September 1996 arXiv papers — page 5

R. Jeannerot

Unified theories containing a $U(1)_{B-L}$ gauge symmetry predict heavy Majorana right-handed neutrinos. In such theories, cosmic strings may form at the $B-L$ breaking scale. If the Higgs field forming the strings is also the Higgs field which gives mass to the right-handed neutrinos, there are right-handed neutrinos trapped as transverse zero modes in the

David H. Lyth, David Roberts

Particle creation during inflation is considered. It could be important for species whose interaction is of gravitational strength or weaker. A complete but economical formalism is given for spin-zero and spin-half particles, and the particle abundance is estimated on the assumption that the particle mass in the early universe is of order the Hubble paramete

B. O. Kerbikov, D. S. Kuzmenko, Yu. A. Simonov

A new approach to effective theory of quarks in the instanton vacuum is presented. Exact equations for the quark propagator and Lagrangian are derived which contain contributions of all quark modes with known coefficients. The resulting effective Lagrangian resembles that of the Nambu--Jona--Lasinio model. The commonly used zero--mode approximation is shown

G. Parente, A. V. Kotikov

We extract the deep inelastic scattering cross-sections ratio $R= σ_L/σ_T$ in the range $10^{-4} \leq x \leq 10^{-1}$ from $F_2$ HERA data using very simple relations based on perturbative QCD. The result depends on only one parameter $δ$, being $x^{-δ}$ the behavior of the parton densities at low $x$, which has been determined recently with a good accuracy

G. M. Shore

The target-independent suppression mechanism proposed as an explanation of the EMC-SMC `proton spin' effect is reviewed and compared to current experimental data. According to this proposal, the anomalous suppression observed in the first moment of the polarised proton structure function g_1^p is not a special property of the proton structure, but reflec

Yuan-ben Dai, Chao-shang Huang, Ming-qiu Huang, Chun Liu

The masses of excited heavy mesons are studied with sum rules in the heavy quark effective theory. A set of interpolating currents creating (annihilating) excited heavy mesons with arbitrary spin and parity are proposed and their properties are discussed. Numerical results at the leading order of the {\cal O}(1/m_Q) expansion are obtained for the lowest doub

M. M. Boyce

The work in this thesis consists of two distinct parts: A class of models called, ``String-flip potential models,'' (SFP's) are studied as a possible candidate for modeling nuclear matter in terms of constituent quarks. These models are inspired from lattice quantum-chromodynamics (QCD) and are nonperturbative in nature. It is shown that they are

M. Goeckeler, R. Horsley, E. -M. Ilgenfritz, H. Oelrich

We report on measurements of the h_1 structure function, relevant to calculating cross-sections for the Drell-Yan process. This is a quantity which can not be measured in Deep Inelastic Scattering, it gives additional information on the spin carried by the valence quarks, as well as insights on how relativistic the quarks are.

G. C. Rossi

In this talk I will discuss a number of approaches designed to deal with the problem of setting up a fully non-perturbative renormalization procedure in lattice QCD. Methods based on Ward-Takahashi identities on hadronic states, on imposing chiral selection rules on amplitudes with external quark/gluon legs, on the use of the Schrödinger functional and on ``

F. I. Cooperstock, S. Jhingan, P. S. Joshi, T. P. Singh

Assuming the weak energy condition, we study the nature of the non-central shell-focussing singularity which can form in the gravitational collapse of a spherical compact object in classical general relativity. We show that if the radial pressure is positive, the singularity is covered by a horizon. For negative radial pressures, the singularity will be cove

X. Hu, Franco Nori

In this paper we investigate coherent and squeezed quantum states of phonons. The latter allow the possibility of modulating the quantum fluctuations of atomic displacements below the zero-point quantum noise level of coherent states. The expectation values and quantum fluctuations of both the atomic displacement and the lattice amplitude operators are calcu

A. Rozhkov, D. Stroud

We consider the quantum melting of a two-dimensional flux lattice at temperature T = 0 in the ``superclean limit.'' In this regime, we find that vortex motion is dominated by the Magnus force. A Lindemann criterion predicts melting when $n_v/n_p \geq β$, where $n_v$ and $n_p$ are the areal number densities of vortex pancakes and Cooper pairs, and $β\

