August 1996 arXiv papers — page 11

Sunao Sakai, Atsushi Nakamura, Kazuhisa Amemiya

The transport coefficients of quark gluon plasma are calculated on a lattice 16**3X8, with the pure gauge models. Matsubara Green's functions of energy momentum tensors have very large fluctuations and about a few million MC sweeps are needed to reduce the errors reasonably small in the case of the standard action. They are much suppressed if Iwasaki&#39

Slawomir Klimek, Andrzej Lesniewski

We define and study the properties of the infinite dimensional quantized Kronecker flow. This $\bC^*$-dynamical system arises as a quantization of the corresponding flow on an infinite dimensional torus. We prove an ergodic theorem for a class of quantized Kronecker flows. We also study the closely related almost periodic quantum field theory of bosonic, fer

Gun Sang Jeon, M. Y. Choi, S. -R. Eric Yang

We investigate the density of states (DOS) near the Fermi energy of one-dimensional spin-polarized electron systems in the quantum regime where the localization length is comparable to or larger than the inter-particle distance. The Wigner lattice gap of such a system, in the presence of weak disorder, can occur precisely at the Fermi energy, coinciding with

Roland Zeyher, Miodrag L. Kulic

The equation for the charge vertex $γ$ of the $t-J$ model is derived and solved in leading order of an 1/N expansion, working directly in terms of Hubbard operators. Various quantities which depend crucially on $γ$ are then calculated, such as the life time and the transport life time of electrons due to a charge coupling to other degrees of freedom and the

Jan Brinckmann

A strong-coupling-perturbation theory around the Atomic Limit of the Anderson model with large $U$ for a localized $f$-orbital coupled to a conduction-electron band is presented. Although an auxiliary-particle representation is {\em not} used, application of the canonical Wick's theorem is possible and yields an expansion in the hybridization $V$ via dre

Holger Friedel, Rainer Grauer, Christiane Marliani

The formation of current sheets in ideal incompressible magnetohydrodynamic flows in two dimensions is studied numerically using the technique of adaptive mesh refinement. The growth of current density is in agreement with simple scaling assumptions. As expected, adaptive mesh refinement shows to be very efficient for studying singular structures compared to

David Tytler

The next decade promises an observational revolution which will change cosmology forever. The precise measurement of the angular anisotropy of the cosmic microwave background should specify to a few percent all of the parameters of the cosmological model which effect astrophysics. The growth of structure will then be determined (but not yet observed) until g

L. Piccirillo, G. Romeo, R. K. Schaefer, M. Limon

We describe a new technique for turning scans of the microwave sky into intensity maps. The technique is based on a Fourier series analysis and is inspired by the lock-in deconvolution used in experiments which typically sweep the sky continuously. We test the technique on computer generated microwave skies and compare it to the more standard map making tech

Dave Strickland, Trevor Ponman, Ian Stevens

We present {\em ROSAT} PSPC and HRI observations of the galactic wind from the starburst galaxy M82. \mbox{X-ray} emission from the wind is detected to a distance of $\sim6\kpc$ from the plane of the galaxy. Making use of the PSPC's mixture of good spatial and spectral characteristics, we separate point source and diffuse emission, and investigate the sp

H. J. A. Röttgering, R. van Ojik, G. K. Miley, K. C. Chambers

We present spectroscopic observations for 64 radio galaxies having ultra steep radio spectra. Twenty-nine objects have redshifts $z>2$, the largest redshifts being almost 4. Our ultra steep spectrum (USS) criterion ($α< -1$) has proven to be the most efficient way of finding distant radio galaxies. We find that even among the USS sources, there is a strong s

V. Karas, P. Kraus

Spectral lines from a source orbiting around a compact object are studied. Time variations of observed frequency and count rate due to motion of the source and gravitational lensing are considered. Gravitational field of the central object is described by the Kerr metric. It is shown that: (i) simultaneous temporal and frequency resolution enables us to rest

Winfried Zimdahl, Diego Pavon, Josep Triginer

Different cooling rates of interacting fluid components of the expanding cosmic medium give rise to entropy producing bulk stresses. With the help of effective bulk pressures, on the other hand, one may phenomenologically take into account cosmological particle production processes. We report on recent progress in bulk viscous cosmology both on the phenomeno

