May 1996 arXiv papers — page 6

Gaetano Fiore, Peter Schupp

Using twisted realizations of the symmetric groups, we show that Bose and Fermi statistics are compatible with transformations generated by compact quantum groups of Drinfel'd type.

Thomas G. Rizzo

The production of top quark pairs in association with a hard gluon in $e^+e^-$ collisions at the NLC provides an opportunity to probe for anomalous $t\bar tg$ couplings, \eg, the chromoelectric and chromomagnetic moments of the top. We demonstrate that an examination of the energy spectrum of the additional gluon jet can yield strong constraints on the size

Rudolph C. Hwa

Erraticity analysis of multiparticle production data is introduced as a way of extracting the maximum amount of information on self-similar fluctuations. It is presented as the next logical step to take beyond the intermittency analysis. An erraticity spectrum $e(α)$ can be determined analogous to the multifractal spectrum $f(α)$. An analytical example is pr

J. Smith, B. W. Harris

We discuss results for heavy quark correlations in next-to-leading order QCD in deep inelastic electroproduction.

V. S. Fadin, R. Fiore, M. I. Kotsky

Evaluating two-loop integrals in the transverse momentum space we obtain the trajectory of the Reggeized gluon in QCD in an explicit form in the two-loop approximation. It is presented as an expansion in powers of $(D-4)$ for the space-time dimension $D$ tending to the physical value $D=4$. As the result of a remarkable cancellation the third order pole in$D

J. Bartels, C. Ewerz, H. Lotter, M. Wuesthoff

We investigate the azimuthal distribution of quark-antiquark jets in DIS diffractive dissociation with large transverse momentum. In this kinematical region the matrix element is expressed in terms of the gluon structure function. For the transverse part of the cross section we find a $\cos(2 ϕ)$-distribution with the maximum at $ϕ= \pm π/2$, i.e.\ the jets

Stéphane Lavignac

The hypothesis of an additional abelian symmetry acting in a different way on the three families of leptons leads to interesting predictions in the neutrino sector. Contrary to what happens in most seesaw models, the structures of the Dirac and the Majorana matrices are determined without any ansatz, and the neutrino masses and mixing angles are fixed once t

J. Gluza, M. Zralek

Theoretical and experimental situation in physics of heavy neutrinos $(M_N>M_Z)$ is briefly presented. Various experimental bounds on heavy neutrino masses and mixings are shortly reviewed. Special attention is paid to possibility of detecting heavy neutrinos in future lepton linear colliders.

Thomas G. Rizzo

We examine the capability of the NLC in the $γe$ collider mode to probe the CP-conserving $γWW$ and $γZZ$ anomalous couplings through the use of the polarization asymmetry. When combined with other measurements, very strong constraints on both varieties of anomalous couplings can be obtained. [To appear in {\it Physics and Technology of the Next Linear Colli

Teruki Kamon

Various recent results of new particle searches at the Fermilab Tevatron are presented. No evidence is found for supersymmetric particles (chargino, gluino), leptoquark bosons and heavy gauge bosons in p-pbar collisions at sqrt{s} = 1.8 TeV. Excluded mass regions for each particle are determined.

H. Liebl, D. V. Vassilevich, S. Alexandrov

A generalized dilaton action is considered of which the standard dilaton black hole and spherically reduced gravity are particular cases. The Arnowitt-Deser-Misner (ADM) and the Bondi-Sachs (BS) mass are calculated. Special attention is paid to both the asymptotic conditions for the metric as well as for the reference space-time. For the latter one we sugges

Nivaldo A. Lemos

We argue that the reasonings that underlie a recent comment by Gotay and Demaret [1, gr-qc/9605025] are defective. We maintain that, contrary to what they assert, our previous papers [2,3,4] are correct and indeed disprove their conjecture that quantum cosmological singularities are predetermined on the classical level by the choice of time.

