August 1995 arXiv papers — page 4

Shin'ichi Nojiri, Masako Kawamura, Akio Sugamoto

We analyze the collective motion of micro-organisms in the fluid and consider the problem of the red tide. The red tide is produced by the condensation of the micro-organisms, which might be a similar phenomenon to the condensation of the strings. We propose a model of the generation of the red tide. By considering the interaction between the micro- organism

Robert Bluhm, Alan Kostelecky

We study radial wave packets produced by short-pulsed laser fields acting on Rydberg atoms, using analytical tools from supersymmetry-based quantum-defect theory. We begin with a time-dependent perturbative calculation for alkali-metal atoms, incorporating the atomic-excitation process. This provides insight into the general wave packet behavior and demonstr

Akira Iwamoto, Peter Moller, J. Rayford Nix, Hiroyuki Sagawa

A detailed understanding of complete fusion cross sections in heavy-ion collisions requires a consideration of the effects of the deformation of the projectile and target. Our aim here is to show that deformation and orientation of the colliding nuclei have a very significant effect on the fusion-barrier height and on the compactness of the touching configur

K. C. Chase, A. Z. Mekjian

We introduce for canonical fragmention models an exact method for computing expectation values which exclude the largest cluster. This method allows for the computation of the reduced multiplicity and other quantities of interest introduced by Campi, and a comparison shows that the percolation model and a recent canonical model differ mostly only in small re

Vladimir Kanovei

We prove that if $\bI$ is a p.\ o. set in a countable transitive model $\gM$ of $\ZFC$ then $\gM$ can be extended by a generic sequence of reals $\a_ı,$ $ı\in\bI,$ such that $\aleph_1^\gM$ is preserved and every $\a_ı$ is Sacks generic over $\gM[\ang{\a_\j:\j<ı}]$. The structure of the degrees of \dd\gM constructibility of reals in the extension is investiga

D. Serban, F. Lesage, V. Pasquier

We derive an exact expression for the single particle Green function in the Calogero-Sutherland model for all rational values of the coupling $β$. The calculation is based on Jack polynomial techniques and the results are given in the thermodynamical limit. Two type of intermediate states contribute. The firts one consists of a particle propagating out of th

Taichi Itoh, Toshiro Sato

Introducing a chemical potential in the functional method, we construct the effective action of QED$_3$ with a Chern-Simons term. We examine a possibility that charge condensation $\langleψ^\daggerψ\rangle$ remains nonzero at the limit of the zero chemical potential. If it happens, spontaneous magnetization occurs due to the Gauss&#39; law constraint which c

Patricia Ball, J. -M. Frere, M. Tytgat

We discuss the effect of $η$--$η&#39;$ mixing and of axial current anomalies on various decay processes. We describe the 2$γ$ decays of $η$ and $η&#39;$, the radiative decays of low-lying vector mesons as well as the decays $η\to 3π$, $J/ψ\toηγ$ and $J/ψ\toη&#39;γ$ in one unified framework, in which they are related to the electromagnetic and strong axial cu

Darwin Chang, Shih-Chang Lee, Paul Turcotte

We derive a simple analytic expression for q \bar{q}, g g -> t \bar{t} -> b W^+ \bar{b} W^- -> b \bar{l} ν_l \bar{b} l&#39; \bar{ν_{l&#39;}} for on shell intermediate states with the interference effects due to the polarizations of the t and \bar{t}. We then investigate how this effect may be measured at Tevatron or other hadronic colliders.

Robert S. Plant, Michael C. Birse

The decays $ρ^0\to 2π^+2π^-$ and $ρ^0\to 2π^0π^+π^-$ are studied using various effective Lagrangians for $π$ and $ρ$ (and in some cases $a_1$) mesons, all of which respect the approximate chiral symmetry of the strong interaction. Partial widths of the order of 1 keV or less are found in all cases. These are an order of magnitude smaller than recent predicti

Janusz Rosiek

We discuss possible manifestations of R parity breaking in the Higgs sector. We illustrate this with three examples: high-energy mono-photon production at LEP, calculation of limits on associated production of invisibly decaying Higgs bosons and discussion of non-standard scalar decays in the MSSM with broken R parity.

