October 1993 arXiv papers — page 2

V. Bardek, M. Doresic, S. Meljanac

The non-relativistic Chern-Simons theory with the single-valued anyonic field is proposed as an example of q-deformed field theory. The corresponding q-deformed algebra interpolating between bosons and fermions,both in position and momentum spaces, is analyzed.A possible generalization to a space with an arbitrary dimension is suggested.

Nathan Berkovits, Cumrun Vafa

We show that bosonic strings may be viewed as a particular class of vacua for N=1 superstrings, and N=1 superstrings may be viewed as a particular class of vacua for N=2 strings. Continuing this line of string hierarchies, we are led to search for a universal string theory which includes all the rest as a special vacuum selection.

H. Arfaei, Noureddine Mohammedi

The implications of gauging the Wess-Zumino-Novikov-Witten (WZNW) model using the Gauss decomposition of the group elements are explored. We show that, contrary to standard gauging of WZNW models, this gauging is carried out by minimally coupling the gauge fields. We find that this gauging, in the case of gauging an abelian vector subgroup, differs from the

G. Barnich

The quantum action principle of renormalisation theory is applied to the antibracket-antifield formalism for Hamiltonian systems. General results on the local BRST cohomology allow one to prove that the anomalies appear in the time development of the BRST charge and violate the nilpotency of this charge. Furthermore they are equivalent to those of the Lagran

F. De Jonghe, S. Vandoren

We discuss in detail the construction of topological field theories using the Batalin--Vilkovisky (BV) quantisation scheme. By carefully examining the dependence of the antibracket on an external metric, we show that differentiating with respect to the metric and the BRST charge do not commute in general. We introduce the energy momentum tensor in this schem

Jean-Marc DAUL, Vladimir A. KAZAKOV

We calculate various Wilson loop averages in a pure $SU(N)$-gauge theory on a two-dimensional sphere, in the large $N$ limit. The results can be expressed through the density of rows in the most probable Young tableau. They are valid in both phases (small and large areas of the sphere). All averages for self-intersecting loops can be reproduced from the aver

John F. Donoghue, Tibor Torma

Building on recent phenomenology of \gpi, we discuss the expectation for two photon production of longitudinal gauge boson pairs in $SU(N)$ technicolor theories. The treatment involves a matching of dispersive techniques with the methodology of chiral perturbation theory.

S. M. Bilenky, C. Giunti

Possibilities of a model independent treatment of the data from future real-time solar neutrino experiments (SNO, Super-Kamiokande and others) are discussed. It is shown that in the general case of transitions of the initial solar $ν_e$'s into $ν_μ$ and/or $ν_τ$ the total flux of initial 8B neutrinos and the $ν_e$ survival probability can be determined d

S. Keller

Little information is known about the polarization of gluons inside a longitudinally polarized proton. I report on the sensitivity of photoproduction experiments to it. Both jet and heavy quark production are considered.

S. Frixione, M. L. Mangano, P. Nason, G. Ridolfi

We critically examine the validity of the Weizsäcker-Williams approximation in electron-hadron collisions. We show that in its commonly used form it can lead to large errors, and we show how to improve it in order to get accurate results. In particular, we present an improved form that is valid beyond the leading logarithmic approximation in the case when a

K. S. Babu, T. M. Gould, I. Z. Rothstein

In this note, we analyze various constraints on the ``visible'' decay modes of a massive $τ$ neutrino, $ν_τ\rightarrowν^\prime\,γ$ and $ν_τ\rightarrowν^\prime\, e^+ e^-$, where $ν^\prime$ is a light neutrino. The BEBC beam dump experiment provides model-independent constraints on these modes. The lifetime for the $ν^\prime\, e^+e^-$ mode is constrain

F. M. Borzumati

The supersymmetric decays of the top quark into charged Higgs plus bottom, $\thb$, and into the supersymmetric partner of the top (${\wti u}_1$) plus the lightest neutralino (${\wti χ}_1^0$), $\tstopneu$, are discussed within the framework of the Minimal Supersymmetric Standard Model with radiatively induced breaking of the gauge group $SU(2)\times U(1)$. Th