J. Abad, M. Rios

We describe a representation for $U_q(\widehat{sl(n)})$, when $q$ is not a root of unity, based on the fundamental representation of $sl(n)$. As $U_q(sl(n))$ has a Hopf algebra structure with a non-commutative co-product, we look for a intertwine matrix $R$ that relates two possible definitions of that co-product. We solve cases for $n=2$ and $n=3$, and then

H. Endres, W. Hanke, H. G. Evertz, F. F. Assaad

In a recent Letter, Kuroki and Aoki [Phys. Rev. Lett. 76, 440 (1996)] presented quantum Monte-Carlo (QMC) results for pairing correlations in the three-band Hubbard model, which describes the Cu-d_{x^2-y^2} and O-p_{x,y} orbitals present in the CuO_2 planes of high-T_c materials. In this comment we argue that (i) the used parameter set is not appropriate for

Ion Androutsopoulos

Most existing natural language interfaces to databases (NLIDBs) were designed to be used with ``snapshot'' database systems, that provide very limited facilities for manipulating time-dependent data. Consequently, most NLIDBs also provide very limited support for the notion of time. The database community is becoming increasingly interested in _tempo

Edouard Audit, Jean-Michel Alimi

In this paper we present a new local Lagrangian approximation to the gravitational dynamics of cold matter. We describe the dynamics of a Lagrangian fluid element through only one quantity, the deformation tensor. We show that this tensor is clearly suited to the study of gravitational dynamics and, moreover, that knowing its evolution is enough to completel

Lars Bildsten, Edward F. Brown

We investigate the thermal stability of nuclear burning on the accreting X-ray pulsar GRO J1744-28. The neutron star&#39;s dipolar magnetic field is <3\times 10^{11} G if persistent spin-up implies that the magnetospheric radius is less than the co-rotation radius. After inferring the properties of the neutron star, we study the thermal stability of hydrogen

Robert L. Gluckstern, Sergey S. Kurennoy

The beam coupling impedances of small axisymmetric obstacles having a semi-elliptical cross section along the beam in the vacuum chamber of an accelerator are calculated at frequencies for which the wavelength is large compared to a typical size of the obstacle. Analytical results are obtained for both the irises and the cavities with such a shape which allo

G. Akemann, P. H. Damgaard, U. Magnea, S. Nishigaki

We prove the universality of correlation functions of chiral unitary and unitary ensembles of random matrices in the microscopic limit. The essence of the proof consists in reducing the three-term recursion relation for the relevant orthogonal polynomials into a Bessel equation governing the local asymptotics around the origin. The possible physical interpre

M. V. Simkin

Two and three dimensional random Ising models with a Gaussian distribution of couplings with variance $J$ and non-vanishing mean value $J_0$ are studied using the zero-temperature domain-wall renormalization group (DWRG). The DWRG trajectories in the ($J_0,J$) plane after rescaling can be collapsed on two curves: one for $J_0/J > r_c$ and other for $J_0/J <

Stavros Garoufalidis, Jerome Levine

We apply the theory of finite-type invariants of homology 3-spheres to investigate the structure of the Torelli group. We construct natural cocycles in the Torelli group and show that the lower central series quotients of the Torelli group map onto a vector space of trivalent graphs. We also have analogous results for two other natural subgroups of the mappi

Paolo Gambino

The corrections induced by a heavy top on the main precision observables are now available up to O(alpha^2 mt^2/mw^2). The new results imply a significant reduction of the theoretical uncertainty and can have a sizable impact on the determination of the effective sine.

David H. Lyth

If an adiabatic density perturbation is responsible for large scale structure and the cmb anisotropy, its spectral index $n$ will be measured in the forseeable future with an accuracy $Δn\sim .01$. This is precisely the kind of accuracy required to distinguish between many models of inflation. Most of them have an inflationary potential $V\simeq V_0(1\pmμϕ^p

M. Gronau

We review the subject of CP violation in $B$ decays in the Standard Model (SM) and beyond the SM. We describe some of the present most promising ways of testing the Cabibbo-Kobayashi-Maskawa (CKM) origin of CP violation through a determination of the three angles of the CKM matrix unitarity triangle. Other sources of CP nonconservation violate SM constraints

Albert Stebbins

This paper details a description of the pattern of galaxy image distortion over the entire sky caused by the gravitational lensing which is the result of large scale inhomogeneities in our universe. We present a tensor spherical harmonic formalism to describe this pattern, giving many useful formulae. This is applied to density inhomogeneities, where we comp

F. Khanna, A. M. Rakhimov, M. M. Musakhanov, U. T. Yakhshiev

A Skyrme type Lagrangian for a skyrmion imbedded in a baryon rich environment is proposed. The dependence of static nucleon properties and nucleon - nucleon tensor interaction on nuclear density is investigated.

