April 1992 arXiv papers — page 2

Shamit Kachru

We show that there is (p-1)(p'-1) dimensional semi-relative BRST cohomology at each non-positive ghost number in the (p,p') minimal conformal field theory coupled to two dimensional quantum gravity. These closed string states are related to currents and symmetry charges of `exotic' ghost number. We investigate the symmetry structure generated by

Stephen D. H. Hsu

We study the contribution of finite energy tunneling to the total vacuum transition rate in a system at finite temperature. We find that in certain models, such as the 1+1 Abelian Higgs model, the quantum contribution is non-negligible even at large temperatures. We show how the persistence of the cosmological baryon asymmetry yields a bound on the inclusive

Toshio Nakatsu, Yuji Sugawara

We study the "topological gauged WZW model associated with $SU(2)/U(1)$",which is defined as the twisted version of the corresponding supersymmetric gauged WZW model. It is shown that this model is equivalent to a topological conformal field theory characterized by two independent topological conformal algebras, one of which is the "twisted Kazam

David M. Larue

The purpose of this note is to prove irreflexivity, and hence the linear ordering, in ZFC, without some of the machinery used by Dehornoy.

Igor R. Klebanov, Andrea Pasquinucci

We rederive the $w_\infty$ Ward identities, starting from the existence of trivial linearized gauge invariances, and using the method of canceled propagators in the operator formalism. Recursion relations for certain classes of correlation functions are derived, and these correlation function are calculated exactly. We clarify the relation of these results w

S. Forste

We calculate gravitational dressed tachyon correlators in non critcal dimensions. The 2D gravity part of our theory is constrained to constant curvature. Then scaling dimensions of gravitational dressed vertex operators are equal to their bare conformal dimensions. Considering the model as d+2 dimensional critical string we calculate poles of generalized Sha

M. Bershadsky, D. Kutasov

The ground ring structure of 1+1 dimensional string theory leads to an infinite set of non linear recursion relations among the `bulk' scattering amplitudes of open and closed tachyons on the disk, which fix them uniquely. The relations are generated by the action of the ring on the tachyon modules; associativity of this action determines all structure c

David Eliezer, Gordon Semenoff

We show that it is possible to formulate Abelian Chern-Simons theory on a lattice as a topological field theory. We discuss the relationship between gauge invariance of the Chern-Simons lattice action and the topological interpretation of the canonical structure. We show that these theories are exactly solvable and have the same degrees of freedom as the ana

Oscar F. Hernandez, Brian R. Hill

The matrix element which determines the B meson decay constant can be measured on the lattice using an effective field theory for heavy quarks. Various discretizations of the heavy-light bilinears which appear in this and other B decay matrix elements are possible. The heavy-light bilinear currently used for the determination of the B meson decay constant on

Michael Creutz

I propose a numerical simulation algorithm for statistical systems which combines a microcanonical transfer of energy with global changes in clusters of spins. The advantages of the cluster approach near a critical point augment the speed increases associated with multi-spin coding in the microcanonical approach. The method also provides a limited ability to

Paul C. Eklof, Alan H. Mekler, Saharon Shelah

The connections between Whitehead groups and uniformization properties were investigated by the third author in [Sh:98]. In particular it was essentially shown there that there is a non-free Whitehead (respectively, aleph_1-coseparable) group of cardinality aleph_1 if and only if there is a ladder system on a stationary subset of omega_1 which satisfies 2-un

Thomas Jech, Saharon Shelah

A stationary subset S of a regular uncountable cardinal kappa reflects fully at regular cardinals if for every stationary set T subseteq kappa of higher order consisting of regular cardinals there exists an alpha in T such that S cap alpha is a stationary subset of alpha. We prove that the Axiom of Full Reflection which states that every stationary set refle

Thomas Jech

A very short proof of Gödel's second incompleteness theorem (for set theory, second order arithmetic etc.)

Thomas Jech

Gives a short proof of Dehornoy's latest result. The same simple argument (and more) was discovered by Laver's student Larue.

