Research archive

arXiv papers from November 1994

The most recent 100 records published that month. Open any paper for its original abstract, citation metadata, related research, and reading tools.

  1. John C. Collins, Glenn A. Ladinsky

    Using the linear sigma model to describe quark--pion interactions, we compute polarization asymmetries in quark fragmentation. We show that the effects of transverse quark polarizations appear in the correlation between the two leading pions in a jet produced by the fragmentation of a quark. Such asymmetries provide a window to the nature of chiral symmetry

  2. David S. Tartakoff

    We prove global analytic hypoellipticity on a product of tori for partial differential operators which are constructed as rigid (variable coefficient) quadratic polynomials in real vector fields satisfying the H\"ormander condition and where $P$ satisfies a `maximal' estimate. We also prove an analyticity result that is local in some variables and global in

  3. Antonio Bove, David S. Tartakoff

    We prove results on the propagation of Gevrey and analytic wave front sets for a class of $C^\infty$ hypoelliptic equations with double characteristics.

  4. J. Rembielinski

    It is shown that tachyons are associated with unitary representations of Poincare mappings induced from SO(2) little group instead of SO(2,1) one. This allows us to treat more seriously possibility that neutrinos are fermionic tachyons according to the present experimental data.

  5. Xiao-Song Lin, Zhenghan Wang

    We study the integral expression of a knot invariant obtained as the second coefficient in the perturbative expansion of Witten's Chern-Simons path integral associated with a knot. One of the integrals involved turns out to be a generalization of the classical Crofton integral on convex plane curves and it is related with invariants of generic plane curves d

  6. Xianzhe Dai, Guofang Wei, Rugang Ye

    We prove that Riemannian metrics with an absolute Ricci curvature bound and a conjugate radius bound can be smoothed to having a sectional curvature bound. Using this we derive a number of results about structures of manifolds with Ricci curvature bounds.

  7. A. De la Macorra, S. Lola

    We investigate the possibility of obtaining inflationary solutions of the slow roll type from a low energy Lagrangian coming from superstrings. The advantage of such an approach is that in these theories the scalar potential has only one free parameter (the Planck scale) and therefore no unnatural fine tuning may be accommodated. We find that in any viable s

  8. Terrence Draper, Craig McNeile, Constantine Nenkov

    We present initial results from Monte Carlo simulations of NRQCD-light, static-light, and NRQCD-NRQCD mesons, using a variational technique (MOST), as part of our ongoing calculation of the $f_{B}$ decay constant. The basis states for the variational calculation are quark-antiquark operators separated by all possible relative distances not equivalent under t

  9. H. J. Munczek

    A proof of Goldstone's theorem is given for the case in which global chiral symmetry is dynamically broken. The proof highlights a needed consistency between the exact Schwinger--Dyson equation for the fermion propagator and the exact Bethe--Salpeter equation for fermion--antifermion bound states. A criterion, based on the Cornwall, Jackiw and Tomboulis effe

  10. H. W. Braden, V. M. Buchstaber

    A new ansatz is presented for a Lax pair describing systems of particles on the line interacting via (possibly nonsymmetric) pairwise forces. Particular cases of this yield the known Lax pairs for the Calogero-Moser and Toda systems, as well as their relativistic generalisations. The ansatz leads to a system of functional equations. Several new functional eq

  11. R. E. Gamboa Saravi, G. L. Rossini, F. A. Schaposnik

    We study parity violation in $2+1$-dimensional gauge theories coupled to massive fermions. Using the $\zeta$-function regularization approach we evaluate the ground state fermion current in an arbitrary gauge field background, showing that it gets two different contributions which violate parity invariance and induce a Chern-Simons term in the gauge-field ef

  12. Brian Gough

    We summarise our current results for calculations of the form factors for $B \to K^* \gamma$, and their extrapolation to the physical b-quark mass.