Dmitriy Palatnik

This paper suggests a generalization of the Born--Infeld action (1932) for the case of electroweak and gravitational fields. Basic notions one deals with are Dirac matrices, $γ_{a}$, and dimensionless covariant derivatives, $π_{a} = - i\ell \nabla_{a}$, given in spinorial and scalar representations. The action contains a characteristic length $\ell$ (which i

H. Lin, H. K. C. Yee, R. G. Carlberg, E. Ellingson

We have computed the luminosity function for 389 field galaxies from the Canadian Network for Observational Cosmology cluster redshift survey (CNOC1), over redshifts z = 0.2-0.6. We find Schechter parameters M^* - 5 log h = -19.6 \pm 0.3 and α= -0.9 \pm 0.2 in rest-frame B_{AB}. We have also split our sample at the color of a redshifted but nonevolving Sbc g

Terry Gannon

The problem of finding all possible effective field theories for the quantum Hall effect is closely related to the problem of classifying all possible modular invariant partition functions for the algebra $u(1)^m$, as was argued recently by Cappelli and Zemba. This latter problem is also a natural one from the perspective of conformal field theory. In this p

Kazunori Itakura

We investigate dynamical symmetry breaking of the Gross-Neveu model in the light-front formalism without introducing auxiliary fields. While this system cannot have zero-mode constraints, we find that a nontrivial solution to the constraint on nondynamical spinor fields is responsible for symmetry breaking. The fermionic constraint is solved by systematic 1/

Itzhak Bars

The algebraic structure of S-Theory and its representations are described. This structure includes up to 13 hidden dimensions. It implies the existence of an SO(10,2) covariant supergravity theory as a limit of the secret theory behind string theory. The black hole entropy is invariant under transformations including the 11th and 12th dimensions. The discuss

Julie D. Blum

Orientifolds of the type IIB superstring that descend from F theory and M theory orbifolds are studied perturbatively. One finds strong evidence that a previously ignored twisted open string is required in these models. An attempt is made to interpret the $J$ type torsion in F theory where one finds a realization of Gimon and Johnson&#39;s models which does

Leonid Slepchenko, Avto Tkabladze

We calculated the color-octet contribution to the $\ps$ hadroproduction at fixed target energies $\sqrt(s)\simeq40$ GeV. We consider the $\ps$ production with transverse momenta which can not be explained by primordial motion of partons, $p_T>1.5$ GeV. It is shown that color octet contribution is dominant at these energies and reduces large dicrepancies betw

Sanatan Digal, Supratim Sengupta, Ajit M. Srivastava

We show that the mechanism of vortex-antivortex pair production via field oscillations, earlier proposed by two of us for systems with first order transitions in presence of explicit symmetry breaking, is in fact very generally applicable. We further argue that this mechanism applies to all sorts of topological defects (e.g. strings, monopoles, textures) and

A. Hoferichter, V. K. Mitrjushkin, M. Müller--Preussker, H. Stüben

We compare the approach to the chiral transition line $~κ_c(\bt)~$ in quenched and full compact lattice QED with Wilson fermions within the confinement phase, especially in the pseudoscalar sector of the theory. We show that in the strong coupling limit ($β=0$) the quenched theory is a good approximation to the full one, in contrast to the case of $β=0.8$. A

Hans - Juergen Schmidt

We present three reasons for rewriting the Einstein equation. The new version is physically equivalent but geometrically more clear. 1. We write $4 π$ instead of $8 π$ at the r.h.s, and we explain how this factor enters as surface area of the unit 2--sphere. 2. We define the Riemann curvature tensor and its contractions (including the Einstein tensor at the

Vassiliki Kalogera, Gordon Baym

Observational identification of black holes as members of binary systems requires the knowledge of the upper limit on the gravitational mass of a neutron star. We use modern equations of state for neutron star matter, fitted to experimental nucleon-nucleon scattering data and the properties of light nuclei, to calculate, within the framework of Rhoades & Ruf

Vassiliki Kalogera

We propose a new formation mechanism (direct-supernova) for low-mass X-ray binaries (LMXBs) that does not involve any prior phase of mass transfer. Survival through the supernova (SN) explosion and shrinkage of the orbit is achieved by a kick velocity of appropriate magnitude and direction imparted to the neutron star at its birth. We present analytical popu