Gordon Semenoff

We show that the strong coupling limit of d-dimensional quantum electrodynamics with $2^{d}/2^{[d/2]}$ flavors of fermions can be mapped onto the s=1/2 quantum Heisenberg antiferromagnet in d-1 space dimensions. The staggered Néel order parameter is the expectation value of a mass operator in QED and the spin-waves are pions. We speculate that the chiral sym

Ashoke Sen

We construct a solution of the classical equations of motion arising in the low energy effective field theory for heterotic string theory. This solution describes a black hole in four dimensions carrying mass $M$, charge $Q$ and angular momentum $J$. The extremal limit of the solution is discussed.

Alberto Blasi, Nicola Maggiore, Silvio P. Sorella

We analyze an abelian gauge model in 3 dimensions which includes massless scalar matter fields. By controlling the trace anomalies with a local dilatation Ward identity, we show that, in perturbation theory and within the BPHZL scheme, the Chern-Simons term has no radiative corrections. This implies, in particular, the vanishing of the corresponding $β$ func

Nicola Maggiore, Silvio P. Sorella

Perturbation theory for a class of topological field theories containing antisymmetric tensor fields is considered. These models are characterized by a supersymmetric structure which allows to establish their perturbative finiteness.

Toshio Nakatsu, Yuji Sugawara

We study the twisted version of the supersymmetric $G/T=SU(n)/U(1)^{\otimes(n-1)} gauged Wess-Zumino-Witten model. By studying its fixed points under BRST transformation this model is shown to be reduced to a simple topological field theory, that is, the topological matter system in the K.Li's theory of 2 dimensional gravity for the case of $n=2$, and it

E. Raiten

We consider the solutions of the field equations for the large $N$ dilaton gravity model in $1+1$ dimensions recently proposed by Callan, Giddings, Harvey and Strominger (CGHS). We find time dependant solutions with finite mass and vanishing flux in the weak coupling regime, as well as solutions which lie entirely in the Liouville region.

A. Aurilia, A. Smailagic, E. Spallucci

We suggest a model of induced gravity in which the fundamental object is a relativistic {\it membrane} minimally coupled to a background metric and to an external three index gauge potential. We compute the low energy limit of the two-loop effective action as a power expansion in the surface tension. A generalized bootstrap hypothesis is made in order to ide

A. Ceresole, R. D'Auria, S. Ferrara, W. Lerche

We investigate the system of holomorphic differential identities implied by special Kählerian geometry of four-dimensional N=2 supergravity. For superstring compactifications on \cy threefolds these identities are equivalent to the Picard-Fuchs equations of algebraic geometry that are obeyed by the periods of the holomorphic three-form. For one variable they

Mathieu Meyer, Shlomo Reisner, M. Schmuckenschlager

It is proved that for a symmetric convex body K in R^n, if for some tau > 0, |K cap (x+tau K)| depends on ||x||_K only, then K is an ellipsoid. As a part of the proof, smoothness properties of convolution bodies ls are studied.

H. Lu, C. N. Pope

It has been known for some time that $W$ algebras can be realised in terms of an energy-momentum tensor together with additional free scalar fields. Some recent results have shown that more general realisations are also possible. In this paper, we consider a wide class of realisations that may be obtained from the Miura transformation, related to the existen

S. Stieberger, D. Jungnickel, J. Lauer, M. Spalinski

The three point correlation functions with twist fields are determined for bosonic $Z_N$ orbifolds. Both the choice of the modular background (compatible with the twist) and of the (higher) twisted sectors involved are fully general. We point out a necessary restriction on the set of instantons contributing to twist field correlation functions not obtained i

Philippe Roche

We give an integrable extension of the lattice models recently considered by I.Kostov in his study of strings in discrete space. These models are IRF models with spin variables living in any connected graph, the vertex model underlying these models is the Izergin-Korepin model. When the graph is taken to be a simply laced Dynkin diagram, it is conjectured th

Andre J. van Tonder

An investigation is made of the super-Calogero model with particular emphasis on its continuum formulation and possible application in the context of supersymmetrizing the bosonic collective d=1 string field theory.

A Donnachie, P V Landshoff

We calculate the cross-section for events at HERA where the proton loses only a minute fraction of its initial energy, all of which goes into producing a single pair of transverse jets.