Juha Merikoski, See-Chen Ying

We present results for collective diffusion of adatoms on a stepped substrate with a submonolayer coverage. We study the combined effect of the additional binding at step edge, the Schwoebel barrier, the enhanced diffusion along step edges, and the finite coverage on diffusion as a function of step density. In particular, we examine the crossover from step--

Mark Srednicki

We show that the condition for the appearance of quantum chaos (Wigner-Dyson distribution of energy eigenvalues, gaussian-random energy eigenfunctions) in a dilute gas of many hard spheres is $λ\ll \ell$, where $λ$ is the wavelength of a typical particle and $\ell$ is the mean free path between collisions. For fermions with Fermi wavelength $λ_F \ll \ell$, t

J. E. Han, M. Alouani, D. L. Cox

We have calculated the band-$f$ hybridizations for Ce$_x$La$_{1-x}$M$_3$ compounds ($x=1$ and $x\rightarrow 0$; M=Pb, In, Sn, Pd) within the local density approximation and fed this into a non-crossing approximation for the Anderson impurity model applied to both dilute and concentrated limits. Our calculations produce crystalline electric field splittings a

G. Sartoni, A. L. Stella

Diffusion on a T fractal lattice under the influence of topological biasing fields is studied by finite size scaling methods. This allows to avoid proliferation and singularities which would arise in a renormalization group approach on infinite system as a consequence of logarithmic diffusion. Within the scheme, logarithmic diffusion is proved on the basis o

Deepak Kumar, R. Rajaraman

We study Umklapp couplings and their renormalisation group flow for electrons in a two dimensional lattice. It is shown that the effective low energy Hamiltonian involves not only forward scattering, but also considerable nonforward umklapp scattering, when the electrons fill a substantial fraction of the valence band. The behaviour of these couplings under

Bianca L. Cerchiai, Peter Schupp

An extended Hubbard model with phonons is considered on a D-dimensional lattice. The symmetries of the model are studied in various cases. It is shown that for a certain choice of the parameters a superconducting SU_q(2) holds as a true quantum symmetry - but only for D=1. In a natural basis the symmetry requires vanishing local phonon coupling; a quantum sy

M. Bijlsma, H. T. C. Stoof

Due to the observation of Bose-Einstein condensation in dilute atomic $^{87}$Rb and $^{23}$Na vapors last year, there is currently a great interest in the properties of a degenerate Bose gas. One aspect that is not yet understood is the effect of the interatomic interactions on the critical temperature of the phase transition. We present here a renormalizati

L. P. Pitaevskii

Rigorous results on the nonlinear dynamics of a dilute Bose gas with a negative scattering length in an harmonic magnetic trap are presented and sufficient conditions for the collapse of the system are formulated. By using the virial theorem for the Gross-Pitaevskii equations in an external field we analyze the temporal evolution of the mean square radius of

Naama Brenner, Shmuel Fishman

The excitation by a high frequency field of multi--level quantum systems with a slowly varying density of states is investigated. A general approach to study such systems is presented. The Floquet eigenstates are characterized on several energy scales. On a small scale, sharp universal quasi--resonances are found, whose shape is independent of the field para

J. P. M. de Carvalho, P. G. Macedo

Conditions for the establishment of small density perturbations in a self-gravitating two component fluid mixture are studied using a dynamical system approach. It is shown that besides the existence of exponentially growing and decaying modes, which are present for values of the perturbation wave-number $k$ smaller than a critical value $k_{_M}$, two other,

John Ellis, Brian D. Fields, David N. Schramm

Nearby supernova explosions may cause geological isotope anomalies via the direct deposition of debris or by cosmic-ray spallation in the earth's atmosphere. We estimate the mass of material deposited terrestrially by these two mechanisms, showing the dependence on the supernova distance. A number of radioactive isotopes are identified as possible diagno

J. K. Cannizzo

We investigate the possible role of an accretion disk instability in producing the giant outbursts seen in GRO J1744-28. Specifically, we study the global, time dependent evolution of the Lightman-Eardley instability which can develop near the inner edge of an accretion disk when the radiation pressure becomes comparable to the gas pressure. Broadly speaking

Daniel J. Eisenstein, Abraham Loeb, Edwin L. Turner

We propose a new method to measure the mass of large-scale filaments in galaxy redshift surveys. The method is based on the fact that the mass per unit length of isothermal filaments depends only on their transverse velocity dispersion. Filaments that lie perpendicular to the line of sight may therefore have their mass per unit length measured from their thi

Emory. F. Bunn, Pedro Ferreira, Joseph Silk

Large-scale cosmic microwave background anisotropies in homogeneous, globally anisotropic cosmologies are investigated. We perform a statistical analysis in which the four-year data from the Cosmic Background Explorer satellite is searched for the specific anisotropy patterns predicted by these models and thereby set definitive upper limits on the amount of