Paolo Provero, Stefano Vinti

The physics of fluid interfaces between domains of different magnetization in the ordered phase of the 3D three-state Potts model is studied by means of a Monte Carlo simulation. It is shown that finite--size effects in the interface free energy are well described by the capillary wave model at two loop order, supporting the idea of the universality of this

Daniel Cangemi

The interaction of matter with gravity in two dimensional spacetimes can be supplemented with a geometrical force analogous to a Lorentz force produced on a surface by a constant perpendicular magnetic field. In the special case of constant curvature, the relevant symmetry does not lead to the de Sitter or the Poincaré algebra but to an extension of them by

Norman J. LaFave

In this paper, a candidate for pregeometry, Ponzano-Regge spin networks, will be examined in the context of the pregeometric philosophy of Wheeler. Ponzano and Regge were able to construct a theory for 3-dimensional quantum gravity based on 3nj-symbols, obtaining the path integral over the metric in the semiclassical limit. However, extension of this model t

Alex Kamenev, Daniel Braun

Exact analytic results for single level current and curvature distribution functions are derived in a framework of a $2\times 2$ random matrix model. Current and curvature are defined as the first and second derivatives of energy with respect to a time--reversal symmetry breaking parameter (magnetic flux). The applicability of the obtained distributions for

Makoto Kaburagi, Takashi Tonegawa

Low-lying excited states as well as the ground state of the spin-1 antiferro- magnetic Heisenberg chain with a spin-1/2 impurity are investigated by means of a variational method and a method of numerical diagonalization. It is shown that 1) the impurity spin brings about massive modes in the Haldane gap, 2) when the the impurity-host coupling is sufficientl

M. Kaburagi, T. Tonegawa

Energy versus magnetic-field diagram of the spin-$1$ Haldane system with an impurity bond is studied in terms of spin-1/2 degree of freedom at the sites neighboring the impurity bond by means of analytical method. We examine the equivalence between the realistic Hamiltonian and the phenomenological Hamiltonian which is composed two spin-1/2 spins representin

B. Drossel, F. Schwabl

We present a general stochastic forest-fire model which shows a variety of different structures depending on the parameter values. The model contains three possible states per site (tree, burning tree, empty site) and three parameters (tree growth probability $p$, lightning probability $f$, and immunity $g$). We review analytic and computer simulation result

G. T. Zimanyi, P. A. Crowell, R. T. Scalettar, G. G. Batrouni

The recent experimental observation of step-like structure in the superfluid density of $^{4}$He films on graphite is interpreted in terms of passage close to Mott insulating lobes in the Bose--Hubbard model. Plateaus develop in the superfluid density near the completion of each layer because of the He-He repulsion. We modify the Bose--Hubbard Hamiltonian, u

Wayne Hu, Naoshi Sugiyama

The integrated Sachs-Wolfe effect (ISW) can be an important factor in the generation of Cosmic Microwave Background anisotropies on all scales, especially in a reionized curvature or lambda dominated universe. We present an analytic treatment of the ISW effect, which is analogous to thick last scattering surface techniques for the Doppler effect, that compar

R. A. Frewin, A. G. Polnarev, P. Coles

We discuss the influence of gravitational waves (GWs) upon the polarisation of the Cosmic Microwave Background Radiation (CMBR). We show how to compute the {\em rms} temperature anisotropy and polarisation of the CMBR induced by GWs of arbitrary wavelength. We find that the ratio of polarisation, $Π$, to anisotropy, $A$, can be as large as $\sim 40$\%, but i

Anthony J. Bracken, Yao-Zhong Zhang, Mark D Gould

This paper is removed from the network permanently. The content in this paper has now been put together with hep-th/9310183. See the recently replaced and widely revised version of the latter.

