February 1996 arXiv papers — page 9

F. Gronwald, F. W. Hehl

We give a short outline, in Sec.\ 2, of the historical development of the gauge idea as applied to internal ($U(1),\, SU(2),\dots$) and external ($R^4,\,SO(1,3),\dots$) symmetries and stress the fundamental importance of the corresponding conserved currents. In Sec.\ 3, experimental results with neutron interferometers in the gravitational field of the earth

D. Kamani, R. Mansouri

Beginning with a special form of the Einstein-Rosen metric, we find new cosmological solutions of the Einstein equations, having two hypersurface-orthogonal Killing vectors , with ideal fluid. The equation of state is in the most cases of the form $p = γρ$.

Pierre Cartier, Cécile DeWitt-Morette

The core of this article is a general theorem with a large number of specializations. Given a manifold $N$ and a finite number of one-parameter groups of point transformations on $N$ with generators $Y, X_{(1)}, \cdots, X_{(d)} $, we obtain, via functional integration over spaces of pointed paths on $N$ (paths with one fixed point), a one-parameter group of

Lian Zheng, S. Das Sarma

We theoretically study energy relaxation via LO-phonon emission in an excited one-dimensional electron gas confined in a GaAs quantum wire structure. We find that the inclusion of phonon renormalization effects in the theory extends the LO-phonon dominated loss regime down to substantially lower temperatures. We show that a simple plasmon-pole approximation

A. -L. Barabási, S. V. Buldyrev, H. E. Stanley, B. Suki

We study a statistical mechanical model for the dynamics of lung inflation which incorporates recent experimental observations on the opening of individual airways by a cascade or avalanche mechanism. Using an exact mapping of the avalanche problem onto percolation on a Cayley tree, we analytically derive the exponents describing the size distribution of the

Ralf Bundschuh, Michael Lassig

We study directed polymers subject to a quenched random potential in d transversal dimensions. This system is closely related to the Kardar-Parisi-Zhang equation of nonlinear stochastic growth. By a careful analysis of the perturbation theory we show that physical quantities develop singular behavior for d to 4. For example, the universal finite size amplitu

Alexander Sokol, Rajiv R. P. Singh, Norbert Elstner

We present an isotropic spin wave (ISW) theory of short-range order in Heisenberg magnets, and apply it to square lattice S=1/2 and S=1 antiferromagnets. Our theory has three identical (isotropic) spin wave modes, whereas the conventional spin wave theory has two transverse and one longitudinal mode. We calculate temperature dependences of various thermodyna

Robert M. Losee

Natural language processing (NLP) applied to information retrieval (IR) and filtering problems may assign part-of-speech tags to terms and, more generally, modify queries and documents. Analytic models can predict the performance of a text filtering system as it incorporates changes suggested by NLP, allowing us to make precise statements about the average e

Per E. Rosenqvist, Gabor Vattay, Andreas Wirzba

The diffraction trace formula ({\em Phys. Rev. Lett.} {\bf 73}, 2304 (1994)) and spectral determinant are tested on the open three disk scattering system. The system contains a generic and exponentially growing number of diffraction periodic orbits. In spite of this it is shown that even the scattering resonances with large imaginary part can be reproduced s

V. G. Makhankov, M. Agüero Granados, A. V. Makhankov

Generalized Coherent States (GCS) are constructed (and discussed) in order to study quasiclassical behaviour of quantum spin models of the Heisenberg type. Several such models are taken to their semiclassical limits, whose form depends on the spin value as well as the Hamiltonian symmetry. In the continuum approximation, SU(2)/U(1) GCS when applied give rise

Myungshin Im, Richard E. Griffiths, Kavan U. Ratnatunga, Vicki L. Sarajedini

The luminosity functions of E/S0 galaxies are constructed in 3 different redshift bins (0.2 < z < 0.55, 0.55 < z < 0.8, 0.8 < z < 1.2), using the data from the Hubble Space Telescope Medium Deep Survey (HST MDS) and other HST surveys. These independent luminosity functions show the brightening in the luminosity of E/S0s by about 0.5~1.0 magnitude at z~1, and

Max Tegmark, Dieter Hartmann, Michael Briggs, Charles Meegan

We compute the angular power spectrum C_l of the BATSE 3B catalog, and find no evidence for clustering on any scale. These constraints bridge the entire range from small scales, probing source clustering and repetition, to large scales constraining possible Galactic anisotropies, or those from nearby cosmological large scale structures.

