March 1998 arXiv papers — page 4

M. A. Lledo, V. S. V. Varadarajan

Poisson-Lie target space duality is a framework where duality transformations are properly defined. In this letter we investigate the pair of sigma models defined by the double SO(3,1) in the Iwasawa decomposition.

F. S. Navarra, M. Nielsen

The $NDΛ_c$ coupling constant is evaluated in a full QCD sum rule calculation. We study the Borel sum rule for the three point function of one pseudoscalar one nucleon and one $Λ_c$ current up to order seven in the operator product expansion. The Borel transform is performed with respect to the nucleon and $Λ_c$ momenta, which are taken to be equal, whereas

P. Q. Hung

An alternative to the famous see-saw mechanism is proposed to explain the smallness of the neutrino masses (if present). This model involves a fourth family which mixes very little with the other three. It contains one heavy neutrino (mN > mZ /2) and three very light neutrinos whose masses are radiatively induced. In contrast with the see-saw mechanism, all

S. F. King, G. G. Ross

We examine the infra-red structure of soft supersymmetry breaking masses of the squarks and sleptons in supersymmetric (SUSY) strong unification schemes where $α_{GUT}\sim 0.2-1$. We show that combinations of soft masses approach fixed points which leads to very simple predictions for soft masses at the intermediate scale. The assumption that the high energy

Charanjit S. Aulakh

A fresh analysis of Left right symmetric supersymmetric models in the generic case where the scale of right handed symmetry breaking $M_R >> M_{SUSY}\sim M_W$ is presented. We conclude that the low energy effective theory for such models is essentially the MSSM with R parity (and therefore B,L symmetry) but the spectrum includes heavy conjugate neutrino supe

Yoshio Koide

Recent development of the universal seesaw mass matrix model is reviewed. The model was proposed in order to explain why quark and lepton masses are so small compared with the electroweak scale Λ_L =<ϕ_L^0>=174 GeV. However, the recently observed top-quark mass m_t\simeq 180 GeV seems to make an objection against the seesaw mass picture. For this problem, it

Chen Jisheng Li Jiarong

The derivative expansion method has been used to solve the semiclassical kinetic equations of quark-gluon plasma (QGP). The nonlinear spatial damping rate, the imaginary part of the wave vector, for the longitudinal secondary color waves in the long wavelength limit has been calculated numerically.

A. H. Hoang

The bottom quark pole mass $M_b$ is determined using a sum rule which relates the masses and the electronic decay widths of the $Υ$ mesons to large $n$ moments of the vacuum polarization function calculated from nonrelativistic quantum chromodynamics. The complete set of next-to-next-to-leading order (i.e. ${\cal{O}}(α_s^2, α_s v, v^2)$ where $v$ is the bott

Dmitri Bardin, Giampiero Passarino

A critical assessment is given of the comparison between the new versions of the programs TOPAZ0 40i and ZFITTER 510. The relevance for precision calculations around the $\zb$ resonance is briefly discussed. << more references added >>

F. A. Gareev, M. Yu. Barabanov, G. S. Kazacha

Elementary particle resonances have been systematically analysed using all available experimental data. We have come to the conclusion that the resonance decay prodact momenta and masses of resonances are to be quantized. The Balmer- like formula for masses of elementary particle resonances was obtained. These observations allow us to formulate a strategy of

V. Azcoiti, G. Di Carlo, E. Follana

We introduce a lattice model with local U(1) gauge symmetry which incorporates explicit frustration in d >2. The form of the action is inspired from the loop expansion of the fermionic determinant in standard lattice QED. We study through numerical simulations the phase diagram of the model, revealing the existence of a frustrated (antiferromagnetic) phase f

L. Giusti, M. L. Paciello, S. Petrarca, B. Taglienti

We address the problem of defining the gauge four-potential on the lattice, in terms of the natural link variables. Different regularized definitions are shown, through non perturbative numerical computation, to converge towards the same continuum renormalized limit.

Robert M. Wald

I briefly review some of the recent progress in quantum field theory in curved spacetime and other aspects of semiclassical gravity, as reported at the D3 Workshop at GR15.