J-P Ader, H. Kachkachi

An effective action is obtained for the $N=1$, $2D-$induced supergravity on a compact super Riemann surface (without boundary) $\hatΣ$ of genus $g>1$, as the general solution of the corresponding superconformal Ward identity. This is accomplished by defining a new super integration theory on $\hatΣ$ which includes a new formulation of the super Stokes theore

John W. Barrett, Bruce W. Westbury

This paper is a study of monoidal categories with duals where the tensor product need not be commutative. The motivating examples are categories of representations of Hopf algebras and the motivating application is the definition of 6j-symbols as used in topological field theories. We introduce the new notion of a spherical category. In the first section we

Sandip K. Chakrabarti, Diego Molteni

We present results of numerical simulation of thin accretion disks and winds. We use the Smoothed Particle Hydrodynamics (SPH) technique for this purpose. We show that the simulation agrees very well with the recent theoretical work on the shock formation. The most significant conclusion is that shocks in an inviscid flow are extremely stable. For the first

Max Tegmark

Some experimental implications of the recent progress on wave function collapse are calculated. Exact results are derived for the center-of-mass wave function collapse caused by random scatterings and applied to a range of specific examples. The results show that recently proposed experiments to measure the GRW effect are likely to fail, since the effect of

Christian Grosche

The path integral on the single-sheeted hyperboloid, i.e.\ in $D$-dimensional imaginary Lobachevsky space, is evaluated. A potential problem which we call ``Kepler-problem'', and the case of a constant magnetic field are also discussed.

Dean Miller, Kimball A. Milton, Stephan Siegemund-Broka

We apply the finite-element lattice equations of motion for quantum electrodynamics to an examination of anomalies in the current operators. By taking explicit lattice divergences of the vector and axial-vector currents we compute the vector and axial-vector anomalies in two and four dimensions. We examine anomalous commutators of the currents to compute div

M. Karliner, R. W. Robinett

We examine the spin-dependence of b-quark production at large transverse momentum in polarized proton-proton collisions. The leading-order (LO) 2 -> 2 subprocesses, g + g -> Q + Q-bar and q+ q-bar -> Q + Q-bar have a large `analyzing power&#39;, as measured by the average spin-spin asymmetry <a-hat_{LL}>, at large p_T, approaching -100%. The contributions fr

E. Suhonen, J. Cleymans, K. Redlich, H. Satz

Particle production in central S-A collisions at 200 GeV/A energy is analysed within a thermal model. Present data imply that the strange particles freeze out at a higher temperature than the non-strange particles and that the strangeness saturation is incomplete.

M. Anselmino, M. Genovese, D. E. Kharzeev

We address the problem of observed charmonium decays which should be forbidden in perturbative QCD. We examine the model in which these decays proceed through a gluonic component of the $J/Ψ$ and the $η_c$, arising from a mixing of $(c\bar c)$ and glueball states. We give some bounds on the values of the mixing angles and propose the study of the $p \bar{p}

C. Michael

We discuss fitting correlated data - with the example of hadron mass spectroscopy in mind. The main conclusion is that the method of minimising correlated $χ^2$ is unreliable if the data sample is too small.

W. Janke, M. Katoot, R. Villanova

We use the single-cluster Monte Carlo update algorithm to simulate the Ising model on two-dimensional Poissonian random lattices of Delaunay type with up to 80\,000 sites. By applying reweighting techniques and finite-size scaling analyses to time-series data near criticality, we obtain unambiguous support that the critical exponents for the random lattice a

B. Grossmann, Sourendu Gupta

We present a numerical determination of the order-disorder interface tension, \sod, for the two-dimensional seven-state Potts model. We find $\sod=0.0114\pm0.0012$, in good agreement with expectations based on the conjecture of perfect wetting. We take into account systematic effects on the technique of our choice: the histogram method. Our measurements are

Louis H. Kauffman

An exposition of Vassiliev invariants is given in terms of the simplest approach to the functional integral construction of link invariants from Chern-Simons theory. This approach gives the top row evaluations of Vassiliev invariants for the classical Lie algebras, and a neat point of view on the results of Bar-Natan. It also clarifies the relation between V

Dieter R. Brill

This is the reply given at the conference ``Mach&#39;s Principle&#34; at Tübingen in July 1993 to the paper by Isenberg (1993a). Unfortunately the Isenberg paper itself was not submitted to gr-qc.

Dieter R. Brill

This is a reply, given at the conference ``Mach&#39;s Principle&#34; in Tübingen in July 1993, to the paper by Pfister (1993). Unfortunately the Pfister paper itself was not sent to gr-qc.