D. J. Nice, R. W. Sayer, J. H. Taylor

PSR J1518+4904 is a recently discovered 40.9~ms pulsar in an 8.6 day, moderately eccentric orbit. We have measured pulse arrival times for this pulsar over 1.4~yr at several radio frequencies, from which we have derived high precision rotational, astrometric, and orbital parameters. The upper limit for the period derivative of the pulsar, dP/dt<4x10^-20, giv

S. E. Woosley, F. X. Timmes

The possibility of making stellar mass black holes in supernovae that otherwise produce viable Type II and Ib supernova explosions is discussed and estimates given of their number in the Milky Way Galaxy. Observational diagnostics of stellar mass black hole formation are reviewed. While the equation of state sets the critical mass, fall back during the explo

C. H. Heller, I. Shlosman

We investigate the dynamical response of stellar orbits in a rotating barred galaxy potential to the perturbation by a nuclear gaseous ring. The change in 3D periodic orbit families is examined as the gas accumulates between the inner Lindblad resonances. It is found that the phase space allowable to the x2 family of orbits is substantially increased and a v

R. J. Protheroe, P. L. Biermann

We make a new estimate of the extragalactic radio background down to kHz frequencies based on the observed luminosity functions and radio spectra of normal galaxies and radio galaxies. We have constructed models for the spectra of these two classes of objects down to low frequencies based on observations of our Galaxy, other normal galaxies and radio galaxie

U. Lisenfeld, H. J. Voelk, C. Xu

This paper presents an analysis of the correlation between the far-infrared (FIR) and the radio emission of starburst galaxies. Data for interacting galaxies, many of which are undergoing a starburst, and for normal galaxies have been analysed and compared in order to test for any influence of the star-formation activity on the ratio between the FIR and the

C. Benoist, S. Maurogordato, L. N. da Costa, A. Cappi

We investigate the variation of galaxy clustering with luminosity using the recently completed SSRS2 sample. Clustering measurements based on the two-point correlation function and the variance of counts in cells reveal the existence of a strong dependence of the clustering amplitude on luminosity for galaxies brighter than L*, while no significant variation

Diego Molteni, Dongsu Ryu, Sandip K. Chakrabarti

We compare the results of numerical simulations of thin and quasi-spherical (thick) accretion flows with existing analytical solutions. We use a Lagrangian code based on the Smooth Particle Hydrodynamics (SPH) scheme and an Eulerian finite difference code based on the Total Variation Diminishing (TVD) scheme. In one-dimensional thin flows, the results of the

S. Massar

Garrison and Wright showed that upon undergoing cyclic quantum evolution a meta-stable state acquires both a geometric phase and a geometric decay probability. This is described by a complex geometric ``phase&#39;&#39; associated with the cyclic evolution of two states and is closely related to the two state formalism developed by Aharonov et al.. Applicatio

R. Schicker, A. Brenschede, K. Garrow, H. Schoen

Design studies for a second generation Dilepton Spectrometer to be built at the SIS accelerator of GSI are presented. The basic design parameters of this system are specified and the different detector components for charged particle tracking and for lepton identification are described. The geometrical acceptance for lepton pairs is given. Results on single

Yong Baek Kim

Hold temporarily. Revised version in progress

George Gasper

We present some elementary derivations of summation and transformation formulas for q-series, which are different from, and in several cases simpler or shorter than, those presented in the Gasper and Bahman [1990] &#34;Basic Hypergeometric Series&#34; book (which we will refer to as BHS), the Bailey [1935] and Slater [1966] books, and in some papers; thus pr

G. L. Kane, S. Mrenna

We argue that it is possible to make a consistent picture of FNAL data including the production and decay of gluinos and squarks. The additional cross section is several pb, about the size of that for Standard Model (SM) top quark pair production. If the stop squark mass is small enough, about half of the top quarks decay to stop squarks, and the loss of SM

I. L. Grach, I. M. Narodetskii, S. Simula

The transition form factors describing the semileptonic decays of heavy pseudoscalar mesons are investigated within a relativistic constituent quark model formulated on the light-front. For the first time, the form factors are calculated in the whole accessible kinematical region, adopting meson wave functions derived from various effective $q \bar{q}$ inter

G. L. Comer, Nathalie Deruelle, David Langlois

Inhomogeneous and anisotropic cosmologies are modeled withing the framework of scalar-tensor gravity theories. The inhomogeneities are calculated to third-order in the so-called long-wavelength iteration scheme. We write the solutions for general scalar coupling and discuss what happens to the third-order terms when the scalar-tensor solution approaches at f