R. Rapp, G. Chanfray, J. Wambach

Rho meson propagation in hot hadronic matter is studied in a model with coupling to $ππ$ states. Medium modifications are induced by a change of the pion dispersion relation through collisions with nucleons and $Δ&#39;s$ in the fireball. Maintaining gauge invariance dilepton production is calculated and compared to the recent data of the CERES collaboration

T. DeGrand, A. Hasenfratz, P. Hasenfratz, F. Niedermayer

We summarize our recent work on the construction and properties of fixed point (FP) actions for lattice $SU(3)$ pure gauge theory. These actions have scale invariant instanton solutions and their spectrum is exact through 1--loop, i.e. in their physical predictions there are no $a^n$ nor $g^2 a^n$ cut--off effects for any $n$. We present a few-parameter appr

W. M. Lesame, G. F. R. Ellis, P. K. S. Dunsby

For irrotational dust the shear tensor is consistently diagonalizable with its covariant time derivative: $σ_{ab}=0=\dotσ_{ab},\; a\neq b$, if and only if the divergence of the magnetic part of the Weyl tensor vanishes: $div~H = 0$. We show here that in that case, the consistency of the Ricci constraints requires that the magnetic part of the Weyl tensor its

Peter Petersen, Guofang Wei, Rugang Ye

We prove that Riemannian metrics with a uniform weak norm can be smoothed to having arbitrarily high regularity. This generalizes all previous smoothing results. As a consequence we obtain a generalization of Gromov&#39;s almost flat manifold theorem. A uniform Betti number estimate is also obtained.

Christopher Kumar Anand

We show that a twistor construction of Hitchin and Ward can be adapted to study unitons (harmonic spheres in a unitary group). Specifically, we show that unitons are equivalent to holomorphic bundles with extra structure over a rational ruled surface with energy given by Chern class. This equivalence allows us to confirm the conjecture of Wood that unitons a

T. Wolenski, J. C. Swihart

We analyze the acoustic attenuation rate in high-$T_c$ superconductors, and find that this method offers an additional way to examine the anisotropy of the superconducting order parameter in these materials. We argue that it should be possible to distinguish the electronic contribution to the acoustic attenuation, which has a strong temperature dependence ne

J. K. Freericks, H. Monien

A strong-coupling expansion for the phase boundary of the (incompressible) Mott insulator is presented for the bose Hubbard model. Both the pure case and the disordered case are examined. Extrapolations of the series expansions provide results that are as accurate as the Monte Carlo simulations and agree with the exact solutions. The shape difference between

R. Cote, A. H. MacDonald

We study the spin-ordering and the magnon collective modes of the two-dimensional Wigner crystal state at strong magnetic fields. Our work is based on the Hartree-Fock approximation for the ground state and the time-dependent Hartree-Fock approximation for the collective modes. We find that the ground state is ferromagnetic, i.e that all spins are aligned at

Yacov Kantor, Mehran Kardar

Spatial configurations of randomly charged polymers, known as polyampholytes (PAs), are very sensitive to the overall excess charge Q. Analytical arguments, supported by Monte Carlo simulations and exact enumeration studies, lead to the following picture: For Q < Q_c = q_0 N^2 (q_0 is the elementary charge, N is the number of monomers in the polymer), the ra

Yoshihiro Nishiyama, Naomichi Hatano, Masuo Suzuki

The ground state of the four-chain Heisenberg ladder model is numerically investigated. Hidden-order correlations suitable for the system are introduced and calculated with an emphasis on the spatially isotropic point, where a corresponding material exists. The existence of a long-range hidden correlation indicates formation of a short-range RVB state in the

Shaw Kambayasi, Junzo Chihara

The density-functional theory proves that an ion-electron mixture can be treated as a one-component liquid interacting only via a {\it pairwise} interaction in the evaluation of the ion-ion radial distribution function (RDF), and provides a set of integral equations: one is an integral equation for the ion-ion RDF and another for an effective ion-ion interac

Hae-Young Kee, Jongbae Hong

The density of states and the optical conductivity of the doped Hubbard model on a Bethe lattice with infinite connectivities have been studied using an analytic variant of the Lanczos continued fraction method. The spectral weight of the gap states and the position of the chemical potential upon hole or electron doping have been studied. We argue that the s

F. N. Loreti, Y. -Z. Qian, G. M. Fuller, A. B. Balantekin

We calculate the effects of random density fluctuations on two-neutrino flavor transformations (${\nu}_{\tau(\mu)} \rightleftharpoons {\nu}_e$) in the post-core-bounce supernova environment. In particular, we follow numerically the flavor evolution of neutrino states propagating through a stochastic field of density fluctuations. We examine the approach to n