R. D. Kamien, P. Le Doussal, D. R. Nelson

We develop a theory of polymers in a nematic solvent by exploiting an analogy with two-dimensional quantum bosons at zero temperature. We argue that the theory should also describe polymers in an {\sl isotropic} solvent. The dense phase is analyzed in a Bogoliubov-like approximation, which assumes a broken symmetry in the phase of the boson order parameter.

D. M. Gaitonde, Dileep P. Jatkar, Sumathi Rao

We study the effect of introducing a weak antiferromagnetic interplanar exchange coupling in the two dimensional frustrated Heisenberg model. We show that a ferromagnetic(FM) ordering of chirality - {\it i.e.}, same chirality on adjacent planes - is energetically favoured, thus leading to bulk violation of the discrete symmetries parity($P$) and time reversa

R. Sekhar Chivukula, Mitchell Golden, M. V. Ramana

If the electroweak symmetry breaking sector contains colored particles weighing a few hundred GeV, then they will be copiously produced at a hadron supercollider. Colored technipions can rescatter into pairs of gauge bosons. As proposed by Bagger, Dawson, and Valencia, this leads to gauge boson pair rates far larger than in the standard model. In this note w

I. Antoniadis, E. Gava, K. S. Narain

We study one-loop, moduli-dependent corrections to gauge and gravitational couplings in supersymmetric vacua of the heterotic string. By exploiting their relation to the integrability condition for the associated CP-odd couplings, we derive general expressions for them, both for $(2,2)$ and $(2,0)$ models, in terms of tree level four-point functions in the i

J. Bijnens, F. Hoogeveen

We have calculated the decay rates of the $B_s$ meson in a number of exclusive two--body decay channels using the Bauer--Stech--Wirbel model for current matrix elements. The influence of the free parameters of the model on the predictions is studied. The total branching ratio of the $B_s$ into final states which only contain stable charged particles is found

Saharon Shelah, Juris Steprāns

Various questions posed by P. Nyikos concerning ultrafilters on $ω$ and chains in the partial order $(ω,<^*)$ are answered. The main tool is the oracle chain condition and variations of it.

Richard Laver

Let $j:V_λ---> V_λ$ be an elementary embedding, with critical point $κ$, and let $f(n)$ be the number of critical points of embeddings in the algebra generated by $j$ which lie between $j^n(κ)$ and $j^{n+1}(κ)$. It is shown that $f(n)$ is finite for all $n$.

Richard Laver

The normal form theorem, proved in R. Laver, On the left distributive law and the freeness of an algebra of elementary embeddings, Advances in Mathematics 91 (1992), 209-231, for the free algebra $\Cal A$ on one generator $x$ satisfying the left distributive law $a(bc) = (ab)(ac)$ is extended by showing that members of $\Cal A$ can be put into a &#34;divisio

Nathan Weiss

We study the Quantum Field Theory of nonrelativistic bosons coupled to a Chern--Simons gauge field at nonzero particle density. This field theory is relevant to the study of anyon superconductors in which the anyons are described as {\bf bosons} with a statistical interaction. We show that it is possible to find a mean field solution to the equations of moti

A. Carlini, F. Fucito, M. Martellini

We study the stability under perturbations of a charged four dimensional stringy black hole arising from gauging a previously studied WZW model. We find that the black hole is stable only in the extremal case $Q=M$.

M. Cvetic, S. Griffies

A recent study of supersymmetric domain walls in $N=1$ supergravity theories revealed a new class of domain walls interpolating between supersymmetric vacua with different non-positive cosmological constants. We classify three classes of domain wall configurations and study the geodesic structure of the induced space-time. Motion of massive test particles in

Daniel Ng

$QCD$ renormalization for the top-quark mass is calculated in a mass geometrical mean hierarchy, $m_d m_b = m_s^2$ and $m_u m_t = m_c^2$. The physical mass, $m_t(m_t) = 160 {\pm} 50 GeV$ is obtained, which agrees very well with electroweak precision measurement.