Ping Xu

The main purpose of the paper is to study hyperkahler structures from the viewpoint of symplectic geometry. We introduce a notion of hypersymplectic structures which encompasses that of hyperkahler structures. Motivated by the work of Kronheimer on (co)adjoint orbits of semi-simple Lie algebras, we define hyper-Lie Poisson structures associated with a compac

Bikash. Ch. Gupta, K. K. Nanda

We have derived the expression for the specific heat by using Ginzburg-Landau (GL) theory by taking $\mid ψ\mid^{4}$ into account in the Hartree approximation. Without this term, the specific heat diverges at $T=T_{c}(B)$. It is also shown that width and shape of the transition depends on the value of $α$ and $β$, the coefficients in the GL free energy.

R. Eder, J. van den Brink, G. A. Sawatzky

Based on exact diagonalization results for small clusters we discuss the effect of inter-site Coulomb repulsion in Mott-Hubbard or charge transfer insulators. Whereas the exchange constant J for direct exchange is substantially enhanced by inter-site Coulomb interaction, that for superexchange is suppressed. The enhancement of J in the single-band models hol

I. Ichinose, T. Matsui, K. Sakakibara

We study the statistics of holons and spinons in the framework of the gauge theory. We start with the t-J model in the slave-boson formalism and use Chern-Simons gauge theory to study the statistics transmutation of quasiexcitations in the charge-spin separated phase.

Y. Fujita, J. Fukumoto, K. Okoshi

The recent {\em ASCA} results show that the iron abundance of the X-ray gas of elliptical galaxies is less than the solar abundance ($Z_{\sun}$). The observed low iron abundance is inconsistent with the predictions of the previous chemical evolution models. In order to solve this problem, we present a simple model of chemical evolution for elliptical galaxie

Paul S. Aspinwall, Mark Gross

The SO(32) heterotic string on a K3 surface is analyzed in terms of the dual theory of a type II string (or F-theory) on an elliptically fibred Calabi-Yau manifold. The results are in beautiful agreement with earlier work by Witten using very different methods. In particular, we find gauge groups of SO(32) x Sp(k) appearing at points in the moduli space iden

A. I. Davydychev, P. Osland, O. V. Tarasov

One-loop off-shell contributions to the three-gluon vertex are calculated, in arbitrary covariant gauge and in arbitrary space-time dimension, including quark-loop contributions (with massless quarks). It is shown how one can get the results for all on-shell limits of interest directly from the general off-shell expression. The corresponding general expressi

Michael C. Liu, James R. Graham, Gillian S. Wright

We present the highest spatial and spectral resolution near-infrared data to date of the $\sim~10^{13}~h^{-2}~L_{\sun}$ {\sl IRAS} source FSC 15307+3252 at $z = 0.93$, apparently the most luminous galaxy in the known Universe. Deep $K$-band (2.2 \micron) images taken in 0\farcs4 seeing at the W.\ M.\ Keck Telescope reveal three components within 2\arcsec. Th

Thomas Ackermann

In this lecture I will report on some recent progress in understanding the relation of Dirac operators on Clifford modules over an even-dimensional closed Riemannian manifold $M$\ and (euclidean) Einstein-Yang-Mills-Higgs models.

Sergio Albeverio, Shao-Ming Fei

A general way to construct chain models with certain Lie algebraic or quantum Lie algebraic symmetries is presented. These symmetric models give rise to series of integrable systems. As an example the chain models with $A_n$ symmetry and the related Temperley-Lieb algebraic structures and representations are discussed. It is shown that corresponding to these

Abhay Ashtekar, Jurek Lewandowski, Donald Marolf, José Mourão

A closed expression of the Euclidean Wilson-loop functionals is derived for pure Yang-Mills continuum theories with gauge groups $SU(N)$ and $U(1)$ and space-time topologies $\Rl^1\times\Rl^1$ and $\Rl^1\times S^1$. (For the $U(1)$ theory, we also consider the $S^1\times S^1$ topology.) The treatment is rigorous, manifestly gauge invariant, manifestly invari