  13. Ehud Reiter

    I survey some recent applications-oriented NL generation systems, and claim that despite very different theoretical backgrounds, these systems have a remarkably similar architecture in terms of the modules they divide the generation process into, the computations these modules perform, and the way the modules interact with each other. I also compare this `co

  14. A. Khoudeir, N. Pantoja

    A manifestly Lorentz and diffeomorphism invariant form for the abelian gauge field action with local duality symmetry of Schwarz and Sen is given. Some of the underlying symmetries of the covariant action are further considered. The Noether conserved charge under continuous local duality rotations is found. The covariant couplings with gravity and the axidil

  15. D. J. Lamb, A. Z. Capri, M. Kobayashi

    In this paper we calculate the particle creation as seen by a stationary observer in an anisotropic universe. By using an observer and geometry dependent time to quantise a massive scalar field we show that a discrete energy spectrum shift occurs. The length scale associated with the geometry provides the energy scale by which the spectrum is shifted. The $\

  16. Bong H. Lian, Shing-Tung Yau

    We study some arithmetic properties of the mirror maps and the quantum Yukawa coupling for some 1-parameter deformations of Calabi-Yau manifolds. First we use the Schwarzian differential equation, which we derived previously, to characterize the mirror map in each case. For algebraic K3 surfaces, we solve the equation in terms of the $J$-function. By derivin

  17. David J. Gross

    In this talk, delivered at the Oscar Klein Centenary Symposium in Stockholm, I review the 1938 conference held in Warsaw devoted to \lq \lq New Theories in Physics". I review all of the talks presented at this meeting and discuss in detail Klein's paper where he proposed a unified model of electromagnetism and the nuclear force that foreshadowed the later de

  18. N. Nakazawa

    We apply stochastic quantization method to matrix models for the second quantization of loops in both discretized and continuum levels. The fictitious time evolution described by the Langevin equation is interpreted as the time evolution in a field theory of loops. The corresponding Fokker-Planck hamiltonian defines a non-critical string field theory. We stu

  19. P. Mitra

    The thermodynamic distribution function for exclusion statistics is derived. Creation and annihilation operators for particles obeying such statistics are discussed. A connection with anyons is pointed out.

  20. A. J. Fendrik, M. J. Sánchez

    We study the decay law of the Sinai Well in $D$ dimensions and relate the behavior of the decay law to internal distributions that characterize the dynamics of the system. We show that the long time tail of the decay is algebraic ($1/t$), irrespective of the dimension $D$.

  21. Christoph Frick, Jiri Jersak

    The strongly coupled lattice gauge models with confined fermion and scalar matter fields, which in a certain phase break dynamically a global chiral symmetry, are reconsidered from the point of view of the existence of heavy fermions. If these models are interpreted as describing a new strong force beyond the standard model, such heavy fermions can arise as

  22. G. Valencia

    In this talk we review the status of the theoretical estimates for CP violating asymmetries in non-leptonic hyperon decays.

  23. S. Antonelli, A. Bartoloni, C. Battista, M. Bellacci

    We present numerical results obtained in full QCD with 2 flavors of Wilson fermions. We discuss the relation between the phase of Polyakov loops and the {\bf sea} quarks boundary conditions. We report preliminary results about the HMC autocorrelation of the hadronic masses, on a $16^3 \times 32$ lattice volume, at $\beta=5.55$ with $k_{sea}=0.1570$.

  24. D. S. Henty, C. Parrinello

    We provide numerical results for the running coupling in $SU(3)$ Yang-Mills theory as determined from an analysis of lattice two and three-point gluon correlation functions. The coupling is evaluated directly, from first principles, by defining suitable renormalisation constants from the lattice triple gluon vertex and gluon propagator. For momenta larger th

  25. G. Valencia

    In these lectures we review the general features necessary to construct $\cp$ odd observables and study illustrative examples. We present in some detail the case of $\cp$ violation in hyperon decays. We survey different observables sensitive to $\cp$ violating new physics, concentrating on the search for electric-dipole moments in high energy experiments.

  26. Brandon Carter

    The hitherto controversial proposition that a ``wiggly" Goto-Nambu cosmic string can be effectively represented by an elastic string model of exactly transonic type (with energy density $U$ inversely proportional to its tension $T$) is shown to have a firm mathematical basis.

