levels. In this case many consecutive Coulomb blockade peaks are due to occupati

Thomas M. Schwarz, Sandra P. Klevansky, Gabor Papp

We reexamine the recent instanton motivated studies of Alford, Rajagopal and Wilczek, and Berges and Rajagopal in the framework of the standard SU(2) Nambu-Jona-Lasinio model. The chiral phase diagram is calculated in the temperature--density plane, and the pressure is evaluated as the function of the density. Obtaining simple approximate relations describin

Igor Kondrashuk

We study possible relations between the full Green&#39;s functions of softly broken supersymmetric theories and the full Green&#39;s functions of rigid supersymmetric theories on the example of the supersymmetric quantum mechanics and find that algebraic relations can exist and can be written in a simple form. These algebraic relations between the Green&#39;

Alessandra Lanotte, Andrea Mazzino

A first analytic assessment of the role of anisotropic corrections to the isotropic anomalous scaling exponents is given for the $d$-dimensional kinematic magneto-hydrodynamics problem in the presence of a mean magnetic field. The velocity advecting the magnetic field changes very rapidly in time and scales with a positive exponent $\xi$. Inertial-range anis

N. N. Achasov, G. N. Shestakov

We would like to point to the strong violation of the putative factorized Pomeron exchange model in the reactions $γγ\to VV&#39;$ in the high-energy region where this model works fairly well in all other cases.

R. De Pietri

The canonical ``loop&#39;&#39; formulation of quantum gravity is a mathematically well defined, background independent, non perturbative standard quantization of Einstein&#39;s theory of General Relativity. Some among the most meaningful results of the theory are: 1) the complete calculation of the spectrum of geometric quantities like the area and the volum

I. Stancu, D. V. Ahluwalia

We show that the L/E-flatness of the electron-like event ratio in the Super-Kamiokande atmospheric neutrino data implies the equality of the expectation values for the muon and tau neutrino masses. We establish this result by obtaining a set of three constraints on the neutrino-oscillation mixing matrix as contained in the indicated flatness. The resulting 3

Miguel A. Ojeda, J. Dorantes-Davila, G. M. Pastor

Noncollinear magnetic states in clusters are studied by using the single-band Hubbard Hamiltonian. The unrestricted Hartree-Fock (UHF) approximation is considered without imposing any symmetry constraints neither to the size or orientation of the local magnetic moments $<\vec S_l>$ nor to the local charge densities $<n_l>$. A variety of qualitatively differe

Joseph Polchinski

I discuss D0-brane quantum mechanics as a nonperturbative formulation of string theory, in particular the relation between the Banks-Fischler-Shenker-Susskind matrix model, the Maldacena conjecture for D0-branes, and type IIA/M-theory duality. Some features of the quantum mechanics of D0-branes are also discussed. Lecture presented at the Nishinomiya-Yukawa

O. W. Greenberg

There are two motivations to consider statistics that are neither Bose nor Fermi: (1) to extend the framework of quantum theory and of quantum field theory, and (2) to provide a quantitative measure of possible violations of statistics. After reviewing tests of statistics for various particles, and types of statistics that are neither Bose nor Fermi, I discu

S. Shelly Sharma, N. K. Sharma, Larry Zamick

We show here that the model Hamiltonian used in our paper for ion vibrating in a q-analog harmonic oscillator trap and interacting with a classical single-mode light field is indeed obtained by replacing the usual bosonic creation and annihilation operators of the harmonic trap model by their q-deformed counterparts. The approximations made in our paper amou

Jean-Pierre Amiet, Stefan Weigert

The density matrix of a spin s is fixed uniquely if the probabilities to obtain the value s upon measuring n.S are known for 4s(s+1) appropriately chosen directions n in space. These numbers are just the expectation values of the density operator in coherent spin states, and they can be determined in an experiment carried out with a Stern-Gerlach apparatus.