E. W. Kolb, R. N. Mohapatra, V. L. Teplitz

We consider the possibility that a light sterile-neutrino species $ν_S$ can be produced by $ν_e$ scattering during the cooling of a proto-neutron star. If we parameterize the sterile neutrino production cross-section by a parameter $A$ as $σ(ν_e X\rightarrow ν_S X) = A σ(ν_e X\rightarrow ν_e X)$, where $X$ is an electron, neutron or proton, we show that $A$

Vicente Azcoiti, Victor Laliena, Xiang-Qian Luo

We propose a new method for the study of the chiral properties of the ground state in Quantum Field Theories (QFT&#39;s) which is based on the computation of the probability distribution function (p.d.f.) of the chiral condensate in the chiral limit. We show how despite of the fact that Grassmann variables cannot be simulated on a computer, an analysis of sp

Akihiro Ishibashi, Tatsuhiko Koike, Masaru Siino, Sadayoshi Kojima

Recently many people have discussed the possibility that the universe is hyperbolic and was in an inflationary phase in the early stage. Under these assumptions, it is shown that the universe cannot have compact hyperbolic time-slices. Though the universal covering space of the universe has a past Cauchy horizon and can be extended analytically beyond it, th

A. A. Golubov, F. K. Wilhelm, A. D. Zaikin

We develop a detailed microscopic analysis of electron transport in normal diffusive conductors in the presence of proximity induced superconducting correlation. We calculated the linear conductance of the system, the profile of the electric field and the densities of states. In the case of transparent metallic boundaries the temperature dependent conductanc

Sergio Albeverio, Shao-Ming Fei

An integral representation of the partition function for general $n$-dimensional Ising models with nearest or non-nearest neighbours interactions is given. The representation is used to derive some properties of the partition function. An exact solution is given in a particular case.

Rob P. Olling

In a previous paper (Olling 1995, \aj, 110, 591; astro-ph/9505002) a method was developed to determine the shapes of dark matter halos of spiral galaxies from an accurate determination of the rotation curve, the flaring of the gas layer and the velocity dispersion in the HI. Here this method is applied to the almost edge-on Scd galaxy NGC 4244 for which the

Rob P. Olling

I present sensitive high resolution HI VLA B+C+D array observations of the edge-on Scd galaxy NGC 4244. The gas layer of NGC 4244 is rather symmetric in all respects, i.e. the surface density distribution, flaring and warping, so that the rotation curve (RC) is determined accurately, despite the fact that i~90^o. The RC rises slowly in the inner 6 kpc, is ~

David Atwood, Shaouly Bar-Shalom, Gad Eilam, Amarjit Soni

The reaction $p\bar p\to t\bar bX$ is found to be rather rich in exhibiting several different types of CP asymmetries. The spin of the top quark plays an important role. Asymmetries are related to form factors arising from radiative corrections of the $tbW$ production vertex due to non-standard physics. As illustrations, effects are studied in two Higgs Doub

J. M. Evans, J. O. Madsen

We consider real forms of Lie algebras and embeddings of sl(2) which are consistent with the construction of integrable models via Hamiltonian reduction. In other words: we examine possible non-standard reality conditions for non-abelian Toda theories. We point out in particular that the usual restriction to the maximally non-compact form of the algebra is u

Andrea Cappelli, Guillermo R. Zemba

We study the partition function for the low-energy edge excitations of the incompressible electron fluid. On an annular geometry, these excitations have opposite chiralities on the two edges; thus, the partition function takes the standard form of rational conformal field theories. In particular, it is invariant under modular transformations of the toroidal

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

The approximate symmetries of Quantum ChromoDynamics in the infinite heavy quark ($Q=c,b$) mass limit ($m_Q \to \infty$) and in the chiral limit for the light quarks ($m_q \to 0,\;q=\,u,\,d,\,s$) can be used together to build up an effective chiral lagrangian for heavy and light mesons describing strong interactions among effective meson fields as well as th

Probir Roy

1. Scope and motivation 2. Lightning review of CMSSM 3. LEP 1 bounds and LEP 1.5 results 4. LEP 2 futurology 5. Bottomline

Omar Almaini, Tom Shanks, Brian J. Boyle, Richard E. Griffiths

Optical spectroscopy has enabled us to identify the optical counterparts to over 200 faint X-ray sources to a flux limit of S_(0.5-2keV)=4x10^-15 erg s^-1 cm^-2 on 5 deep ROSAT fields. Here we present a spectral analysis of all the X-ray sources to investigate claims that the average source spectra harden at faint X-ray flux. From a hardness ratio analysis w