D. M. Terndrup, E. M. Sadler, R. M. Rich

This is the first in a series of papers in which we analyze medium--resolution spectra of over 400 K and M giants in Baade's Window. Our sample was selected from the proper motion study of Spaenhauer et al. [AJ, 103, 297 (1992)]. We have measured radial velocities for most of the sample, as well as line--strength indices on the system of Faber et al. [ApJS,

Y. P. Jing, G. Boerner

In this paper we investigate the velocity dispersion profiles of clusters of galaxies for seven cosmological models. One model is the SCDM model, and the others are six low-density models with the density parameter $Ω=0.1$, 0.2 or 0.3 and with or without a cosmological constant $Λ=1-Ω$. We find that the velocity dispersion profiles depend both on $Ω$ and on

S. V. H. Haugan

It is demonstrated that the 1988-90 microlensing events in image A of Q2237+0305 reported by Racine (1992) do not exclude microlensing models with very low average mass, making the source radius larger than the projected Einstein radius $η_0$ (Refsdal and Stabell 1991, 1993). This is contrary to what has been claimed by Witt and Mao (1994). Since these event

Peter L. Biermann, Richard G. Strom, Heino Falcke

Using the model of particle acceleration in shocks in stellar winds developed by Biermann (1993) and Biermann and Cassinelli (1993) we demonstrate that the nonthermal radio emission spectrum from the cataclysmic variable binary star GK Per can be interpreted consistently. We propose that the radio spectrum results from hadronic secondary electrons/positrons,

D. S. Salopek

Hamilton-Jacobi theory provides a natural starting point for a covariant description of the gravitational field. Using a spatial gradient expansion, one may solve for the phase of the wavefunction by using a line-integral in superspace. Each contour of integration corresponds to a particular choice of time-hypersurface, and each yields the same answer. In th

Gustav W. Delius, Mark D. Gould, Yao-Zhong Zhang

We construct spectral parameter dependent R-matrices for the quantized enveloping algebras of twisted affine Lie algebras. These give new solutions to the spectral parameter dependent quantum Yang-Baxter equation.

E. G. Floratos, S. Nicolis

Motivated by recent findings due to Wiegmann and Zabrodin, Faddeev and Kashaev concerning the appearence of the quantum U_q(sl(2)) symmetry in the problem of a Bloch electron on a two-dimensional magnetic lattice, we introduce a modification of the tight binding Azbel--Hofstadter Hamiltonian that is a specific spin-S Euler top and can be considered as its ``

Gustavo Burdman

The possibility of using charm meson physics to test the Standard Model (SM) is reviewed. In the case of $D^0-\bar{D}^0$ mixing, the SM contributions are carefully considered and the existence of a window for the observation of new physics is discussed. Some examples of extensions of the SM giving large mixing signals are presented. Finally, some distinctive

Smaragda Lola

We discuss the local density fluctuations which arise due to the topological defects that appear after the phase transition of light pseudo-Goldstone bosons. It has been found that in a post-inflationary universe the fluctuations of these defects at large scales may have led to galaxy formation, while being consistent with the measurements of the cosmic micr

T. P. Devereaux, D. Belitz

A theory for the effects of nonmagnetic disorder on the magnetic pair breaking rate $α$ induced by paramagnetic impurities in quasi two-dimensional superconductors is presented. Within the framework of a strong-coupling theory for disordered superconductors, we find that the disorder dependence of $α$ is determined by the disorder enhancements of both the el

M. Gluck, E. Reya, M. Stratmann, W. Vogelsang

A next-to-leading order QCD analysis of spin asymmetries and structure functions in polarized deep inelastic lepton nucleon scattering is presented within the framework of the radiative parton model. A consistent NLO formulation of the $Q^2$-evolution of polarized parton distributions yields two sets of plausible NLO spin dependent parton distributions in th

Penny D. Sackett

Gravitational lensing is one of a number of methods used to probe the distribution of dark mass in the Universe. On galactic scales, complementary techniques include the use of stellar kinematics, kinematics and morphology of the neutral gas layer, kinematics of satellites, and morphology and temperature profile of X-ray halos. These methods are compared, wi