A. L. Melott, S. F. Shandarin, R. J. Splinter, Y. Suto

Two-body scattering and other discreteness effects are unimportant in cosmological gravitational clustering in most scenarios, since the dark matter has a small particle mass. The collective field should determine evolution: Two-body scattering in simulations violates the Poisson-Vlasov equations. We test this in PM, P$^3$M, Tree, and NGPM codes, noting that

Deane Yang

Using a flow first introduced by J.P. Anderson, we obtain some existence theorems for harmonic maps from a noncompact complete Riemannian manifold into a complete Riemannian manifold. In particular, we prove as a corollary a recent result of Hardt and Wolf stating that any quasisymmetric map of the sphere that is sufficiently close to the identity can be ext

Fyodor V. Tkachov

The ideas behind the concept of algebraic (&#34;integration-by-parts&#34;) algorithms for multiloop calculations are reviewed. For any topology and mass pattern, a finite iterative algebraic procedure is proved to exist which transforms the corresponding Feynman-parametrized integrands into a form that is optimal for numerical integration, with all the poles

W. Melnitchouk, M. Sargsian, M. Strikman

We demonstrate that measurement of tagged structure functions of the deuteron in (e,e&#39;N) semi-inclusive reactions can discriminate between different hypotheses on the origin of the nuclear EMC effect. By choosing extreme backward kinematics for the spectator nucleon to minimize effects from the deuteron wave function and final state interactions, one can

F. Cardarelli, E. Pace, G. Salme&#39;, S. Simula

A parameter-free evaluation of the $N - P_{11}(1440)$ electromagnetic transition form factors is performed within a light-front constituent quark model, using for the first time the eigenfunctions of a mass operator which generates a large amount of configuration mixing in baryon wave functions. A one-body electromagnetic current, which includes the phenomen

Giuseppe Bono, Filippina Caputo, Santi Cassisi, Vittorio Castellani

This paper presents evolutionary computations which investigate the theoretical predictions concerning metal rich RR Lyrae pulsators found both in the Galactic field and in the Galactic bulge. The main aim of this investigation is to provide a homogeneous evolutionary context for further analyses concerning the pulsational properties of these evolving struct

W-S. Chung

In this paper two types of coherent states of $gl_q(2)$-covariant oscillators are investigated.

Doug Bullock, Charles Frohman, Joanna Kania-Bartoszynska

This is a survey article describing the various ways in which the Kauffman bracket skein module is a quantization of surface group characters. These include a purely heuristic sense of deformation of a presentation, a Poisson quantization, and a lattice gauge field theory quantization.

Nobuyuki Ishibashi

We study a theory of particles interacting with strings. Considering such a theory for Type IIA superstring will give some clue about M-theory. As a first step toward such a theory, we construct the particle-particle-string interaction vertex generalizing the D-particle boundary state.

Masayasu Harada, Francesco Sannino, Joseph Schechter

We comment on the recent paper by N.A. Tornqvist and M. Roos published in Phys. Rev. Lett. 76, 1575 (1996).

Tomas Kopf

For a physical interpretation of a theory of quantum gravity, it is necessary to recover classical spacetime, at least approximately. However, quantum gravity may eventually provide classical spacetimes by giving spectral data similar to those appearing in noncommutative geometry, rather than by giving directly a spacetime manifold. It is shown that a global

Myron Bander

The approach to equilibrium for systems interacting with their environment by being regularly exposed to low energy, low intensity pulses of some type of quanta is studied. Assuming a randomness condition on the interaction of these quanta with the system, but making no assumptions about the accessible states of the system, we show that microcanonical equili

Grzegorz Haran, A. D. S. Nagi

A theory of nonmagnetic impurities in an anisotropic superconductor including the effect of anisotropic (momentum-dependent) impurity scattering is given. It is shown that for a strongly anisotropic scattering the reduction of the pair-breaking effect of the impurities is large. For a significant overlap between the anisotropy functions of the scattering pot