V. Frolov, S. Hendy, A. L. Larsen

A new tool for the investigation of 2+1 dimensional gravity is proposed. It is shown that in a stationary 2+1 dimensional spacetime, the eigenvectors of the covariant derivative of the timelike Killing vector form a rigid structure, the {\it principal Killing triad}. Two of the triad vectors are null, and in many respects they play the role similar to the pr

K. M. Bitar, R. G. Edwards, U. M. Heller, A. D. Kennedy

We test the asymptotic scaling behavior of state-of-the-art simulations of QCD with two flavors of light Wilson fermions. This is done by matching $π$ and $ρ$ masses on lattices of size $16^3\times32$ and $8^3\times16$. We find that at $β=6/g^2=5.3$ matching is not possible over a range extending down to $β=3.5$. The large lattice data at $β=5.5$ matches the

C. S Kochanek, T. S. Kolatt, M. Bartelmann

Precise determinations of the image positions in quad gravitational lenses using VLBI can be used to measure the transverse velocity of the lens galaxy and the observer. The typical proper motions are $μ$as yr$^{-1}$, so the time scale to measure the motion is ten years. By measuring the dipole of the proper motions in an ensemble of lenses we can set limits

John Ellis, N. E. Mavromatos, D. V. Nanopoulos, E. Winstanley

We display a logarithmic divergence in the density matrix of a scalar field in the presence of an Einstein-Yang-Mills black hole in four dimensions. This divergence is related to a previously-found logarithmic divergence in the entropy of the scalar field, which cannot be absorbed into a renormalization of the Hawking-Bekenstein entropy of the black hole. As

A. Duncan, S. Pernice, E. Schnapka

The systematic errors inherent in the QCD sum rule approach to meson wavefunctions are examined in the context of QCD in 1+1 spacetime dimensions in the large N limit where the theory is exactly solvable. It is shown that the truncation of high momentum modes induced in a lattice discretization automatically produces a Chernyak-Zhitnitsky \cite{CZ} type meso

E. Chikovani, V. Kartvelishvili, R. Shanidze, G. Shaw

We calculate the production cross-sections for the vector and pseudoscalar bound states of two gluinos. It is shown that existing and future colliders imply a realistic chance of observing gluinonium as a narrow peak in the two-jet invariant mass spectrum. With an integrated luminosity of 0.2 fb$^{-1}$ at the Tevatron, and the high efficiency for tagging hea

B. Holdom

We show how a dynamical Majorana mass for a fourth family left-handed neutrino can make a significant negative contribution to the electroweak correction parameter T without making a large contribution to S or U. We also comment on other possible contributions to T in the context of dynamical symmetry breaking.

Fabio Cardarelli, Jorge Piekarewicz

We examine the effect of isospin-violating meson-nucleon coupling constants and of $\pi$-$\eta$ mixing on the binding-energy differences of mirror nuclei in a model that possesses no contribution from $\rho$-$\omega$ mixing. The ${}^{3}$He-${}^{3}$H binding-energy difference is computed in a nonrelativistic approach using a realistic wave function. We find t

P. A. Raczka, A. Szymacha

The next-next-to-leading order QCD corrections to the e+e- annihilation into hadrons are considered. The stability of the predictions with respect to change of the renormalization scheme is discussed in detail for the case of five, four and three active quark flavors. The analysis is based on the recently proposed condition for selecting renormalization sche

P. E. Berche, B. Berche, L. Turban

Two-dimensional layered aperiodic Ising systems are studied in the extreme anisotropic limit where they correspond to quantum Ising chains in a transverse field. The modulation of the couplings follows an aperiodic sequence generated through substitution. According to Luck&#39;s criterion, such a perturbation becomes marginal when the wandering exponent of t

Reginald T. Cahill, Susan M. Gunner

The often used Gell-Mann-Oakes-Renner mass formula for Nambu-Goldstone (NG) bosons in QCD, such as the pions, involves the condensate $<\overline{q}q>$, $f_π$ and the quark current masses. Within the context of the Global Colour Model (GCM) for QCD a manifestly different formula was recently found by Cahill and Gunner. Remarkably Langfeld and Kettner have sh

S. Ambrosanio, G. L. Kane, Graham D. Kribs, Stephen P. Martin

We have analyzed the single $\eegg + \slashchar{E}_T$ event at CDF and found that the expected rate and kinematics are consistent with selectron pair production. We consider two classes of general low-energy supersymmetric theories, where either the lightest neutralino (``neutralino LSP&#39;&#39; scenario) or the gravitino (``light gravitino&#39;&#39; scenar