Eric Charron, Annick Giusti-Suzor, Frederick Mies

The photodissociation of the HD+ molecular ion in intense short- pulsed linearly polarized laser fields is studied using a time- dependent wave-packet approach where molecular rotation is fully included. We show that applying a coherent superposition of the fundamental radiation with its second harmonic can lead to asymmetries in the fragment angular distrib

Alan Huckleberry, Dmitri Zaitsev

We study the actions of a Lie group $G$ by birationally extendible automorphisms on a domain $D\subset C^n$. For a large class of such domains defined by polynomial inequalities, all automorphisms are of this type. In the cases 1) $G$ has finitely many components or 2) the degree of the automorphisms is bounded, we prove that the action of $G$ is projectivel

J. Gamboa

The problem of how to put interactions in two-dimensional quantum gravity in the strong coupling regime is studied. It shows that the most general interaction consistent with this symmetry is a Liouville term that contain two parameters $(α, β)$ satisfying the algebraic relation $2β- α=2$ in order to assure the closure of the diffeomorphism algebra. The mode

S. F. King, P. L. White

We discuss the discovery reach of LEP2 for the Higgs sector of a general extension of the MSSM including a single gauge singlet field. This change introduces a new quartic Higgs boson self-coupling which can increase the masses of the CP-even states, and also allows mixing between singlet and non-singlet states which can reduce the couplings of the mass eige

Andrei A. Bytsenko, Guido Cognola, Sergio Zerbini

The first quantum corrections to the free energy for massive fields in $D$-dimensional space-times of the form $\R\times\R^+\times\M^{N-1}$, where $D=N+1$ and $\M^{N-1}$ is a constant curvature manifold, is investigated by means of the $ζ$-function regularization. It is suggested that the nature of the divergences, which are present in the thermodynamical qu

K. Ziegler

Dirac fermions on a two-dimensional lattice with disorder are considered. The Dirac mass, which controls the gap between the two bands of the fermions, is subject to random fluctuations. Another type of disorder is discussed presented by a random vector potential. It is shown that the imaginary part of the one-particle Green&#39;s function can be written as

M. R. Gaberdiel

It is shown that a WZW model corresponding to a general simple group possesses in general different quantisations which are parametrised by $Hom(π_1(G),Hom(π_1(G),U(1)))$. The quantum theories are generically neither monodromy nor modular invariant, but all the modular invariant theories of Felder et.al. are contained among them. A formula for the transforma

Teiji Kunihiro

It is shown that the renormalization group (RG) method for global analysis can be formulated in the context of the classical theory of envelopes: Several examples from partial differential equations are analyzed. The amplitude equations which are usually derived by the reductive perturbation theory are shown to be naturally derived as the equations describin

Yoshihiro Asai

Superconducting, magnetic, and charge correlation functions and dynamic spin correlation functions of the doped two-chain Hubbard model is studied with the projector Quantum Monte carlo method and Lanczos recursion method. Of the three correlation functions, the interchain singlet superconducting correlation function is the most long range. Our data is not c

Robert Bluhm, Alan Kostelecky

We outline an analytical framework for the treatment of radial Rydberg wave packets produced by short laser pulses in the absence of external electric and magnetic fields. Wave packets of this type are localized in the radial coordinates and have p-state angular distributions. We argue that they can be described by a particular analytical class of squeezed s

Y. Aharonov, S. Nussinov, S. Popescu, B. Reznik

Forces related to A-B phases between fluxons with $Φ=αΦ_0\ \ \ $ $α\ne integer$ are discussed. We find a $α^2\ln(r)$ type interaction screened on a scale $λ_s$. The forces exist only when the fluxons are actually immersed in the region with non vanishing charge density and are periodic in $α$. We briefly comment on the problem of observing such forces.

Gustav W. Delius, Mark D. Gould, Andreas Hüffmann, Yao-Zhong Zhang

Quantum Lie algebras $\qlie{g}$ are non-associative algebras which are embedded into the quantized enveloping algebras $U_q(g)$ of Drinfeld and Jimbo in the same way as ordinary Lie algebras are embedded into their enveloping algebras. The quantum Lie product on $\qlie{g}$ is induced by the quantum adjoint action of $U_q(g)$. We construct the quantum Lie alg

J. Helgesson, J. Randrup

Dispersion relations and amplitudes of collective pionic modes are derived in a pi + nucleon-hole + delta-hole model for use in transport descriptions by means of a local density approximation. It is discussed how pionic modes can be converted to real particles when penetrating the nuclear surface and how earlier treatments can be improved. When the surface