Fabian H. L. Essler, Vladimir E. Korepin

We consider the one-dimensional half-filled Hubbard model. We show that the excitation spectrum is given by the scattering states of four elementary excitations, which form the fundamental representation of $SU(2)\times SU(2)$. We determine the exact two-particle Scattering matrix, which a solution of the Yang-Baxter equation and reflects the $SO(4)$ symmetr

Haye Hinrichsen

We consider the anisotropic $XY$ chain in a magnetic field with special boundary conditions described by a two-parameter Hamiltonian. It is shown that the exchange of the parameters corresponds to a similarity transformation, which reduces in a special limit to the Ising duality transformation.

Marc Kamionkowski, Arthur Kosowsky, Michael S. Turner

We consider the stochastic background of gravity waves produced by first-order cosmological phase transitions from two types of sources: colliding bubbles and hydrodynamic turbulence. First we discuss the fluid mechanics of relativistic spherical combustion. We then numerically collide many bubbles expanding at a velocity $v$ and calculate the resulting spec

P. Catelan, P. Coles, S. Matarrese, L. Moscardini

We consider a weighted biasing scheme for galaxy clustering. This differs from previous treatments in the fact that the biased density field coincides with the background mass--density whenever the latter exceeds a given threshold value. There is some physical motivation for this scheme and it is in better accord with intuitive ideas than models based on the

Zurab Kakushadze, S. -H. Henry Tye

We derive the Kac and new determinant formulae for an arbitrary (integer) level $K$ fractional superconformal algebra using the BRST cohomology techniques developed in conformal field theory. In particular, we reproduce the Kac determinants for the Virasoro ($K=1$) and superconformal ($K=2$) algebras. For $K\geq3$ there always exist modules where the Kac det

Robert H. Brandenberger

Topological defects are produced during phase transitions in the very early Universe. They arise in most unified theories of strong, weak and electromagnetic interactions. These lectures focus on the role of topological defects in cosmology, with particular emphasis on the models of structure formation based on defects. The role of topological defects in bar

K. Sfetsos, A. A. Tseytlin

String backgrounds associated with gauged $G/H$ WZNW models generically depend on $α&#39;$ or $1/k$. The exact expressions for the corresponding metric $G_{\m\n}$, antisymmetric tensor $B_{\m\n}$, and dilaton $ϕ$ can be obtained by eliminating the $2d$ gauge field from the local part of the effective action of the gauged WZNW model. We show that there exists

Y. Kazama, Y. Satoh

We describe in detail how one can extract space-time geometry in an exactly solvable model of quantum dilaton gravity of the type proposed by Callan, Giddings, Harvey and Strominger ( CGHS ). Based on our previous work, in which a model with 24 massless matter scalars was quantized rigorously in BRST operator formalism, we compute, without approximation, mea

Guenther Huck, Stephan Rosebrock

The idea of applying isoperimetric functions to group theory is due to M.Gromov. We introduce the concept of a ``bicombing of narrow shape&#39;&#39; which generalizes the usual notion of bicombing. Our bicombing is related to but different from the combings defined by M. Bridson. If the Cayley graph of a group with respect to a given set of generators admits

D. B. Uglov, V. E. Korepin

We discovered new hidden symmetry of the one-dimensional Hubbard model. We showthat the one-dimensional Hubbard model on the infinite chain has the infinite-dimensional algebra of symmetries. This algebra is a direct sum of two $ sl(2) $-Yangians. This $ Y(sl(2)) \oplus Y(sl(2)) $ symmetry is an extension of the well-known $ sl(2) \oplus sl(2) $ . The deform

Michele Maggiore

We discuss the idea of black hole complementarity, recently suggested by Susskind et al., and the notion of stretched horizon, in the light of the generalized uncertainty principle of quantum gravity. We discuss implications for the no-hair theorem and we show that within this approach quantum hair arises naturally.

Y. Kazama, Y. Satoh

Based on our previous work, in which a model of two dimensional dilaton gravity of the type proposed by Callan, Giddings, Harvey and Strominger was rigorously quantized, we explicitly demonstrate how one can extract space-time geometry in exactly solvable theory of quantum gravity. In particular, we have been able to produce a prototypical configuration in w

Michael Martin Nieto

We point out that Rydberg wave packets (and similar ``coherent&#34; molecular packets) are, in general, squeezed states, rather than the more elementary coherent states. This observation allows a more intuitive understanding of their properties; e.g., their revivals.

