February 1993 arXiv papers — page 4

E. Kiritsis

There is substancial overlap with hepth-9211081. More results are presented for duality in the non-compact case. It is argued that duality persists as a symmetry also in that case.

D. Dalmazi, E. Abdalla

We discuss the structure of correlators involving the spinor emission vertex in non critical $N=1$ superstring theory. The technique used in the computation is the zero mode integration to arrive at the integral representation, and later an analysis of the pole structure of the integrals which are thus obtained. Our analysis has been done primarily for the 5

A. A. Abrikosov

I study the time evolution of the density matrices of quantum Fermi systems interacting with classic external Fermi fields. This interaction either changes the temperature of the system or it affects the density of particles. For relativistic Dirac fermions, variations of temperature lead to creation (annihilation) of particle - antiparticle pairs. The chang

F. D. T. Smith

A physical interpretation is given for some Hermitian Jordan triple systems (HJTS) that were recently discussed by Gunaydin (hep-th/9301050). Quadratic Jordan algebras derived from HJTS provide a formulation of quantum mechanics that is a natural framework within which exceptional structures are identified with physically realistic structures of a quantum fi

Wei Chen, Yuri Makeenko, Gordon W Semenoff

We formulate the conformal bootstrap approach to four--fermion theory at its strong coupling fixed point in dimensions $2<d<4$. We present a solution of the bootstrap equations in the five--vertex approximation. We show that the bootstrap approach gives a particularly simple way to obtain next to leading order corrections to critical exponents in the large $

Kamran Saririan

The left and right handed fermion zero-modes are examined. Their behaviour under the variation of the size of the instanton, $\ri$, and the size of the Higgs core, $\rh$, for a range of Yukawa couplings corresponding to the fermion masses in the electroweak theory are studied. It is shown that the characteristic radii of the zero-modes, in particlar those th

R. D. Pisarski

Using a program of perturbative resummation I compute the damping rates for fields at nonzero spatial momentum to leading order in weak coupling in hot $QCD$. Sum rules for spectral densities are used to simplify the calculations. For massless fields the damping rate has an apparent logarithmic divergence in the infrared limit, which is cut off by the screen

R. D. Pisarski

I discuss three subjects in thermal field theory: why in \sun gauge theories the \zn symmetry is broken at high (instead of low) temperature, the possible singularity structure of gauge variant propagators, and the problem of how to compute the viscosity from the Kubo formula.

S. A. Larin

The prescription for the $γ_5$-matrix within dimensional regularization in multiloop calculations is elaborated. The three-loop anomalous dimension of the singlet axial current is calculated.

E. V. Shuryak, J. J. M. Verbaarschot

A general model-independent discussion of mesonic correlation functions is given. We derive new inequalities, including one stronger than Weingarten&#39;s inequality. Mesonic correlation functions are calculated in the random instanton vacuum and are compared with phenomenological expectations and lattice results. Both diagonal and non-diagonal correlators o

E. V. Shuryak, J. J. M. Verbaarschot

This is the first of a series of papers devoted to a systematic study of QCD correlation functions in a framework of &#39;instanton vacuum&#39; models. The topic of this paper is to work out approximate formulae for quark propagators in a multi-instanton environment. As an application, and also as a necessary step toward understanding the correlation functio

Piotr A. Rcaczka, Andrzej Szymacha, Stanisław Tatur

A simple model of the neutrino mixing is considered, which contains only one right-handed neutrino field, coupled via the mass term to the three usual left-handed fields. This is a simplest model that allows for three-flavour neutrino oscillations. The existing experimental limits on the neutrino oscillations are used to obtain constraints on the two free mi

Luis E. Ibanez, Fernando Quevedo

We discuss two independent issues about the baryon asymmetry of the universe. First, assuming that it is generated by an unspecified source at high temperatures, we study the effects of non-perturbative $SU(2)_W$ dynamics above the electroweak scale, in the context of supersymmetric models. We find that there is a substantial difference with the nonsupersymm

Arthur Mezhlumian

This talk presents some progress achieved in collaboration with A.Linde and D.Linde towards understanding the true nature of the global spatial structure of the Universe as well as the most general stationary characteristics of its time-dependent state with eternally growing total volume.