Michael Luke, Aneesh V. Manohar, Martin J. Savage

The interaction of quarkonium with nuclei is studied in the $m_Q\rightarrow \infty$ limit of QCD, where the binding energy is found to be exactly computable. The dominant contribution to the interaction is from two-gluon operators. The forward matrix elements of these two-gluon operators can be determined from the QCD scale anomaly, and from deep inelastic s

Sinya Aoki

We calculate the S parameter of the standard model at one loop of fermions, using three different regularizations (dimensional, Pauli-Villars and lattice) and find an extra contribution to the S parameter besides the standard one for each case. This shows that the extra contribution recently reported for the lattice regularization is {\it not} necessarily ti

M. E. Agishtein, A. A. Migdal

We performed detailed study of the phase transition region in Four Dimensional Simplicial Quantum Gravity, using the dynamical triangulation approach. The phase transition between the Gravity and Antigravity phases turned out to be asymmetrical, so that we observed the scaling laws only when the Newton constant approached the critical value from perturbative

C. F. Baillie, D. A. Johnston

We perform Monte Carlo simulations using the Wolff cluster algorithm of {\it multiple} $q=2,3,4$ state Potts models on dynamical phi-cubed graphs of spherical topology in order to investigate the $c>1$ region of two-dimensional quantum gravity. Contrary to naive expectation we find no obvious signs of pathological behaviour for $c>1$. We discuss the results

C. F. Baillie, D. A. Johnston

We perform Monte Carlo simulations using the Wolff cluster algorithm of the q=2 (Ising), 3, 4 and q=10 Potts models on dynamical phi-cubed graphs of spherical topology with up to 5000 nodes. We find that the measured critical exponents are in reasonable agreement with those from the exact solution of the Ising model and with those calculated from KPZ scaling

M. I. Dobroliubov, I. I. Kogan, G. W. Semenoff

We investigate pairing instabilities in the Fermi-liquid-like state of a single species of anyons. We describe the anyons as Fermions interacting with a Chern-Simons gauge field and consider the weak coupling limit where their statistics approaches that of Fermions. We show that, within the conventional BCS approach, due to induced repulsive Coulomb and curr

Srinandan Dasmahapatra, Rinat Kedem, Barry M. McCoy

We find the rules which count the energy levels of the 3 state superintegrable chiral Potts model and demonstrate that these rules are complete. We then derive the complete spectrum of excitations in the thermodynamic limit in the massive phase and demonstrate the existence of excitations which do not have a quasi-particle form. The physics of these excitati

Ramesh Narayan, Bohdan Paczyński, Tsvi Piran

It is proposed that gamma-ray bursts are created in the mergers of double neutron star binaries and black hole neutron star binaries at cosmological distances. Bursts with complex profiles and relatively long durations are the result of magnetic flares generated by the Parker instability in a post-merger differentially-rotating disk. Some bursts may also be

Viqar Husain

A three dimensional generally covariant theory is described that has a 2+1 canonical decomposition in which the Hamiltonian constraint, which generates the dynamics, is absent. Physical observables for the theory are described and the classical and quantum theories are compared with ordinary 2+1 gravity.

Miao Li

Picture changed operators are discussed in $N=2$ strings with space-time signature $(2,2)$. A gauge symmetry algebra is derived in a background of torus space-time $T^{2,2}$ and its simple representation on the picture changed operators is given. Simple Ward identities associated with the gauge algebra and their consequences for three and four point amplitud

Subir Sachdev, Jinwu Ye

The universal dynamic and static properties of two dimensional antiferromagnets in the vicinity of a zero-temperature phase transition from long-range magnetic order to a quantum disordered phase are studied. Random antiferromagnets with both Néel and spin-glass long-range magnetic order are considered. Explicit quantum-critical dynamic scaling functions are

Avinash Dhar, Gautam Mandal, Spenta R. Wadia

We formulate the $c=1$ matrix model as a quantum fluid and discuss its classical limit in detail, emphasizing the $\hbar$ corrections. We view the fermi fluid profiles as elements of \winf-coadjoint orbit and write down a geometric action for the classical phase space. In the specific representation of fluid profiles as `strings&#39; the action is written in

P. Fre&#39;, L. Girardello, A. Lerda, P. Soriani

We consider the realization of N=2 superconformal models in terms of free first-order $(b,c,β,γ)$-systems, and show that an arbitrary Landau-Ginzburg interaction with quasi-homogeneous potential can be introduced without spoiling the (2,2)-superconformal invariance. We discuss the topological twisting and the renormalization group properties of these theorie

