December 1996 arXiv papers — page 12

N. Cardiel, J. Gorgas, A. Aragon-Salamanca

We present new results on line-strength gradients in a sample of 18 brightest cluster galaxies (13 in clusters with cooling flows and 5 in clusters without). Here we focus on the study of the Mg2 index and the 4000A break. We find that line-strength gradients vary markedly from galaxy to galaxy, depending both on the mass deposition rate and the presence or

L. Mantegazza, E. Poretti

We use moment method developed by Balona (1987) to identify the dominant mode of the multimode pulsating Delta Scuti star X Cae. It is shown as a l=1 and m=-1 non-radial mode gives a satisfactory fit of the amplitudes and phases of light and line moments variations provided that the rotational axis has i<45 degrees. The physical parameters corresponding to t

E. Poretti, C. Akan, M. Bossi, C. Koen

A multisite campaign involving five observatories allowed us to solve the light curve of the Gamma Doradus star HD 224945. The multiperiodic content, the high frequency term at 3.00 c/d and the frequency spacing between the observed terms strongly support its pulsational nature. Considering the low frequency terms observed in Gamma Dor stars, it seems that g

S. J. Peale

The statistical distribution of the masses of planets about stars between the Sun and the center of the galaxy is constrained to within a factor of three by an intensive search for planets during microlensing events. Projected separations in terms of the lens Einstein ring radius yield a rough estimate of the distribution of planetary semimajor axes with pla

Eli Waxman

The cosmological gamma-ray burst (GRB) model for the production of ultra- high energy cosmic rays is described, and the current observational evidence which support it discussed. Several predictions of the model are presented, which would allow it to be tested by future high energy cosmic ray and gamma- ray experiments. If the predicted signatures of the GRB

Ezra Getzler

The semi-classical approximation is an explicit formula of mathematical physics for the sum of Feynman diagrams with a single circuit.In this paper, we study the same problem in the setting of modular operads (see dg-ga/9408003); instead of being a number, the interaction at a vertex of valence n is an S_n-module. As an application, we calculate the S_n-equi

Dan-Di Wu

The tree level diagonalization of a neutrino mass matrix with both Majorana and Dirac masses is discussed in a general context. Flavor changing neutral currents in such models are inevitable. Rephasing invariant quantities characterizing CP violation in FCNC Fermion-Higgs interactions are identified. At the one loop level, the mass eigenstates become an impu

H. Arfaei, M. M. Sheikh-Jabbari

Using world-sheet parity we show that mixed D and N components of D-strings are dual to the anti-symmetric $B_{μν}$ field. The contribution of the latter is responsible for the reduction and even removal of all the interactions between two dissimilar D-branes.

Yuval Grossman, Mihir P. Worah

We make a systematic analysis of the effects of new physics in the B decay amplitudes on the CP asymmetries in neutral B decays. Although these are expected to be smaller than new physics effects on the mixing amplitude, they are easier to probe in some cases. The effects of new contributions to the mixing amplitude are felt universally across all decay mode

Felipe B. Rizzato, Sergio R. Lopes, Abraham C. -L. Chian

In this paper we re-examine the one-dimensional interaction of electromagnetic and ion acoustic waves in a plasma. Our model is similar to one solved by Rao et al. (Phys. Fluids, vol. 26, 2488 (1983)) under a number of analytical approximations. Here we perform a numerical investigation to examine the stability of the model. We find that for slightly over de

Chongying Dong, Haisheng Li, Geoffrey Mason

Let V be a vertex operator algebra. We construct a sequence of associative algebras A_n(V) (n=0,1,2,...) such that A_{n}(V) is a quotient of A_{n+1}(V) and a pair of functors between the category of A_n(V)-modules which are not A_{n-1}(V)-modules and the category of admissible V-modules. These functors exhibit a bijection between the simple modules in each c

S. M. Bradbury, T. Deckers, D. Petry, A. Konopelko

A detection of TeV $γ$-rays from Mkn 501 is reported, based on observations made between March and August 1996 with the first HEGRA Cherenkov telescope (CT1). From the image analysis, 351 excess candidate $γ$-ray events are obtained from the 147 h dataset. The statistical significance of the excess is 5.2 $σ$. The average excess rate is $2.4 \pm 0.5$ h$^{-1}