  27. Steven Spencer, Henrik Jeldoft Jensen

    We simulate the low temperature behaviour of an elastic chain in a random potential where the displacements $u(x)$ are confined to the {\it longitudinal} direction ($u(x)$ parallel to $x$) as in a one dimensional charge density wave--type problem. We calculate the displacement correlation function $g(x)=< (u(x)-u(0))^2>$ and the size dependent average square

  28. Jose F. Nieves, Palash B. Pal

    In general the zero momentum limit of thermal self-energies calculated in perturbation theory depends on the order in which the time and the space components of the momentum are taken to zero. We show that this is an artifact of the perturbative calculation, and in fact the non-analyticity of the one-loop self-energy disappears when it is calculated with imp

  29. G. D'Ambrosio, G. Ecker, G. Isidori, H. Neufeld

    We investigate to what extent DA$\Phi$NE will be able to test the Standard Model in the confinement regime with radiative kaon decays. We concentrate on processes which can be detected at DA$\Phi$NE and we review briefly those decays where only upper limits can be expected. The Standard Model predictions for these decays are analyzed in the framework of chir

  30. G. 't Hooft

    A lattice regularization procedure for gauge theories is proposed in which fermions are given a special treatment such that all chiral flavor symmetries that are free of Adler-Bell-Jackiw anomalies are kept intact. There is no doubling of fermionic degrees of freedom. A price paid for this feature is that the number of fermionic degrees of freedom per unit c

  31. A. Bassetto, L. Griguolo

    A family of theories which interpolate between vector and chiral Schwinger models is studied on the two--sphere $S^{2}$. The conflict between the loss of gauge invariance and global geometrical properties is solved by introducing a fixed background connection. In this way the generalized Dirac--Weyl operator can be globally defined on $S^{2}$. The generating

  32. F. Guinea, G. Gomez-Santos, M. Sassetti, M. Ueda

    Conductance through weak constrictions in Luttinger liquids is shown to vanish with frequency $\omega$ as $c_1 \omega^2 + c_2 \omega^{2/g - 2}$, where $g$ is a dimensionless parameter characterizing the Luttinger liquid phase, and $c_1$ and $c_2$ are nonuniversal constants. The first term arises from the ^^ Coulomb blockade' effect and dominates for $g < 1/2

  33. Satoshi Yukawa, Macoto Kikuchi

    We propose a new model of one-dimensional traffic flow using a coupled map lattice. In the model, each vehicle is assigned a map and changes its velocity according to it. A single map is designed so as to represent the motion of a vehicle properly, and the maps are coupled to each other through the headway distance. By simulating the model, we obtain a plot

  34. D. P. Bennett, C. Alcock, R. A. Allsman, T. S. Axelrod

    We review recent gravitational microlensing results from the EROS, MACHO, and OGLE collaborations, and present some details of the very latest MACHO results toward the Galactic Bulge. The MACHO collaboration has now discovered in excess of 40 microlensing events toward the Galactic Bulge during the 1993 observing season. A preliminary analysis of this data s

  35. R. V. Gavai, S. Gupta, P. L. McGaughey, E. Quack

    A systematic study of the inclusive single heavy quark and heavy-quark pair production cross sections in pp collisions is presented for RHIC and LHC energies. We compare with existing data when possible. The dependence of the rates on the renormalization and factorization scales is discussed. Predictions of the cross sections are given for two different sets

  36. Sh. Fujita, H. Nishimura

    In this paper, we investigate the associative memory in recurrent neural networks, based on the model of evolving neural networks proposed by Nolfi, Miglino and Parisi. Experimentally developed network has highly asymmetric synaptic weights and dilute connections, quite different from those of the Hopfield model. Some results on the effect of learning effici

  37. I. V. Andreev, M. Plümer, B. R. Schlei, R. M. Weiner

    The variation of radii, lifetimes, correlation lengths and the chaoticity parameter of particle sources with the collision energy $\sqrt{s}$ is studied by analysing and comparing two-particle Bose-Einstein correlation data obtained by the NA22 Collaboration at $\sqrt{s}=22\ GeV$ and by the UA1-Minimum-Bias Collaboration at $\sqrt{s}=630\ GeV$. The UA1-data a

  38. M. Reuter, C. Wetterich

    We employ nonperturbative flow equations for the description of the effective action in Yang-Mills theories. We find that the perturbative vacuum with vanishing gauge field strength does not correspond to the minimum of the Euclidean effective action. The true ground state is characterized by a nonvanishing gluon condensate.