Atish Dabholkar, Jaemo Park

A new orientifold of Type-IIB theory on $K3$ is constructed that has $N=1$ supersymmetry in six dimensions. The orientifold symmetry consists of a $Z_2$ involution of $K3$ combined with orientation-reversal on the worldsheet. The closed-string sector in the resulting theory contains nine tensor multiplets and twelve neutral hypermultiplets in addition to the

S. Kaliszewski, John Quigg, Iain Raeburn

Consider a coaction $\delta$ of a locally compact group $G$ on a \cstar algebra $A$, and a closed normal subgroup $N$ of $G$. We prove, following results of Echterhoff for abelian $G$, that Mansfield's imprimitivity between $A\times_{\delta|}G/N$ and $A\times_\delta G\times_{\deltahat,r}N$ implements equivalences between Mansfield induction of representation

Jens Erler

I introduce a class of string constructions based on asymmetric orbifolds leading to level two models. In particular, I derive in detail various models with gauge groups $E_6$ and SO(10), including a four generation $E_6$ model with two adjoint representations. The occurrence of multiple adjoint representations is a generic feature of the construction. In th

S. Kaliszewski, John Quigg

We give a condition on a full coaction $(A,G,δ)$ of a (possibly) nonamenable group $G$ and a closed normal subgroup $N$ of $G$ which ensures that Mansfield imprimitivity works; i.e. that $A\times_{δ{\vert}} G/N$ is Morita equivalent to $A\times_δG\times_{\deltahat,r} N$. This condition obtains if $N$ is amenable or $δ$ is normal. It is preserved under Morita

R. Chakrabarti, R. Jagannathan

The dually conjugate Hopf algebras $Fun_{p,q}(R)$ and $U_{p,q}(R)$ associated with the two-parametric $(p,q)$-Alexander-Conway solution $(R)$ of the Yang-Baxter equation are studied. Using the Hopf duality construction, the full Hopf structure of the quasitriangular enveloping algebra $U_{p,q}(R)$ is extracted. The universal ${\cal T}$-matrix for $Fun_{p,q}(

J. A. de Azcarraga, J. C. Perez Bueno

We re-examine all the contractions related with the ${\cal U}_q(su(2))$ deformed algebra and study the consequences that the contraction process has for their structure. We also show using ${\cal U}_q(su(2))\times{\cal U}(u(1))$ as an example that, as in the undeformed case, the contraction may generate Hopf algebra cohomology. We shall show that most of the

A. Bender, C. D. Roberts, L. v. Smekal

The quark Dyson-Schwinger equation and meson Bethe-Salpeter equation are studied in a truncation scheme that extends the rainbow-ladder approximation such that, in the chiral limit, the isovector, pseudoscalar meson remains massless. Quark-quark (diquark) correlations, which are bound in rainbow-ladder approximation, are destabilised by repulsive contributio

S. Bernard, J. A. Maruhn, W. Greiner, D. H. Rischke

We investigate freeze--out in hydrodynamic models for relativistic heavy--ion collisions. In particular, instantaneous freeze--out across a hypersurface of constant temperature (``isothermal&#39;&#39; freeze--out) is compared with that across a hypersurface at constant time in the center-of-momentum frame (``isochronous&#39;&#39; freeze--out). For one--dimen

H. Kim, S. Schramm, C. J. Horowitz

Neutrino-nucleus cross sections for the detection of atmospheric neutrinos are calculated in relativistic impulse and random phase approximations. Pion production is estimated via inclusive Delta-hole nuclear excitations. The number of pion events can confuse the identification of the neutrino flavor. As a further source of pions we calculate coherent pion p

A. P. Kobushkin, D. O. Riska

The coupling of the breathing and rotational modes of the skyrmion-skyrmion system leads to a nucleon-nucleon spin-orbit interaction of short range, as well as to spin-orbit potentials for the transitions $NN \to N(1440)N$, $NN \to NN(1440)$ and $NN \to N(1440)N(1440)$. The longest range behaviour of these spin-orbit potentials is calculated in closed form.