I. B. Khriplovich, M. E. Pospelov

Magnetic quadrupole moment of $W$-boson in Kobayashi-Maskawa model, I.B. Khriplovich and M.E. Pospelov, BUDKERINP 93--88 Due to CP-invariance violation a vector particle can acquire T- and P-odd electromagnetic moment, magnetic quadrupole one. The W-boson magnetic quadrupole moment is calculated in the Kobayashi-Maskawa model. This is the only known CP-odd m

V. G. Benza, Franco Nori, Oscar Pla

We model the dynamics of avalanches in granular assemblies in partly filled rotating cylinders using a mean-field approach. We show that, upon varying the cylinder angular velocity $ω$, the system undergoes a hysteresis cycle between an intermittent and a continuous flow regimes. In the intermittent flow regime, and approaching the transition, the avalanche

V. Sadov

(In the revised version the relevant aspect of noncompactness of the moduli of instantons is discussed. It is shown nonperturbatively that any BRST trivial deformation of A-model which does not change the ranks of BRST cohomology does not change the topological correlation functions either) We show that the Floer cohomology and quantum cohomology rings of th

Marco Matone

We connect Liouville theory, anyons and Higgs model in a purely geometrical way.

S. V. Kryukov, Ya. P. Pugay

We represent Feigin&#39;s construction [11] of lattice W algebras and give some simple results: lattice Virasoro and $W_3$ algebras. For simplest case $g=sl(2)$ we introduce whole $U_q(sl(2))$ quantum group on this lattice. We find simplest two-dimensional module as well as exchange relations and define lattice Virasoro algebra as algebra of invariants of $U

Philippe Marcq, Hugues Chate&#39;, Robert Conte

Exact solitary wave solutions of the one-dimensional quintic complex Ginzburg-Landau equation are obtained using a method derived from the Painlevé test for integrability. These solutions are expressed in terms of hyperbolic functions, and include the pulses and fronts found by van Saarloos and Hohenberg. We also find previously unknown sources and sinks. Th

Simon Capstick, Winston Roberts

We examine the decays of nonstrange baryons to the final states $Δπ$, $Nρ$, $Nη$, $Nη^\prime$, $Nω$, $N1/2^+(1440)π$, and $\Delta3/2^+(1600)π$, in a relativized pair-creation($^3P_0$) model which has been developed in a previous study of the $Nπ$ decays of the same baryon states. As it is our goal to provide a guide for the possible discovery of new baryon s

C. Ciofi degli Atti, E. Pace, G. Salme`, S. Scopetta

Nuclear effects in Deep Inelastic Scattering of polarized electrons off polarized $^3$He are analyzed in terms of a spin dependent spectral function taking into account $S&#39;$ and $D$ waves in $^3$He, as well as Fermi motion and binding effects. A simple and reliable equation relating the neutron and $^3$He spin structure functions is proposed.

Herbert W. Hamber

I discuss some results we have obtained recently in a lattice model for quantized gravity coupled to scalar matter in four dimensions. We have looked at how the continuous phase transition separating the smooth from the rough phase of gravity is influenced by the presence of the scalar field. We find that close to the critical point, where the average curvat

I. Antoniadis, K. Benakli

Perturbative breaking of supersymmetry in four-dimensional string theories predict in general the existence of new large dimensions at the TeV scale. Such dimensions can be consistent with perturbative unification up to the Planck scale in a class of string models and open the exciting possibility of lowering a part of the massive string spectrum at energies

R. Coquereaux, R. Haussling, F. Scheck

For any manifold $M$, we introduce a $\ZZ $-graded differential algebra $Ξ$, which, in particular, is a bi-module over the associative algebra $C(M\cup M)$. We then introduce the corresponding covariant differentials and show how this construction can be interpreted in terms of Yang-Mills and Higgs fields. This is a particular example of noncommutative geome