S. Ferrara, P. Frè, P. Soriani

We describe the duality group $Γ=SU(3,3,Z)$ for the Narain lattice of the $T^6/Z_3$ orbifold and its action on the corresponding moduli space. A symplectic embedding of the momenta and winding numbers allows us to connect the orbifold lattice to the special geometry of the moduli space. As an application, a formal expression for an automorphic function, whic

Olaf Lechtenfeld, Chiara Nappi

We study a general class of two-dimensional theories of the dilaton-gravity type inspired by string theory and show that they admit charged multiple-horizon black holes. These solutions are proved to satisfy scalar no-hair theorems.

Ruth Gregory, Jeffrey Harvey

It is shown that the Dirac operator in the background of a magnetic %Reissner-Nordström black hole and a Euclidean vortex possesses normalizable zero modes in theories containing superconducting cosmic strings. One consequence of these zero modes is the presence of a fermion condensate around magnetically charged black holes which violates global quantum num

J. Panvel

Proposals that $O(d,d)$ boosts of trivial backgrounds lead to non-trivial conformally invariant backgrounds are checked to two loop order. We find that conformal invariance can be achieved by adding simple higher order corrections to the metric and dilaton.

E. Ivanov, S. Krivonos

We present a manifestly $N=2$ supersymmetric formulation of $N=2$ super-$W_3$ algebra (its classical version) in terms of the spin 1 and spin 2 supercurrents. Two closely related types of the Feigin-Fuchs representation for these supercurrents are found: via two chiral spin $\frac{1}{2}$ superfields generating $N=2$ extended $U(1)$ Kac-Moody algebras and via

Rajesh R. Parwani

A resummed perturbative expansion is used to obtain the self-energy in the high-temperature \(g^2ϕ^4\) field theory model up to order $g^4$. From this the zero momentum pole of the effective propagator is evaluated to determine the induced thermal mass and damping rate for the bosons in the plasma to order $g^3$. The calculations are performed in the imagina

Alexander Balatsky, Elihu Abrahams

A new class of singlet superconductors with a gap function $Δ(\bk, ω_n)$ which is {\it odd} in both momentum and Matsubara frequency is considered. Some of the physical properties of this superconductivity are discussed and it is argued that: i) the electron-phonon interaction can produce this kind of pairing, ii) in many cases there is no gap in the quasipa

Alexander Balatsky

We show that the Halperin-Haldane SQHE wave function can be written in the form of a product of a wave function for charged semions in a magnetic field and a wave function for the Chiral Spin Liquid of neutral spin-$\12$ semions. We introduce field-theoretic model in which the electron operators are factorized in terms of charged spinless semions (holons) an

Daniel Henry Gottlieb

We give an argument that magnetic monopoles should not exist. It is based on the concept of the index of a vector field. The thrust of the argument is that indices of vector fields are invariants of space-time orientation and of coordinate changes, and thus physical vector fields should preserve indices. The index is defined inductively by means of an equati

N. Manojlovic, A. Mikovic

Pure (2+1)-dimensional Einstein gravity is analysed in the Ashtekar formulation, when the spatial manifold is a torus. We have found a set of globally defined observables, forming a closed algebra. This allowed us to solve the quantum constraints, and to show that the reduced phase space of the Ashtekar formulation is greater then the corresponding space of

Claudio Coriano&#39;

The low energy limit of an axion field coupled to gauge fields is investigated through the behaviour of the gauge field propagator in a local vaccum angle background. The local (singular) part of the effective action for the axion field is calculated at one loop level. In the case of a timelike, linearly growing axion field, representing a massive axion, we

D. Gepner, A. Schwimmer

The fusion of fields in a rational conformal field theory gives rise to a ring structure which has a very particular form. All such rings studied so far were shown to arise from some potentials. In this paper the fusion rings of the WZW models based on the symplectic group are studied. It is shown that they indeed arise from potentials which are described. T

L. Bonora, C. S. Xiong

We show that there exists an alternative procedure in order to extract differential hierarchies, such as the KdV hierarchy, from one--matrix models, without taking a continuum limit. To prove this we introduce the Toda lattice and reformulate it in operator form. We then consider the reduction to the systems appropriate for one--matrix model.