Sagar A. Pandit, Anil D. Gangal

A geometric formulation of a generalization of Nambu mechanics is proposed. This formulation is carried out, wherever possible, in analogy with that of Hamiltonian systems. In this formulation, a strictly nondegenerate constant 3-form is attached to a 3n-dimensional phase space. Time evolution is governed by two Nambu functions. A Poisson bracket of 2-forms

Paolo de Bernardis, Amedeo Balbi, Giancarlo De Gasperis, Alessandro Melchiorri

We study the anisotropy of the cosmic microwave background (CMB) in cold and mixed dark matter (CDM and MDM) models, with non scale-invariant primordial power spectra (i.e. $n \neq 1$) and a late, sudden reionization of the intergalactic medium at redshift $z_{rh}$. We test these models against recent detections of CMB anisotropy at large and intermediate an

P. A. Sturrock, G. Walther

In order to explore a recent proposal that the solar core may contain a component that varies periodically with a period in the range 21.0 - 22.4 days, due either to rotation or to some form of oscillation, we have examined the time series formed from measurements of the solar neutrino flux by means of the GALLEX, Homestake and Kamiokande experiments. Direct

She-Sheng Xue

We analyze the dynamics of an $SU_L(2)\otimes U_R(1)$ chiral gauge theory on a lattice with a large multifermion coupling $1\ll g_2 < \infty$. It is shown that no spontaneous symmetry breaking occurs; the ``spectator&#39;&#39; fermion $ψ_R(x)$ is a free mode; doublers are decoupled as massive Dirac fermions consistently with the chiral gauge symmetry. Whethe

C. Barbero, J. M. Cline, F. Krmpotic, D. Tadic

We have developed a formalism, based on the Fourier-Bessel expansion, that facilitates the evaluation of matrix elements involving nucleon recoil operators, such as appear in serveral exotic forms of neutrinoless double beta decay ($ββ_{0ν}$). The method is illustrated by applying it to the ``charged&#39;&#39; majoron model, which is one of the few that can

A. Djouadi, V. Driesen, W. Hollik, J. Rosiek

We calculate the cross sections for the production of Higgs particles in association with a photon in $e^+ e^-$ collisions, $e^+ e^- \to γ+$Higgs, allowing for the longitudinal polarization of the initial electron and positron beams. We consider the associated production of both the Standard Model Higgs boson, and the neutral CP-even and CP-odd Higgs particl

A. Djouadi, W. Hollik, C. Junger

In supersymmetric theories, the main decay modes of scalar quarks are decays into quarks plus charginos or neutralinos, if the gluinos are heavy enough. We calculate the O($α_s$) QCD corrections to these decay modes in the minimal supersymmetric extension of the Standard Model. In the case of scalar top and bottom quarks, where mixing effects can be importan

J. G. Rodrigo, F. Guinea, S. Vieira, F. G. Aliev

Tunnel and point contact experiments have been made in a URu$_2$Si$_2$ single crystal along the c-axis. The experiments were performed changing temperature and contact size in a low temperature scanning tunneling microscope. A resonance develops at the Fermi level at $T\sim 60$ K. This resonance splits and becomes asymmetric when the 17.5 K phase transition

Alexander Altland, Martin R. Zirnbauer

The quantum kicked rotor is investigated by field theoretical methods. It is shown that the effective theory describing the long wave length physics of the system is precisely the supersymmetric nonlinear sigma-model for quasi one-dimensional metallic wires. This proves that the analogy between chaotic systems with dynamical localization and disordered metal

O. F. Dayi

The standard and anti-standard ordered operators acting on two-dimensional q-deformed phase space are shown to satisfy algebras which can be called W_\infty. q-star products and q-Moyal brackets corresponding to these algebras are constructed. Some applications like defining q-classical mechanics and q-path integrals are discussed.

Ralph Blumenhagen, Rolf Schimmrigk, Andreas Wisskirchen

We generalize the previously established (0,2) triality of exactly solvable models, Landau-Ginzburg theories and Calabi-Yau manifolds to a number of different classes of (0,2) compactifications derived from (2,2) vacua. For the resulting models we show that the known (2,2) mirror constructions induce mirror symmetry in the (0,2) context.