S. Gardner, C. J. Horowitz, J. Piekarewicz

We compute isospin-violating meson-nucleon coupling constants and their consequent charge-symmetry-breaking nucleon-nucleon potentials. The couplings result from evaluating matrix elements of quark currents between nucleon states in a nonrelativistic constituent quark model; the isospin violations arise from the difference in the up and down constituent quar

A. Bianconi, S. Jeschonnek, N. N. Nikolaev, B. G. Zakharov

The intrinsic single particle momentum distributions in nuclei are supposed to show a universal behavior at large momenta, dominated by short-range correlated pairs, or quasi-deuterons. We discuss whether the quasi-deuteron universality survives the final state interaction effects, which are present in the missing momentum spectra measured in $A(e,e&#39;p)$

I. B. Khriplovich, A. I. Milstein, S. S. Petrosyan

The low-energy theorem for the forward Compton scattering is generalized to the case of an arbitrary target spin. The generalization is used to calculate the corresponding contribution to the deuterium hyperfine structure. The nuclear-structure corrections are quite essential in this case due to the deuteron large size. Corrections of this type calculated he

Alexander Berkovich, Barry M. McCoy

We present generalized Rogers-Ramanujan identities which relate the fermi and bose forms of all the characters of the superconformal model $SM(2,4ν).$ In particular we show that to each bosonic form of the character there is an infinite family of distinct fermionic $q-$ series representations.

Anni Koubek

Contribution to the proceedings of Schladming 1995. A review of the form factor approach and its utilisation to determine the space of local operators of integrable massive quantum theories is given. A few applications are discussed.

David R. Morrison, M. Ronen Plesser

Superconformal sigma models with Calabi--Yau target spaces described as complete intersection subvarieties in toric varieties can be obtained as the low-energy limit of certain abelian gauge theories in two dimensions. We formulate mirror symmetry for this class of Calabi--Yau spaces as a duality in the abelian gauge theory, giving the explicit mapping relat

Ali Mostafazadeh

The ($p=2$) parabose-parafermi supersymmetry is studied in general terms. It is shown that the algebraic structure of the ($p=2$) parastatistical dynamical variables allows for (symmetry) transformations which mix the parabose and parafermi coordinate variables. The example of a simple parabose-parafermi oscillator is discussed and its symmetries investigate

S. G. Rajeev, O. T. Turgut

We describe a finite analogue of the Poisson algebra of Wilson loops in Yang-Mills theory. It is shown that this algebra arises in an apparently completely different context; as a Lie algebra of vector fields on a non-commutative space. This suggests that non-commutative geometry plays a fundamental role in the manifestly gauge invariant formulation of Yang-

Levan R. Surguladze, Mark A. Samuel

A summary of the current understanding of methods of analytical higher order perturbative computations of total cross sections and decay widths in Quantum Chromodynamics is presented. As examples, the total cross section in electron positron annihilation, the hadronic decay rates of the tau lepton and Higgs boson up to O(α_s^2) and O(α_s^3) are considered. T

Bing An Li

A mass relation of rho and a_[1} mesons has been obtained from Weinberg&#39;s first sum rule and KSFR sum rule.

Cai-Dian Lu

QCD corrections to $b \to s γ$ decay in the two Higgs doublet model are calculated from the energy scale of top quark to that of bottom. The constraints on the two Higgs doublet model from the new experimental bounds of $b\to sγ$ by CLEO and the latest top quark mass by CDF and D0 are reanalyzed. It shows that the constraints become more stringent than that

S. Aoki, K. Nagai

We have carried out a numerical simulation of a domain-wall model in $(2+1)$-dimensions, in the presence of a dynamical gauge field only in an extra dimension, corresponding to the weak coupling limit of a ( 2-dimensional ) physical gauge coupling. Using a quenched approximation we have investigated this model at $β_{s} ( = 1 / g^{2}_{s} ) =$ 0.5 ( ``symmetr

H. R. Fiebig, O. Linsuain, H. Markum, K. Rabitsch

A potential between mesons is extracted from 4-point functions within lattice gauge theory taking 2+1 dimensional QED as an example. This theory possesses confinement and dynamical fermions. The resulting meson-meson potential has a short-ranged hard repulsive core and the expected dipole-dipole forces lead to attraction at intermediate distances. Sea quarks