T. Kojima

We study density correlation functions for an impenetrable Bose gas in a finite box, with Neumann or Dirichlet boundary conditions in the ground state. We derive the Fredholm minor determinant formulas for the correlation functions. In the thermodynamic limit, we express the correlation functions in terms of solutions of non-linear differential equations whi

H. A. Kastrup

The known canonical quantum theory of a spherically symmetric pure (Schwarzschild) gravitational system describes isolated black holes by plane waves exp(-iMc^2τ/\hbar) with respect to their continuous masses M and the proper time τof obsevers at spatial infinity. On the other hand Bekenstein and Mukhanov postulated discrete mass levels for such black holes

A. Djouadi, W. Hollik, C. Junger

In supersymmetric theories, the top quark can decay into its scalar partner plus a neutralino, with an appreciable rate. We calculate the $O(α_s)$ QCD corrections to this decay mode in the minimal supersymmetric extension of the Standard Model. These corrections can be either positive or negative and increase logarithmically with the gluino mass. For gluino

W. F. Chen, H. C. Lee, Z. Y. Zhu

We apply differential renormalization method to the study of three-dimensional topologically massive Yang-Mills and Chern-Simons theories. The method is especially suitable for such theories as it avoids the need for dimensional continuation of three-dimensional antisymmetric tensor and the Feynman rules for three-dimensional theories in coordinate space are

J. O. Eeg, K. Kumericki, I. Picek

We present a full account of the two-loop electroweak, two-photon mediated short-distance dispersive $K_L \toμ^+μ^-$ decay amplitude. QCD corrections change the sign of this amplitude and reduce it by an order of magnitude. Thus, the QCD-corrected two-loop amplitude represents only a small fraction (with the central value of 5 %) of the one-loop weak short-d

Chigak Itoi, Masa-Hide Kato

We study the phase transition of isotropic spin-1 models in the vicinity of the Uimin-Lai-Sutherland model by using the SU(3)_1 WZW model with certain marginal perturbations. The unstable RG trajectory by a marginally relevant perturbation generates a mass gap for the Haldane phase, and thus the universality class of the transition from the massless phase to

Chih-Lung Chou

We investigate three classes of supersymmetric models which can be obtained by breaking the chiral SU(2k+3) gauge theories with one antisymmetric tensor and 2k-1 antifundamentals. For N=3, the chiral SU(2k)$\times$SU(3)$\times$U(1) theories break supersym metry by the quantum deformations of the moduli spaces in the strong SU(2k) gauge coupling limit. For N=

Gustav W. Delius, Mark D. Gould

Quantum Lie algebras are generalizations of Lie algebras which have the quantum parameter h built into their structure. They have been defined concretely as certain submodules of the quantized enveloping algebras. On them the quantum Lie bracket is given by the quantum adjoint action. Here we define for any finite-dimensional simple complex Lie algebra g an

Ayse Humeyra Bilge

We obtain the classification of integrable equations of the form $u_t=u_{xxx}+f(t,x,u,u_x,u_{xx})$ using the formal symmetry method of Mikhailov et al [A.V.Mikhailov, A.B.Shabat and V.V.Sokolov, in {\it What is Integrability} edited by V.E. Zakharov (Springer-Verlag, Berlin 1991)]. We show that all such equations can be transformed to an integrable equation

Arkady Vaintrob

We give a very short proof of the Melvin-Morton conjecture relating the colored Jones polynomial and the Alexander polynomial of knots. The proof is based on the explicit evaluation of the corresponding weight systems on primitive elements of the Hopf algebra of chord diagrams which, in turn, follows from simple identities between four-valent tensors on the

F. Bonechi, R. Giachetti, M. A. del Olmo, E. Sorace

We study the most elementary aspects of harmonic analysis on a homogeneous space of a deformation of the two-dimensional Euclidean group, admitting generalizations to dimensions three and four, whose quantum parameter has the physical dimensions of a length. The homogeneous space is recognized as a new quantum plane and the action of the Euclidean quantum gr

Gustav W. Delius

Quantum Lie algebras are generalizations of Lie algebras whose structure constants are power series in $h$. They are derived from the quantized enveloping algebras $\uqg$. The quantum Lie bracket satisfies a generalization of antisymmetry. Representations of quantum Lie algebras are defined in terms of a generalized commutator. In this paper the recent gener