R. Cid Fernandes, I. Aretxaga, R. Terlevich

The relationship between variability, luminosity and redshift in the South Galactic Pole QSO sample is examined in an effort to disentangle the effects of luminosity and redshift in the amplitude of the optical variations. The anticorrelation between variability and luminosity found by other authors is confirmed. Our analysis also supports claims that variab

Ilona Bednarek, Ryszard Manka

The evolution of a soliton star filled with fermions is studied in the framework of general relativity. Such a system can be described by the surface tension $σ$, the bag constant $B$, and the fermion number density $ρ_{0}$. Usually one of these parameters prevails in the system and thus affects the spacetime inside the soliton. Whether it is described by Fr

Una Hwang, Eric V. Gotthelf

We present X-ray images of Tycho&#39;s supernova remnant in emission line features of Mg, Si, S, Ar, Ca, and Fe, plus the continuum, using data obtained by the imaging spectrometers onboard the ASCA X-ray satellite. All the images show the shell-like morphology characteristic of previously obtained broad-band X-ray images, but are clearly distinct from each

Andrzej Weber

Suppose $M^{n+1}$ is a complex manifold and K is a hypersurface with isolated singularities. Let $ω$ be a holomorphic form on $M\setminus K$ with the first order pole on K. The Leray residue of such form gives an element in the n-th homology of K which is the Alexander dual to $[ω]\in H^{n+1}(M\setminus K)$. It always lifts to the intersection homology if 0

Keiichi Akama, Hidezumi Terazawa

The significant excess recently found by the CDF Collaboration in the inclusive jet cross section for jet transverse energies $E_T \ge 200$ GeV over current QCD predictions can be explained either by possible production of excited bosons (excited gluons, weak bosons, Higgs scalars, etc.) or by that of excited quarks. The masses of the excited boson and the e

Simon Davis

Symmetries of generalized gravitational actions, yielding field equations which typically involve at most second-order derivatives of the metric, are considered. The field equations for several different higher-derivative theories in the first-order formalism are derived, and variations of a generic set of higher-order curvature terms appearing in string eff

R. J. Protheroe, P. L. Biermann

Gamma rays have been observed from two blazars at TeV energies. One of these, Markarian 421, has been observed also at GeV energies and has roughly equal luminosity per decade at GeV and TeV energies. Photon-photon pair production on the infrared background radiation is expected to prevent observation above about 1 TeV. However, the infrared background is no

Klaus Behrndt, Renata Kallosh, Joachim Rahmfeld, Marina Shmakova

We find double-extreme black holes associated with the special geometry of the Calabi-Yau moduli space with the prepotential F=STU. The area formula is STU-moduli independent and has ${[SL(2,Z)]}^3$ symmetry in space of charges. The dual version of this theory without prepotential treats the dilaton S asymmetric versus T,U-moduli. We display the dual relatio

O. Benhar, S. Fantoni, N. N. Nikolaev, J. Speth

We explore the missing momentum dependence of the CT effects in quasielastic (e,e&#39;p) scattering. We develop the coupled-channel multiple-scattering theory (CCMST) description of final-state interaction including both the coherent and incoherent rescatterings of the ejectile state. We demonstrate that the contribution of the off-diagonal incoherent rescat

Toshiyuki Harano, Masatoshi Sato

Microscopic tests of the exact results are performed in $N=2$ supersymmetric $SU(2)$ QCD. We present the complete construction of the multi-instanton in $N=2$ supersymmetric QCD. All the defining equations of the super instanton are reduced to the algebraic equations. Using this result, we calculate the two-instanton contribution ${\cal F}_2$ to the prepoten

B. B. Levchenko

The planed HERA upgrade will increase the integrated luminosity by two orders of magnitude.A new program of electron-nucleus collisions at HERA is under discussion now.In this connection we present prospects for the study of a light neutral Higgs boson, SUSY-particle, hadrons and leptons productionin the two-photon coherent eA collisions at HERA energies.