R. Coquereaux, E. Ragoucy

We define currents on a Grassmann algebra $Gr(N)$ with $N$ generators as distributions on its exterior algebra (using the symmetric wedge product). We interpret the currents in terms of ${\Z}_2$-graded Hochschild cohomology and closed currents in terms of cyclic cocycles (they are particular multilinear forms on $Gr(N)$). An explicit construction of the vect

Edmond L. Berger, Ruibin Meng

We study the transverse momentum distribution for a $pair$ of heavy quarks produced in hadron-hadron interactions. Predictions for the large transverse momentum region are based on exact order $α_s^3$ QCD perturbation theory. For the small transverse momentum region, we use techniques for all orders resummation of leading logarithmic contributions associated

Kingman Cheung

The studies of the electroweak symmetry breaking sector (EWSBS) at $γγ$ colliders were considered previously in the loop processes of $γγ\to w_Lw_L,\,z_Lz_L$, but they are suffered from the huge $W_T W_T$ and $Z_TZ_T$ backgrounds. Here we present another possible process that involves spectator $W$&#39;s and $W_L$&#39;s, the latter of which are scattered str

T. S. Evans

A new time contour is used to derive real-time thermal field theory. Unlike previous path integral approaches, no contributions to the generating functional are dropped.

M. Consoli, P. M. Stevenson

The strong evidence for the `triviality&#39; of (lambda Phi^4)_4 theory is not incompatible with spontaneous symmetry breaking. Indeed, for a `trivial&#39; theory the effective potential should be given exactly by the classical potential plus the free-field zero-point energy of the shifted field; i.e., by the one-loop effective potential. When this is renorm

Howard Georgi

If the number of colors is large, the ratio $m_η/m_{η&#39;}$ is bounded from above. The bound is not satisfied by the observed $η$ and $η&#39;$ masses.

R. F. Alvarez-Estrada, A. Dobado, A. Gomez Nicola

We discuss the finite temperature extension of the anomalous Wess-Zumino -Witten lagrangian. The finite temperature S^1\times S^3 compactification makes a structure in disconnected sectors, corresponding to different baryon numbers appear naturally. The consistency of the anomalous functional is proved for arbitrary baryon number configurations. The anomalou

R. F. Langbein, K. Langfeld, H. Reinhardt, L. v. Smekal

It is shown that the non-perturbative dynamics of a phase change to the non-trivial phase of $λφ^4$-theory in the early universe can give rise to slow-rollover inflation without recourse to unnaturally small couplings.

C. J. Isham

The long history of the study of quantum gravity has thrown up a complex web of ideas and approaches. The aim of this article is to unravel this web a little by analysing some of the {\em prima facie\/} questions that can be asked of almost any approach to quantum gravity and whose answers assist in classifying the different schemes. Particular emphasis is p

M. Vekic, S. R. White

We introduce a new type of boundary conditions, {\it smooth boundary conditions}, for numerical studies of quantum lattice systems. In a number of circumstances, these boundary conditions have substantially smaller finite-size effects than periodic or open boundary conditions. They can be applied to nearly any short-ranged Hamiltonian system in any dimension

A. V. Chubukov, S. Sachdev, A. Sokol

We present a theoretical expression for the spin-echo decay rate, 1/T_2G, in the quantum-critical regime of square lattice quantum antiferromagnets. Our results are in good agreement with recent experimental data by Imai et al. [Phys. Rev. Lett. v.71, 1254 (1993)] for La_2CuO_4.

G. Troll

In this paper we study parameter families of truncated horseshoes as models of multiscattering systems which show a transition to chaos without losing hyperbolicity, so that the topological features of the transition are completely describable by a parameterized family of symbolic dynamics. At a fixed parameter value the corresponding horseshoe represents th

David Schlegel, Marc Davis, Frank Summers, Jon A. Holtzman

The local galaxy distribution offers an interesting constraint to cosmological models of structure formation. The galaxies are distributed in a long, filamentary structure, presumably the result of large amplitude gravitational instability, yet the local velocity field is cold. In particular, there are no blueshifted galaxies within 5h^-1 Mpc except those wi