Philippos Papadopoulos, Jose A. Font

Despite the fact that the Schwarzschild and Kerr solutions for the Einstein equations, when written in standard Schwarzschild and Boyer-Lindquist coordinates, present coordinate singularities, all numerical studies of accretion flows onto collapsed objects have been widely using them over the years. This approach introduces conceptual and practical complicat

Jun-ichirou Koga, Kei-ichi Maeda

We analyze black hole thermodynamics in a generalized theory of gravity whose Lagrangian is an arbitrary function of the metric, the Ricci tensor and a scalar field. We can convert the theory into the Einstein frame via a &#34;Legendre&#34; transformation or a conformal transformation. We calculate thermodynamical variables both in the original frame and in

Pio J. Arias

The distinct models that describe spin 1 and 2 massive excitations in 2+1 dimensions are analized, showing their equivalence (between models of same spin) and analogies (between models of different spin). Topics as spontaneous symmetry breaking and anyonic behaviour, in these models, are analized. A massive gravity model is introduced. This model is diffeomo

P. Punyindu, S. Das Sarma

We show that a multiple hit noise reduction technique involving the acceptance of only a fraction of the allowed atomistic deposition events could, by significantly suppressing the formation of high steps and deep grooves, greatly facilitate the identification of the universality class of limited mobility discrete solid-on-solid conserved nonequilibrium mode

J. Jaklic, P. Prelovsek

We review recent results for the properties of doped antiferromagnets, obtained by the numerical analysis of the planar t-J model using the novel finite-temperature Lanczos method for small correlated systems. First we shortly summarize our present understanding of anomalous normal-state properties of cuprates, and present the electronic phase diagram, pheno

Laurent J Lewis, Normand Mousseau

Tight-binding (TB) molecular dynamics (MD) has emerged as a powerful method for investigating the atomic-scale structure of materials --- in particular the interplay between structural and electronic properties --- bridging the gap between empirical methods which, while fast and efficient, lack transferability, and ab initio approaches which, because of exce

V. G. Benza, B. Cardinetti

We study a two-dimensional spinless particle in a disordered gaussian magnetic field with short time fluctuations, by means of the evolution equation for the density matrix $<x^{(1)} |\hatρ (t)| x^{(2)}>$; in this description the two coordinates are associated with the retarded and advanced paths respectively. The static part of the vector potential correlat

S. -R. Eric Yang, J. H. Han

We have investigated the electron occupation number of the edge of a quantum Hall (QH) droplet at $ν=1/2$ using exact diagonalization technique and composite fermion trial wavefunction. We find that the electron occupation numbers near the edge obey a scaling behavior. The scaling result indicates the existence of a well-defined edge corresponding to the rad

Ruben Weht, W. E. Pickett

The intermetallic compound Fe2VAl looks non-metallic in transport and strongly metallic in thermodynamic and photoemission data. It has in its band structure a highly differentiated set of valence and conduction bands leading to a semimetallic system with a very low density of carriers. The pseudogap itself is due to interaction of Al states with the d orbit

Inès Safi, H. J. Schulz

We investigate a one--dimensional wire of interacting electrons connected to one--dimensional noninteracting leads in the absence and in the presence of a backscattering potential. The ballistic wire separates the charge and spin parts of an incident electron even in the noninteracting leads. The Fourier transform of nonlocal correlation functions are comput

G. Roepke, A. Schnell, P. Schuck, P. Nozieres

Four-particle correlations in fermion systems at finite temperatures are investigated with special attention to the formation of a condensate. Instead of the instability of the normal state with respect to the onset of pairing described by the Gorkov equation, a new equation is obtained which describes the onset of quartetting. Within a model calculation for

I. Borukhov, D. Andelman, H. Orland

The behavior of polyelectrolytes between charged surfaces immersed in semi-dilute solutions is investigated theoretically. A continuum mean field approach is used for calculating numerically concentration profiles between two electrodes held at a constant potential. A generalized contact theorem relates the inter-surface forces to the concentration profiles.

Maksim Skorobogatiy, Hong Guo, Martin J. Zuckermann

We have considered the problem of protein design based on a model where the contact energy between amino acid residues is fitted phenomenologically using the Miyazawa--Jernigan matrix. Due to the simple form of the contact energy function, an analytical prescription is found which allows us to design energetically stable sequences for fixed amino acid residu

A. Ramsak, T. Rejec, J. H. Jefferson

The effect of deconfinement due to finite band offsets on transport through quantum wires with two constrictions is investigated. It is shown that the increase in resonance linewidth becomes increasingly important as the size is reduced and ultimately places an upper limit on the energy (temperature) scale for which resonances may be observed.