P. S. Joshi, I. H. Dwivedi

Generalizing the results of Joshi and Dwivedi in Commun.Math.Phys. 146, p.333 (1992), it is pointed out that strong curvature naked singularities could occur in the self-similar gravitational collapse of any form of matter satisfying the weak energy condition for the positivity of mass-energy density.

S. C. Power

Let $A$ denote the alternation limit algebra, studied by Hopenwasser and Power, and by Poon, which is the closed direct limit of upper triangular matrix algebras determined by refinement embeddings of multiplicity $r_k$ and standard embeddings of multiplicity $s_k$. It is shown that the quotient of the isometric automorphism group by the approximately inner

S. C. Power

This is a revised and corrected version of a preprint circulated in 1990 in which various non-self-adjoint limit algebras are classified. The principal invariant is the scaled $K_0$ group together with the algebraic order on the scale induced by partial isometries in the algebra.

Ruy Exel

We describe both the Bunce-Deddens C*-algebras and their Toeplitz versions, as crossed products of commutative C*-algebras by partial automorphisms. In the latter case, the commutative algebra has, as its spectrum, the union of the Cantor set and a copy the set of natural numbers N, fitted together in such a way that N is an open dense subset. The partial au

Zhigang Xi, Bulbul Chakraborty

We study the kinetics of ordering in Cu3Au using a model Hamiltonian derived from the effective medium theory of chemical bonding. Monte Carlo simulations are used to investigate universal and non-universal features of the growth kinetics. Anisotropic scaling of the structure factor is observed in late-stage growth of ordered domains. The anisotropy is a non

A. Sokol, E. Gagliano, S. Bacci

The problem of the nuclear spin-lattice relaxation in La$_2$CuO$_4$ is revisited in connection with the recent measurements of the NQR relaxation rate for temperatures up to $ 900\mbox{K} $ [T.\ Imai {\em et al.}, Phys.\ Rev.\ Lett., in press]. We use an approach based on the exact diagonalization for the Heisenberg model to calculate the short wavelength co

Sacha Sardo-Infirri

A simple convex lattice polytope $\Box$ defines a torus-equivariant line bundle $\LB$ over a toric variety $\XB.$ Atiyah and Bott&#39;s Lefschetz fixed-point theorem is applied to the torus action on the $d&#39;&#39;$-complex of $\LB$ and information is obtained about the lattice points of $\Box$. In particular an explicit formula is derived, computing the n

Roberto Paoletti

This paper explores the geometric meaning of the failure of certain kinds of Wahl maps to surject on a general curve. Sufficient conditions for surjectivity are given. An approach used by Voisin to study canonical Wahl maps is applied in this direction.

A. O. Barvinsky, A. Yu. Kamenshchik, I. P. Karmazin

We develop a renormalization-group formalism for non-renormalizable theories and apply it to Einstein gravity theory coupled to a scalar field with the Lagrangian $L=\sqrt{g} [R U(ϕ)-{1/2} G(ϕ) g^{μν} \partial_μϕ\partial_νϕ- V(ϕ)]$, where $U(ϕ), G(ϕ)$ and $V(ϕ)$ are arbitrary functions of the scalar field. We calculate the one-loop counterterms of this theor

O. Aharony, O. Ganor, J. Sonnenschein, S. Yankielowicz

The physical states on the free field Fock space of the ${SL(2,R)\over SL(2,R)$ model at any level are computed. Using a similarity transformation on $Q_{BRST}$, the cohomology of the latter is mapped into a direct sum of simpler cohomologies. We show a one to one correspondence between the states of the $k=-1$ model and those of the $c=1$ string model. A fu

Adrian Ocneanu

We discuss a simplicial dimension shift which associates to each n-manifold an n-1-manifold. As a corollary we show that an invariant which was recently proposed by Ooguri and by Crane and Yetter for the construction of 4-dimensional quantum field theories out of 3-dimensional theories is trivial.