Sergey N. Solodukhin

Formulating the statistical mechanics for a scalar field with non-minimal $ξR ϕ^2$ coupling in a black hole background we propose modification of the original &#39;t Hooft ``brick wall&#39;&#39; prescription. Instead of the Dirichlet condition we suggest some scattering ansatz for the field functions at the horizon. This modifies the energy spectrum of the s

Walter Dehnen, James Binney

A parameterized model of the mass distribution within the Milky Way is fitted to the available observational constraints. The most important single parameter is the ratio of the scale length R_d* of the stellar disk to R0. The disk and bulge dominate v_c(R) at R<R0 only for R_d*/R0< 0.3. Since the only knowledge we have of the halo derives from studies like

David Garfinkle

The relationship of Choptuik scaling to the scale invariance of Einstein's equation is explored. Ordinary dynamical systems often have limit cycles: periodic orbits that are the asymptotic limit of generic solutions. We show how to separate Einstein's equation into the dynamics of the overall scale and the dynamics of the ``scale invariant'' part of the metr

Juergen Baacke, Katrin Heitmann, Carsten Paetzold

The term `preheating&#39; has been introduced recently to denote the process in which energy is transferred from a classical inflaton field into fluctuating field (particle) degrees of freedom without generating yet a real thermal ensemble. The models considered up to now include, besides the inflaton field, scalar or fermionic fluctuations. On the other han

S. M. Kasahara, the Soudan 2 collaboration

Deep underground muon events recorded by the Soudan 2 detector, located at a depth of 2100 meters of water equivalent, have been used to infer the nuclear composition of cosmic rays in the &#34;knee&#34; region of the cosmic ray energy spectrum. The observed muon multiplicity distribution favors a composition model with a substantial proton content in the en

Guy Bonneau

We analyse in a systematic way the four dimensionnal Einstein-Weyl spaces equipped with a diagonal Kähler Bianchi IX metric. In particular, we show that the subclass of Einstein-Weyl structures with a constant conformal scalar curvature is the one with a conformally scalar flat - but not necessarily scalar flat - metric ; we exhibit its 3-parameter distance

Dao-Neng Gao, Mu-Lin Yan, Bing-An Li

Employing $U(3)_L\times U(3)_R$ chiral field theory, we find that Dashen&#39;s theorem, which holds for pseudoscalar mesons, can be generalized to the sector of axial-vector mesons, however, fails for vector mesons.

Magnus Selhammar

Artificial viscosity is needed in Smooth Particle Hydrodynamics to prevent interparticle penetration, to allow shocks to form and to damp post shock oscillations. Artificial viscosity may, however, lead to problems such as unwanted heating and unphysical solutions. A modification of the standard artificial viscosity recipe is proposed which reduces these pro

A. E. Garcia, A. Zepeda-Navratil, A. Camacho, D. Olguin

Based on a successful description of II-VI ternary alloys, which introduces an empirical bowing parameter to the widely used virtual crystal approximation, we set up a tight-binding Hamiltonian to describe the Zn_{1-y}Cd_ySe_{1-x}Te_x and Zn_{.9}Cd_{.1}S_{.07}Se_{.93} quaternary alloys. We just use a formula that can be thought as a straightforward generaliz

A. P. Balachandran, S. Vaidya

There are numerous examples of approximately degenerate states of opposite parity in molecular physics. Theory indicates that these doubles can occur in molecules that are reflection-asymmetric. Such parity doubles occur in nuclear physics as well, among nuclei with odd A $\sim$ 219-229. We have also suggested elsewhere that such doubles occur in particle ph

Ali Shojai, Mehdi Golshani

In the extension of the de-Broglie-Bohm causal quantum theory of motion to the relativistic particles, one faces with serious problems, like the problem of superluminal motion. This forces many authors to believe that there is not any satisfactory causal theory for particles of integer spin. In this paper, it is shown that the quantal behaviour is the result

Ali Shojai, Mehdi Golshani

It is always stated that the position operator for massless particles has non-comutting components. It is shown that the reason is that the commutation relations between coordinates and momenta differs for massive and massless particles. The correct one for massless particles and a position operator with commuting components are derived.