D. Haim, G. Li, Q. Ouyang, W. D. McCormick

A quasi-2-dimensional stationary spot in a disk-shaped chemical reactor is observed to bifurcate to an oscillating spot when a control parameter is increased beyond a critical value. Further increase of the control parameter leads to the collapse and disappearance of the spot. Analysis of a bistable activator-inhibitor model indicates that the observed behav

C. J. Burden, Lu Qian, C. D. Roberts, P. C. Tandy

A confining, Goldstone theorem preserving, separable Ansatz for the ladder kernel of the two-body Bethe-Salpeter equation is constructed from phenomenologically efficacious $u$, $d$ and $s$ dressed-quark propagators. The simplicity of the approach is its merit. It provides a good description of the ground-state isovector-pseudoscalar, vector and axial-vector

Bao-An Li, Wolfgang Bauer, Che Ming Ko

The question whether there is a pion transparency in 500 MeV $C(π, π^{&#39;})$ scatterings is studied using a semiclassical, hadronic transport model. The double differential cross sections of this reaction measured at LAMPF can be largely accounted for, if one uses energy-dependent, anisotropic angular distributions which are fitted to pion-nucleon scatteri

E. L. Bratkovskaya, W. Cassing, U. Mosel

We investigate the production of $e^+e^-$ pairs from $p + Be$ and nucleus-nucleus collisions from 2 GeV/A to 200 GeV/A within a covariant transport approach and focus on the dilepton angular anisotropies as a function of the dilepton invariant mass. Whereas the low mass regime yields information about the Dalitz decays of the $Δ, η$ and $ω$, above M $\approx

David Hoffman, Hermann Karcher, Fusheng Wei

We prove the existence of a complete, embedded, singly periodic minimal surface, whose quotient by vertical translations has genus one and two ends. The existence of this surface was announced in our paper in {\it Bulletin of the AMS}, 29(1):77--84, 1993. Its ends in the quotient are asymptotic to one full turn of the helicoid, and, like the helicoid, it con

Vladimir Shpilrain

We study endomorphisms of a free group of finite rank by means of their action on specific sets of elements. In particular, we prove that every endomorphism of the free group of rank 2 which preserves an automorphic orbit (i.e., acts ``like an automorphism&#34; on one particular orbit), is itself an automorphism. Then, we consider elements of a different nat

Vladimir Shpilrain

We consider IA-endomorphisms (i.e., Identical in Abelianization) of a free metabelian group of finite rank, and give a matrix characterization of their fixed points which is similar to (yet different from) the well-known characterization of eigenvectors of a linear operator in a vector space. We then use our matrix characterization to elaborate several prope

S. Penati, A. Santambrogio, D. Zanon

We consider a bosonic $\s$--model coupled to two--dimensional gravity. In the semiclassical limit, $c\rightarrow -\infty$, we compute the gravity dressing of the $\b$--functions at two--loop order in the matter fields. We find that the corrections due to the presence of dynamical gravity are {\em not} expressible simply in terms of a multiplicative factor as

T. Kojima, Y. H. Quano

Presented is an integral formula for solutions to the quantum Knizhnik--Zamolodchikov equation of level $0$ associated with the vector representation of $U_q (\widehat{ sl_n})$. This formula gives a generalization of both our previous work for $U_q (\widehat{ sl_2})$ and Smirnov&#39;s formula for form factors of $SU(n)$ chiral Gross-Neveu model.

M. Consoli, P. M. Stevenson

We respond to Tarrach&#39;s criticisms (hep-th/9511034) of our work on lambda Phi^4 theory. Tarrach does not discuss the same renormalization procedure that we do. He also relies on results from perturbation theory that are not valid. There is no &#34;infrared divergence&#34; or unphysical behaviour associated with the zero-momentum limit of our effective ac

Zhang Xiaofei, Li Jiarong

The non-Abelian Kubo formula is derived from the kinetic theory. That expression is compared with the one obtained using the eikonal for a Chern-Simons theory. The multiple time-scale method is used to solve the non-Abelian Kubo formula, and the damping rate for longitudinal color waves is computed.