Eric W. Deutsch, Scott F. Anderson, Bruce Margon, Ronald A. Downes

The intense, bursting X-ray source in the globular cluster NGC 1851 was one of the first cluster sources discovered, but has remained optically unidentified for 25 years. We report here on results from Hubble Space Telescope WFPC2 multicolor images in NGC 1851. Our high spatial resolution images resolve ~200 objects in the 3&#39;&#39; radius Einstein X-ray e

Erik A. Martinez

The general principles and logical structure of a thermodynamic formalism that incorporates strongly self-gravitating systems are presented. This framework generalizes and simplifies the formulation of thermodynamics developed by Callen. The definition of extensive variables, the homogeneity properties of intensive parameters, and the fundamental problem of

A. V. Tsiganov

The 2x2 monodromy matrices for the Kowalewski top on the Lie algebras e(3), so(4) and so(3,1) are presented. The corresponding quadratic R-matrix structure is the dynamical deformation of the standard R-matrix algebras. Some tops and Toda lattices related to the Kowalewski top are discussed.

Suemi Rodriguez-Romo

We present a short review of the action and coaction of Hopf algebras on Clifford algebras as an introduction to physically meaningful examples. Some q-deformed Clifford algebras are studied from this context and conclusions are derived.

P. Navratil, B. R. Barrett

Large-space no-core shell model calculations have been performed for A=3-6 nuclei, using a starting-energy-independent two-body effective interaction derived by application of the Lee-Suzuki similarity transformation. This transformation can be performed by direct calculation or by different iteration procedures, which are described. A possible way of reduci

E. Hernandez, M. J. Gillan, C. M. Goringe

In the framework of a recently reported linear-scaling method for density-functional-pseudopotential calculations, we investigate the use of localized basis functions for such work. We propose a basis set in which each local orbital is represented in terms of an array of `blip functions&#39;&#39; on the points of a grid. We analyze the relation between blip-

Suemi Rodriguez-Romo

We present a new real space renormalization-group map, on the space of probabilities, to study the renormalization of the SUSY ϕ^4. In our approach we use the random walk representation on a lattice labeled by an ultrametric space. Our method can be extended to any ϕ^n. New stochastic meaning is given to the parameters involved in the flow of the map and res

B. M. Barbashov

Boundary equations for the relativistic string with masses at ends are formulated in terms of geometrical invariants of world trajectories of masses at the string ends. In the three--dimensional Minkowski space $E^1_2$, there are two invariants of that sort, the curvature $K$ and torsion $κ$. Curvatures of trajectories of the string ends with masses are alwa

Dietrich Bödeker

We consider quantum corrections to classical real time correlation functions at finite temperature. We derive a semi-classical expansion in powers of $\hbar$ with coefficients including all orders in the coupling constant. We give explicit expressions up to order $\hbar^2$. We restrict ourselves to a scalar theory. This method, if extended to gauge theories,

P. Saltsidis

We present the mass spectrum of the tensionless string in 2 dimensions where it has been found that the space time conformal symmetry survives quantization. A BRST treatment of the physical states reveals that the string collapses into a massless particle, a result which agrees with the classical treatment.

V. B. Kopeliovich

The quantization condition derived previously for SU(2) solitons quantized with SU(3)-collective coordinates is generalized for SU(3) skyrmions with strangeness content different from zero. Quantization of the dipole-type configuration with large strangeness content found recently is considered as an example.

J. R. Pelaez

Within the chiral lagrangian formalism it is possible to describe the general strongly coupled Symmetry Breaking Sector in terms of a few parameters. Based on a dispersive approach we have studied the resonance spectrum up to 3 TeV in the chiral parameter space. This procedure could also be useful to extract the higher energy resonant behavior from low-energ

M. G. Olsson

The experimental and theoretical evidence relating spin dependence and long range confinement is reviewed. One of the simplest confinement ideas, the dynamic electric flux tube picture of Buchmüller, can be exploited to yield a complete effective Hamiltonian. In addition to pure Thomas spin-orbit splitting the other relativistic corrections are calculated. I

J. Blümlein, T. Doyle, F. Hautmann, M. Klein

An introduction and summary is given of the main results achieved by working group 1: Structure Functions in Deep Inelastic Scattering at HERA. The prospects were discussed of future measurements of the structure functions $F_{2}, F_{L}, xG_{3}, F_{2}^{Q\overline{Q}}$ and $F_π$ at HERA. The results represent a long term programme of experimentation with high