  39. A. Szczurek, G. D. Bosveld, A. E. L. Dieperink

    The semi-inclusive cross section for producing slow protons in charged current deep inelastic (anti-) neutrino scattering on protons and neutrons is calculated as a function of the Bjorken $x$ and the proton momentum. The standard hadronization models based upon the colour neutralization mechanism appear to underestimate the rate of slow proton production on

  40. Nicoletta Stella

    We present the preliminary results of an exploratory study of heavy baryon spectroscopy, using the $O(a)$-improved fermionic action. Estimates of masses and splittings at the charm and beauty physical limit are reported.

  41. Y. Ohta, K. Kajiwara, J. Satsuma

    Bilinear structure for the discrete Painlev\'e I equation is investigated. The solution on semi-infinite lattice is given in terms of the Casorati determinant of discrete Airy function. Based on this fact, the discrete Painlev\'e I equation is naturally extended to a discrete coupled system. Corresponding matrix model is also mentioned.

  42. Akira Takamura, Shoji Sawada, Shinsaku Kitakado

    We calculate the $F/D$ ratios of spin 1/2 baryon vertex for both the non-relativistic quark model and the chiral soliton model with arbitrary number of color degrees of freedom $N_c$ and examine the results in terms of the consistency condition approach for the baryon vertices recently developed by Dashen, Jenkins and Manohar from the viewpoint of QCD. We sh

  43. Jan Louis, Yosef Nir

    We investigate low energy implications of string loop corrections to supergravity couplings which break a possible flavor universality of the tree level. If Supersymmetry is broken by the dilaton $F$-term, universal soft scalar masses arise at the leading order but string loop corrections generically induce flavor-non-diagonal soft terms. Constraints from fl

  44. Michael J. Booth

    Quenched chiral perturbation theory is extended to include heavy-light mesons. Non-analytic corrections to the decay constants, Isgur-Wise function and masses and mixing of heavy mesons are then computed. The results are used to estimate the error due to quenching in lattice computations of these quantities. For reasonable choices of parameters, it is found

  45. T. J. Weiler, W. A. Simmons, S. Pakvasa, J. G. Learned

    Gamma ray burst (GRB) objects are now widely thought to be at cosmological distances, and thus represent enormous energy emission. Gamma ray spectra extending to $GeV$ energies suggest the possiblity of accompanying neutrino emission, and there are several models proposed suggesting the potential detectability of such coincident neutrino bursts. With this in

  46. M. A. van Eijck, Denjoe O'Connor, C. R. Stephens

    We study $\l\f^4$ theory using an environmentally friendly finite-temperature renormalization group. We derive flow equations, using a fiducial temperature as flow parameter, develop them perturbatively in an expansion free from ultraviolet and infrared divergences, then integrate them numerically from zero to temperatures above the critical temperature. The

  47. David R. Morrison

    We review the applications of mirror symmetry to the study of the moduli spaces of two-dimensional conformal field theories with $N{=}(2,2)$ supersymmetry, particularly those constructed from Calabi--Yau manifolds. (Lecture delivered at the Zurich ICM, section on mathematical physics.)

  48. S. Riemersma, J. Smith, W. L. van Neerven

    The coefficient functions for heavy-flavour production in deeply inelastic electron-hadron scattering have been calculated previously. Analytic expressions are impossible to publish due to their length. Therefore we have tabulated them as two-dimensional arrays as is often done for the scale-dependent parton densities. Using this computer program we present

  49. Maxim Kontsevich

    This is my talk at ICM, Zurich 1994. It contains a short introduction, two basic examples and a refined version of the Mirror Conjecture formulated in terms of homological algebra.

  50. Karl M. Westerberg

    We explore kaon condensation using the bound-state approach to the Skyrme model on a 3-sphere. The condensation occurs when the energy required to produce a $K^-$ falls below the electron fermi level. This happens at the baryon number density on the order of 3--4 times nuclear density.