Ali Shojai, Mehdi Golshani

We show that the problem of superluminal motion in causal, particle interpretation of bosonic fields is not observable at macroscopic distances.

Ali Shojai, Mehdi Golshani

It is shown that the retarded Bohm&#39;s theory has at least four novel properties. (1) The center of mass of an isolated two-body system is accelerated. (2) Hydrogen-like atoms are unstable. (3) The distribution function differs from the standard one. (4) The definition of energy needs some care.

Ali Shojai, Mehdi Golshani

It is argued that the quantal behaviours may be understood in the framework of direct particle interactions. A specific example is introduced. The assumed potential predicts that at sufficiently large distances quantal behaviours arise, while at very large distances gravitational-like forces are present. The latter is true provided all particles have interna

Louis Crane, David Yetter

We define the cohomology and formal deformation theories for algebra and bialgebra categories. We suggest some approaches to finding nontrivial deformations of the categories associated to the quantum groups by the work of Lusztig.

P. Navratil, M. Thoresen, B. R. Barrett

We use a large-scale 6 hbar Omega calculation for Li6 with microscopically derived two-body interaction to construct the 0 hbar Omega 0p-shell effective hamiltonian, electric quadrupole, and magnetic dipole operators. While the E2 and M1 6 hbar Omega operators are one-body operators with free nucleon charges, the effective operators are two-body operators wi

K. Varga, Y. Ohbayasi, Y. Suzuki

This paper extends the application of the stochastic variational method to noncentral interactions. Several examples are presented for three- and four-nucleon systems with realistic nuclear forces. The correlated Gaussians easily cope with the strong short range repulsion of the potential and the stochastic variational method efficiently selects the most imp

Wolfram Koepf, Dieter Schmersau

In this article explicit formulas for the recurrence equation p_{n+1}(x) = (A_n x + B_n) p_n(x) - C_n p_{n-1}(x) and the derivative rules sigma(x) p&#39;_n(x) = alpha_n p_{n+1}(x) + beta_n p_n(x) + gamma_n p_{n-1}(x) and sigma(x) p&#39;_n(x) = (alpha_n-tilde x + beta_n-tilde) p_n(x) + gamma_n-tilde p_{n-1}(x) respectively which are valid for the orthogonal p

Michael R. Douglas, David A. Lowe, John H. Schwarz

We study multiple 3-branes on an F theory orientifold. The world-volume theory of the 3-branes is d=4, N=2 Sp(2k) gauge theory with an antisymmetric tensor and four flavors of matter in the fundamental. The solution of this gauge theory is found for vanishing bare mass of the antisymmetric tensor matter, and massive fundamental matter. The integrable system

J. Fuchs, U. Ray, A. N. Schellekens, C. Schweigert

We associate to outer automorphisms of generalized Kac-Moody algebras generalized character-valued indices, the twining characters. A character formula for twining characters is derived which shows that they coincide with the ordinary characters of some other generalized Kac-Moody algebra, the so-called orbit Lie algebra. Some applications to problems in con

H. O. Girotti

The noncovariant duality symmetric action put forward by Schwarz-Sen is quantized by means of the Dirac bracket quantization procedure. The resulting quantum theory is shown to be, nevertheless, relativistically invariant.

H. O. Girotti, F. Fonseca Romero

The formulation of Berry for the Aharonov-Bohm effect is generalized to the relativistic regime. Then, the problem of finding the self-adjoint extensions of the (2+1)-dimensional Dirac Hamiltonian, in an Aharonov-Bohm background potential, is solved in a novel way. The same treatment also solves the problem of finding the self-adjoint extensions of the Dirac

Aharon Casher, Yigal Shamir

A supersymmetry anomaly is found in the presence of non-perturbative fields. When the action is expressed in terms of the correct quantum variables, anomalous surface terms appear in its supersymmetric variation - one per each collective coordinate. The anomalous surface terms do not vanish in general when inserted in two- or higher-loop bubble diagrams, and