H. R. Fiebig, O. Linsuain, H. Markum, K. Rabitsch

A potential between mesons is extracted from 4-point functions within lattice gauge theory taking 2+1 dimensional QED as an example. This theory possesses confinement and dynamical fermions. The resulting meson-meson potential has a short-ranged hard repulsive core due to antisymmetrization. The expected dipole-dipole forces lead to attraction at intermediat

M. Kuhlen

Results on hadronic final states in deeply inelastic scattering are reviewed. They comprise jet production and its interpretation in perturbative QCD, signatures to distinguish conventional QCD dynamics from possible new features of QCD at small $x$, and measurements of inclusive charged particle production. Theoretical developments such as color dipole emis

R. D. Daniels, G. M. Shore

The effective action for QED in curved spacetime includes equivalence principle violating interactions between the electromagnetic field and the spacetime curvature. These interactions admit the possibility of superluminal yet causal photon propagation in gravitational fields. In this paper, we extend our analysis of photon propagation in gravitational backg

Kamilla Piotrkowska

Several problems in physics, in particular the averaging problem in gravity, can be described in a formalism derived from the real-space Renormalization Group (RG) methods. It is shown that the RG flow is provided by the Ricci-Hamilton equations which are thereby provided with a {\it physical} interpretation. The connection between a manifold deformation acc

A. Mazzolo, E. L. Pollock, G. Zerah

Using the polarizability of a free electron gas in a magnetic field and the Current-Density Functional Theory (CDFT) developed by Vignale and Rasolt, we derive the gradient and current corrections for the energy functional of a non-uniform electronic system in a strong magnetic field. First, we find the Tomishima-Shinjo functional by neglecting the current v

Alexander D. Mirlin

The long-time relaxation of the average conductance in a 2D mesoscopic sample is studied within the method recently suggested by Muzykantskii and Khmelnitskii and based on a saddle-point approximation to the supermatrix $σ$--model. The obtained far asymptotics is in perfect agreement with the result of renormalization group treatment by Altshuler, Kravtsov a

C. R. da Silva, F. A. Tamarit, E. M. F. Curado

We study both analytically and numerically the effects of including refractory periods in the Hopfield model for associative memory. These periods are introduced in the dynamics of the network as thresholds that depend on the state of the neuron at the previous time. Both the retrieval properties and the dynamical behaviour are analyzed.

A. J. Connolly, I. Csabai, A. S. Szalay, D. C. Koo

As a means of better understanding the evolution of optically selected galaxies we consider the distribution of galaxies within the multicolor space $U$, $B_J$, $R_F$ and $I_N$. We find that they form an almost planar distribution out to $B_J =22.5$ and $z<0.3$. The position of a galaxy within this plane is dependent on its redshift, luminosity and spectral

Eric L. N. Jensen, Robert D. Mathieu, Gary A. Fuller

We present 800 micron continuum photometry of pre-main-sequence binary stars with projected separations a_p < 150 AU in the Sco-Oph star-forming region. Combining our observations with published 1300 micron photometry, we find that binaries in Sco-Oph with 1 < a_p < 50--100 AU have lower submillimeter fluxes than wider binaries or single stars, as previously

Patrick Petitjean, Ruediger Riediger, Michael Rauch

We present a high S/N ratio optical spectrum of the bright quasar HS1700+6416. These data usefully complement the UV HST data from Vogel and Reimers (1995). We analyse the metal line systems using photo-ionization models allowing for inhomogeneities in the gas. The models are able to reproduce within a factor of two the large N(HeI)/N(HI) ratio together with

Brian D. Fields, Keith A. Olive

We derive constraints from standard (with $N_ν= 3$) BBN arising solely from two cosmologically produced nuclides, \he4 and \li7, from which the extrapolation to primordial abundances is straightforward. The abundances of D and \he3 are at present only inferred from their solar and local interstellar medium values using models of galactic chemical evolution.