  51. J. R. Anglin, R. Laflamme, W. H. Zurek, J. P. Paz

    We analyze a system consisting of an oscillator coupled to a field. With the field traced out as an environment, the oscillator loses coherence on a very short {\it decoherence timescale}; but, on a much longer {\it relaxation timescale}, predictably evolves into a unique, pure (ground) state. This example of {\it re-coherence} has interesting implications b

  52. Alexander Bochkarev

    We propose to calculate the gluon condensate in lattice QCD in an indirect way by extracting it from the correlator of hadronic currents of heavy quarks. Moments (derivatives with respect to momentum at vanishing momentum) of the vector and pseudoscalar correlators are evaluated. The contribution of the continuum spectrum in addition to the low-lying resonan

  53. Pavel I. Etingof, Alexander A. Kirillov

    This paper is a continuation of our papers [EK1, EK2]. In [EK2] we showed that for the root system A_n-1 one can obtain Macdonald's polynomials - a new interesting class of symmetric functions recently defined by I. Macdonald {M1] - as weighted traces of intertwining operators between certain finite-dimensional representations of U_q sl_n. The main goal of t

  54. Enrique Diez, Angel Sanchez, Francisco Dominguez-Adame

    We introduce a simple, solvable model of double-barrier resonant tunneling structure which includes the effects of electron-electron and electron-phonon scattering. The model is based on a generalized effective-mass equation where a nonlinear coupling is introduced to account for those inelastic scattering phenomena. The nonlinear term depends on one paramet

  55. Ana Campos

    To distinguish between the different models proposed to understand the excess of faint field counts over the predictions from non-evolving models, a number of redshift surveys have been undertaken. The answer has not arrived yet due to the high rate of incompleteness achieved. Un-identified galaxies have been shown to be bluer than identified ones. In this p

  56. C. Bernard, T. Blum, A. De, T. DeGrand

    Preliminary results from the MILC collaboration for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios are presented. We compute in the quenched approximation at $\beta=6.3$, 6.0 and 5.7 with Wilson light quarks and static and Wilson heavy quarks. We attempt to quantify systematic errors due to finite volume, finite lattice spacing, large $am$, and fitting

  57. D. J. Lamb, A. Z. Capri, S. M. Roy

    We show explicitly that there is particle creation in a static spacetime. This is done by studying the field in a coordinate system based on a physical principle which has recently been proposed. There the field is quantized by decomposing it into positive and negative frequency modes on a particular spacelike surface. This decomposition depends explicitly o

  58. Wolfgang Bock

    Regge's method for regularizing euclidean quantum gravity is applied to two dimensional gravity. Using topologies with genus zero and two and a scale invariant measure, we show that the Regge method fails to reproduce the values of the string susceptibilities of the continuum model.

  59. Su Houng Lee, Seungho Choe, Thomas D. Cohen, David K. Griegel

    Standard QCD sum-rule analyses of the nucleon mass give results that are inconsistent with chiral perturbation theory due to an overly simple continuum ansatz on the phenomenological side of the sum rule. We show that a careful treatment of the continuum, including $\pi$-$N$ states and other states with virtual pions, resolves the inconsistency associated wi

  60. S. Yu. Khlebnikov

    Proceeding from WKB quantization conditions, we derive a semiclassical expression for the current of fermions scattered off a propagating bubble wall in the presence of longitudinal gauge field. It agrees with the expression used by Nasser and Turok in semiclassical analysis of instability of electroweak bubble walls with respect to longitudinal $Z$ condensa

  61. Pimentel L O, Camacho A, Macias A

    The Weyl equation (massless Dirac equation) is studied in a family of metrics of the G\"odel type. The field equation is solved exactly for one member of the family.

  62. Pimentel L O, Obregon O

    For pure fourth order (${\cal{L}} \propto R^2$) quantum cosmology the Wheeler-DeWitt equation is solved exactly for the closed homogeneous and isotropic model. It is shown that by imposing as boundary condition that $\Psi = 0$ at the origin of the universe the wave functions behave as suggested by Vilenkin.