V. Kartvelishvili, M. Margvelashvili, G. Shaw

Recent experimental data on tau decays are used to reconstruct the difference in hadronic spectral densities with vector and axial-vector quantum numbers. The saturation of Das-Mathur-Okubo and Weinberg sum rules is studied. Two methods of improving convergence and decreasing errors are applied, and good agreement with the predictions of current algebra and

Rafel Escribano, Eduard Masso

Using electroweak data and an effective Lagrangian approach we obtain stringent bounds on the tau anomalous magnetic moment, $-0.004 \leq a_τ\leq 0.006$, and on its electric dipole moment, $|d_τ| \leq 1.1 \times 10^{-17} e$ cm. This significantly improves our previous bounds. With the same method, we obtain limits on the dipole moments of other fermions.

A. Denner, S. Dittmaier, G. Weiglein

The application of the background-field method to the electroweak Standard Model and its virtues are reviewed. Special emphasis is directed to the Ward identities that follow from the gauge invariance of the background-field effective action. They are compatible with on-shell renormalization and imply a decent behavior of the background-field vertex function

D. Atwood, A. Soni

Top quark is extremely sensitive to non-standard CP violating phases. General strategies for exposing different types of phases at the NLC are outlined. SUSY phase(s) cause PRA in $t\to Wb$. The transverse polarization of the $τ$ in the reaction $t\to bτν$ is extremely sensitive to a phase from the charged Higgs sector. Phase(s) from the neutral Higgs sector

M. R. Pennington, J. Portoles

A way of testing the $ππ$ predictions of Chiral Perturbation Theory against experimental data is to use dispersion relations to continue experimental information into the subthreshold region where the theory should unambiguously apply. Chell and Olsson have proposed a test of the subthreshold behaviour of chiral expansions which highlights potential differen

Michael Krämer

I discuss the impact of color-octet contributions and higher-order QCD corrections on the cross section for inelastic $J/ψ$ photoproduction. The theoretical predictions are compared with recent experimental data obtained at HERA.

Amitava Datta, Monoranjan Guchait, Nirmalaya Parua

It is shown that if the sneutrino is the second lightest SUSY particle, then the decay products of squarks and gluinos produced at the TEVATRON collider tend to have i) more leptons, ii) smaller number of jets and iii) two or more carriers of missing E_T. This may relax the existing limits on the squark and gluino masses. This effect is likely to be even mor

Rajendran Raja

We demonstrate a new likelihood method for extracting the top quark mass from events of the type ttbar-->bW(l+nu)bW(l+nu) This method estimates the top quark mass correctly from an ensemble of dilepton events. The method proposed by Dalitz and Goldstein [1] is shown to result in a systematic underestimation of the top quark mass. Effects due to the spin corr

L. Blanchet

Gravitational radiation reaction forces and balance equations for energy and momenta are investigated to 3/2 post-Newtonian (1.5PN) order beyond the quadrupole approximation, corresponding to the 4PN order in the equations of motion of an isolated system. By matching a post-Newtonian solution for the gravitational field inside the system to a post-Minkowskia

Vladimir Y. Rovenskii, Victor A. Toponogov

The survey is devoted to Toponogov&#39;s conjecture, that {\it if a complete simply connected Riemannian manifold with sectional curvature $\le 4$ and injectivity radius $\ge π/2$ has extremal diameter $π/2$, then it is isometric to CROSS}. In Section 1 the relations of problem with geodesic foliations of a round sphere are considered, but the proof of conje

Josef Dorfmeister, Guido Haak

We investigate CMC-surfaces with periodic metric in a dressing orbit of the cylinder. It is shown, that such surfaces are always of finite type. Using the periodicity conditions for the extended frame of a CMC-surface, we develop an alternative approach to the classification of CMC-tori given by Pinkall and Sterling.