V. Khatsymovsky

Renormalized vacuum expectation values of electromagnetic stress-energy tensor are calculated in the background spherically-symmetrical metric of the wormhole&#39;s topology. Covariant geodesic point separation method of regularization is used. Violation of the weak energy condition at the throat of wormhole takes place for geometry sufficiently close to tha

Jürgen Audretsch, Karl-Peter Marzlin

The influence od space-time curvature on quantum matter which can be theoretically described by covariant wave equations has not been experimentally established yet. In this paper we analyse in detail the suitability of the Ramsey atom beam interferometer for the measurement of the phase shift caused by the Riemannian curvature of the earth. It appears that

Yoav Achiman, Thorsten Greiner

Fritzsch&#39;s texture is imposed on {\em all} mass matrices in a SUSY-SO(10) via a family $U(1)_{PQ}$ symmetry. The observed charged fermion parameters fix the $ν$-masses and mixing, while the later are evolved from the GUT scale to low energies using the RG. Large $\sin^2 2θ_{12}$ results. As in a SUSY-GUT no intermediate scale is allowed, the RH-neutrino

Stephan Pinsky, Brett van de Sande

We discuss spontaneous symmetry breaking of (1+1)-dimensional $ϕ^4$ theory in light-front field theory using a Tamm-Dancoff truncation. We show that, even though light-front field theory has a simple vacuum state which is an eigenstate of the full Hamiltonian, the field can develop a nonzero vacuum expectation value. This occurs because the zero mode of the

Johannes Voit

We compute the spectral function rho(q,omega) of the one- dimensional Luttinger model. We discuss the distinct influences of charge-spin separation and of the anomalous dimensions of the fermion operators and their evolution with correlation strength. Charge-spin separation shows up in finite spectral weight at frequencies between v_sigma * q and v_rho * q w

R. Timmermans, Th. A. Rijken, J. J. de Swart

Invited talk presented by the first author at the XIVth European Conference of Few-Body Problems in Physics, Amsterdam, August 23-28, 1993

J. Ryckebusch, L. Machenil, M. Vanderhaeghen, V. Van der Sluys

The similarities in the experimental indications for multinucleon mechanisms in $(γ,p)$ and $(e,e&#39;p)$ processes are pointed out. For both types of reactions, the substantial role of two-nucleon emission processes for transitions to high excitation energies in the residual nucleus is stressed. A microscopic model for the calculation of the two-body knocko

G. Bhattacharya, A. Ghosh, P. Mitra

The Schwinger model is studied with a new one - parameter class of gauge invariant regularizations that generalizes the usual point - splitting or Fujikawa schemes. The spectrum is found to be qualitatively unchanged, except for a limiting value of the regularizing parameter, where free fermions appear in the spectrum.

G. Marmo, A. Simoni, A. Stern

We find a new Hamiltonian formulation of the classical isotropic rotator where left and right $SU(2)$ transformations are not canonical symmetries but rather Poisson Lie group symmetries. The system corresponds to the classical analog of a quantum mechanical rotator which possesses quantum group symmetries. We also examine systems of two classical interactin

Matthias Blau, George Thompson

These are lecture notes of lectures presented at the 1993 Trieste Summer School, dealing with two classes of two-dimensional field theories, (topological) Yang-Mills theory and the G/G gauged WZW model. The aim of these lectures is to exhibit and extract the topological information contained in these theories, and to present a technique (a Weyl integral form

R. Brustein, M. Faux, B. Ovrut

Non-perturbative interactions in the effective action of two-dimensional bosonic string theory are described. These interactions are due to ``stringy&#34; instantons that are associated with a space-varying coupling parameter. We present progress towards identifying similar non-perturbative interactions in the effective action of two-dimensional superstring

D. M. Gitman, Sh. M. Shvartsman

Representations by means of path integrals are used to find spinor and isospinor structure of relativistic particle propagators in external fields. For Dirac propagator in an external electromagnetic field all grassmannian integrations are performed and a general result is presented via a bosonic path integral. The spinor structure of the integrand is given

Guido Cognola, Klaus Kirsten, Luciano Vanzo, Sergio Zerbini

The finite temperature one-loop effective potential for a scalar field defined on an ultrastatic spacetime, whose spatial part is a compact hyperbolic manifold, is studied. Different analytic expressions, especially valuable at low and high temperature are derived. Based on these results, the symmetry breaking and the topological mass generation are discusse