  63. Wolfhard Janke, Stefan Kappler

    We performed Monte Carlo simulations of two-dimensional $q$-state Potts models with $q=10,15$, and $20$ and measured the spin-spin correlation function at the first-order transition point $\beta_t$ in the disordered and ordered phase. Our results for the correlation length $\xi_d(\beta_t)$ in the disordered phase are compatible with an analytic formula. Esti

  64. Pimentel L O, Diaz-Rivera L M

    The effect of bulk viscisity on the evolution of the homogeneous and isotropic cosmological models is considered. Solutions are found, with a barotropic equation of state, and a viscosity coefficient that is proportional to a power of the energy density of the universe. For flat space, power law expansions, related to extended inflation are found as well as

  65. Wolfhard Janke, Stefan Kappler

    Inspired by the multicanonical approach to simulations of first-order phase transitions we propose for $q$-state Potts models a combination of cluster updates with reweighting of the bond configurations in the Fortuin-Kastelein-Swendsen-Wang representation of this model. Numerical tests for the two-dimensional models with $q=7, 10$ and $20$ show that the aut

  66. Christopher T. Hill

    A condensate, $\overline{t}t$, arising from $O(TeV)$ scale ``topcolor,'' in addition to technicolor (and ETC) may naturally explain the gauge hierarchy, the large top quark mass, and contains a rich system of testable consequences. A triplet of strongly coupled pseudo--Nambu--Goldstone bosons, ``top-pions,'' near the top mass scale is a generic prediction of

  67. L. Beldjoudi, Tran N. Truong

    Using chiral low energy theorems and elastic unitarity assumption, the $\tau\to\pi K \nu $ decay is investigated. The vector and scalar $\pi K$ form factors are calculated. It is found that the $\pi K$ spectrum is dominated by the $K^*$ resonance. By measuring the forward-backward asymmetry, it is shown that the S wave $\pi K$ phase shift can be determined n

  68. F. P. Devecchi, M. Fleck, H. O. Girotti, M. Gomes

    The Maxwell-Chern-Simons theory is canonically quantized in the Coulomb gauge by using the Dirac bracket quantization procedure. The determination of the Coulomb gauge polarization vector turns out to be intrincate. A set of quantum Poincar\'e densities obeying the Dirac-Schwinger algebra, and, therefore, free of anomalies, is constructed. The peculiar analy

  69. Alex Deckmyn, Ruud Siebelink, Walter Troost, Alexander Sevrin

    A large class of non-critical string theories with extended worldsheet gauge symmetry are described by two coupled, gauged Wess-Zumino-Witten Models. We give a detailed analysis of the gauge invariant action and in particular the gauge fixing procedure and the resulting BRST symmetries. The results are applied to the example of ${\cal W}_3$ strings.

  70. Christoph Best, Andreas Schäfer

    We use a self-guided random walk to solve the ground-state problem of Hamiltonian U(1) pure gauge theory in 2+1 dimensions in the string sector. By making use of the electric-field representation, we argue that the spatial distribution of the electric field can be more easily measured than in ordinary Monte Carlo simulations.

  71. Rulin Xiu

    We use the off-shell string effective action method developed by E.S. Fradkin and A.A. Tseytlin to obtain the formula for all-genus string effective action with and without compactification at the low-energy approximation in the massless background fields. We find that for the bosonic string, one can determine the dilaton vacuum expectation value from the al

  72. Brandon Carter, Patrick Peter

    A new cosmic string model specified by two independent mass parameters is introduced for the purpose of providing a realistic representation of the macroscopic dynamical behaviour of Witten type (superconducting) vortex defects of the vacuum. Unlike the self dual single mass parameter models previously used for this purpose, the new model successfully repres

  73. Franco Ferrari

    In this paper the free gauge field theories on a Riemann surface of any genus are quantized in the covariant gauge. The propagators of the gauge fields are explicitly derived and their properties are analysed in details. As an application, the correlation functions of a Yang-Mills field theory with gauge group $SU(N)$ are computed at the lowest order.