V. D. Ivashchuk, V. N. Melnikov

A multidimensional gravitational model on the manifold $M = M_0 \times \prod_{i=1}^{n} M_i$, where M_i are Einstein spaces ($i \geq 1$), is studied. For $N_0 = dim M_0 > 2$ the $σ$ model representation is considered and it is shown that the corresponding Euclidean Toda-like system does not satisfy the Adler-van-Moerbeke criterion. For $M_0 = R^{N_0}$, $N_0 =

L. E. Gordon

The cross section for inclusive prompt photon production with polarized hadron beams is calculated at order $αα_s^2$ using the phase space slicing or analytic/Monte Carlo method. Isolation cuts are placed on the photon and the results are compared to a previous fully analytic calculation. Numerical results for the isolated cross section are presented for for

K. Hagiwara, T. Hatsukano, S. Ishihara, R. Szalapski

The process e+e- --> W+W- provides a valuable laboratory to test the Standard Model (SM) and to search for new physics. The most general helicity amplitudes for this process require the introduction of nine form-factors which we calculate in the context of SU(2) X U(1) gauge-invariant extensions of the SM. The contributions of new physics are parametrized vi

R. Sekhar Chivukula

Recently Appelquist, Terning, and Wijewardhana investigated the zero temperature chiral phase transition in SU(N) gauge theory as the number of fermions N_f is varied. They argued that there is a critical number of fermions N^c_f, above which there is no chiral symmetry breaking and below which chiral symmetry breaking and confinement set in. They further ar

Myron Bander

A sum rule relating the widths of the decays of mesons belonging to heavy quark multiplets, having the same parity and light quark spin j, into the low lying $0^-$ and $1^-$ multiplet is obtained. As this sum rule follows from properties of the axial charges, it is protected from heavy quark spin dependent $1/m_Q$ corrections. The sum rule works well for mes

Yakov Azimov, Isard Dunietz

While present vertex technology cannot measure x_s much beyond 20, the Standard Model accomodates significantly larger x_s values. This note presents a method to determine very large x_s with present technology. The determination is based upon subtle coherence effects between initial B_s mesons and daughter neutral kaons, discovered by one of us several year

Thierry Gousset

The physics of diffractive vector meson production in virtual photon nucleon scattering at NMC energies is reviewed. A particular attention is paid to the physical aspects of the reaction and how they influence the observables. The reaction is a good probe to investigate both soft exchange mechanisms and hadronic wave functions. Extension to either HERA or E

A. Ali

These lectures review some of the progress made in the quantitative understanding of B decays. The emphasis here is on applications of QCD using perturbative and non-perturbative techniques. In some cases, however, phenomenological models must at present be invoked to make meaningful comparison with data. The resulting picture is consistent with the standard

M. Carena, P. H. Chankowski, M. Olechowski, S. Pokorski

We present a bottom-up approach to the question of supersymmetry breaking in the MSSM. Starting with the experimentally measurable low-energy supersymmetry breaking parameters, which can take any values consistent with present experimental constraints, we evolve them up to an arbitrary high energy scale. Approximate analytical expressions for such an evoluti

W. Beenakker, A. Denner, S. Dittmaier, J. Hoogland

We describe the gauge-invariant treatment of the finite-width effects of W and Z bosons in the fermion-loop scheme and its application to the six-fermion (LEP2) processes e^- e^+ -> four fermions, with massless external fermions. The fermion-loop scheme consists in including all fermionic one-loop corrections in tree-level amplitudes and resumming the self-e

Hisakazu Minakata

I summarize the results of barely model-dependent phenomenological analyses of the structure of the neutrino flavor mixing. The analyses are based on the three-flavor mixing framework without sterile neutrinos and utilize the hints from solar and atmospheric neutrino observations as well as that from mixed dark matter cosmology. It will be demonstrated that