Daniel Cangemi, Roman Jackiw

We discuss in detail how string-inspired lineal gravity can be formulated as a gauge theory based on the centrally extended Poincaré group in $(1+1)$ dimensions. Matter couplings are constructed in a gauge invariant fashion, both for point particles and Fermi fields. A covariant tensor notation is developed in which gauge invariance of the formalism is manif

Christian Münkel, Dieter W. Heermann

We present the crumpling transition in three-dimensional Euclidian space of dynamically triangulated random surfaces with edge extrinsic curvature and fixed topology of a sphere as well as simulations of a dynamically triangulated torus. We used longer runs than previous simulations and give new and more accurate estimates of critical exponents. Our data ind

Shin&#39;ichi Nojiri, Ichiro Oda

We present a new class of quantum two dimensional dilaton gravity model, which is described by $SL(2,R)/U(1)$ gauged Wess-Zumino-Witten model deformed by $(1,1)$-operator. We analyze the model by ${1 \over k}$ expansion ($k$ is the level of $SL(2,R)$ Wess-Zumino-Witten model) and we find that the curvature singularity does not appear when $k$ is large and th

Stephen D. H. Hsu

Complementarity - the absence of a phase boundary separating the Higgs and confinement phases of a gauge theory - can be violated by the addition of chiral fermions. We utilize chiral symmetry violating fermion correlators such as $ \langle \bps ψ\rangle $ as order parameters to investigate this issue. Using inequalities similar to those of Vafa-Witten and W

J. Lopez, D. Nanopoulos, H. Pois, X. Wang

We show that the present LEPI lower bound on the Standard Model Higgs boson mass ($M_H\gsim60\GeV$) applies as well to the lightest Higgs boson ($h$) of the minimal $SU(5)$ and no-scale flipped $SU(5)$ supergravity models. This result would persist even for the ultimate LEPI lower bound ($M_H\gsim70\GeV$). We show that this situation is a consequence of a de

A. Gocksch, R. D. Pisarski

In a gauge theory at nonzero temperature the eigenvalues of the Wilson line form a set of gauge invariant observables. By constructing the corresponding partition function for the phases of these eigenvalues, we prove that the trivial vacuum, where the phases vanish, is a minimum of the free energy.

M. Burkardt, R. L. Jaffe

Measurement of the helicity asymmetric cross section for semi-inclusive production of $Λ$-hyperons in $e^+e^-$ annihilation near the $Z^0$ resonance allows a complete determination of the spin-dependent fragmentation functions for the different quark flavors into the $Λ$. The parity violating, self analyzing, decay of the final state $Λ$ makes the experiment

Claudio Coriano&#39;, Hsiang-nan Li

We compare two approaches to the description of pion Compton scattering at moderate momentum transfer, one being based on local duality QCD sum rules for the invariant amplitudes of the process, which have been derived recently, and the other on the modified factorization formula with Sudakov effects included. We find that perturbative QCD predictions are do

Xiao-Gang He, J. P. Ma, Bruce McKellar

We study CP violation in fermion pair decays of Higgs boson. We idenfy some CP odd observables related to the tree level decay amplitude. We find that a few thousand Higgs boson decay events can already provide important information about CP violation. If the Higgs boson is produced, such an analysis could be carried out at the SSC, LHC and NLC.

B. A. Sanborn, Ben Yu-Kuang Hu, S. Das Sarma

We show that, for some semiconductor devices and physical experiments, processes which scatter electrons {\em into} a state $|{\bf k}\rangle$ can contribute strongly to the decay of a nonequilibrium electron occupation of $|{\bf k}\rangle$. For electrons, the decay rate $γ({\bf k})$ is given by the sum of the total scattering-out {\em and scattering-in} rate

N. I. Chernov, G. L. Eyink, J. L. Lebowitz, Ya. G. Sinai

We study nonequilibrium steady states in the Lorentz gas of periodic scatterers when an external field is applied and the particle kinetic energy is held fixed by a ``thermostat&#39;&#39; constructed according to Gauss&#39; principle of least constraint (a model problem previously studied numerically by Moran and Hoover). The resulting dynamics is reversible

L. Brink, T. H. Hansson, S. Konstein, M. A. Vasiliev

We discuss several applications and extensions of our previous operator solution of the $N$-body Calogero problem, \ie N particles in 1 dimension subject to a two-body interaction of the form $\half \sum_{i,j}[ (x_i - x_j)^2 + g/ {(x_i - x_j)^2}]$. Using a complex representation of the deformed Heisenberg algebra underlying the Calogero model, we explicitly