Oscar J. P. Eboli

We obtain the constraints on scalar leptoquarks coming from radiative corrections to $Z$ physics. We perform a global fitting to the LEP data including the contributions of the most general effective Lagrangian for scalar leptoquarks, which exhibits the $SU(2)_L \times U(1)_Y$ gauge invariance. Our bounds on leptoquarks that couple to the top quark are much

A. Donini, G. Martinelli, C. T. Sachrajda, M. Talevi

We compute the renormalised four-fermion operator $O^{ΔS=2}$ using a non-perturbative method recently introduced for determining the renormalisation constants of generic lattice composite operators. Because of the presence of the Wilson term, $O^{ΔS=2}$ mixes with operators of different chiralities. A projection method to determine the mixing coefficients is

Joseph H. G. Fu, Clint McCrory

A geometric construction of Sullivan&#39;s Stiefel-Whitney homology classes of a real analytic variety $X$ is given by means of the conormal cycle of an embedding of $X$ in a smooth variety. We prove that the Stiefel-Whitney classes define additive natural transformations from certain constructible functions to homology. We also show that, for a complex anal

Joan Sola

We discuss possible non-standard contributions to the top-quark width, particularly the virtual effects on the standard decay $t\rightarrow W^+\,b$ within the context of the MSSM. We also place a renewed emphasis on the unconventional mode $t\rightarrow H^+\,b$ in the light of recent analyses of $Z$-boson observables. It turns out that in the region of param

Alan Kostelecky

This paper begins with some background information and a summary of results in atomic supersymmetry. The connection between the supersymmetric Coulomb and oscillator problems in arbitrary dimensions is outlined. Next, I treat the issue of finding a description of supersymmetry-based quantum-defect theory in terms of oscillators. A model with an anharmonic te

H. Awata, H. Kubo, S. Odake, J. Shiraishi

We derive a quantum deformation of the $W_N$ algebra and its quantum Miura transformation, whose singular vectors realize the Macdonald polynomials.

Yuli V. Nazarov, T. H. Stoof

We present a novel mechanism of phase-dependent electric transport in diffusive normal metal-superconductor structures. We provide a detailed theoretical and numerical analysis of recent unexplained experiments essentially explaining them.

Hisashi Kikuchi

The standard model prediction for a magnetic dipole moment of a neutrino is proportional to the neutrino mass and extremely small. It also generates a flavor-changing process, but the GIM mechanism reduces the corresponding amplitude. These properties of a neutrino magnetic moment change drastically in a degenerate electron plasma. We have shown that an elec

R. Konik, A. LeClair, G. Mussardo

Exact expressions of the boundary state and the form factors of the Ising model are used to derive differential equations for the one-point functions of the energy and magnetization operators of the model in the presence of a boundary magnetic field. We also obtain explicit formulas for the massless limit of the one-point and two-point functions of the energ

N. Nakazawa

I propose the Langevin equation for 3-geometries in the Ashtekar&#39;s formalism to describe 4D Euclidean quantum gravity, in the sense that the corresponding Fokker-Planck hamiltonian recovers the hamiltonian in 4D quantum gravity exactly. The stochastic time corresponds to the Euclidean time in the gauge, N=1 and $N^i=0$. In this approach, the time evoluti

V. B. Kuznetsov, E. K. Sklyanin

An integral operator $M$ is constructed performing a separation of variables for the 3-particle quantum Calogero-Sutherland (CS) model. Under the action of $M$ the CS eigenfunctions (Jack polynomials for the root system $A_2$) are transformed to the factorized form $ϕ(y_1)ϕ(y_2)$, where $ϕ(y)$ is a trigonometric polynomial of one variable expressed in terms

J. Finkelstein

Widom, Srivastava, and Sassaroli have published [Phys. Lett. A 203, 255 (1995)] a calculation which purports to show that &#34;future events can affect present events&#34;. In this note an error in their calculation is identified.

M. Alishahiha

In this article we construct $GL_{h}(3)$ from $GL_{q}(3)$ by a singular map. We show that there exist two singular maps which map $GL_{q}(3)$ to new quantum groups. We also construct their $R$-matrices and will show although the maps are singular but their $R$-matrices are not. Then we generalize these singular maps to the case $GL(N)$ and for $C_{n}$ series

S. Kuyucak, M. Honma, T. Otsuka

The interacting boson model is extended to describe the spectroscopy of superdeformed bands. Microscopic structure of the model in the second minimum is discussed and superdeformed bosons are introduced as the new building blocks. Solutions of a quadrupole Hamiltonian are implemented through the $1/N$ expansion method. Effects of the quadrupole parameters on

A. P. C. Malbouisson, N. F. Svaiter

We study the behavior of two diferent models at finite temperature in a $D$-dimensional spacetime. The first one is the $λφ^{4}$ model and the second one is the Gross-Neveu model. Using the one-loop approximation we show that in the $λφ^{4}$ model the thermal mass increase with the temperature while the thermal coupling constant decrese with the temperature.