  74. H. C. Rosu

    This is a short note on the spatiotemporal complexity of the dynamical state(s) of the universe at subhorizon scales (up to 300 Mpc). There are reasons, based mainly on infrared radiative divergences, to believe that one can encounter a flicker noise in the time domain, while in the space domain, the scaling laws are reflected in the (multi)fractal distribut

  75. Ehud Reiter, Chris Mellish, John Levine

    Natural-language generation (NLG) techniques can be used to automatically produce technical documentation from a domain knowledge base and linguistic and contextual models. We discuss this application of NLG technology from both a technical and a usefulness (costs and benefits) perspective. This discussion is based largely on our experiences with the IDAS do

  76. Marco Cavaglia`, Vittorio de Alfaro, Alexandre T. Filippov

    Starting from the Lagrangian formulation of the Einstein equations for the vacuum static spherically symmetric metric, we develop a canonical formalism in the radial variable $r$ that is time--like inside the Schwarzschild horizon. The Schwarzschild mass turns out to be represented by a canonical function that commutes with the $r$--Hamiltonian. We investiga

  77. Hartmut Wittig

    We report on a set of simulations performed at several values of the lattice spacing on the Cray T3D at Edinburgh. Different methods to extract the lattice scale from the static quark potential are discussed.

  78. V. P. Nair

    Summation over hard thermal loops, by themselves and as insertions in higher order Feynman diagrams, is important in thermal perturbation theory for Quantum Chromodynamics, so that all contributions of a given order in the coupling constant can be consistently taken into account. I review some of the basic properties of hard thermal loops and how the generat

  79. Per Kraus, Frank Wilczek

    We extend our previous analysis of the modification of the spectrum of black hole radiance due to the simplest and probably most quantitatively important back-reaction effect, that is self-gravitational interaction, to the case of charged holes. As anticipated, the corrections are small for low-energy radiation when the hole is well away from extremality, bu

  80. L. Beldjoudi, Tran N. Truong

    The decays of $\tau \to 3\pi \nu $ and $\tau \to \pi K^{*} \nu, K\rho \nu $ are calculated using the hard pion and kaon current algebra and assuming the Axial-Vector meson dominance of the hadronic axial currents. Using the experimental data on their masses and widths, the $\tau$ decay branching ratios into these channels are calculated and found to be in a

  81. M. J. W. Dodgson, M. A. Moore

    The free energy costs for various defects within an Abrikosov lattice of vortices are calculated using the lowest Landau level approximation (LLL). Defect solutions with boundary conditions for lines to meet at a point (crossing defect) and for lines to twist around each other (braid defect) are sought for 2, 3, 6, and 12 lines. Many results have been unexpe

  82. A. Franceschini, P. Andreani

    We report on observations performed at 1.25 $mm$ of a southern galaxy sample, selected from the IRAS PSC and complete to $S_{60}=2 Jy$. We detected 18 sources and set significant limits on 10 further objects. We use these data to discuss the spatial distribution of cold dust, the broad-band far-IR/mm spectra, the overall amount of dust, the gas-to-dust mass

  83. Gorazd Cvetic

    We investigated a general framework of the Standard Model with two Higgs doublets (2HDSM) with suppressed flavor-changing neutral currents (FCNC's). Loop-induced FCNC (and CP-violating) effects, when confronted with experimental constraints for the $K$-$\bar K$, $B$-$\bar B$ and $D$-$\bar D$ mixing and for the $(b \to s \gamma)$ decay, provide us with constr

  84. Xiang-Qian Luo, Wolfgang Franzki

    We report the recent results from the computer simulations of a fermion-gauge-scalar model with dynamical chiral-symmetry breaking and chiral transition induced by the scalar field. This model might be considered to be a possible alternative to the Higgs mechanism of mass generation. A new scheme is developed for detecting the chiral transition. Our results

  85. R. Aurich, T. Hesse, F. Steiner

    Based on an accurate computation of the first 1851 quantal energy levels of the truncated hyperbola billiard, we have found an anomalous long-range modulation in the integrated level density. It is shown that the observed anomaly can be explained by an additional term in Gutzwiller's trace formula. This term is given as a sum over families of closed, non-per

  86. Dennis Bonatsos, C. Daskaloyannis, P. Kolokotronis, D. Lenis

    The symmetry algebra of the N-dimensional anisotropic quantum harmonic oscillator with rational ratios of frequencies is constructed by a method of general applicability to quantum superintegrable systems. The special case of the 3-dim oscillator is studied in more detail, because of its relevance in the description of superdeformed nuclei and nuclear and at

  87. Hyun Kyu Lee, Mannque Rho, Sang-Jin Sin

    We present a renormalization-group (RG) flow argument for s-wave kaon condensation in dense nuclear-star matter predicted in chiral perturbation theory. It is shown that it is the {\it relevant} mass term together with {\it any} attractive interaction for the kaon in medium that triggers the instability. We show that a saddle point of multi-dimensional RG fl