F. Kirchhoff, J. M. Holender, M. J. Gillan

Ab initio molecular-dynamics simulations have been used to investigate the structure, dynamics and electronic properties of the liquid alloy Ag(1-x)Se(x) at 1350 K and at the three compositions x=0.33, 0.42 and 0.65. The calculations are based on density-functional theory in the local density approximation and on the pseudopotential plane-wave method. The re

Teruhiko Kawano

We study $N=1$ supersymmetric $SO(10)$ gauge theory with a field in the spinorial representaition and $N_f$ ($\leq8$) fields in the defining representation. It is shown that this theory for $N_f=7,8$ has a dual description, which is $N=1$ supersymmetric $SU(N_f-5)$ gauge theory. Its matter content for $N_f=7$ is different {}from the one for $N_f=8$; for $N_f

Yoonbai Kim, Kei-ichi Maeda, Nobuyuki Sakai

We review how the continuous symmetry can support a soliton inside a high-temperature bubble at the time of its nucleation. This solitonic island in disoriented phase remains stable during the growth of bubbles before their collision.

P. Pouliot, M. J. Strassler

We study ${\cal N}=1$ supersymmetric $Spin(10)$ chiral gauge theories with a single spinor representation and $N$ vector representations. We present a dual description in terms of an ${\cal N}=1$ supersymmetric $SU(N-5)$ chiral gauge theory with a symmetric tensor, one fundamental and $N$ antifundamental representations. The $Spin(10)$ theory with $N=0$ brea

Karl-Peter Marzlin

The electromagnetic field inside an isotropic optically active medium is quantized on the base of Fedorov&#39;s model for optical activity. The modified photon propagator is derived. Using this result it is shown that the QED correction to the electron mass contains chiral terms which nevertheless are parity invariant. The spontaneous emission rate of a two-

M. Carena, P. Zerwas, E. Accomando, P. Bagnaia

In this report we review the prospects for Higgs physics at LEP2. The theoretical aspects and the phenomenology of Higgs particles are discussed within the Standard Model (SM) and the Minimal Supersymmetric Standard Model (MSSM). The experimental search techniques are described and the discovery limits for Higgs bosons in the LEP2 energy range are summarized

M. Genovese, N. N. Nikolaev, B. G. Zakharov

We develop the pQCD description of the diffraction dissociation (DD) of longitudinal photons. We demonstrate that the longitudinal diffractive structure function does not factor into the flux of pomerons and the partonic structure function of the pomeron, thus defying the usually assumed Regge factorization. In contrast to DD of the transverse photons, DD of

J. G. K&#34;orner

I discuss the structure of current-induced bottom baryon to charm baryon transitions, and the structure of pion and photon transitions between heavy charm or bottom baryons in the Heavy Quark Symmetry limit as $m_Q\rightarrow\infty$. The emphasis is on the structural similarity of the Heavy Quark Symmetry predictions for the three types of transitions. The d

Yuan-ben Dai, Chao-shang Huang, Chun Liu, Cai-dian Lü

The 1/m corrections to heavy baryon masses are calculated from the QCD sum rules within the framework of the heavy quark effective theory. Numerical results for the heavy baryons are obtained. The implications of the results are discussed.

H. Jallouli, H. Sazdjian

The relativistic two-body potentials of constraint theory for systems composed of two spin-0 or two spin-1/2 particles are calculated, in perturbation theory, by means of the Lippmann-Schwinger type equation that relates them to the scattering amplitude. The cases of scalar and vector interactions with massless photons are considered. The two-photon exchange

W. Beirl, D. A. Johnston

We suggest a generalization of the dynamical triangulation approach to quantum gravity with both timelike and spacelike edges, which can serve as a toy model for quantum gravity in the Lorentz sector in two dimensions. It is possible to consider the model in a purely Lorentzian sector or to relax this constraint and allow local signature changing moves. We s

W. P. Petersen

In this paper is described a general 2-nd order accurate (weak sense) procedure for stablizing Monte-Carlo simulations of Ito stochastic differential equations. The splitting procedure includes explicit Runge-Kutta methods, semi-implicit methods, and trapezoidal Rule. We prove the semi-implicit method of Oettinger and note that it may be generalized for arbi

G. Boyd, J. Engels, F. Karsch, E. Laermann

The pressure and the energy density of the $SU(3)$ gauge theory are calculated on lattices with temporal extent $N_τ= 4$, 6 and 8 and spatial extent $N_σ=16$ and 32. The results are then extrapolated to the continuum limit. In the investigated temperature range up to five times $T_c$ we observe a $15\%$ deviation from the ideal gas limit. We also present new

Sutapa Mukherji\cite, Somendra M. Bhattacharjee

We consider the behavior of the overlap of $m (\geq 2)$ paths at the spin glass transition for a directed polymer in a random medium. We show that an infinite number of exponents is required to describe these overlaps. This is done in an $ε= d-2$ expansion without using the replica trick.