Yuksel Gunal, P B Visscher

Conventional methods for the simulation of diffusive systems are quite slow when applied to strongly inhomogeneous systems. We present a new hierarchical approach based on dynamic renormalization-group ideas and on the Walsh transform (or Haar wavelet) of signal-processing theory. The method is very efficient for simulation of petroleum reservoirs or other s

T. C. Lubensky

Soft condensed matter physics is the study of materials, such as fluids, liquid crystals, polymers, colloids, and emulsions, that are ``soft&#34; to the touch. This article will review some properties, such as the dominance of entropy, that are unique to soft materials and some properties such as the interplay between broken-symmetry, dynamic mode structure,

Frithjof B. Anders, Mark Jarrell, D. L. Cox

The paramagnetic phase of the two channel Anderson Lattice model in the Kondo limit is investigated in infinite spatial dimensions using the non-crossing approximation. The resistivity exhibits a Kondo upturn with decreasing $T$, followed by a slow decrease to a finite value at $T=0$. The decrease reflects lattice coherence effects in concert with particle-h

M. Jaime, M. B. Salamon, M. Rubinstein, R. E. Treece

Thermoelectric power, electrical resistivity and magnetization experiments, performed in the paramagnetic phase of La_{2/3}Ca_{1/3}MnO_3, provide evidence for polaron-dominated conduction in CMR materials. At high temperatures, a large, nearly field-independent difference between the activation energies for resistivity (rho) and thermopower (S), a characteri

Mark Jarrell, Hanbin Pang, D. L. Cox

The phase diagram of the two-channel Kondo lattice model is examined with a Quantum Monte Carlo simulation in the limit of infinite dimensions. Commensurate (and incommensurate) antiferromagnetic and superconducting states are found. The antiferromagnetic transition is very weak and continuous; whereas the superconducting transition is discontinuous to an od

Qimiao Si

I summarize recent work on non-Fermi liquids within certain generalized Anderson impurity model as well as in the large dimensionality ($D$) limit of the two-band extended Hubbard model. The competition between local charge and spin fluctuations leads either to a Fermi liquid with renormalized quasiparticle excitations, or to non-Fermi liquids with spin-char

V. B. Geshkenbein, L. B. Ioffe, A. I. Larkin

We discuss the phenomenology of the superconductivity resulting from the bose condensation of the preformed pairs coexisting with unpaired fermions. We show that this transition is more mean field like than usual bose condensation, i.e. it is characterized by a relatively small value of the Ginzburg parameter. We consider the Hall effect in the vortex flow r

H. -G. Doebereiner, U. Seifert

Giant phospholipid vesicles are shown to exhibit thermally activated transitions between a prolate and an oblate shape on a time scale of several seconds. From the fluctuating contour of such a vesicle we extract ellipticity as an effective reaction coordinate whose temporal probability distribution is bimodal. We then reconstruct the effective potential fro

Liang Fu, Lorenzo Resca

We show that the interface effect on the properties of composite media recently proposed by Torquato and Rintoul (TR) [Phys. Rev. Lett. 75, 4067 (1995)] is in fact elementary, and follows directly from taking the limit in the dipolar polarizability of a coated sphere: the TR ``critical values&#39;&#39; are simply those that make the dipolar polarizability va

D S Dean, I T Drummond, R R Horgan

By means of rather general arguments, based on an approach due to Derrida that makes use of samples of finite size, we analyse the effective diffusivity and drift tensors in certain types of random medium in which the motion of the particles is controlled by molecular diffusion and a local flow field with known statistical properties. The power of the Derrid

R. E. Bartolo, N. Giordano, X. Huang, G. H. Bernstein

We have investigated a mesoscopic photovoltaic (PV) effect in micron-size Au rings in which a dc voltage Vdc is generated in response to microwave radiation. The effect is due to the lack of inversion symmetry in a disordered system. Aharonov-Bohm PV oscillations with flux period h/e have been observed at low microwave intensities for temperatures ranging fr

H. Fehske, G. Wellein, B. Bäuml, H. Büttner

Ground-state and dynamical properties of the 2D Holstein t-J model are examined by means of direct Lanczos diagonalization, using a truncation method of the phononic Hilbert space. The single-hole spectral function shows the formation of a narrow hole-polaron band as the electron-phonon coupling increases, where the polaronic band collapse is favoured by str

V. I. Anisimov, S. Yu. Ezhov, T. M. Rice

The ordered alloy La_2Li_{0.5}Cu_{0.5}O_4 is found to be a band insulator in local density approximation (LDA) calculations with the unoccupied conduction band having predominantly d_{x^2-y^2}-symmetry and substantial weight in O 2p-orbitals. This is equivalent to a predominant local singlet configuration d^9L or a low spin Cu^{3+}-ion with both holes in orb