E. Celeghini

Usual quantum statistics is written in Fock space but it is not an algebraic theory. We show that at a deeper level it can be algebraically formalized defining the different statistics as (multi-mode) coherent states of the appropriate (but different from the usual ones) Lie-Hopf groups. The traditional connection between groups and statistics, established i

H. Diamant, D. Andelman

We present a model treating the kinetics of adsorption of soluble surface-active molecules at the interface between an aqueous solution and another fluid phase. The model accounts for both the diffusive transport inside the solution and the kinetics taking place at the interface using a free-energy formulation. In addition, it offers a general method of calc

M. P. Blencowe

We investigate the phononic energy transport properties of mesoscopic, suspended dielectric wires. The Landauer formula for the thermal conductance is derived and its universal aspects discussed. We then determine the variance of the energy current in the presence of a steady state current flow. In the final part, some initial results are presented concernin

Yu. E. Lozovik, A. V. Poushnov

The unusual two-photon emission by Bose-condensed excitons caused by simultaneous recombination of two excitons with opposite momenta leaving the occupation numbers of excitonic states with momenta $p nonequal to 0$ unchanged (below coherent two-exciton recombination) is investigated. Raman scattering accompanied by the analogous two-exciton recombination (o

Ioan Kosztin, Simon Kos, Michael Stone, Anthony J. Leggett

A new method for calculating the free energy of an inhomogeneous superconductor is presented. This method is based on the quasiclassical limit (or Andreev approximation) of the Bogoliubov-de Gennes (or wave function) formulation of the theory of weakly coupled superconductors. The method is applicable to any pure bulk superconductor described by a pair poten

M. T. Batchelor, B. I. Henry, S. D. Watt

We investigate a class of stochastic growth models involving competition between two phases in which one of the phases has a competitive advantage. The equilibrium populations of the competing phases are calculated using a mean field analysis. Regression probabilities for the extinction of the advantaged phase are calculated in a leading order approximation.

Piero Olla, Paolo Paradisi

Some techniques for the study of intermittency by means of wavelet transforms, are presented on an example of synthetic turbulent signal. Several features of the turbulent field, that cannot be probed looking at standard structure function scaling, become accessible in this way. The concept of a directly measurable intermittency scale, distinct from the scal

Toshiyuki Gotoh, Robert H. Kraichnan

Burgers turbulence supported by white-in-time random forcing at low wavenumbers is studied analytically and by computer simulation. It is concluded that the probability density Q of velocity gradient displays four asymptotic regimes at very large Reynolds number: (A) a region of large positive gradient where Q decays rapidly (reduction of gradient by stretch

Shunichi Tsuge, Burtsitsig Bai

A six-dimensional Navier-Stokes equation derived by one of the authors(ST) is solved for a turbulent mixing layer to demonstrate that it has a solitary wave solution. Turbulence intensities and Reynolds&#39; stress are calculated using this solution, showing satisfactory agreement with experiments although no emperical constants are involved in the theory.

K. H. Andersen, T. Bohr, M. H. Jensen, P. Olesen

We study a &#34;burst&#34; event, i. e. the evolution of an initial condition having support only in a finite interval of k-space, in the continuum shell model due to Parisi. We show that the continuum equation without forcing or dissipation can be explicitly written in characteristic form and that the right and left moving parts can be solved exactly. When

Luis C. Ho

I review the status of observational determinations of central masses in nearby galactic nuclei. Results from a variety of techniques are summarized, including ground-based and space-based optical spectroscopy, radio VLBI measurements of luminous water vapor masers, and variability monitoring studies of active galactic nuclei. I will also discuss recent X-ra

S. Rauzy, V. G. Gurzadyan

The problem of the relative motion of the substructures of the Local Group of galaxies revealed via S-tree method, as well as of the velocity of the Local Group itself, is considered. The existence of statistically significant bulk flow of the Milky Way subsystem is shown via 3D reconstruction procedure, which uses the information on the radial velocities of