Erik Verlinde, Herman Verlinde

We study the black hole information paradox in the context of a two-dimensional toy model given by dilaton gravity coupled to $N$ massless scalar fields. After making the model well-defined by imposing reflecting boundary conditions at a critical value of the dilaton field, we quantize the theory and derive the quantum quantum $S$-matrix for the case that $N

Nobuyasu Ito, Macoto Kikuchi, Yutaka Okabe

The correlation between a random sequence and its transformed sequences is studied. In the case of a permutation operation or, in other word, the shuffling operation, it is shown that the correlation can be so small that the sequences can be regarded as independent random sequences. The applications to the Monte Carlo simulations are also given. This method

Boguslaw Broda

A direct relationship between the (non-quantum) group SU(2) and the Kauffman bracket in the framework of Chern-Simons theory is explicitly shown.

Jihn E. Kim, B-A Lindholm

We investigate a model with an extra $Z_{2}$ gauge symmetry in the Standard Model. We assume that only the scalars and the leptons carry non-zero charge. The symmetry gives a structure to the mass matrix for the neutrinos. With two extra Higgs singlets and two extra singlet right-handed neutrinos we can build a model that fits the requirements of the MSW-sol

Howard E. Haber, Yosef Nir

In LEP searches for the neutral CP-odd scalar $A^0$ of a multi-Higgs doublet model, experimenters have searched for $Z\rightarrow h^0 A^0$ (where $h^0$ is the lightest CP-even scalar). No model-independent limit on the $A^0$ mass can be deduced from present data if $m_{h^0}>m_Z$. In this paper, we compute the rates for $Z\rightarrow A^0 A^0ν\barν$ and $e^+e^

M. Long, X. Zotos

We use exact diagonalisation in order to study the infinite - $U$ limit of the two dimensional Hubbard model. As well as looking at single-particle correlations, such as $n_{{\bf k}σ}=\langle c^\dagger _{{\bf k}σ}c_{{\bf k}σ} \rangle $, we also study {\it N-particle correlation functions} which compare the relative positions of {\it all} the particles in dif

Frederic Mila, Xenophon Zotos

We used exact diagonalization of small clusters and exact results in various limits to determine the phase diagram and the critical exponents of the one dimensional (1D) $U-V$ model at quarter-filling. We found an instability of the Luttinger liquid to a charge-density wave (CDW) insulator across a boundary going from ($U$,$V$) =($+\infty$,$2t$) to ($4t$,$+\

HoSeong La

Classical vortex solutions in various two-Higgs systems are studied. The systems we consider include the standard model with two Higgs doublets, in which case the vortex appears as part of a string-like object. The Higgs potentials contain several different couplings in general and the spontaneous symmetry breaking involves with two different vacuum expectat

C. J. Horowitz, J. Piekarewicz

The parity violating longitudinal asymmetry ${\cal A}$ is calculated for quasielastic electron scattering. We use a variety of relativistic mean field models for the response of nuclear matter and $^{12}$C at a momentum transfer of q=550 MeV/c. Relativistic effects from a reduced nucleon mass, RPA correlations and vacuum polarization can all change ${\cal A}

Jean-Marc Richard

Summmary talk at the Workshop on Sin and Flavour in Hadronic and Electromagnetic Interactions, Turin (Italy), september 1992, to appear in the Proceedings,

Petr Horava

This paper analyzes spacetime symmetries of topological string theory on a two dimensional torus, and points out that the spacetime geometry of the model is that of the Batalin-Vilkovisky formalism. Previously I found an infinite symmetry algebra in the absolute BRST cohomology of the model. Here I find an analog of the BV $Δ$ operator, and show that it defi

J. A. Casas, C. Munoz

We propose a simple mechanism for solving the $μ$ problem in the context of minimal low--energy supergravity models. This is based on the appearance of non--renormalizable couplings in the superpotential. In particular, if $H_1H_2$ is an allowed operator by all the symmetries of the theory, it is natural to promote the usual renormalizable superpotential $W_

S. G. Naculich, C. -P. Yuan

If the electroweak symmetry-breaking sector becomes strongly interacting at high energies, it can be probed through longitudinal $W$ scattering. We present a model with many inelastic channels in the $W_L W_L$ scattering process, corresponding to the production of heavy fermion pairs. These heavy fermions affect the elastic scattering of $W_L$&#39;s by propa