K. Richter, D. Ullmo, R. A. Jalabert

We present a general semiclassical theory of the orbital magnetic response of noninteracting electrons confined in two-dimensional potentials. We calculate the magnetic susceptibility of singly-connected and the persistent currents of multiply-connected geometries. We concentrate on the geometric effects by studying confinement by perfect (disorder free) pot

K. Richter, D. Ullmo, R. A. Jalabert

We present a semiclassical theory of weak disorder effects in small structures and apply it to the magnetic response of non-interacting electrons confined in integrable geometries. We discuss the various averaging procedures describing different experimental situations in terms of one- and two-particle Green functions. We demonstrate that the anomalously lar

Ya. M. Blanter, C. Bruder, Rosario Fazio, Herbert Schoeller

We investigate Aharonov-Bohm-type oscillations of the thermopower of a quantum dot embedded in a ring for the case when the interaction between electrons can be neglected. The thermopower is shown to be strongly flux dependent, and typically the amplitude of oscillations exceeds the background value. It is also shown to be essentially dependent on the phase

S. Daul, P. Pieri, M. Dzierzawa, D. Baeriswyl

A one-dimensional Hubbard model with nearest and (negative) next-nearest neighbour hopping is studied variationally. This allows to exclude saturated ferromagnetism for $U < U_c$. The variational boundary $U_c (n)$ has a minimum at a ``critical density&#39;&#39; $n_c$ and diverges for $n \rightarrow 1$.

Bambi Hu, Jian Zhou

The effects of a magnetic field on a modulated phase is studied. A modulated phase is found to have two critical fields $H_{1}$ and $H_{2}$. For a large enough magnetic field. $H_1$ can be approximated by a linear law. As a result, the minimum magnetic field needed to destroy a modulated phase is a constant. The minimum magnetic field also greatly depends on

D. Olguin, R. Baquero

We present an electronic structure calculation of the valence band for some II--VI binary/ternary alloy interfaces. We use the empirical tight-binding method and the surface Green&#39;s function matching method. For the ternary alloys we use our previously set Hamiltonians they describe well the band gap change with composition obtained experimentally. At th

Ross H. McKenzie

The effect of disorder on the quantum phase transitions induced by a transverse field, anisotropy, and dimerization in XY spin chains is investigated. The low-energy behavior near the critical point is described by a Dirac-type equation with a random mass for which an exact analytic treatment is possible. Results obtained for the dynamical critical exponent,

S. Succi, G. Bella, F. Papetti

A simple extension of the Lattice Boltzmann equation is proposed, which permits to handle reactive flow dynamics in the limit of fast chemistry at virtually no extra-cost with respect to the purely hydrodynamic scheme.

P. A. Sturrock

It has been established that the Rieger periodicity of approximately 153 days is part of a complex of periodicities, all multiples of a basic period of approximately 25.5 days. However, it has not been clear why the sixth subharmonic of this periodicity should be preferentially manifested. We here note that if the Sun contains two rotating elements, with dif

Guillermo Gonzalez

The stars 55 Cnc, 51 Peg, 47 UMa, 70 Vir, and HD 114762 have recently been proposed to harbor planetary mass companions. Using spectrospic methods we find that 55 Cnc and 51 Peg are super metal- rich, 47 UMa and 70 Vir have roughly solar metallicities, and HD 114762 is metal-poor. Otherwise, the abundance patterns, expressed as [X/Fe], are approximately sola

Christopher W. Mauche, Y. Paul Lee, Timothy R. Kallman

We present a statistical analysis of the ultraviolet emission lines of cataclysmic variables (CVs) based on $\approx 430$ ultraviolet spectra of 20 sources extracted from the International Ultraviolet Explorer Uniform Low Dispersion Archive. These spectra are used to measure the emission line fluxes of N V, Si IV, C IV, and He II and to construct diagnostic

Insu Yi

We present a model for the cosmological evolution of quasars (QSOs) under the assumption that they are powered by massive accreting black holes. Accretion flows around massive black holes make a transition from high radiative efficiency ($\sim 10%$) to low efficiency, advection-dominated flows when ${\dot M}/{\dot M}_{Edd}$ falls below the critical rate $\si