Chong-Xing Yue, Hong-Yi Zhou, Yu-Ping Kuang, Gong-Ru lu

We study the contributions of the neutral pseudo Goldstone bosons (technipions and top-pions) to the t anti-t production cross sections at the Tevatron and the LHC in topcolor-assisted multiscale technicolor (TOPCMTC) models via the gluon-gluon fusion process from the loop-level couplings between the pseudo Goldstone bosons and the gluons. The MRS set A&#39;

Wu-Ki Tung

We report on an extensive global QCD analysis of new DIS and hadronic inclusive jet production data emphasizing the impact of these recent data on the determination of the gluon distribution, and on the interpretation of the high $E_t$ jets highlighted by the CDF collaboration. This analysis results in (i) a better handle on the range of uncertainty of the g

Manuela Campanelli, Carlos O. Lousto

In this paper we show how quantum corrections, although perturbatively small, may play an important role in the analysis of the existence of some classical models. This, in fact, appears to be the case of static, uniform--density models of the interior metric of cosmic strings and neutron stars. We consider the fourth order semiclassical equations and first

Brian P. Dolan, Kevin P. Haugh

A Lorentz and general co-ordinate co-variant form of canonical gravity, using Ashtekar&#39;s variables, is investigated. A co-variant treatment due to Crnkovic and Witten is used, in which a point in phase space represents a solution of the equations of motion and a symplectic functional two form is constructed which is Lorentz and general co-ordinate invari

Eric Loubeau

Pluriharmonic maps form an important class of harmonic maps which includes holomorphic maps. We study their morphisms, in particular the inter-relationships between $(1,1)$-geodesic, pluriharmonic and $\pm$holomorphic maps. Then we characterise pluriharmonic morphisms between Hermitian manifolds. We make a special study of the situation where the target is K

Olav F. Syljuasen

Recently there has been much interest in gauge theories applied to condensed matter physics. I show that for a system of nonrelativistic electrons coupled to a U(1) gauge field in the presence of a Fermi surface, the beta-function to one-loop order is, for a particular family of gauge-choices, independent of the gauge-choice.

K. M. Gorski, B. Ratra, R. Stompor, N. Sugiyama

Cut-sky orthogonal mode analyses of the COBE-DMR 53 and 90 GHz sky maps are used to determine the normalization of a variety of open cosmogonical models based on the cold dark matter scenario. To constrain the allowed cosmological-parameter range for these open cosmogonies, the predictions of the DMR-normalized models are compared to various observational me

Ilona Bednarek, Marek Biesiada, Ryszard Manka

In this paper we discuss the QCD phase-transitions in the nontopological soliton model of quark confinement and explore possible astrophysical consequences. Our key idea is to look at quark stars (which are believed to exist since the quark matter is energetically preferred over the ordinary matter) from the point of view of soliton model. We propose that th

R. Cowsik, Charu Ratnam, P. Bhattacharjee

Gates et al (astro-ph/9606132) have raised several issues in their Comment on our Letter (Phys. Rev. Lett. Vol. 76, p.3886 (1996); astro-ph/9605001). We clarify these issues and show that our results are robust, and there is no inconsistency of our results with any established observational facts.

Hung Cheng, S. P. Li

We present a method to perform renormalized perturbation calculation in gauge theories with chiral fermions. We find it proper to focus directly on the Ward-Takahashi identities, relegating dimensional regularization into a supplementary and secondary role. We show with the example of the Abelian-Higgs theory how to handle amplitudes involving fermions, part

Matias Zaldarriaga

I discuss the physics of polarization in models with early reionization. For sufficiently high optical depth to recombination the polarization is boosted on large scales while it is suppressed on smaller scales. New peaks appear in the polarization power spectrum, their position is proportional to the square root of the redshift at which the reionization occ

Eric M. Kramer

The elastic energy functional of a thin elastic rod or sheet is generalized to the case of an M-dimensional manifold in N-dimensional space. We derive potentials for the stress field and curvatures and find the generalized von Karman equations for a manifold in elastic equilibrium. We perform a scaling analysis of an M-1 dimensional ridge in an M = N-1 dimen

Leon Balents, Matthew P. A. Fisher, Martin R. Zirnbauer

The electrons on the surface of a disordered multi-layer integer quantum Hall system constitute an unusual chiral metal with ballistic motion transverse to the field, and diffusive motion parallel to it. We present a non-perturbative analytic treatment of an appropriate model, consisting of disordered chiral Fermions in two dimensions. A supersymmetric gener

J. Leon

A suitable operator for the time-of-arrival at a detector is defined for the free relativistic particle in 3+1 dimensions. For each detector position, there exists a subspace of detected states in the Hilbert space of solutions to the Klein Gordon equation. Orthogonality and completeness of the eigenfunctions of the time-of-arrival operator apply inside this

L. Ya. Glozman

It is shown that the binding effect that is associated with the short range part of the Goldstone boson exchange interaction between constituent quarks provides a good description of the $πN$ $σ$-term.