Walter T. Giele, E. W. Nigel Glover, David A. Kosower

We describe a general method of calculating the fully differential cross section for the production of jets at next-to-leading order in a hadron collider. This method is based on a `crossing' of next-to-leading order calculations with all partons in the final state. The method introduces universal crossing functions that allow a modular approach to next-to-l

Ulrich Ellwanger

The radiative corrections to the $3\times3$scalar and the $2\times2$ pseudoscalar neutral Higgs boson massmatrices are calculated in the supersymmetric extension of the standard model including a gauge singlet superfield in the effective potential approach. The full $t$ and $b$ quark/squark contributions including the nonlogarithmic terms are taken into acco

B. A. Campbell, S. Davidson, K. A. Olive

We evaluate the constraints that the COBE observations put on baryogenesis in inflationary cosmologies.We consider the supersymmetric version of the proposal of Fukugita and Yanagida, that the baryon asymmetry of the universe is created by nonperturbative electroweak reprocessing of a lepton asymmetry generated in the decay of heavy right-handed see-saw (s)n

B. A. Campbell, S. Davidson, K. A. Olive

We propose a new mechanism for baryogenesis in supersymmetric extensions of the standard model, that does not depend on (super)GUT interactions. It occurs by the non-perturbative electroweak reprocessing of a lepton asymmetry. This lepton asymmetry is generated by the effects of lepton number violating induced operators, arising from &#34;see-saw&#34; (s)neu

B. A. Campbell, S. Davidson, J. Ellis, And K. A. Olive

Non-perturbative electroweak effects, in thermal equilibrium in the early universe, have the potential to erase the baryon asymmetry of the universe, unless it is encoded in a B-L asymmetry, or in some &#34;accidentally&#34; conserved quantity. We first consider the possibility that the BAU may be regenerated from lepton flavour asymmetries even when initial

J. Gegenberg, G. Kunstatter

A solvable 2-dimensional conformally invariant midi-superspace model for black holes is obtained by imposing spherical symmetry in 4-dimensional conformally invariant Einstein gravity. The Wheeler-DeWitt equation for the theory is solved exactly to obtain the unique quantum wave functional for an isolated black hole with fixed mass. By suitably relaxing the

F. M. Paiva, M. J. Rebouças, M. A. H. MacCallum

A coordinate-free approach to limits of spacetimes is developed. The limits of the Schwarzschild metric as the mass parameter tends to 0 or $\infty$ are studied, extending previous results. Besides the known Petrov type D and 0 limits, three vacuum plane-wave solutions of Petrov type N are found to be limits of the Schwarzschild spacetime.

S. D. Odintsov

The method of the calculation of effective potential (in linear curvature approximation and at any loop) in massless gauge theory in curved space- time by the direct solution of RG equation is given.The closed expression for two-loop effective potential is obtained.Two-loop effective potential in scalar self-interacting theory is written explicitly.Some comm

Nobuyasu Ito

{}From the non-equilibrium critical relaxation study of the two-dimensional Ising model, the dynamical critical exponent $z$ is estimated to be $2.165 \pm 0.010$ for this model. The relaxation in the ordered phase of this model is consistent with $\exp (-\sqrt{t/τ})$ behavior. The interface energy of the three-dimensional Ising model is studied and the criti

Roberto Artuso, Giulio Casati, Roberto Lombardi

We introduce a novel technique to find the asymptotic time behaviour of deterministic systems exhibiting anomalous diffusion. The procedure is tested for various classes of simple but physically relevant 1-D maps and possible relevance of our findings for more complicated problems is briefly discussed.

O. Heinonen, M. D. Johnson

We present an approach to steady-state mesoscopic transport based on the maximum entropy principle formulation of nonequilibrium statistical mechanics. Our approach is not limited to the linear response regime. We show that this approach yields the quantization observed in the integer quantum Hall effect at large currents, which until now has been unexplaine

Karl Mannheim

Considering shock-accelerated protons in addition to electrons in a synchrotron radio jet naturally produces the observed X- through gamma ray continuum emission of flat-spectrum radio-loud AGN, whereas the corresponding shock-accelerated electrons produce the infrared through optical continuum. All of these emission components are rapidly variable on short