K. Cheung, S. Godfrey, J. Hewett

Fermion compositeness and other new physics can be signalled by the presence of a strong four-fermion contact interaction. Here we present a study of $\ell\ell qq$ and $\ell\ell\ell&#39;\ell&#39;$ contact interactions using the reactions: $\ell^+ \ell^- \to \ell&#39;^+\ell&#39;^-,b\bar b, c\bar c$ at future $e^+e^-$ linear colliders with $\sqrt s=0.5-5$ TeV

Jan Plefka, Stuart Samuel

A $θ$ term, which couples to topological charge, is added to the lattice $CP^{N-1}$ model. The strong-coupling character expansion is developed. The series for the free energy and mass gap are respectively computed to tenth order and fourth order. Several features of the strong-coupling analysis emerge. One is the loss of superconfinement. Another is that in

G. Koutsoumbas, I. Montvay

As a preparation for the numerical study of the SU(2) gauge theory with gluinos, the spectral properties of the fermion matrix and the masses of pseudoscalar and scalar states are investigated in the quenched approximation. The behaviour of the disconnected fermion diagrams on small lattices is also studied.

Mattias Marklund

The properties of some locally rotationally symmetric (LRS) perfect fluid space-times are examined in order to demonstrate the usage of the description of geometries in terms of the Riemann tensor and a finite number of its covariant derivatives for finding solutions to Einstein&#39;s field equations. A new method is introduced, which makes it possible to ch

V. Khatsymovsky

We calculate renormalised vacuum expectation values of electromagnetic stress-energy tensor in the static spherically-symmetrical wormhole topology. We find that for metric tensor sufficiently slow varied with distance violation of the averaged weak energy condition takes place irrespectively of the detailed form of metric. This is a necessary condition for

A. Borowiec, M. Ferraris, M. Francaviglia, I. Volovich

It is shown that the first order (Palatini) variational principle for a generic nonlinear metric-affine Lagrangian depending on the (symmetrized) Ricci square invariant leads to an almost-product Einstein structure or to an almost-complex anti-Hermitian Einstein structure on a manifold. It is proved that a real anti-Hermitian metric on a complex manifold sat

W. A. Atkinson, J. P. Carbotte

The electromagnetic response of a system with two planes per unit cell involves, in addition to the usual intraband contribution, an added interband term. These transitions affect the temperature dependence and the magnitude of the zero temperature c-axis penetration depth. When the interplane hopping is sufficiently small, the interband transitions dominate

Y. S. Kim

As Einstein&#39;s $E = mc^{2}$ unifies the energy-momentum relation for massive and massless particles, Wigner&#39;s little group unifies their internal space-time symmetries. It is pointed out that translational symmetries play essential roles both in formulating the problem, and in deriving the conclusions. The input translational symmetry is the space-tim

S. Daul, R. Noack

The one dimensional Hubbard model with nearest and (negative) next-nearest neighbour hopping has been studied with the density-matrix renormalization group (DMRG) method. A large region of ferromagnetism has been found for finite density and finite on-site interaction.

Ugur Tirnakli, Dogan Demirhan, Fevzi Buyukkilic

In this study, the internal energy and the specific heat of the one- dimensional Ising model obtained in the frame of the generalized statistical thermodynamics by Andrade [Physica A175 (1991) 285], have been extended somewhat and compared with the internal energy and the specific heat which have been calculated in the standard statistical thermodynamics.

Gene F. Mazenko, Robert A. Wickham

The vortex-vortex and vortex-antivortex correlation functions are determined for the two-dimensional O(2) model undergoing phase ordering. We find reasonably good agreement with simulation results for the vortex-vortex correlation function where there is a short-scaled distance depletion zone due to the repulsion of like-signed vortices. The vortex-antivorte

P. Svoboda, G. Nachtwei, C. Breitlow, S. Heide

The temperature dependence of both components of the resistivity tensor $\varrho_{xx}(T)$ and $\varrho_{xy}(T)$ has been studied at T $\geq$ 4.2 K within IQHE plateaux around filling factors ν=2 and ν=4 of medium- -mobility GaAs/AlGaAs heterostructures. In the middle of the mobility gap standard activated conductivity has been found with activation energies