A. P. C. Malbouisson, F. S. Nogueira, N. F. Svaiter

We rederive non-perturbatively the Coleman-Weinberg expression for the effective potential for massless scalar QED. Our result is not restricted to small values of the coupling constants. This shows that the Coleman- Weinberg result can be established beyond the range of validity of perturbation theory. Also, we derive it in a manifestly renormalization grou

Olaf Lechtenfeld

We analyze the BRST cohomology of the critical N=2 NSR string using chiral bosonization. Picture-changing and spectral flow is made explicit in a holomorphic field basis. The integration of fermionic and U(1) moduli is performed and yields picture- and U(1) ghost number-changing insertions into the string measure for n-point amplitudes at arbitrary genus and

Toshihiro Sasada

We investigate asymmetric orbifold models constructed from non-supersymmetric heterotic strings. We systematically classify the asymmetric orbifold models with standard embeddings and present a list of asymmetric orbifolds which are geometrically interpreted as toroidal compactifications of non-supersymmetric heterotic strings. By studying non-standard embed

Shamit Kachru, Eva Silverstein

We begin a search for nonsupersymmetric/supersymmetric dual string pairs by constructing candidate critical nonsupersymmetric strings as solitons in supersymmetric string theories. Using orbifold techniques, one can construct cosmic string solutions which lie in supersymmetric vacua but which do not fall in supermultiplets. We discuss two three-dimensional e

M. Carena, M. Quiros, C. E. M. Wagner

We generalize the analytical expressions for the two-loop leading-log neutral Higgs boson masses and mixing angles to the case of general left- and right-handed soft supersymmetry breaking stop and sbottom masses and left--right mixing mass parameters ($m_Q, m_U, m_D, A_t, A_b$). This generalization is essential for the computation of Higgs masses and coupli

J. Huston, Jeff Owens

The event structure associated with the production of massive photon pairs is studied to ${\cal O}(α^2/alpha_s)$. The cross sections for two photon and two photon plus one jet events are given. The Dalitz plot structure of events with two photons and a jet is also presented. These distributions will provide checks on our understanding of the production mecha

M. K. Banerjee, J. Milana

The paper deals with two issues. First, we explore the quantitiative importance of higher multiplets for properties of the $Δ$ decuplet in chiral perturbation theory. In particular, it is found that the lowest order one--loop contributions from the Roper octet to the decuplet masses and magnetic moments are substantial. The relevance of these results to the

Ernest Ma, Daniel Ng

The apparent excess of $Z \rightarrow b \bar b$ events at LEP may be an indication of new physics beyond the standard model. However, in either the two-Higgs-doublet model or the minimal supersymmetric standard model, any explanation would lead to an important new decay mode of the top quark and suppresses the $t \rightarrow W b$ branching fraction, which go

M. Klasen, G. Kramer

We have calculated inclusive two-jet production in low $Q^2$ $ep$ collisions at O($αα_s^2$) superimposing direct and resolved contributions. The results are compared with recent experimental data from the ZEUS collaboration at HERA.

C. W. Kim, T. H. Lee, J. Song

We study some observational consequences of a recently proposed scale--dependent cosmological model for an inhomogeneous Universe. In this model the Universe is pictured as being inside a highly dense and rapidly expanding shell with the underdense center. For nearby objects ($z \ll 1$), the linear Hubble diagram is shown to remain valid even in this model,

Ahmed Ali

A status report on the theory and phenomenology of rare radiative $B$ decays in the standard model is presented with emphasis on the measured decays $B \to X_s γ$ and $B \to K^* γ$. Standard model is in agreement with experiments though this comparison is not completely quantitative due to imprecise data and lack of the complete next-to-leading order contrib

J. G. Körner, K. Melnikov, O. I. Yakovlev

This note is devoted to the calculation of the two-loop $O(G_F {M_H}^2)$ radiative corrections to the Higgs decay width $H \to γγ$ for large values of the Higgs boson mass $M_H$ within the Minimal Standard Model. The use of the Equivalence Theorem makes it possible to reduce the problem to the consideration of the physical Higgs boson field and the Goldstone