Jae-Kwon Kim

A comment on a recent Letter by Baker and Kawashima (Phys. Rev. Lett. {\bf 75}, 994 (1995)).

J. K. Freericks, Ch. Gruber, N. Macris

The ground states of the one-dimensional Falicov-Kimball model are investigated in the small-coupling limit, using nearly degenerate perturbation theory. For rational electron and ion densities, respectively equal to $\frac{p}{q}$, $\frac{p_i}{q}$, with $p$ relatively prime to $q$ and $\frac{p_i}{q}$ close enough to $\frac{1}{2}$, we find that in the ground

Alexander Moroz

The single-particle densitity of states (DOS) for the Pauli and the Schrödinger Hamiltonians in the presence of an Aharonov-Bohm potential is calculated for different values of the particle magnetic moment. The DOS is a symmetric and periodic function of the flux. The Krein-Friedel formula can be applied to this long-ranged potential when regularized with th

E. B. Sonin

The theory of the ultrasound propagation in the mixed state of type-II superconductors is suggested which takes into account the Magnus force on vortices, the anti-Magnus force on ions, and diamagnetism of the mixed state. The acoustic Faraday effect (rotation of polarization of the transverse ultrasonic wave propagating along vortices) is shown to be linear

A. B. Harris, C. Micheletti, J. M. Yeomans

We consider a three-dimensional Ising model in a transverse magnetic field, $h$ and a bulk field $H$. An interface is introduced by an appropriate choice of boundary conditions. At the point $(H=0,h=0)$ spin configurations corresponding to different positions of the interface are degenerate. By studying the phase diagram near this multiphase point using quan

Peter Kopietz

We compare two non-perturbative techniques for calculating the single-particle Green&#39;s function of interacting Fermi systems with dominant forward scattering: our recently developed functional integral approach to bosonization in arbitrary dimensions, and the eikonal expansion. In both methods the Green&#39;s function is first calculated for a fixed conf

Allan Griffin

We derive and discuss the equations of motion for the condensate and its fluctuations for a dilute, weakly interacting Bose gas in an external potential within the self--consistent Hartree--Fock--Bogoliubov (HFB) approximation. Account is taken of the depletion of the condensate and the anomalous Bose correlations, which are important at finite temperatures.

Lian Zheng, S. Das Sarma

We calculate the electronic resistivity of a GaAs-based semiconductor quantum wire in the presence of acoustic phonon scattering. We find that the usual Drude-Boltzmann transport theory leads to a low temperature activated behavior instead of the well-known Bloch-Grüneisen power law. Many-body electron-phonon renormalization, which is entirely negligible in

A. V. Balatsky, M. I. Salkola

The absence of localization of impurity-induced low-energy quasiparticle states in a two-dimensional $d$-wave superconductor is argued for any amount of disorder in the limit of unitary scatterers. This surprising result follows from the fact that a unitary impurity produces a marginally-bound state at zero energy which decays as a power-law along the nodes

F. Halzen, G. Jaczko

We show that the detection of neutrinos from a typical gamma ray burst requires a kilometer-scale detector. We argue that large bursts should be visible with the neutrino telescopes under construction. We emphasize the 3 techniques by which neutrino telescopes can perform this search: by triggering on i) bursts of muons from muon neutrinos, ii) muons from ai

Xiang-Ping Wu, Li-Zhi Fang

Motivated by the significant overdensity of background bright quasars recently detected behind the foreground clusters of galaxies on scale of $10$ arcminutes, we have investigated the possibility of attributing the quasar-cluster associations to gravitational lensing by large-scale matter inhomogeneities. Based on the conventional lensing models, we have sh

Silvia Zane, Roberto Turolla, Luciano Nobili, Myris Erna

In this paper we present a characteristic method for solving the transfer equation in differentially moving media in a curved spacetime. The method is completely general, but its capabilities are exploited at best in presence of symmetries, when the existence of conserved quantities allows to derive analytical expressions for the photon trajectories in phase

Neil Humphreys, Roy Maartens, David Matravers

We calculate the off--center observational relations in a spherically symmetric dust universe that is inhomogeneous at small redshifts. In contrast to the usual model, in which the CMBR dipole is interpreted as a Doppler effect due to peculiar velocity, our model explores an alternative interpretation, in which the CMBR dipole is non--Doppler, and the observ