A. Sacuto, R. Combescot, N. Bontemps, P. Monod

Pure electronic Raman spectra with no phonon structures superimposed to the electronic continuum, are reported, in optimally doped HgBa_{2}CaCu_{2}O_{6+δ} single crystals (T_{c }=126 K). As a consequence, the spectra in the A_{1g }, B_{1g } and B_{2g } symmetries, including the crucial low energy frequency dependence of the electronic scattering, are directl

Michael E. Bleich, David Hochheiser, Jerome V. Moloney, Joshua E. S. Socolar

We investigate a control technique for spatially extended systems combining spatial filtering with a previously studied form of time-delay feedback. The scheme is naturally suited to real-time control of optical systems. We apply the control scheme to a model of a transversely extended semiconductor laser in which a desirable, coherent traveling wave state e

A. Amengual, E. Hernandez-Garcia, R. Montagne, M. San Miguel

Synchronization of spatiotemporally chaotic extended systems is considered in the context of coupled one-dimensional Complex Ginzburg-Landau equations (CGLE). A regime of coupled spatiotemporal intermittency (STI) is identified and described in terms of the space-time synchronized chaotic motion of localized structures. A quantitative measure of synchronizat

Bogdan I. Epureanu, Henry S. Greenside

An intriguing and unexpected result for students learning numerical analysis is that Newton&#39;s method, applied to the simple polynomial z^3 - 1 = 0 in the complex plane, leads to intricately interwoven basins of attraction of the roots. As an example of an interesting open question that may help to stimulate student interest in numerical analysis, we inve

C. P. Dettmann, G. P. Morriss

We propose that cycle expansions be ordered with respect to stability rather than orbit length for many chaotic systems, particularly those exhibiting crises. This is illustrated with the strong field Lorentz gas, where we obtain significant improvements over traditional approaches.

James Binney, Walter Dehnen

A straightforward determination of the circular-speed curve vc(R) of the Milky Way suggests that near the Sun, vc starts to rise approximately linearly with R. If this result were correct, the Galactic mass density would have to be independent of radius at R ~> R0. We show that the apparent linear rise in v_c arises naturally if the true circular-speed curve

Ennio Poretti, Ilaria Pardo

By considering the least-squares fits of the double-mode Cepheid light curves discussed in Paper I we defined their properties by their Fourier parameters and generalized phase differences $G_{i,j}$. When plotting the latter quantities as a function of the respective order, the second order terms are confined in the region just below 3/2$π$; the third order

Ennio Poretti, Ilaria Pardo

We submitted the available photometric V data of all the known galactic Double Mode Cepheids (DMCs) to a careful frequency analysis with the aim of detecting in each case the importance of the harmonics and of the cross coupling terms. For each object, starting from different data subsets, we progressively built a homogenous set of data, checking the consist

D. E. Harris, J. A. Biretta, W. Junor

We present the evidence for X-ray variability from the core and from knot A in the M87 jet based on data from two observations with the Einstein Observatory High Resolution Imager (HRI) and three observations with the ROSAT HRI. The core intensity showed a 16% increase in 17 months (&#39;79-&#39;80); a 12% increase in the 3 years &#39;92 to &#39;95; and a 17

Craig L. Sarazin

Elliptical galaxies are generally luminous sources of X-ray radiation, and contain large amounts of hot, interstellar gas. In the brighter X-ray galaxies, the inferred masses of hot gas are consistent with those expected given the present rates of stellar mass loss. The required rates of heating of the gas are also roughly consistent with those expected from

S. Degl&#39;Innocenti, W. A. Dziembowski, G. Fiorentini, B. Ricci

We present a systematical analysis of uncertainties in the helioseismological determination of quantities characterizing the solar structure. We discuss the effect of errors on the measured frequencies, the residual solar model dependence and the uncertainties of the inversion method. We find Y_{ph}=0.238-0.259, $R_b/R_\odot=0.708-0.714$ and $ρ_b=(0.185-0.19

Craig L. Sarazin

Recent results on cluster cooling flows are reviewed. Observations of excess soft X-ray provides the only direct evidence for a major repository for the cooled gas. Unfortunately, the frequency of occurrence of large excess columns is uncertain. There is also great uncertainty about the physical state of the material producing the absorption. Radio observati