D. V. Gal&#39;tsov, P. S. Letelier

A $2p + 5$ parametric family of black holes is constructed in dilaton--axion gravity with $p$ vector fields using a holomorphic representation of U--duality in three dimensions. The metric of the non--extremal black holes has a Reissner--Nordström type structure and generically possesses an internal horizon. However in the extremal limit the generic solution

C. D. Fosco, F. A. Schaposnik

The bosonization of a massless fermionic field coupled to both vector and axial-vector external sources is developed, following a path-integral approach. The resulting bosonized theory contains two antisymmetric tensor fields whose actions consist of non-local Kalb-Ramond-like terms plus interactions. Exact bosonization rules that take the axial anomaly for

Ken Dykema, Uffe Haagerup, Mikael Rordam

It is proved that the reduced group C*-algebra C*_{red}(G) has stable rank one (i.e. its group of invertible elements is a dense subset) if G is a discrete group arising as a free product G_1*G_2 where |G_1|>=2 and |G_2|>=3. This follows from a more general result where it is proved that if (A,tau) is the reduced free product of a family (A_i,tau_i), i\in I,

E. Elizalde

Series of extended Epstein type provide examples of non-trivial zeta functions with important physical applications. The regular part of their analytic continuation is seen to be a convergent or an asymptotic series. Their singularity structure is completely determined in terms of the Wodzicki residue in its generalized form, which is proven to yield the res

S. D. Bass, D. Schütte

The pion cloud renormalises the light-cone wavefunction of the nucleon which is measured in hard, exclusive photon-nucleon reactions. We discuss the leading twist contributions to high-energy exclusive reactions taking into account both the pion cloud and perturbative QCD physics. The nucleon&#39;s electromagnetic form-factor at high $Q^2$ is proportional to

G. M. Gandenberger, N. J. MacKay

The identification in affine Toda field theory of the quantum particle with the lowest breather allows us to re-interpret discrete modes of excitation of solitons as breathers bound to solitons, and thus to investigate them through the proposed soliton-breather S-matrices. There are implications for the physical spectrum and for the semiclassical soliton mas

Hideo Kodama, Takashi Hamazaki

In the investigation of the evolution of cosmological perturbations in inflationary universe models the behavior of perturbations during the reheating stage is the most unclear point. In particular in the early reheating phase in which a rapidly oscillating scalar field dominates the energy density, the behavior of perturbations are not known well because th

Ali Mostafazadeh

A convenient framework is developed to generalize Berry&#39;s investigation of the adiabatic geometrical phase for a classical relativistic charged scalar field in a curved background spacetime which is minimally coupled to electromagnetism and an arbitrary (non-electromagnetic) scalar potential. It involves a two-component formulation of the corresponding K

P. J. Hirschfeld, S. M. Quinlan, D. J. Scalapino

Results of a calculation of the c-axis infrared conductivity sigma_c for a d_{x^2-y^2}-wave superconductor which include both elastic impurity and inelastic spin-fluctuation scattering are presented and compared with the ab-plane conductivity sigma_{ab} in the same model. In this model,the interlayer c-axis coupling is taken to be weak and diffusive. While i

Katsushi Ito, Naoki Sasakura

We study the low-energy effective theory in N=2 super Yang-Mills theories by microscopic and exact approaches. We calculate the one-instanton correction to the prepotential for any simple Lie group from the microscopic approach. We also study the Picard-Fuchs equations and their solutions in the semi- classical regime for classical gauge groups with rank r \

Kazuo Fujikawa

The general treatment of a separable Hamiltonian of Liouville-type is well-known in operator formalism. A path integral counterpart is formulated if one starts with the Jacobi&#39;s principle of least action, and a path integral evaluation of the Green&#39;s function for the hydrogen atom by Duru and Kleinert is recognized as a special case. The Jacobi&#39;s

L. Burakovsky, L. P. Horwitz

It is argued that the mass spectrum of a meson nonet is linear, consistent with the standard Gell-Mann--Okubo mass formula and leading to an extra Gell-Mann--Okubo mass relation for the masses of the isoscalar states. This relation is shown to hold with an accuracy of up to $\sim $3\% for all well-established nonets. It also suggests a new $q\bar{q}$ assignm

L. Burakovsky, L. P. Horwitz

Using a linear mass spectrum of an $SU(4)$ meson hexadecuplet, we derive the Gell-Mann--Okubo mass formula for the charmed mesons, in good agreement with experiment. Possible generalization of this method to a higher symmetry group is briefly discussed.