W. Poeschl, B. Mueller

The dynamics of gluons and quarks in a relativistic nuclear collision are described, within the framework of a classical mean-field transport theory, by the coupled equations for the Yang-Mills field and a collection of colored point particles. The particles are used to represent color source effects of the valence quarks in the colliding nuclei. The possibi

Mireille Boutin

Corrected versions of the numerically invariant expressions for the affine and Euclidean signature of a planar curve proposed by E.Calabi et. al are presented. The new formulas are valid for fine but otherwise arbitrary partitions of the curve. We also give numerically invariant expressions for the four differential invariants parametrizing the three dimensi

Haisheng Li, Shuqin Wang

Let $A$ be a $Z$-graded associative algebra and let $ρ$ be an irreducible $N$-graded representation of $A$ on $W$ with finite-dimensional homogeneous subspaces. Then it is proved that $ρ(\tilde{A})=gl_{J}(W)$, where $\tilde{A}$ is the completion of $A$ with respect to a certain topology and $gl_{J}(W)$ is the subalgebra of $\End W$, generated by homogeneous

Ruy Exel, Marcelo Laca

We compute the K-theory of the Cuntz-Krieger C^*-algebras associated to infinite matrices.

A. Stern

We construct dual Lagrangians for $G/H$ models in two space-time dimensions for arbitrary Lie groups $G$ and $H\subset G$. Our approach does not require choosing coordinates on $G/H$, and allows for a natural generalization to Lie-Poisson duality. For the case where the target metric on $G/H$ is induced from the invariant metric on $G$, the dual system is a

Orlando Alvarez, L. A. Ferreira, J. Sanchez Guillen

We review the developments of a recently proposed approach to study integrable theories in any dimension. The basic idea consists in generalizing the zero curvature representation for two-dimensional integrable models to space-times of dimension $d+1$ by the introduction of a $d$-form connection. The method has been used to study several theories of physical

Reza Abbaspur

In this paper, we investigate about two physically distinct classes of the `one-dimensional&#39; worldvolume solutions describing the status of an arbitrary brane in the presence of another arbitrary (flat) brane which supplies the required supergravity background. One of these classes concerns with a relative (transverse) motion of two parallel flat branes,

D. G. Caldi, Alan Chodos

We investigate the possibility that neutrinos form superfluid-type condensates in background cosmological densities. Such condensates could give rise to small neutrino masses and splittings, as well as an important contribution, perhaps, to the cosmological constant. We discuss various channels in the context of the standard model. Many of these do not suppo

A. Capella, C. A. Salgado

We present an improved version of the dual parton model which contains a new realization of the diquark breaking mechanism of baryon stopping. We reproduce in this way the net baryon yield in nuclear collisions. The model, which also considers strings originating from diquark-antidiquark pairs in the nucleon sea, reproduces the observed yields of p and Lambd

H. Eberl, S. Kraml, W. Majerotto

We calculate within the MSSM the one-loop Yukawa coupling corrections to the processes e+ e- \to stops, sbottoms, and staus in order of Yukawa coupling squared. These corrections are due to the exchange of charginos, neutralinos, charged and neutral Higgs bosons, and charged and neutral Higgs ghosts. We give the complete analytical formulae. We also perform

Stanislaw Tatur, Jan Bartelski, Miroslaw Kurzela

We have made next to leading order QCD fit to the deep inelastic spin asymmetries on nucleons and we determined polarised quark and gluon densities. The functional form for such distributions was inspired by the Martin, Roberts and Stirling fit for unpolarised case. In addition to usually used data points (averaged over $x$ and $Q^2$) we have also considered

M. Ciuchini, S. E. Derkachov J. A. Gracey, A. N. Manashov

We compute the d-dimensional critical exponents corresponding to the wave function and mass renormalization of the quark in QCD in the Landau gauge at a new order, O(1/N_f^2), in the large N_f expansion. The computations are simplified by the establishment in d-dimensions of the critical point equivalence of QCD and the non-abelian Thirring model beyond lead

Bogdan A. Dobrescu

The fundamental Higgs doublet may be replaced in the Standard Model by certain non-perturbative four-quark interactions, whose effect is to induce a composite Higgs sector responsible for electroweak symmetry breaking. A simple composite two-Higgs-doublet model is presented. The four-quark interactions arise naturally if there are either extra spatial dimens