J. Bijnens

The electromagnetic contribution to the $K^+ - K^0$ mass difference is calculated in the $1/N_c$ approach including the $SU(3)$ breaking contributions due to a non-zero strange quark mass. The short-distance contribution can be unambiguously determined in terms of the known parameters of the next-to-leading order chiral lagrangian. The long distance part is

Dimitri Polyakov

The submitted paper regards the example of the Conformal Field Theory on a 2d manifold which metric has a point-like singularity.Since this manifold is not conformally equivalent to that with the flat space-time metric,it&#39;s naturally to expect that the theory cannot be trivially reduced to the well-known consideration of the CFT on a plane,and some modif

Carsten Schütt

Let K be a convex body in $R^d$. A random polytope is the convex hull $[x_1,...,x_n]$ of finitely many points chosen at random in K. $\Bbb E(K,n)$ is the expectation of the volume of a random polytope of n randomly chosen points. I. Bárány showed that we have for convex bodies with $C^3$ boundary and everywhere positive curvature $$ c(d)\lim_{n \to \infty} \

Robert R. Phelps

This is a 30 page set of lecture notes, in Plain TeX, which were prepared for and presented as a series of lectures (10 1/2 hours over two weeks) at the 2nd Summer School on Banach Spaces, Related Areas and Applications in Prague and Paseky, Czech Republic, during August, 1993. They consist of a largely self-contained exposition of both classical and recent

Paddy N. Dowling, Christopher J. Lennard

The main result of this paper is that every non-reflexive subspace $Y$ of $L_1[0,1]$ fails the fixed point property for closed, bounded, convex subsets $C$ of $Y$ and nonexpansive (or contractive) mappings on $C$. Combined with a theorem of Maurey we get that for subspaces $Y$ of $L_1[0,1]$, $Y$ is reflexive if and only if $Y$ has the fixed point property. F

M. Defant, Marius Junge

We will show that for $q<p$ there exists an $\al < \infty$ such that \[ π_{pq}(T) \pl \le c_{pq} π_{pq}^{[n^α]}(T) \mbox{for all $T$ of rank $n$.}\] Such a polynomial number is only possible if $q=2$ or $q<p$. Furthermore, the growth rate is linear if $q=2$ or $\frac{1}{q}-\frac{1}{p}>\frac{1}{2}$. Unless $\frac{1}{q}-\frac{1}{p}=\frac{1}{2}$ this is also a

Marius Junge

We will prove an abstract comparision principle which translates gaussian cotype in Rademacher cotype conditions and vice versa. More precisely, let $2\!<\!q\!<\!\infty$ and $T:\,C(K)\,\to\,F$ a linear, continous operator. T is of gaussian cotype q if and only if ( \summ_1^n (\frac{|| Tx_k||_F}{\sqrt{\log(k+1)}})^q )^{1/q} \, \le c || \summ_1^n \varepsilon_k

Sy D. Friedman

In this note I show that a pi-1-2 singleton R of L-degree strictly between 0 and 0# can be obtained so as to be the unique solution to a pi-1-2 formula which provably has at most one solution, in the theory ZFC+(*) where (*) has the approximate strength of an ineffable cardinal.

J. Rembielinski

We propose a new wiew on the structure of quantum mechanics and postulate a q-deformed algebra of observables. We find equations of motion for this system, which guarantee a unitary time developement. We solve this equations for simple models. We write this formalism in terms of twisted deRham complex.

Roberto Iengo

We summarize a study of an Abelian gauge theory in 2+1 dimensions, the gauge field being coupled to nonrelativistic Fermions. The Action for the gauge field is a combination of the Maxwell term and a Chern-Simons (CS) term. We study the limit of vanishing Fermions&#39; charge, keeping fixed the gauge field mass induced by the CS term. By considering a closed

Ll. Ametller, J. Bijnens, A. Bramon, F. Cornet

We calculate the $O(p^6)$ corrections to the anomalous form factors appearing in $π^+$, $K^+ \to e^+ νγ,\ μ^+νγ$ and $K_{l4}$ decays in Chiral Perturbation Theory. The relevant dimension $6$ terms of the lagrangian are evaluated assuming their saturation by the vector meson contribution.