Frederick T. Hawes, Tom Sizer, Anthony G. Williams

We study renormalized quenched strong-coupling QED in four dimensions in arbitrary covariant gauge. Above the critical coupling leading to dynamical chiral symmetry breaking, we show that there is no finite chiral limit. This behaviour is found to be independent of the detailed choice of photon-fermion proper vertex in the Dyson-Schwinger equation formalism,

L. Burakovsky, L. P. Horwitz

The equation of state of hot hadronic matter is obtained, by taking into account the contribution of the massive states with the help of the resonance spectrum $τ(m)\sim m^3$ justified by the authors in previous papers. This equation of state is in agreement with that provided by the low-temperature expansion for the pion intracting gas. It is shown that in

L. Burakovsky, L. P. Horwitz

The formulas for the temperature dependences of the non-strange and strange quark condensates are derived by taking into account the contribution of the massive resonances. Critical temperature of the chiral symmetry restoration transition is established to be 190 MeV if only meson resonances are considered, and 175 MeV if both meson and baryon resonances ar

L. Burakovsky, L. P. Horwitz

It is argued that the mass spectrum of a baryon octet is linear, consistent with a Gell-Mann--Okubo type relation for the squared masses of the baryons obtained previously by Balázs and Nicolescu. The mass spectrum of a baryon decuplet is briefly discussed.

L. Burakovsky

In the model of a first order quark-gluon/hadron phase transition in which the hadronic phase is considered as vacuum bubbles growing in the quark-gluon background with chiral symmetry broken inside the bubble, we find the estimate for the length scale associated with inhomogeneities originated during the transition, $10$ m $\;\stackrel{<}{\sim }\ell \stackr

T. Goldman, B. H. J. McKellar, G. J. Stephenson

We examine the effects of a scalar field, coupled only to neutrinos, on oscillations among weak interaction current eigenstates. The existence of a real scalar field is manifested as effective masses for the neutrino mass eigenstates, the same for $\nbar$ as for $\n$. Under some conditions, this can lead to a vanishing of $δm^2$, giving rise to MSW-like effe

Frank Wilczek

I discuss some central issues in particle physics which are potentially relevant to cosmology. I first briefly review the present (glorious) experimental status of the Standard Model, emphasizing that it provides a firm foundation both for early Universe cosmology and for further exploration toward the basic laws of Nature. I then provide a critique, arguing

H. F. Jones, A. Ritz, I. L. Solovtsov

We show that renormalization group improvement, making use of analyticity and the structure of the operator product expansion, combined with a non-perturbative expansion method allows one to describe quarkonium states via QCD sum rules without the need for explicit power corrections. This technique also allows an accurate determination of parameters related

P. H. Soldan

We present a status report on our study of long-distance contributions to the decay amplitudes A(K^0 --> pi pi, I) in the framework of the 1/N expansion. We argue that a modified prescription for the identification of meson momenta in the chiral loop corrections has to be used to gain a self-consistent picture which allows an appropriate matching with the sh

Kurt Riesselmann, Scott Willenbrock

Previous work has suggested that perturbation theory is unreliable for Higgs- and Goldstone-boson scattering, at energies above the Higgs mass, for relatively small values of the Higgs quartic coupling $λ(μ)$. By performing a summation of nonlogarithmic terms, we show that perturbation theory is in fact reliable up to relatively large coupling. This eliminat

A. G. Williams, K. Kusaka, K. M. Simpson

There is a need for covariant solutions of bound state equations in order to construct realistic QCD based models of mesons and baryons. Furthermore, we ideally need to know the structure of these bound states in all kinematical regimes, which makes a direct solution in Minkowski space (without any 3-dimensional reductions) desirable. The Bethe-Salpeter equa

Yuan-ben Dai, Chao-shang Huang, Ming-qiu Huang, Chun Liu

The 1/m_c and 1/m_b corrections to the Λ_b to Λ_c semi- leptonic decay are analyzed by QCD sum rules. Within the framework of heavy quark effective theory,the subleading baryonic Isgur-Wise func- tion of Λ_b to Λ_c has been calculated. It is shown that the corrections due to the 1/m Lagrangian insertion are negligibly small. The sizable 1/m_Q effect to the d

Attilio Cucchieri, Tereza Mendes

We study the problem of critical slowing-down for gauge-fixing algorithms (Landau gauge) in $SU(2)$ lattice gauge theory on $2$ and $4$ dimensional lattices, both numerically and analytically. We consider five such algorithms, and we measure four different observables. A detailed discussion and analysis of the tuning of these algorithms is also presented.