Kostas Orginos, R. L. Sugar, Doug Toussaint

We study the effects of different &#34;fat link&#34; actions for Kogut-Susskind quarks on flavor symmetry breaking. Our method is mostly empirical - we compute the pion spectrum with different valence quark actions on common sets of sample lattices. Different actions are compared, as best we can, at equivalent physical points. We find significant reductions

Richard Cross

Measurements of the proton structure function F_2 for 0.11 < Q^2 < 20000 GeV^2 and 1.2 X 10^-5 < x < 0.65 from ZEUS 1994-1997 measurements are presented. From ZEUS 1994 and 1995 F_2 data the slopes d(F_2)/d(ln Q^2) at fixed x and d(ln F_2)/d(ln(1/x)) for x < 0.01 at fixed Q^2 are derived. For the latter E665 data are also used. The transition region in Q^2 i

Vladimir Dzhunushaliev, Douglas Singleton

In this work spherically symmetric solutions to 5D Kaluza-Klein theory, with &#34;electric&#34; and/or &#34;magnetic&#34; fields are examined. Different relative strengths of the &#34;electric&#34; and &#34;magnetic&#34; charges of the solutions are studied by varying certain parameters in our metric ansatz. As the strengths of these two charges are varied t

Michael E. Fisher, Anatoly B. Kolomeisky

The stochastic driving force exerted by a single molecular motor (e.g., a kinesin, or myosin) moving on a periodic molecular track (microtubule, actin filament, etc.) is discussed from a general viewpoint open to experimental test. An elementary &#34;barometric&#34; relation for the driving force is introduced that (i) applies to a range of kinetic and stoch

S. Schinzer, M. Sokolowski, M. Biehl, W. Kinzel

We investigate the influence of step edge diffusion (SED) and desorption on Molecular Beam Epitaxy (MBE) using kinetic Monte-Carlo simulations of the solid-on-solid (SOS) model. Based on these investigations we propose two strategies to optimize MBE growth. The strategies are applicable in different growth regimes: During layer-by-layer growth one can exploi

Jonathan Doye, Mark Miller, David Wales

Disconnectivity graphs are used to characterize the potential energy surfaces of Lennard-Jones clusters containing 13, 19, 31, 38, 55 and 75 atoms. This set includes members which exhibit either one or two `funnels&#39; whose low-energy regions may be dominated by a single deep minimum or contain a number of competing structures. The graphs evolve in size du

L. De Santis, R. Resta

The bonding pattern of a covalent semiconductor is disrupted when a surface is cut while keeping a rigid (truncated bulk) geometry. The covalent bonds are partly reformed (with a sizeable energy gain) when reconstruction is allowed. We show that the ``electron localization function&#39;&#39; (ELF)---applied within a first--principles pseudopotential framewor

Richard P. Sear

Classical nucleation theory is used to estimate the free-energy barrier to nucleation of the solid phase of particles interacting via a potential which has a short-ranged attraction. Due to the high interfacial tension between the fluid and solid phases, this barrier is very large, much larger than in hard spheres. It is divergent in the limit that the range

J. Gruneberg

The algebraic Bethe ansatz is a powerful method to diagonalize transfer-matrices of statistical models derived from solutions of (graded) Yang Baxter equations, connected to fundamental representations of Lie (super-)algebras and their quantum deformations respectively. It is, however, very difficult to apply it to models based on higher dimensional represen

Biplab Sanyal, Parthapratim Biswas, Abhijit Mookerjee, Hemant G. Salunke

In this communication we propose the use of the Augmented Space Recursion as an ideal methodology for the study of electronic and magnetic structures of rough surfaces, interfaces and overlayers. The method can take into account roughness, short-ranged clustering effects, surface dilatation and interdiffusion. We illustrate our method by an application of Fe

P. Butera, M. Comi

We show how to compute the generating function of the self-avoiding polygons on a lattice by using the statistical mechanics Schwinger-Dyson equations for the correlation functions of the $N$-vector spin model on that lattice.