W. Steffen, J. L. Gomez, R. J. R. Williams, A. C. Raga

We present non-adiabatic hydrodynamic simulations of a supersonic light jet propagating into a fully ionized medium of uniform density on a scale representative of the narrow line region (NLR) in Seyfert galaxies with associated radio jets. In this regime the cooling distance of the swept up gas in the bowshock of the jet is of the same order as the transver

Craig L. Sarazin

The cooling cores of clusters of galaxies are among the brightest thermal X-ray line sources in the universe. High resolution X-ray spectra would allow individual line fluxes to be measured. The fluxes of low ionization X-ray lines in cooling flows should be directly proportional to the cooling rate at relatively cool temperatures, and could be used to deter

Craig L. Sarazin, Brian R. McNamara

The cluster A2597 was observed in X-rays with the ROSAT PSPC and HRI detectors. The X-ray isophotes are oriented similarly to the optical isophotes of the central cD galaxy and to the isopleths of the galaxy distribution in the cluster, but are otherwise quite regular, suggesting that this cluster is reasonably relaxed and in hydrostatic equilibrium. The mer

W. C. Haxton, K. Langanke, Y. -Z. Qian, P. Vogel

If the r-process occurs deep within a Type II supernova, probably the most popular of the proposed sites, abundances of r-process elements may be altered by the intense neutrino flux. We point out that the effects would be especially pronounced for 8 isotopes that can be efficiently synthesized by the neutrino reactions following r-process freeze-out. We sho

Neta A. Bahcall

How is the universe organized on large scales? How did this structure evolve from the unknown initial conditions to the present time? The answers to these questions will shed light on the cosmology we live in, the amount, composition and distribution of matter in the universe, the initial spectrum of density fluctuations, and the formation and evolution of g

L. Wen, A. Panaitescu, P. Laguna

We have developed a one-dimensional code to solve ultra-relativistic hydrodynamic problems, using the Glimm method for an accurate treatment of shocks and contact discontinuities. The implementation of the Glimm method is based on an exact Riemann solver and van der Corput sampling sequence. In order to improve computational efficiency, the Glimm method is r

J. A. Grifols, R. N. Mohapatra, A. Riotto

In some supergravity models, the superlight gravitino is accompanied by a light weakly coupled scalar (S) and pseudo-scalar (P) particle. The coupling of these particles to matter is inversely proportional to the product of the gravitino mass and the Planck mass. As a result, their emission from the stars and supernovae via the photon electron scattering rea

N. M. Bogoliubov, A. G. Izergin, N. A. Kitanine

We introduce the phase model on a lattice and solve it using the algebraic Bethe ansatz. Time-dependent temperature correlation functions of phase operators and the &#34;darkness formation probability&#34; are calculated in the thermodynamical limit. These results can be used to construct integrable equations for the correlation functions and to calculate th

J. L. Goity

Spin-flavor symmetry breaking in the levels of excited Baryons are studied to leading order in the 1/$N_c$ expansion. This breaking occurs at zeroth order. For non-strange Baryons with a single quark excited, it is shown that to first order of perturbation theory the breaking is given by one 1-body operator (spin-orbit), and three 2-body operators, all invol

R. Delbourgo, D. Liu

It is possible to determine a propapagator for heavy quarks to order 1/m in any covariant gauge, which applies universally to all quarks, by using the gauge technique. The leading behaviour is given by a _0F_2 function and the result is reliable in the infrared limit, accounting for soft-gluon corrections to the quark in internal loops.

L. B. Okun

An introductory talk at a Meeting on results and prospects of collaboration of Russian research organizations with European organization for nuclear research (CERN), which took place at the Ministry of science and technical policy of Russia on 8 July, 1996.

Rebecca A. W. Elson

Using the Hubble Space Telescope, we resolve the red giant branch in the halo of the S0 galaxy NGC 3115. We measure magnitudes and $(V-I)$ colours for stars down to 1.5 magnitudes below the tip of the red giant branch. From the brightest stars we estimate a distance modulus $(m-M)_0=30.21 \pm 0.30$, corresponding to a distance of $11.0 \pm 1.5$ Mpc. This is

R. A. McCorkle

Fundamental electroweak properties arise from a spacetime theory of matter, permitting evaluation of low energy coupling constants from first principles.