Colin Morningstar, Mike Peardon

Results from a calculation of the low-lying glueball spectrum of pure-gauge SU(3) are used as a test of the effectiveness of improved discretisation schemes in reducing finite spacing errors. Glueball masses are extracted from simulations on anisotropic lattices, where the temporal lattice spacing is much shorter than the spatial ones. This allows clearer re

M. Lüscher, S. Sint, R. Sommer, P. Weisz

It is shown how on-shell O(a) improvement can be implemented non-perturbatively in lattice QCD with Wilson quarks. Improvement conditions are obtained by requiring the PCAC relation to hold exactly in certain matrix elements. These are derived from the QCD Schrödinger functional which enables us to simulate directly at vanishing quark masses. In the quenched

K. Jansen, C. Liu, H. Simma, D. Smith

An exploratory study of the low-lying eigenvalues of the Wilson-Dirac operator and their corresonding eigenvectors is presented. Results for the eigenvalues from quenched and unquenched simulations are discussed. The eigenvectors are studied with respect to their localization properties in the quenched approximation for the cases of SU(2) and SU(3).

F. Karsch, B. Beinlich, J. Engels, R. Joswig

The thermodynamics of the SU(3) gauge theory has been analyzed with tree level and tadpole improved Symanzik actions. A comparison with the continuum extrapolated results for the standard Wilson action shows that improved actions lead to a drastic reduction of finite cut-off effects already on lattices with temporal extent $N_τ=4$. Results for the pressure,

M. Goeckeler, R. Horsley, E. -M. Ilgenfritz, H. Perlt

Recent lattice calculations of hadron structure functions are described.

B. K. Darian, H. P. Kunzle

We construct the most general form of axially symmetric SU(2)-Yang-Mills fields in Bianchi cosmologies. The dynamical evolution of axially symmetric YM fields in Bianchi I model is compared with the dynamical evolution of the electromagnetic field in Bianchi I and the fully isotropic YM field in Friedmann-Robertson-Walker cosmologies. The stochastic properti

Eric Loubeau

We study a geometrical condition (PHWC) which is weaker than horizontal weak conformality. In particular, we show that harmonic maps satisfying this condition, which will be called {\em pseudoharmonic morphisms}, include harmonic morphisms and can be described as pulling back certain germs to certain other germs. Finally, we construct a canonical f-structure

J. M. Tranquada, J. D. Axe, N. Ichikawa, A. R. Moodenbaugh

Previously we have presented evidence for stripe order of holes and spins in La(1.6-x)Nd(0.4)Sr(x)CuO(4) with x=0.12. Here we show, via neutron diffraction measurements of magnetic scattering, that similar order occurs in crystals with x=0.15 and 0.20. Zero-field-cooled magnetization measurements show that all 3 compositions are also superconducting, with th

V. Celebonovic

The aim of this contribution is to present expressions for the bulk modulus of a material and its pressure derivative,obtained by using the semiclassical theory of dense matter proposed by P.Savic and R.Kasanin. Some possibilities for the application of these expressions are briefly discussed.

Robert John Freeman

A key problem in the description of language structure is to explain its contradictory properties of specificity and generality, the contrasting poles of formulaic prescription and generative productivity. I argue that this is possible if we accept analogy and similarity as the basic mechanisms of structural definition. As a specific example I discuss how it

Michael Brenner, Sascha Hilgenfeldt, Detlef Lohse, ;

Sound driven gas bubbles in water can emit light pulses (sonoluminescence). Experiments show a strong dependence on the type of gas dissolved in water. Air is found to be one of the most friendly gases towards this phenomenon. Recently, \cite{loh96} have suggested a chemical mechanism to account for the strong dependence on the gas mixture: the dissociation

Fabio Sattin, Luca Salasnich

A numerical study has been done of collisions between protons and hydrogen atoms, treated as classical particles, at low impact velocities. The presence of chaos has been looked for by investigating the processes with standard techniques of the chaotic--scattering theory. The evidence of a sharp transition from nearly regular scattering to fully developed ch