D. Dal Fiume, M. Orlandini, F. Frontera, S. Del Sordo

BeppoSAX observed several galactic binary X-ray pulsars during the Science Verification Phase and in the first year of the regular program. The complex emission spectra of these sources are an ideal target for the BeppoSAX instrumentation, that can measure the emission spectra in an unprecedented broad energy band. Using this capability of BeppoSAX a detaile

S. Campana, L. Stella, S. Mereghetti, M. Colpi

We report on the March-April 1997 BeppoSAX observations of Aql X-1, the first to monitor the evolution of the spectral and time variability properties of a neutron star soft X-ray transient from the outburst decay to quiescence. We observed a fast X-ray flux decay, which brought the source luminosity from ~10^36 to ~10^{33} erg/s in less than 10 days. The X-

E. Antonello

The shape of the radial velocity and light curves of 24 long-period (30 < P < 134 days) Cepheids in the Magellanic Clouds shows a progression with the period. The sequences of the radial velocity and light curves are based only on a small sample of stars; however, evident changes of the shape can be seen in Cepheids with period between 90 and 134 d. The Four

Vassiliki Kalogera, Ulrich Kolb, Andrew King

We consider the formation of low-mass X-ray binaries containing accreting neutron stars via the helium-star supernova channel. The predicted relative number of short-period transients provides a sensitive test of the input physics in this process. We investigate the effect of varying mean kick velocities, orbital angular momentum loss efficiencies, and commo

Bernard de Wit, Kasper Peeters, Jan Plefka

We construct part of the superspace vielbein and tensor gauge field in terms of the component fields of 11-dimensional on-shell supergravity. The result can be utilized to describe supermembranes and corresponding matrix models for Dirichlet particles in nontrivial supergravity backgrounds to second order in anticommuting coordinates. We exhibit the kappa-in

D. Belitz, F. Evers, T. R. Kirkpatrick

In a recent paper (cond-mat/9703164) a general field-theoretical description of many-fermion systems with short-ranged interactions has been developed. Here we extend this theory to the case of disordered electrons interacting via a Coulomb potential. A detailed discussion is given of the Ward identity that controls the soft modes in the system, and the gene

Zurab Kakushadze

Extending the recent work in hep-th/9803076, we consider string perturbative expansion in the presence of D-branes and orientifold planes imbedded in orbifolded space-time. In the $α&#39;\to 0$ limit the weak coupling string perturbative expansion maps to `t Hooft&#39;s large N expansion. We focus on four dimensional ${\cal N}=1,2,4$ supersymmetric theories,

Emidio Gabrielli, Uri Sarid

We calculate the inclusive branching ratio for B--> X_s gamma, the inclusive branching ratios and asymmetries for B--> X_s l+ l- and the anomalous magnetic moment g-2 of the muon, within a minimal gauge-mediated SUSY-breaking model which naturally generates a large ratio tan(beta) of Higgs field vacuum expectation values. These predictions are highly correla

Michael Finkelberg, Alexander Kuznetsov, Nikita Markarian, Ivan Mirković

Let $G$ be a semisimple complex Lie group with a Borel subgroup $B$. Let $X=G/B$ be the flag manifold of $G$. Let $C=P^1\ni\infty$ be the projective line. Let $α\in H_2(X,{\Bbb Z})$. The moduli space of $G$-monopoles of topological charge $α$ (see e.g. [Jarvis]) is naturally identified with the space $M_b(X,α)$ of based maps from $(C,\infty)$ to $(X,B)$ of d

Faez Miri, Ramin Golestanian

A path integral formulation is developed to study the spectrum of radiation from a perfectly reflecting (conducting) surface. It allows us to study arbitrary deformations in space and time. The spectrum is calculated to second order in the height function. For a harmonic traveling wave on the surface, we find many different regimes in which the radiation is

Saul A. Teukolsky

Neutron stars in binary orbit emit gravitational waves and spiral slowly together. During this inspiral, they are expected to have very little vorticity. It is in fact a good approximation to treat the system as having zero vorticity, i.e., as irrotational. Because the orbital period is much shorter than the radiation reaction time scale, it is also an excel