E. Brezin, S. Hikami

In the usual matrix-model approach to random discretized two-dimensional manifolds, one introduces n Ising spins on each cell, i.e. a discrete version of 2D quantum gravity coupled to matter with a central charge n/2. The matrix-model consists then of an integral over $2^{n}$ matrices, which we are unable to solve for $n>1$. However for a fixed genus we can

Gian F. Giudice

A new ansatz for quark and lepton mass matrices is proposed in the context of supersymmetric grand unified theories. The 13 parameters describing fermion masses and mixings are determined in terms of only 6 free parameters, allowing 7 testable predictions. The values of $V_{us}$, $V_{cb}$, $V_{ub}$, $m_u$, $m_d$, $m_s$, and $m_b$ are then predicted as a func

Bernd A. Berg, Tarik Celik

We present a recursive procedure to calculate the parameters of the recently introduced multicanonical ensemble and explore the approach for spin glasses. Temperature dependence of the energy, the entropy and other physical quantities are easily calculable and we report results for the zero temperature limit. Our data provide evidence that the large $L$ incr

U. Hansmann, B. A. Berg, T. Neuhaus

We modified the recently proposed multicanonical MC algorithm for the case of a magnetic field driven order--order phase transition. We test this {\it multimagnetic} Monte Carlo algorithm for the D=2 Ising model at $β=0.5$ and simulate square lattices up to size $100 \times 100$. On these lattices with periodic boundary conditions it is possible to enhance t

Khalil M. Bitar, Pavlos M. Vranas

A Monte Carlo simulation of the O(4) $λϕ^4$ theory in the broken phase is performed on a hypercubic lattice in search of an I=1, J=1 resonance. The region of the cutoff theory where the interaction is strong is investigated since it is there that a resonance would be expected to have a better chance to form. In that region the presence of an I=1, J=1 resonan

B. A. Berg, T. Neuhaus

Relying on the recently proposed multicanonical algorithm, we present a numerical simulation of the first order phase transition in the 2d 10-state Potts model on lattices up to sizes $100\times100$. It is demonstrated that the new algorithm $lacks$ an exponentially fast increase of the tunneling time between metastable states as a function of the linear siz

S. Gottlieb, U. M. Heller, A. D. Kennedy, J. B. Kogut

Lattice QCD with 2 light staggered quark flavours is being simulated on a $16^3\times8$ lattice to study the transition from hadronic matter to a quark gluon plasma. We have completed runs at $m_q=0.0125$ and are extending this to $m_q=0.00625$. We also examine the addition of a non-dynamical &#34;strange&#34; quark. Thermodynamic order parameters are being

Joe Kiskis, Rajamani Narayanan, Pavlos Vranas

The distance scale for a quantum field theory is the correlation length $ξ$, which diverges with exponent $ν$ as the bare mass approaches a critical value. If $t=m^{2}-m_{c}^{2}$, then $ξ=m_{P}^{-1} \sim t^{-ν}$ as $t \to 0$. The two-point function of a scalar field has a random walk representation. The walk takes place in a background of fluctuations (close

Wolfhard Janke, Bernd A. Berg, Mohammad Katoot

Using the recently proposed multicanonical ensemble, we perform Monte Carlo simulation for the 2d 7-state Potts model and calculate its surface free energy density (surface tension) to be $2 f^s = 0.0241 \pm 0.0010$. This is an order of magnitude smaller than other estimates in the recent literature. Relying on existing Monte Carlo data, we also give a preli

A. D. Kennedy, R. G. Edwards

We describe recent results obtained as part of the High Energy Monte Carlo Grand Challenge (HEMCGC) project concerning the behaviour of lattice QCD with light dynamical Wilson quarks. We show that it is possible to reach regions of parameter space with light pions $m_π\ll0.2/a$, but that the equilibration time for such a system is at least of the order of 1,

Khalil M. Bitar

We explore a new approach to the path integral for a latticized quantum theory. This talk is based on work with N. Khuri and H. Ren.