A. Bressan, C. Chiosi, R. Tantalo

In this paper we address the question whether age and metallicity effects can be disentangled with the aid of the broad-band colours and spectral indices from absorption feature strengths, so that the age of elliptical galaxies can be inferred. The observational data under examination are the indices Hbeta and [MgFe], and the velocity dispersion Sigma for th

Axel Brandenburg, Kari Enqvist, Poul Olesen

We investigate hydromagnetic turbulence of primordial magnetic fields using magnetohydrodynamics (MHD) in an expanding universe. We present the basic, covariant MHD equations, find solutions for MHD waves in the early universe, and investigate the equations numerically for random magnetic fields in two spatial dimensions. We find the formation of magnetic st

Jorge G. Hirsch, Peter O. Hess, Osvaldo Civitarese

The proton-neutron monopole Lipkin model, which exhibits some properties which are relevant for those double beta decay ($ββ$) transitions mediated by the Fermi matrix elements, is solved exactly in the proton-neutron two-quasiparticle space. The exact results are compared with the ones obtained by using the Quasiparticle Random Phase (QRPA) and renormalized

John W. Harris, Berndt Müller

We provide an overview of the present understanding of the transition from hadrons to a quark-gluon plasma, its signatures, and the experimental results so far. We discuss results of numerical simulations of the lattice gauge theory and critically evaluate the various observables that have been proposed as signatures of the QCD phase transition. We place the

E. Giallongo, S. Cristiani, S. D&#39;Odorico, A. Fontana

We present results from high resolution (R\simeq 28000) spectra of six high- redshift QSOs taken at the ESO NTT telescope that allow the detailed study of the Ly-alpha population in the redshift interval z=2.8-4.1. The typical Doppler parameters found for the Ly-alpha lines lie in the interval b=20\div30 km/s, corresponding to temperatures T>24000K, with a f

D. Boyanovsky, M. D'Attanasio, H. J. de Vega, R. Holman

Using the O(4) linear $\sigma$ model, we address the topic of non-equilibrium relaxation of an inhomogeneous initial configuration due to quantum and thermal fluctuations. The space-time evolution of an inhomogeneous fluctuation of the condensate in the isoscalar channel decaying via the emission of pions in the medium is studied within the context of disori

Sebastian Eggert

Field theory calculations predict multiplicative logarithmic corrections to correlation functions from marginally irrelevant operators. However, for the numerically most suitable model - the spin-1/2 chain - these corrections have been controversial. In this paper, the spin-spin correlation function of the antiferromagnetic spin-1/2 chain is calculated numer

A. Pérez-Lorenzana

Using the modified factorization method employed by Mielnik for the harmonic oscillator, we show that isospectral structures associated with a second order operator $H$, can always be constructed whenever $H$ could be factored, or exist ladder operators for its eigenfunctions. Three examples are shown, and properties like completeness and integrability are d

Alberto S. Cattaneo

A generating function for cabled Wilson loops in three-dimensional BF theories is defined, and a careful study of its behavior for vanishing cosmological constant is performed. This allows an exhaustive description of the unframed knot invariants coming from the pure BF theory based on SU(2), and in particular, it proves a conjecture relating them to the Ale

A. Amengual, D. Walgraef, M. San Miguel, E. Hernandez-Garcia

We study the effect of spatial frequency-forcing on standing-wave solutions of coupled complex Ginzburg-Landau equations. The model considered describes several situations of nonlinear counterpropagating waves and also of the dynamics of polarized light waves. We show that forcing introduces spatial modulations on standing waves which remain frequency locked

E. J. Beise, J. Arrington, D. H. Beck, E. Candell

Recently, there has been considerable theoretical interest in determining strange quark contributions to hadronic matrix elements. Such matrix elements can be accessed through the nucleon&#39;s neutral weak form factors as determined in parity violating electron scattering. The SAMPLE experiment will measure the strange magnetic form factor $G_M^s$ at low mo

Ramon Rodriguez, Yutaka Hosotani

We evaluate Polyakov loops and string tension in two-dimensional QED with both massless and massive $N$-flavor fermions at zero and finite temperature. External charges, or external electric fields, induce phases in fermion masses and shift the value of the vacuum angle parameter $θ$, which in turn alters the chiral condensate. In particular, in the presence