M. R. Matthews, D. S. Hall, D. S. Jin, J. R. Ensher

A two-photon transition is used to convert an arbitrary fraction of the 87Rb atoms in a |F=1,m_f=-1> condensate to the |F=2,m_f=1> state. Transferring the entire population imposes a discontinuous change on the condensate&#39;s mean-field repulsion, which leaves a residual ringing in the condensate width. A calculation based on Gross-Pitaevskii theory agrees

Eric L. N. Jensen, David H. Cohen, Ralph Neuhauser

We present new observations of the isolated young stars HD 98800 and CD-33_7795. Pointed ROSAT observations show that their X-ray properties, including X-ray luminosity and variability, are consistent with those of pre-main-sequence (PMS) stars. These observations do not reveal any additional PMS candidates in 40&#39; fields centered on HD 98800 and CD-33_77

Dominic Lee, Georgios Metikas

We consider various ways of treating the infrared divergence which appears in the dynamically generated fermion mass, when the transverse part of the photon propagator in N flavour $QED_{3}$ at finite temperature is included in the Matsubara formalism. This divergence is likely to be an artefact of taking into account only the leading order term in the $1 \o

Mu-In Park, Young-Jai Park

A new gauge invariant formulation of the relativistic scalar field interacting with Chern-Simons gauge fields is considered. This formulation is consistent with the gauge fixed formulation. Furthermore we find that canonical (Noether) Poincar\'e generators are not gauge invariant even on the constraints surface and do not satisfy the (classical) Poincar\'e a

A. D. Martin, R. G. Roberts, W. J. Stirling, R. S. Thorne

We present a new analysis of parton distributions of the proton. This incorporates a wide range of new data, an improved treatment of heavy flavours and a re-examination of prompt photon production. The new set (MRST) shows systematic differences from previous sets of partons which can be identified with particular features of the new data and with improveme

A. Perez Madrid, T. Alarcon, J. M. G. Vilar, J. M. Rubi

We present a mesoscopic approach to analyze the dynamics of a single magnetic dipole under the influence of an oscillating magnetic field, based on the formulation of a Fokker-Planck equation. The dissipated power and the viscosity of a suspension of such magnetic dipoles are calculated from non-equilibrium thermodynamics of magnetized systems. By means of t

B. M. Zupnik

A modification of the harmonic superfield formalism in $D=4, N=2$ supergravity using a subsidiary condition of covariance under the background supersymmetry with a central charge ($B$-covariance) is considered. Conservation of analyticity together with the $B$-covariance leads to the appearance of linear gravitational superfields. Analytic prepotentials aris

Pavol Severa

We show for any oriented surface, possibly with a boundary, how to generalize Kramers-Wannier duality to the world of quantum groups. The generalization is motivated by quantization of Poisson-Lie T-duality from the string theory. Cohomologies with quantum coefficients are defined for surfaces and their meaning is revealed. They are functorial with respect t

Shun-Qing Shen, Z. D. Wang

We investigate the ground state properties of electronic models for doped manganites and nickelates. An effective t - J like Hamiltonian is derived from the case of strong Hund coupling between the conduction electrons and localized spins by means of the projection technique. An attractive interaction for conduction electrons and an anti-ferromagnetic coupli

Shijong Ryang

In the Matrix theories compactified on the $d$ dimensional torus with $d = 5, 6, 7$ which are described by the theories of D$d$-branes in the type IIA or IIB theory on the $d$ dimensional dual torus we analyze the BPS bound states of the background D$d$-brane with other objects by taking the matrix theory limit. Through the Nahm duality transformation the fl

Anupam Garg

Decoherence is studied in an attractive proposal for an actual implementation of a quantum computer based on trapped ions. Emphasis is placed on the decoherence arising from the vibrational motion of the ions, which is compared with that due to spontaneous emission from excited states of the ions. The calculation is made tractable by exploiting the vast diff

Luca Salasnich

We study the classical and quantum perturbation theory for two non--resonant oscillators coupled by a nonlinear quartic interaction. In particular we analyze the question of quantum corrections to the torus quantization of the classical perturbation theory (semiclassical mechanics). We obtain up to the second order of perturbation theory an explicit analytic

Salvatore De Martino, Silvio De Siena, F. Illuminati

Building on a model recently proposed by F. Calogero, we postulate the existence of a coherent, long--range universal tremor affecting any stable and confined classical dynamical system. Deriving the characteristic fluctuative unit of action for each classical interaction, we obtain in all cases its numerical coincidence with the Planck action constant. We t