K. M. Bitar, R. Edwards, T. A. DeGrand, Steven Gottlieb

We present preliminary results from the 1991 HEMCGC simulations with staggered dynamical fermions on a $16^3 \times 32$ lattice at $β= 5.6$ with sea quark masses $am_q = 0.025$ and 0.01. The spectroscopy was done both for staggered valence quarks with mass equal to the sea quark masses and for Wilson valence quarks at six different values for $κ$, 0.1320, 0.

U. M. Heller, M. Klomfass, H. Neuberger, P. Vranas

The cutoff dependence of the Scalar Sector of the Minimal Standard Model can result in an increase of the existing triviality bound estimates of the Higgs mass. We present a large $N$ calculation and some preliminary N=4 results that suggest that the increase can be as large as 30%, resulting to a bound of about 850 G eV.

S. Caracciolo, R. G. Edwards, A. Pelissetto, A. D. Sokal

We study the performance of a Wolff-type embedding algorithm for $RP^N$ $σ$-models. We find that the algorithm in which we update the embedded Ising model à la Swendsen-Wang has critical slowing-down as $z_χ\approx 1$. If instead we update the Ising spins with a perfect algorithm which at every iteration produces a new independent configuration, we obtain $z

R. V. Gavai, U. M. Heller, F. Karsch, B. Plache

Results of investigations of the O(4) spin model at finite temperature using anisotropic lattices are presented. In both the large $N$ approximation and the numerical simulations using the Wolff cluster algorithm we find that the ratio of the symmetry restoration temperature $T_{\rm SR}$ to the Higgs mass $m_{\rm H}$ is independent of the anisotropy. We obta

Jonas Berlin

To gain understanding of the Higgs-fermion sector of the standard model, we study the one-component $Z_2$ symmetric and the four-component O(4) symmetric scalar models coupled to staggered fermions using the hybrid Monte Carlo algorithm. We map out the phase diagrams, and show that the $Z_2$ model has a tree level perturbative behaviour at all points in the

Robert G. Edwards, Sabino José Ferreira, Jonathan Goodman, Alan D. Sokal

We study the dynamic critical behavior of the multi-grid Monte Carlo (MGMC) algorithm with piecewise-constant interpolation applied to the two-dimensional O(4)-symmetric nonlinear $σ$-model [= SU(2) principal chiral model], on lattices up to $256 \times 256$. We find a dynamic critical exponent $z_{int,{\cal M}^2} = 0.60 \pm 0.07$ for the W-cycle and $z_{int

Hans Gerd Evertz

Contrary to conventional wisdom, the construction of clusters on a lattice can easily be vectorized, namely over each ``generation&#39;&#39; in a breadth first search. This applies directly to, e.g., the {\it single cluster} variant of the Swendsen-Wang algorithm. On a Cray Y-MP, total CPU time was reduced by a factor 3.5 -- 7 in actual applications.

Nelsons A. Alves, Bernd Al. Berg, Sergiu Sanielevici

We present spectral density reweighting techniques adapted to the analysis of a time series of data with a continuous range of allowed values. In a first application we analyze action and Polyakov line data from a Monte Carlo simulation on $L_t L^3 (L_t=2,4)$ lattices for the SU(3) deconfining phase transition. We calculate partition function zeros, as well

U. M. Heller, H. Neuberger, P. Vranas

Lattice work, exploring the Higgs mass triviality bound, seems to indicate that a strongly interacting scalar sector in the minimal standard model cannot exist while low energy QCD phenomenology seems to indicate that it could. We attack this puzzle using the 1/N expansion and discover a simple criterion for selecting a lattice action that is more likely to

Sanjay Jain, Samir D. Mathur

We show that the surface roughness for $c<1$ matter theories coupled to $2D$ quantum gravity is described by a self-similar structure of baby universes. There exist baby universes whose neck thickness is of the order of the ultraviolet cutoff, the largest of these having a macroscopic area $\sim A^{1 \over {1-γ}}$, where $A$ is the total area and $γ$ the str

E. Ivanov, S. Krivonos, A. Pichugin

We deduce the $sl_{3}$ Toda realization of classical $W_3$ symmetry on two scalar fields in a geometric way, proceeding from a nonlinear realization of some associate higher-spin symmetry $W_{3}^{\infty}$. The Toda equations are recognized as the constraints singling out a two-dimensional fully geodesic subspace in the initial coset space of $W_{3}^{\infty}$