D. Comelli, C. Verzegnassi

We have evaluated the one loop correction to the bound on the lightest Higgs mass valid in the minimal, $ E_{6}$ based, supersymmetric $ η$ model. Under the assumption that the theory remains perturbative up to the $10^{16}$ GeV scale, we derive a conservative bound that decreases with the top mass for $M_t \leq 2 M_W$ and varies from $ \sim 160$ GeV to $\si

K. Kołodziej, F. Jegerlehner, G. J. van Oldenborgh

A calculation of the hard bremsstrahlung process e+ e- -> mu+ mu- gamma gamma is presented and compared with recent results from the L3 Collaboration.

Meng Y. Wang, Eric D. Carlson

We discuss why the SU(3)^3 supersymmetric model with the most general superpotential can naturally break to the standard model if gauge singlets and a discrete symmetry are included. This mechanism does away with the need for fine-tuning in the form of the assumed absence of certain terms in the superpotential. It also automatically guarantees that any abeli

Zhong-Shui Ma, Zhao-Bin Su

We build the constraint that all electrons are in the lowest Landau level into the Chern-Simons field theory approach for the fractional quantum Hall system. We show that the constraint can be transmitted from one hierarchical state to the next. As a result, we derive in generic the equations of the fractionally charged vortices ( quasi-particles ) for arbit

Joerg P. Rachen, Todor Stanev, Peter L. Biermann

We compare the expected contribution of FR-II hot spots to the ultra-high energy cosmic ray spectrum (Rachen & Biermann 1993, A&A in press, BB paper astro-ph/9301010) to improved experimental results. We introduce a &#34;world data set&#34; of UHE cosmic rays by comparing the data of various experiments, extracting relative systematic errors in the energy de

G. De Zotti, A. Franceschini, L. Toffolatti, P. Mazzei

We present a short overview on the extragalactic background radiation from radio to X-rays, with an eye to the relation to galaxy formation and emphasizing on astrophysical backgrounds (as opposed to cosmological). As the radio background, the wealth of data on source counts make possible reliable estimations of the contribution from extragalactic sources. A

M. S. Turner

Talk presented at NAS Special Colloquium on Physical Cosmology

Eugene Tyurin

We study a class of classical dilaton vacua in string theory that depend on the light-cone variable $z=t\pm x$ and, thus, have wavelike behavior. One of the interesting results is the existence of a solution subclass with perfectly regular space-time geometry, where the string coupling constant can be made arbitrarily small.

Yue Hu, Michael S. Turner, Erick J. Weinberg

We discuss in some detail the requirements on an early-Universe model that solves the horizon and flatness problems during the epoch of classical cosmology ($t\ge t_i\gg 10^{-43}\sec$). We show that a dynamical resolution of the horizon problem requires superluminal expansion (or very close to it) and that a truly satisfactory resolution of the flatness prob

D. Nunez, H. P. de Oliveira, J. Salim

We analyse the dynamics of the collision of two spherical massive shells in a generally spherically symmetric background, obtaining an expression from the conservation law that imposes a constraint between the different parameters involved. We study the light-like limit and make some comparisons of the predictions of our master equation with the results obta

T. Brzezinski, J. Rembielinski, K. A. Smolinski

We describe a $q$-deformed dynamical system corresponding to the quantum free particle moving along the circle. The algebra of observables is constructed and discussed. We construct and classify irreducible representations of the system.

Mark B. Mineev--Weinstein

Extending our previous work on 2D growth for the Laplace equation we study here {\it multidimensional} growth for {\it arbitrary elliptic} equations, describing inhomogeneous and anisotropic pattern formations processes. We find that these nonlinear processes are governed by an infinite number of conservation laws. Moreover, in many cases {\it all dynamics o

Michael Beyer

Internal target experiments with high quality proton beams allow for a new class of experiments providing null tests of time reversal symmetry in forward scattering. This could yield more stringent limits on T-odd P-even observables. A excellent candidate for such experiments is the proton deuteron system. This system is analyzed in terms of effective T-viol

N. Tenney Peck

Let F be a quasi-linear map on a separable normed space X, and assume that F splits on an infinite-dimensional subspace of X. Then the twisted sum topology induced by F on the direct sum of X and the real line can be written as the supremum of a nearly convex topology and a trivial dual topology. (This partially answers a question of Klee.) The result applie