A. Vercin

The metaplectic covariance for all forms of the Weyl-Wigner-Groenewold-Moyal quantization is established with different realizations of the inhomogeneous symplectic algebra. Beyond that, in its most general form $W_{\infty}$ -covariance of this quantization scheme is investigated, and explicit expressions for the quantum-deformed Hamiltonian vector fields ar

J. I. Latorre, P. Pascual, R. Tarrach

Optimal and finite positive operator valued measurements on a finite number $N$ of identically prepared systems have been presented recently. With physical realization in mind we propose here optimal and minimal generalized quantum measurements for two-level systems. We explicitly construct them up to N=7 and verify that they are minimal up to N=5. We finall

Paul J. Freitas

Examination of the Einstein energy-momentum relationship suggests that simple unbound forms of matter exist in a four-dimensional Euclidean space. Position, momentum, velocity, and other vector quantities can be expressed as Euclidean four-vectors, with the magnitude of the velocity vector having a constant value, the speed of light. We see that charge may b

Andrew E. Chubykalo, Stoyan J. Vlaev

We considered the electromagnetic field of a charge moving with a constant acceleration along an axis. We found that this field obtained from the Liénard-Wiechert potentials does not satisfy Maxwell equations if one considers exclusively a retarded interaction (i.e. pure implicit dependence this field on time). We show that if and only if one takes into acco

Salvatore De Martino, Silvio De Siena, Fabrizio Illuminati

A recent proposal (see quant-ph/9803068) to simulate semiclassical corrections to classical dynamics by suitable classical stochastic fluctuations is applied to the specific instance of charged beam dynamics in particle accelerators. The resulting picture is that the collective beam dynamics, at the leading semiclassical order in Planck constant can be descr

Itzhak Tserruya

The highlights of Quark Matter &#39;97 on dileptons and direct photons are presented.

J. J. McDonald, R. Nabben, M. Neumann, H. Schneider

In this paper, we consider matrices whose inverses are tridiagonal Z--matrices. Based on a characterization of symmetric tridiagonal matrices by Gantmacher and Krein, we show that a matrix is the inverse of a tridiagonal Z--matrix if and only if, up to a positive scaling of the rows, it is the Hadamard product of a so called weak type $\D$ matrix and a flipp

Shicheng Wang, Ying-Qing Wu, Qing Zhou

Given a pair of curves C_1 and C_2 on a hyperbolic surface F, when does there exist a pseudo-Anosov map sending one to another? More generally, one may ask the same question for C_i to be sets of disjoint simple closed curves. We will give necessary and sufficient conditions for the existence of such maps.

Ann Maes, Alfons Van Daele

We have written down a set of notes on compact quantum groups from which all the different aspects can be learned in an easy way and such that a lot of insight can be obtained without too much effort. Compact quantum groups have been studied by several authors, from different points of view. The difference lies mainly in the choice of the axioms and conseque

Frederic Campana, Thomas Peternell

We study holomorphic 2-forms on projective (or compact Kaehler) threefolds not of general type and prove that in almost all cases the 2-form is created by some standard process. This means roughly that every 2-form is induced by a meromorphic map to a surface, a torus or a symplectic manifold. If the 2-form has only finitely many zeroes, more precise results

Yukari Ito, Hiraku Nakajima

Let $G$ be a nontrivial finite subgroup of $\SL_n(\C)$. Suppose that the quotient singularity $\C^n/G$ has a crepant resolution $π\colon X\to \C^n/G$ (i.e. $K_X = \shfO_X$). There is a slightly imprecise conjecture, called the McKay correspondence, stating that there is a relation between the Grothendieck group (or (co)homology group) of $X$ and the represen

Sergei Khoroshkin, Vadim Schechtman

The aim of this note is a combinatorial description of a category of $D$-modules over an affine space, smooth along the stratification defined by an arrangement of hyperplanes. These $D$-modules are assumed to satisfy certain non-resonance condition. The main result, see Theorem 4.1, generalizes [S.Khoroshkin, $D$-modules over arrangements of hyperplanes, Co