T. T. Burwick, A. H. Chamseddine, K. Meissner

Matter is coupled to three-dimensional gravity such that the topological phase is allowed and the (anti-) de Sitter or Poincaré symmetry remains intact. Spontaneous symmetry breaking to the Lorentz group occurs if a scalar field is included. This Higgs field can then be used to couple matter so that the familiar form of the matter coupling is established in

R. Sekhar Chivukula, Stephen B. Selipsky, Elizabeth H. Simmons

Extended technicolor theories generate potentially large corrections to the $\Zbb$ vertex which can be observed in current experiments at LEP.

J. A. Casas, J. García--Bellido, M. Quiros

We study new physical phenomena and constraints in generalized scalar--tensor theories of gravity with $Φ$--dependent masses. We investigate a scenario (which can arise in string theories) with two types of $Φ$--dependent masses which could correspond to visible and dark matter sectors. The parameters of this theory are constrained from post--Newtonian bound

John Ellis, Yitzhak Frishman, Amihay Hanany, Marek Karliner

We exhibit static solutions of multi-flavour QCD in two dimensions that have the quantum numbers of baryons and mesons, constructed out of quark and anti-quark solitons. In isolation the latter solitons have infinite energy, corresponding to the presence of a string carrying the non-singlet colour flux off to spatial infinity. When $N_c$ solitons of this typ

Joseph A. Minahan

We propose a random matrix model as a representation for $D=1$ open strings. We show that the model is equivalent to $N$ fermions with spin in a central potential that also includes a long-range ferromagnetic interaction between the fermions that falls off as $1/(r_{ij})^2$. We find two interesting scaling limits and calculate the free energy for both situat

J. Bagger, S. Dawson, G. Valencia

We compute the effects of anomalous gauge-boson couplings at high-energy hadron colliders using next-to-leading order $SU(2) \times SU(2)$ chiral perturbation theory. By comparing the yields from the universal $p^2$ terms with those arising from new physics at order $p^4$, we estimate the sensitivity of the SSC and LHC to the indirect effects of electroweak

William J. Mitchell

We use the core model for sequences of measures to prove a new lower bound for the consistency strength of the failure of the SCH: THEOREM (i) If there is a singular strong limit cardinal $κ$ such that $2^κ> kappa^+$ then there is an inner model with a cardinal $κ$ such that for all ordinals $α<κ$ there is an ordinal $ν< κ$ with $o(ν) > α$. (ii) If there is

C. G. Torre

Beginning with the work of Dirac and Arnowitt, Deser, Misner in the late fifties and early sixties, and then after subsequent development by Kucha\v r, the canonical dynamical structure of general relativity has often been viewed as that of a parametrized field theory in which the many-fingered spacetime variables are hidden amongst the geometrodynamical fie

B. de Carlos, J. A. Casas, C. Muñoz

We study in a systematic and modular invariant way gaugino condensation in the hidden sector as a potential source of hierarchical supersymmetry breaking and a non--trivial potential for the dilaton $S$ whose real part corresponds to the tree level gauge coupling constant (${\rm Re}\ S\sim g_{gut}^{-2}$). For the case of pure Yang--Mills condensation, we sho

Anton Rebhan

Baier et al. have reported the damping rate of long-wavelength fermionic excitations in high-temperature QED and QCD to be gauge-fixing-dependent even within the resummation scheme due to Braaten and Pisarski. It is shown that this problem is caused by the singular nature of the on-shell expansion of the fermion self-energy in the infra-red. Its regularizati

B. Machet

Some spontaneously broken gauge theories with left couplings to fermions, like the abelian model that we propose here, can be endowed with a composite scalar sector and Wess-Zumino field ; their quantization in the functionnal integral formalism accordingly requires the introduction of constraints that, together with the breaking of the gauge symmetry by the

Aneesh V. Manohar

The main focus of these lectures is on those aspects of deep inelastic scattering that can be derived directly from QCD using quantum field theory, without recourse to phenomenological models. The emphasis is on spin dependent scattering, but the theory of spin averaged scattering is also discussed. A detailed analysis is given for the case of spin 1/2 targe