M. G. Harris, J. Ambjorn

The model of p Ising spins coupled to 2d gravity, in the form of a sum over planar phi-cubed graphs, is studied and in particular the two-point and spin-spin correlation functions are considered. We first solve a toy model in which only a partial summation over spin configurations is performed and, using a modified geodesic distance, various correlation func

Christof Gattringer

We construct QED_2 with mass and flavor and an extra Thirring term. The vacuum expectation values are carefully decomposed into clustering states using the U(1)-axial symmetry of the considered operators and a limiting procedure. The properties of the emerging expectation functional are compared to the proposed theta-vacuum of QCD. The massive theory is boso

Andrea Pasquinucci, Kaj Roland

We study the space-time CPT properties of string theories formulated in a flat Minkowski background of even dimension. We define CPT as a world-sheet transformation acting on the vertex operators and we prove the CPT invariance of the string $S$-matrix elements. Some related issues, including the connection between spin and statistics of physical string stat

P. Di Francesco, O. Golinelli, E. Guitter

The statistics of meanders is studied in connection with the Temperley-Lieb algebra. Each (multi-component) meander corresponds to a pair of reduced elements of the algebra. The assignment of a weight $q$ per connected component of meander translates into a bilinear form on the algebra, with a Gram matrix encoding the fine structure of meander numbers. Here,

D. V. Shirkov

We begin with personal notes describing the atmosphere of &#34;Bogoliubov renormalization group&#34; birth. Then we expose the history of RG discovery in the QFT and of the RG method devising in the mid-fifties. The third part is devoted to proliferation of RG ideas into diverse parts of theoretical physics. We conclude with discussing the perspective of RG

M. Z. Iofa

An expression for energy in string-inspired dilaton gravity is obtained in canonical approach.

J. F. Gunion, A. Stange, S. Willenbrock

We review the search for the standard Higgs boson, the Higgs bosons of the supersymmetric standard model, and Higgs bosons from a variety of other models at present and future colliders.

R. Engel, A. Schiller, V. G. Serbo

The radiation caused by particles of one bunch in the collective electromagnetic field of the short oncoming bunch is studied. Quantum effects are calculated for the spectrum of radiated photons. Using this spectrum, the dependence of the relative energy loss delta on a quantum parameter kappa is dicussed. It is shown that the behaviour of delta changes cons

Robert L. Jaffe

These notes provide an introduction to polarization effects in deep inelastic processes in QCD. We emphasize recent work on transverse asymmetries, subdominant effects, and the role of polarization in fragmentation and in purely hadronic processes. After a review of kinematics and some basic tools of short distance analysis, we study the twist, helicity, chi

A. Djouadi, H. E. Haber, P. M. Zerwas

The cross sections for the multiple production of the lightest neutral Higgs boson at high--energy $e^+ e^-$ colliders are presented in the framework of the Minimal Supersymmetric extension of the Standard Model (MSSM). We consider production through Higgs--strahlung, associated production of the scalar and the pseudoscalar bosons, and the fusion mechanisms

A. D. Dolgov, S. Pastor, J. W. F. Valle

We consider the influence of non-equilibrium electronic neutrinos (and anti-neutrinos) on the neutron-to-proton ratio. These neutrinos would come from massive $ν_τ$ annihilations $\bar ν_τν_τ\rightarrow \bar ν_e ν_e$. For sufficiently large $ν_τ$ masses this new effect would strongly enhance the (n/p)-ratio, leading to a very stringent bound on the $ν_τ$ mas

Emilian Dudas

We review recent work on the structure of the fermion mass matrices in supergravity effective superstrings. They are generally given at low energy by non-trivial functions of the gauge singlet moduli fields. Interesting structures appear in particular if they are homogeneous functions of zero degree in the moduli. In this case we find Yukawa matrices very si

N. Armesto, E. G. Ferreiro, C. Pajares, Yu. M. Shabelski

The inclusion of string fusion in Dual Parton Model results in the appearance of diquark-antidiquark pairs in the sea with comparatively large Feynman-$x$. Such antidiquarks can fragment into fast antibaryons, thus increasing several times the corresponding yields in high energy $pp$ collisions for $x_F \sim 0.8 ÷0.9$. String fusion also results in an unusua

H. Holtmann, G. Levman, N. N. Nikolaev, A. Szczurek

We suggest a method of determination of the pion structure function down to x \simeq 10^{-4} based on semi-exclusive deep inelastic scattering off protons. The idea is to exploit the nonperturbative πN$ and πΔFock components of the nucleon, which contribute significantly to deep inelastic scattering and dominate the fragmentation of protons into fast neutron