A. Ballesteros, F. J. Herranz, M. A. del Olmo, M. Santander

A global model of $q$-deformation for the quasi--orthogonal Lie algebras generating the groups of motions of the four--dimensional affine Cayley--Klein geometries is obtained starting from the three dimensional deformations. It is shown how the main algebraic classical properties of the CK systems can be implemented in the quantum case. Quantum deformed vers

R. W. Gebert, J. A. Teschner

Borcherds algebras represent a new class of Lie algebras which have almost all the properties that ordinary Kac-Moody algebras have, and the only major difference is that these generalized Kac-Moody algebras are allowed to have imaginary simple roots. The simplest nontrivial examples one can think of are those where one adds ``by hand&#39;&#39; one imaginary

S. G. Rajeev, S. Kalyana Rama, Siddhartha Sen

We describe the symplectic structure and Hamiltonian dynamics for a class of Grassmannian manifolds. Using the two dimensional sphere ($S^2$) and disc ($D^2$) as illustrative cases, we write their path integral representations using coherent state techniques. These path integrals can be evaluated exactly by semiclassical methods, thus providing examples of l

A. Deandrea

Within the framework of the factorization approximation, two body non-leptonic decays of $B$ mesons are related to semileptonic matrix elements and form factors, evaluated with an effective lagrangian incorporating both chiral and heavy quark symmetries. Using semileptonic $D$-decay data, estimates for nonleptonic processes are obtained.

J. F. Gunion, S. Geer

I review new developments in Higgs physics and electroweak symmetry breaking that have resulted from the Madison--Argonne workshops on SSC physics.

Peter Cho, Mikolaj Misiak

The rare radiative decay $b \to s γ$ is studied in $SU(2)_L \times SU(2)_R \times U(1)$ extensions of the Standard Model. Matching conditions for coefficients of operators appearing in the low energy effective Hamiltonian for this process are derived, and QCD corrections to these coefficients are analyzed. The $b \to s γ$ decay rate is then calculated and co

V. Bernard, N. Kaiser, T. -S. H. Lee, Ulf-G. Meißner

Electroproduction of pions on the nucleon near the threshold is analyzed within the framework of baryon chiral perturbation theory. We give a thorough discussion of the low--energy theorems related to charged and neutral electropionproduction. It is shown how the axial radius of the nucleon can be related to the S--wave multipoles $E_{0+}^{(-)}$ and $L_{0+}^

Markus H. Thoma

The relevance of parton interaction rates for observables of a quark- gluon plasma and for testing field theoretical methods is exhibited. Using the Braaten-Pisarski method the interaction rate as well as the transport rate beyond the leading logarithm approximation are estimated. Limts on the validity of perturbative QCD for relativistic heavy ion collision

Frank Cuypers

We study the production and decay of \lgl s in \ep\ collisions. We suggest a signature which suffers little from backgrounds and argue that the \lgl\ window can already be closed with the existing LEP data, provided the gluino lifetime is such that it decays within the detectors.

A. Deandrea, N. Di Bartolomeo, R. Gatto, F. Feruglio

We present a study of non-leptonic B-meson decays, partial widths and CP asymmetries, and discuss the possibilities of determining the penguin contributions through less model-dependent phenomenological analyses. In the last section we employ a specific model to give more definite numerical predictions.

Claude Bernard, Thomas A. DeGrand, Carleton DeTar, Steven Gottlieb

We describe a series of simulations of high temperature QCD with two flavors of Wilson quarks aimed at clarifying the nature of the high temperature phase found in current simulations. Most of our work is with four time slices, although we include some runs with six and eight time slices for comparison. In addition to the usual thermodynamic observables we s

R. Sommer

We introduce a hadronic scale $R_0$ through the force $F(r)$ between static quarks at intermediate distances $r$. The definition $F(R_0)R_0^2=1.65$ amounts to $R_0 \simeq 0.5$~fm in phenomenological potential models. Since $R_0$ is well defined and can be calculated accurately in a Monte Carlo simulation, it is an ideal quantity to set the scale. In SU(2) pu