Emily S. C. Ching, Victor S. L&#39;vov, Evgeni Podivilov, Itamar Procaccia

We consider turbulent advection of a scalar field $T(\B.r)$, passive or active, and focus on the statistics of gradient fields conditioned on scalar differences $ΔT(R)$ across a scale $R$. In particular we focus on two conditional averages $\langle\nabla^2 T\big|ΔT(R)\rangle$ and $\langle|\nabla T|^2\big|ΔT(R) \rangle$. We find exact relations between these

Julian H. Krolik

A global view is given of how emission lines have been, and may in the future, be used to enhance our understanding of AGN. Lines from the microwave to the X-ray bands all contribute. Although we have a deep understanding of the physical processes by which line photons are generated, when the circumstances of line emission are complicated, models become too

Jeremiah P. Ostriker, Nickolay Y. Gnedin

We note that current observational evidence strongly favors a conventional recombination of ionized matter subsequent to redshift z=1200, followed by reionization prior to redshift z=5 and compute how this would have occurred in a standard scenario for the growth of structure. Extending prior semi-analytic work, we show by direct, high-resolution numerical s

Andrew D. Silber, Scott F. Anderson, Bruce Margon, Ronald A. Downes

The magnetic cataclysmic variable DQ Herculis was observed with the Faint Object Spectrograph onboard the Hubble Space Telescope (HST) over four consecutive satellite orbits, including the first observation in the UV of DQ Her through eclipse minimum. Strong emission in N V, C IV, Si IV, and He II and weak emission in O I, S III, Ni II, N IV, Si III, and C I

Andrew Gould

Follow the big stars! I review the theory of detection and parameter measurement of planetary systems by follow-up observations of ongoing microlensing events. Two parameters can generically be measured from the event itself: the planet/star mass ratio, $q$, and the planet/star separation in units of the Einstein ring. I emphasize the advantages of monitorin

Simon D. M. White

I discuss and illustrate the development of large-scale structure in the Universe, emphasising in particular the physical processes and cosmological parameters that most influence the observationally accessible aspects of structure at large redshift. Statistical properties of this structure can be measured from the apparent positions of faint galaxies and qu

Ian P. Dell&#39;Antonio, J. Anthony Tyson

In this Letter we present calibrated observations of the average mass of galaxies with 22< I < 25 in the Hubble Deep Field. We measure the mean mass profile using the statistical gravitational lens distortion of faint blue background galaxies, based on 2221 foreground-background pairs. The observed weak lensing distortion is calibrated via full 3-D simulatio

David Wands, Juan Garcia-Bellido

We discuss metric perturbations produced during a period of inflation in the early universe where two scalar fields evolve. The final scalar perturbation spectrum can be calculated in terms of the perturbed expansion along neighbouring trajectories in field-space. In the usual single field case this is fixed by the values of the fields at horizon-crossing, b

Peter Anninos, Yu Zhang, Tom Abel, Michael L. Norman

We have developed a method of solving for multi-species chemical reaction flows in non--equilibrium and self--consistently with the hydrodynamic equations in an expanding FLRW universe. The method is based on a backward differencing scheme for the required stability when solving stiff sets of equations and is designed to be efficient for three-dimensional ca

T. Abel, P. Anninos, Y. Zhang, M. L. Norman

We have reviewed the chemistry and cooling behaviour of low-density (n<10^4 cm^-3) primordial gas and devised a cooling model wich involves 19 collisional and 9 radiative processes and is applicable for temperatures in the range (1 K < T < 10^8 K). We derived new fits of rate coefficients for the photo-attachment of neutral hydrogen, the formation of molecul

Juergen T. Stockburger, C. H. Mak

We present a real-time path integral theory for the rate of electron transfer reactions. Using graph theoretic techniques, the dynamics is expressed in a formally exact way as a set of integral equations. With a simple approximation for the self-energy, the rate can then be computed analytically to all orders in the electronic coupling matrix element. We pre

A. Riotto, O. Tornkvist, R. N. Mohapatra

We present the predictions for the mass $M_h$ of the lightest Higgs boson in models with gauge-mediated supersymmetry breaking as a function of the SUSY-breaking scale. We include all radiative corrections up to two loops and point out that if the CDF e+ e- two-photon event is interpreted in terms of these models, then the lightest Higgs boson should be ligh