Gautam Dutta, Anjan S. Joshipura

The approximate conservation of $CP$ can be naturally understood if it arises as an automatic symmetry of the renormalizable Lagrangian. We present a specific realistic example with this feature. In this example, the global Peccei-Quinn symmetry and gauge symmetries of the model make the renormalizable Lagrangian $CP$ invariant but allow non zero hierarchica

A. Edin, G. Ingelman, J. Rathsman

We discuss our model for soft colour interactions and present results on the diffractive structure function $F_2^D(\beta,x_\pom,Q^2)$ and inclusive transverse energy flows, which agree with available HERA data.

J. F. Gunion, Xiao-Gang He

We demonstrate that certain weighted moments of $t\anti t \h$ production can provide a determination of the CP nature of a light neutral Higgs boson produced and detected in this mode at the CERN LHC.

O. Philipsen, M. Teper, H. Wittig

We calculate the masses of the low-lying states with quantum numbers $J^{PC}=0^{++},1^{--}$ in the Higgs and confinement regions of the three-dimensional SU(2) Higgs model, which plays an important rôle in the description of the thermodynamic properties of the standard model at finite temperatures. We extract the masses from correlation functions of gauge-in

A. Duncan, E. Eichten, H. Thacker

A method for computing electromagnetic properties of hadrons in lattice QCD is described and preliminary numerical results are presented. The electromagnetic field is introduced dynamically, using a noncompact formulation. Employing enhanced electric charges, the dependence of the pseudoscalar meson mass on the (anti)quark charges and masses can be accuratel

Sergiu I. Vacaru, Sergiu V. Ostaf

In this work a proposal for definition of twistors on generic curved spaces is exposed and investigated. We consider superpositions of nearly autoparallel and nearly geodesic maps (nearly conformal maps, nc-maps) of (pseudo-)Riemannian spaces as generalizations of conformal transforms. We introduce the nearly autoparallel twistor equations being compatible o

A. L. Larsen, C. O. Lousto

We study the existence and stability of spherical membranes in curved spacetimes. For Dirac membranes in the Schwarzschild--de Sitter background we find that there exists an equilibrium solution. By fine--tuning the dimensionless parameter $ΛM^2,$ the static membrane can be at any position outside the black hole event horizon, even at the stretched horizon,

J. Gonzalez, F. Guinea, M. A. H. Vozmediano

We study by means of renormalization group techniques the effect that on the two-dimensional electron liquid may have the van Hove singularities observed experimentally in the copper-oxide superconductors. We find significant deviations from Fermi liquid behavior, that lead to the appearance of an unstable fixed point in the renormalization group flow of the

M. Marsili, A. J. Bray

A modified Kardar-Parisi-Zhang (KPZ) equation is introduced, and solved exactly in the infinite-range limit. In the low-noise limit the system exhibits a weak-to-strong coupling transition, rounded for non-zero noise, as a function of the KPZ non-linearity. The strong-coupling regime is characterised by a double-peaked height distribution in the stationary s

F. Marsiglio, J. P. Carbotte

We compute the single particle inverse lifetime, evaluated in the superconducting state. Within the BCS framework, the calculation can be done non-perturbatively, i.e. poles can be found well away from the real axis. We find that perturbative calculations are in good agreement with these results, even for non-zero impurity scattering. With electron-phonon sc

F. Marsiglio, J. P. Carbotte, A. Puchkov, T. Timusk

The frequency dependence of the imaginary part of the infrared conductivity is calculated for a superconductor. Sharp structure, characteristic of superconductivity with an order parameter with s-wave symmetry, appears in the BCS limit as a minimum at a frequency equal to twice the gap value. This structure scales with temperature but gets progressively smea

Hiroshi Kontani, Kosaku Yamada

In the orbitally degenerate ($J=5/2$) Periodic Anderson Model, the magnetic susceptibility is composed of both the Pauli term and the Van Vleck term, as is well known. The former is strongly enhanced by the strong correlation between $f$-electrons. But, for the latter, the influence of the strong correlation has been obscure for years. In this paper we give

Subir Sachdev, T. Senthil

The purpose of this work is to understand the zero temperature phases, and the phase transitions, of Heisenberg spin systems which can have an extensive, spontaneous magnetic moment; this entails a study of quantum transitions with an order parameter which is also a non-abelian conserved charge. To this end, we introduce and study a new class of lattice mode