Jong Hyun Kung

Wheeler-DeWitt equation is applied to $k > 0$ Friedmann Robertson Walker metric with various types of matter. It is shown that if the Universe ends in the matter dominated era (e.g., radiation or pressureless gas) with zero cosmological constant, then the resulting Wheeler-DeWitt equation describes a bound state problem. As solutions of a non-degenerate boun

F. Vanderseypen

We present a quantum geometric framework for stochastic quantisation in the case of a free Klein-Gordon field on Euclidean space. In this approach the noise is part of the background space, spacetime is fuzzy. We extend the notion of sharp point limit and show how fuzzy spacetime and the Klein-Gordon field gives the Euclidean space and the stochastically qua

J. Ambjørn, L. Chekhov, C. F. Kristjansen, Yu. Makeenko

We propose an improved iterative scheme for calculating higher genus contributions to the multi-loop (or multi-point) correlators and the partition function of the hermitian one matrix model. We present explicit results up to genus two. We develop a version which gives directly the result in the double scaling limit and present explicit results up to genus f

Gerald Kelnhofer

Covariant anomalies are studied in terms of the theory of secondary characteristic classes of the universal bundle of Yang-Mills theory. A new set of descent equations is derived which contains the covariant current anomaly and the covariant Schwinger term. The counterterms relating consistent and covariant anomalies are determined. A geometrical realization

F. Belgiorno, A. S. Cattaneo, M. Martellini, F. Fucito

In this paper we investigate in more detail our previous formulation of the dilaton-gravity theory by Bilal--Callan--de~Alwis as a $SL_2$-conformal affine Toda (CAT) theory. Our main results are: i) a field redefinition of the CAT-basis in terms of which it is possible to get the black hole solutions already known in the literature; ii) an investigation the

Michael Crescimanno

We study two-dimensional dilaton gravity coupled to massless scalar fields for static solutions. In addition to the well known black hole, we find another class of solutions that may be understood as that of the black hole in equilibrium with a radiation bath. We claim that there is a solution that is qualitatively unchanged after including Hawking radiation

M. N. Butler, M. J. Savage, R. P. Springer

We compute the leading contribution to the E2/M1 mixing ratio of the decay $Δ\rightarrow Nγ$ in heavy baryon chiral perturbation theory. We find the mixing ratio to be $4\% \ltap |δ_{\rm E2/M1}| \ltap 11\%$, much larger than estimates based on the quark model and other hadronic models. We also compute the mixing ratio for the radiative decay of the hyperon r

Eric Braaten, Daniel Segel

We present a unified approach which is accurate at all temperatures and densities for calculating the energy loss from a stellar plasma due to the plasma process, the decay of photons and plasmons into neutrino pairs. To allow efficient numerical calculations, an analytic approximation to the dispersion equations for photons and plasmons is developed. It is

Tony Gherghetta, Gerard Jungman

Cosmological constraints on grand unified theories with spontaneous lepton number violation are analysed. We concentrate on $SO(10)$, the simplest of the models possessing this property. It has been noted previously that the consistency of these models with the observed baryon asymmetry generically implies strict upper bounds on the light neutrino masses. In

P. Nason, M. Porrati

We compute the effect of small-size instanton corrections to current-current correlators, for all combinations of axial, vector, and possibly flavour non-diagonal currents. We apply our result to the hadronic decays of the $τ$ lepton, in order to assess the reliability of the determination of $\as$ from the $τ$ hadronic width.

A. G. Cohen, D. B. Kaplan, A. E. Nelson

Recent work on generating the excess of matter over antimatter in the early universe during the electroweak phase transition is reviewed.

Mohammad R. Ahmady, Dongsheng Liu, Zhijian Tao

We use the new symmetries in the heavy quark limit to calculate the exclusive B-decays $B \rightarrow K^i ψ$ where $K^i$ are higher resonances of K-meson. We then estimate the long distance contributions to $B \rightarrow K^i γ$ decays via $ψ- γ$ conversion. The results point to around $30 \%$ uncertainty in the top quark mass determined by measurements of r

S. A. Larin, J. A. M. Vermaseren

The analytic calculation of the three-loop QCD $β$-function and anomalous dimensions within the minimal subtraction scheme in an arbitrary covariant guage is presented. The result for the $β$-function coincides with the previous calculation \cite{tvz}.