S. E. Konstein

The associative superalgebra of observables of 3-particle Calogero model giving all wavefunctions of the model via standard Fock procedure has 2 independent supertraces. It is shown here that when the coupling constant νis equal to n+1/3, n-1/3 or n+1/2 for any integer n the existence of 2 independent supertraces leads to existence of nontrivial two-sided id

M. Pernici, M. Raciti

We derive the Gell-Mann and Low renormalization group equation in the Wilsonian approach to renormalization of massless $gϕ^4$ in four dimensions, as a particular case of a non-linear equation satisfied at any scale by the Wilsonian effective action. We give an exact expression for the $β$ and $γ_ϕ$ functions in terms of the Wilsonian effective action at the

Jaume Garriga

The singularity in Hawking and Turok&#39;s model (hep-th/9802030) of open inflation has some appealing properties. We suggest that this singularity should be regularized with matter. The singular instanton can then be obtained as the limit of a family of ``no-boundary&#39;&#39; solutions where both the geometry and the scalar field are regular. Using this pr

A. Pashnev, M. Tsulaia

The BRST approach is applied to the description of irreducible massless higher spins representations of the Poincare group in arbitrary dimensions. The total system of constraints in such theory includes both the first and the second class constraints. The corresponding nilpotent BRST charge contains terms up to the seventh degree in ghosts.

G W Gibbons

Branes may be approximated semi-classically by solutions of supergravity theories with event and Cauchy horizons. I suggest that if one wishes to avoid singularities and to capture accurately some of the properties of branes then these classical spacetimes must be identified so as to render them periodic in time.

D. Freed, J. A. Harvey, R. Minasian, G. Moore

We study gravitational anomalies for fivebranes in M theory. We show that an apparent anomaly in diffeomorphisms acting on the normal bundle is cancelled by a careful treatment of the M theory Chern-Simons coupling in the presence of fivebranes. One interesting aspect of our treatment is the way in which a magnetic object (the fivebrane) is smoothed out thro

A. S. Mueller, A. C. Kalloniatis, H. -C. Pauli

We study the role of bosonic zero modes in light-cone quantisation on the invariant mass spectrum for the simplified setting of two-dimensional SU(2) Yang-Mills theory coupled to massive scalar adjoint matter. Specifically, we use discretised light-cone quantisation where the momentum modes become discrete. Two types of zero momentum mode appear -- constrain

G W Gibbons

A BIon may be defined as a finite energy solution of a non-linear field theory with distributional sources. By contrast a soliton is usually defined to have no sources. I show how harmonic coordinates map the exteriors of the topologically and causally non-trivial spacetimes of extreme p-branes to BIonic solutions of the Einstein equations in a topologically

J. S. Dowker

We shed doubt on a commonly used manipulation in computing the partition function for a matrix valued operator together with its attendant invocation of the multiplicative anomaly.

T. Krajewski

Using noncommutative geometry, the standard tools of differential geometry can be extended to a broad class of spaces whose coordinates are noncommuting operators acting on a Hilbert space. In the simplest case of coordinates being matrix valued functions on space-time, the standard model of particle physics can be reconstructed out of a few basic principles

J. C. Montero, V. Pleitez, M. C. Rodriguez

We consider, in the electroweak standard model context, several left-right asymmetries in $μe$ elastic scattering at fixed target and collider experiments. For the former case, we show that the muon mass effects are important in a wide energy range. We also show that these asymmetries are sensitive to the electroweak mixing angle $θ_W$. The effect of an extr

J. Dias de Deus, F. O. Duraes

We discuss the possibility of the asymmetry in $D^-/D^+$ production, from $π^-$ beams, being a direct consequence of the properties of the light quark fragmentation function into heavy mesons. The main features of the asymmetry, as a function of $x_F$, are easily described. An integrated sum-rule for the $D^-, D^+$ difference, is presented. Predictions for t

Yuichiro Kiyo, Jiro Kodaira, Hiroshi Tochimura

The double logarithmic terms $α_{s} \ln^{2}x $ are important to predict precisely the small $x$ behavior of the spin structure function $g_{1}$. We numerically analyze the evolution of the flavor non-singlet $g_{1}$ including the all-order resummed effect of these terms. It is pointed out that the next-to-leading logarithmic corrections produce an unexpected