F. Pisano, J. A. Silva-Sobrinho, M. D. Tonasse

It is discussed a recently proposed connection among U(1)$_{\rm em}$ electromagnetic gauge invariance and the nature of the neutrino mass terms in the framework of $\mbox {SU(3)}_C\otimes G_W \otimes {\mbox U(1)}_N$, $G_W$ = SU(3)$_L$, extensions of the Standard Model. The impossibility of that connection, also in the extended case $G_W $ = SU(4)$_L$, is dem

Joao A. N. Filipe, Alan J. Bray

The ordering dynamics of the Higgs field is studied, using techniques inspired by the study of phase ordering in condensed matter physics, as a first step to understanding the evolution of cosmic structure through the formation of topological defects in the early universe. The common feature of these different physical processes is scaling. A fully analytica

J. L. Diaz-Cruz, G. Lopez Castro, J. H. Munoz

We compute isospin corrections to the charmless semileptonic $B \rightarrow V$ transitions arising from $ρ-ω$ mixing and discuss its relevance in the determination of $V_{ub}$.

R. Huerta, M. Maya, O. G. Miranda

The meaning of $N_ν$ in the Left-Right Symmetric Model (LRSM) is discussed. In its original definition $N_ν$ is the number of neutrinos or generations of leptons, so, in the Standard Model its value is three. However the determination of $N_ν$ in experiments and in astrophysical observations is subject to different theoretical interpretations. We present arg

S. Lupia

The Modified Leading Log Approximation of QCD and the local parton hadron duality picture are shown to give a fully satisfactory description of data on charged particle energy spectra in $e^+e^-$ annihilation. The analysis of data in terms of moments points out the running of $α_s$ both at very low $cms$ energy (${\cal O}$(3 GeV)) and at very low particle en

A. Djouadi, J. Kalinowski, P. Ohmann, P. M. Zerwas

The production mechanisms and decay modes of the heavy neutral and charged Higgs bosons in the Minimal Supersymmetric Standard Model are investigated at future $e^+ e^-$ colliders in the TeV energy regime. We generate supersymmetric particle spectra by requiring the MSSM Higgs potential to produce correct radiative electroweak symmetry breaking, and we assum

G. Martinelli, C. T. Sachrajda

We discuss the evaluation of power corrections to hard scattering and decay processes for which an operator product expansion is applicable. The Wilson coefficient of the leading-twist operator is the difference of two perturbative series, each of which has a renormalon ambiguity of the same order as the power corrections themselves, but which cancel in the

M. Blasone, P. A. Henning, G. Vitiello

Field mixing transformations are studied in quantum field theory and the generator of the transformations is found to induce an SU(2) coherent structure in the vacuum state, both for bosons and for fermions. The Fock space for mixed fields is unitarily inequivalent to the Fock space of the unmixed fields in the infinite volume limit. We study neutrino mixing

S. Y. Choi, K. Hagiwara, M. S. Baek

We demonstrate in a general framework that polarized photons by backscattered laser beams of adjustable frequencies at a TeV linear $e^+e^-$ collider provide us with a very efficient mechanism to probe CP violation in two-photon collisions. CP violation in the process $γγ\rightarrow W^+W^-$ is investigated in detail with linearly polarized photon beams. Ther

Mauricio Cataldo, Patricio Salgado

We obtain a two-parameter set of solutions, which represents a spherically symmetric space-time with a superposition of a neutral fluid and an electric field. The electromagnetic four-potential of this Einstein-Maxwell space-time is taken in the form A=(q/n)(r^n)dt, when n=/0 and A=q*ln(r)dt, when n=0 (where q and n are arbitrary constants)

C. Alvarez, R. B. Mann

We consider possible tests of the Einstein Equivalence Principle for physical systems in which quantum-mechanical vacuum energies cannot be neglected. Specific tests include a search for the manifestation of non-metric effects in Lamb-shift transitions of Hydrogenic atoms and in anomalous magnetic moments of massive leptons. We discuss how current experiment

J Schray, T Dray, C A Manogue, R W Tucker

We examine some of the subtleties inherent in formulating a theory of spinors on a manifold with a smooth degenerate metric. We concentrate on the case where the metric is singular on a hypersurface that partitions the manifold into Lorentzian and Euclidean domains. We introduce the notion of a complex spinor fibration to make precise the meaning of continui

T Dereli, J Schray, Robin W Tucker

We demonstrate that the left (and right) invariant Maurer-Cartan forms for any semi-simple Lie group enable one to construct solutions of the Yang-Mills equations on the group manifold equipped with the natural Cartan-Killing metric. For the unitary unimodular groups the Yang-Mills action integral is finite for such solutions. This is explicitly exhibited fo