  88. Wolfgang Franzki, Xiang-Qian Luo

    The strongly coupled lattice gauge models show an interesting mechanism of dynamical mass generation. If a suitable continuum limit can be found, one may think of it as an alternative to the Higgs mechanism. We present data on the spectrum, obtained in the model with U(1) gauge symmetry with dynamical fermions. They indicate that the fermion mass scales in t

  89. Itzhak Bars

    The complete set of solutions of two dimensional classical string theory are constructed for any curved spacetime. They describe folded strings moving in curved spacetime. Surprizing stringy behavior becomes evident at singularities such as black holes.The solutions are given in the form ofa map from the world sheet to target spacetime, where the world sheet

  90. Yuri Novozhilov, Andrei Pronko, Dmitri Vassilevich

    We introduce extended chiral transformation, which depends both on pseudoscalar and diquark fields as parameters and determine its group structure. Assuming soft symmetry breaking in diquark sector, bosonisation of a quasi-Goldstone $ud$-diquark is performed. In the chiral limit the $ud$-diquark mass is defined by the gluon condensate, $m_{ud}\approx 300 MeV

  91. Krzysztof Byczuk, Jozef Spalek

    We point to the possibility of existence of the statistical-spin-liquid state as the state which differs from either Fermi or Luttinger liquid states. In the statistical spin liquid the double occupancies are excluded from the physical space. Each of the above three cases (Fermi, Luttinger and spin liquids) represents an universality class for the interactin

  92. Aravind K Joshi

    In this paper we discuss the following issue: How do we decide whether a certain property of language is a competence property or a performance property? Our claim is that the answer to this question is not given a-priori. The answer depends on the formal devices (formal grammars and machines) available to us for describing language. We discuss this issue in

  93. Sergei V. Zenkin

    We argue that non-trivial fixed points bordering on the paramagnetic and ferromagnetic phases are most likely to exist in the Higgs-Yukawa systems that have a connected domain with the paramagnetic phase and no ferrimagnetic phase. We find three examples of such systems; among them is the U(1) system with naive fermions.

  94. Igor Halperin

    We discuss the non-factorizable terms in color suppressed (Class II) decays. Our emphasis is on the non-perturbative soft gluon exchange mechanism, which has been previously found to be responsible for the rule of discarding $ 1/N_{c} $ in the Class I decays. The non-factorizable contribution to the decays $ \bar{B}^{0} \rightarrow D^{0} \pi^{0} $ at the tre

  95. Spenta R. Wadia

    We review the gauge invariant formulation of 2-dim. QCD. We show that the non-linear gauge invariant phase space is the coset $W_\infty/W_{+\infty}\times W_{-\infty}$ ,which is specified by the $N=\infty$ master-field of this model. The meson fields correspond to the local coordinates of the coset. We comment on the stringy collective coordinates of the soli

  96. E. Elizalde, S. Leseduarte, S. D. Odintsov

    We discuss the phase structure of a higher derivative four-fermion model in four dimensions in curved spacetime in frames of the $\frac{1}{N_c}$-expansion. First, we evaluate in our model the effective potential of two composite scalars in the linear curvature approximation using a local momentum representation in curved spacetime for the higher-derivative p

  97. Janos Polonyi

    It is pointed out that the universality might seriously be violated by models with several fixed points.

  98. Bas V. de Bakker

    Due to the unrecognizability of certain manifolds there must exist pairs of triangulations of these manifolds that can only be reached from each other by going through an intermediate state that is very large. This might reduce the reliability of dynamical triangulation, because there will be states that will not be reached in practice. We investigate this p

  99. N. Persky, R. Ben-Av, S. Solomon

    We present a new measure of the Dynamical Critical behavior: the "Multi-scale Dynamical Exponent (MDE)"

  100. Sorin Solomon

    Many complex systems are representable as macroscopic set of elements which interact by simple rules. The complex macroscopically relevant phenomena are then the result of the generic emergence of a space-time multi-scale dynamics. Critical Slowing Down labels the emerging global features and describes their complex collective evolution. This paradigm is qui