Takao Morinari

We show that the imaginary vector potential causes a pair-breaking effect in the composite fermion theory, and discuss its irrelevance in the pairing state. The Hamiltonian for pairing states of composite fermions is proposed. The advantage of non-unitary transformations and the meaning of the non-Hermitian term are discussed.

Ralf Bundschuh, Michael Lassig

Semi-flexible manifolds such as fluid membranes or semi-flexible polymers undergo delocalization transitions if they are subject to attractive interactions. We study manifolds with short-ranged interactions by field-theoretic methods based on the operator product expansion of local interaction fields. We apply this approach to manifolds in a random potential

Fabricio Toscano, Alfredo M. Ozorio de Almeida

We construct a semiclassical expression for the Husimi function of autonomous systems in one degree of freedom, by smoothing with a Gaussian function an expression that captures the essential features of the Wigner function in the semiclassical limit. Our approximation reveals the &#34;center and chord&#34; estructure that the Husimi function inherits from t

C. Wagner, R. Klages, G. Nicolis

We apply a recently proposed novel thermostating mechanism to an interacting many-particle system where the bulk particles are moving according to Hamiltonian dynamics. At the boundaries the system is thermalized by deterministic and time-reversible scattering. We show how this scattering mechanism can be related to stochastic boundary conditions. We subsequ

Keith A. Olive

A brief review of standard big bang nucleosynthesis theory and the related observations of the light element isotopes is presented. Implications of BBN on chemical evolution and constraints on particle properties will also be discussed.

M. J. Geller, Antonaldo Diaferio, M. J. Kurtz

We use a new redshift survey complete to m_R=15.4 within 4.25 deg from the center of the Coma cluster to measure the mass profile of the cluster to r=5.5 Mpc/h. We extend the profile to r=10 Mpc/h with a further sample complete to m_R=15.4 in 42% of the area within a 10 deg radius and to m_{Zw}=15.5 in the remaining area. Galaxies within this region are fall

M. Ruffert

The hydrodynamics of a variant of classical Bondi-Hoyle-Lyttleton accretion is investigated: a totally absorbing sphere moves at various Mach numbers (3 and 10) relative to a medium, which is taken to be an ideal gas having a density gradient (of 3%, 20% or 100% over one accretion radius) perpendicular to the relative motion. Similarly to the 3D models publi

Mariano Mendez, Michiel van der Klis

We have analyzed seventeen observations of the low-mass X-ray binary and atoll source 4U 1728-34, carried out by the Rossi X-ray Timing Explorer in 1996 and 1997. We obtain precise measurements of the frequencies of the two simultaneous kilohertz quasi-periodic oscillations (kHz QPOs) in this source. We show that the frequency separation between the two QPO,

G. L. Israel, S. Covino, V. F. Polcaro, L. Stella

We present the results of optical observations performed between May and September 1998 of the stars within the position error circle of the recently discovered 12min pulsating X-ray source 1WGA J1958.2+3232. Based on photometry and slitless spectroscopy, we selected a likely optical counterpart, which was subsequently determined to be a m_V=15.7 B0Ve star,

Rosa M. Gonzalez Delgado

Starburst galaxies are powered by massive stars. These stars dominate the heating and enrichment with heavy elements of the interstellar medium, gas out of which new stars form. Thus, high-mass stars, and in consequence starburst galaxies, are an important (in some cases the dominant) energy source for the evolution of galaxies and the universe. In this cont

Scott Burles, Kenneth M. Nollett, Michael S. Turner

We summarize the history, theory, observational status, and implications of big-bang nucleosynthesis.

Sisir Roy, Menas Kafatos, Suman Dutta

The frequency shift of spectral lines is most often explained by the Doppler Effect in terms of relative motion, whereas the Doppler broadening of a particular line mainly depends on the absolute temperature. The Wolf effect on the other hand deals with the correlation induced spectral change and explains both the broadening and shift of the spectral lines.

Juan Maldacena, Gregory Moore, Andrew Strominger

We derive a $U$-duality invariant formula for the degeneracies of BPS multiplets in a D1-D5 system for toroidal compactification of the type II string. The elliptic genus for this system vanishes, but it is found that BPS states can nevertheless be counted using a certain topological partition function involving two insertions of the fermion number operator.