George Japaridze, Avto Tkabladze

We investigate $J/ψ$ production at a Photon Linear Collider (PLC) in the framework of NRQCD factorization approach. It was shown that color octet contribution is dominating in charmonium production at PLC. The main fraction of $J/ψ$ comes from the single and double resolved photon processes. Expected cross sections of charmonium states production are large e

J. F. Bennett, J. A. Gracey

We compute the O(1/N_f) correction to the predominantly gluonic flavour singlet twist-2 anomalous dimension used in polarized deep inelastic scattering. It is consistent with known two loop perturbation theory and we determine the three loop contribution at O(1/N_f). The treatment of the epsilon-tensor in the large N_f d-dimensional critical point formalism

K. Funakubo, A. Kakuto, S. Otsuki, F. Toyoda

By studying the effective potential of the MSSM at finite temperature, we find that CP can be spontaneously broken in the intermediate region between the symmetric and broken phases separated by the bubble wall created at the phase transition. If CP is violated in this manner, there could be a bubble wall connecting CP conserving vacua and violating CP halfw

Fl. Stancu

We study the stability of the pentaquarks uuddQbar, uudsQbar and udssQbar (Q = c, b, or t) of positive parity in a constituent quark model based on Goldstone boson exchange interaction between quarks. The pentaquark parity is the antiquark parity times that of a quark excited to a p-shell. We show that the Goldstone boson exchange interaction favors these pe

Chun Wa Wong

The color mixing of mesons propagating in a nucleus is studied with the help of a color-octet Pomeron partner present in the two-gluon model of the Pomeron. For a simple model with four meson-nucleon channels, color mixings are found to be absent for pointlike mesons and very small for small mesons. These results seem to validate the absorption model with tw

O. V. Teryaev

The leading order evolution of parton orbital angular momenta is treated in the probabilistic manner. As a result, the splitting probability matrix, while coinciding with the recent explicit calculations, is expressed in the terms of the standard spin-dependent and spin-averaged kernels. The implied relations between spin and orbital angular momenta evolutio

T. Okude, S. Kitahara, O. Miyamura, F. Shoji

We study quenched hadron spectra with Wilson fermion in abelian gauge fields extracted by maximal abelian projection and in fields induced by monopoles on $16^3 \times 32 $ and $ 12^3 \times 24$ lattices. Pion mass squared and quark mass defined through the axial Ward identity satisfy the PCAC relation. Gross features of the light hadron spectra are almost s

The OPAL Collaboration, K. Ackerstaff et al

A search for stable and long-lived massive particles of electric charge |Q/e| = 1 or 2/3, pair-produced in e+e- collisions at centre-of-mass energies from 130 to 183 GeV, is reported by the OPAL collaboration at LEP. No evidence for production of these particles was observed in a mass range between 45 and 89.5 GeV. Model-independent upper limits on the produ

L. Herrera, A. Di Prisco, J. Martinez

We analyze the effects of thermal conduction in a relativistic fluid just after its departure from spherical symmetry, on a time scale of the order of relaxation time. Using first order perturbation theory, it is shown that, as in spherical systems, at a critical point the effective inertial mass density of a fluid element vanishes and becomes negative beyon

Frans Pretorius, Werner Israel

Quasi-spherical light cones are lightlike hypersurfaces of the Kerr geometry that are asymptotic to Minkowski light cones at infinity. We develop the equations of these surfaces and examine their properties. In particular, we show that they are free of caustics for all positive values of the Kerr radial coordinate r. Useful applications include the propagati

J. R. Kirtley, K. A. Moler, G. Villard, A. Maignan

We have magnetically imaged interlayer Josephson vortices emerging from an ac face of single crystals of the single layer cuprate high-Tc superconductor (Hg,Cu)Ba2CuO4+d. These images provide a direct measurement of the c-axis penetration depth of about 10 microns. This length is a factor of 10 longer than predicted by the interlayer tunneling model for the

Anupam Garg

The short ranged antiferromagnetism recently seen in UPt_3 is proved incompatible with two dimensional (2D) order parameter models that take the antiferromagnetism as a symmetry breaking field. To adjust to the local moment direction, the order parameter twists over very long length scales as per the Imry-Ma argument. A variational solution to the Ginzburg-L