G. &#39;t Hooft

A deterministic model with a large number of continuous and discrete degrees of freedom is described, and a statistical treatment is proposed. The model exactly obeys a Schrodinger equation, which has to be interpreted exactly according to the Copenhagen prescriptions. After applying a Hartree-Fock approximation, the model appears to describe genuine quantum

Ferenc Niedermayer, Max Niedermaier, Peter Weisz

We show, by explicit computation, that bare lattice perturbation theory in the two-dimensional O(n) nonlinear $σ$ models with superinstanton boundary conditions is divergent in the limit of an infinite number of points $|Λ|$. This is the analogue of David&#39;s statement that renormalized perturbation theory of these models is infrared divergent in the limit

Yi Cheng, Zhifeng Li

In analogy to the KP theory, the second Poisson structure for the dispersionless KP hierarchy can be defined on the space of commutative pseudodifferential operators $L=p^n+\sum_{j=-\infty}^{n-1}u_j p^j$. The reduction of the Poisson structure to the symplectic submanifold $u_{n -1}=0$ gives rise to the w-algebras. In this paper, we discuss properties of thi

Jintai Ding

The particles with a scattering matrix R(x) are defined as operators $Φ_i(z)$ satisfying the relation $ R_{i,j}^{j&#39;,i&#39;}(x_1/x_2) Φ_{i&#39;}(x_1)Φ_{j&#39;}(x_2)= Φ_i(x_2)Φ_j(x_1)$. The algebra generated by those operators is called a Zamolochikov algebra. We construct a new Hopf algebra by adding half of the FRTS construction of a quantum affine algeb

J. Gomis, K. Kamimura, R. Kuriki

We construct the Wess-Zumino terms from anomalies in case of quasigroups for the following situations. One is effective gauge field theories of Nambu-Goldstone fields associated with spontaneously broken global symmetries and the other is anomalous gauge theories. The formalism that we will develop can be seen as a generalization of the non-linear realizatio

A. Harindranath

In these lectures we hope to provide an elementary introduction to selected topics in light-front dynamics. Starting from the study of free field theories of scalar boson, fermion, and massless vector boson, the canonical field commutators and propagators in the instant and front forms are compared and contrasted. Poincare algebra is described next where the

H. C. Rosu, J. Socorro

We present the supersymmetric Witten and double Darboux (strictly isospectral) constructions as applied to the diffusion of thermal neutrons from an infinitely long line source. While the Witten construction is just a mathematical scheme, the double Darboux method introduces a one-parameter family of diffusion solutions which are strictly isospectral to the

Z. Thomova, P. Winternitz, W. J. Zakrzewski

We use the methods of group theory to reduce the equations of motion of two spin systems in (2+1) dimensions to sets of coupled ordinary differential equations. We present solutions of some classes of these sets and discuss their physical significance.

Jintai Ding, Boris Feigin

We construct a commutative current operator $\bar x^+(z)$ inside $U_q(\hat{\frak sl}(2))$. With this operator and the condition of quantum integrability on the quantum current of $U_q(\hat{\frak sl}(2))$, we derive the quantization of the semi-infinite construction of integrable modules of $\hat{\frak sl}(2)$ with the current operator $e(z)$ of $\hat{\frak s

A. Ludu, W. Scheid

Using a complex deformation q=exp(is) of su(2) we obtain extensions of the finite-dimensional representations towards the infinite-dimensional ones. A generalised q-deformation of su(2), as a Hopf algebra is introduced. We present the corresponding Schrodinger picture, by using a differential realisation, and a large class of potentials is obtained.A connect

János Komlós, Gabor N. Sarkozy, Endre Szemerédi

Recently we have developed a new method in graph theory based on the Regularity Lemma. The method is applied to find certain spanning subgraphs in dense graphs. The other main general tool of the method, beside the Regularity Lemma, is the so-called Blow-up Lemma. This lemma helps to find bounded degree spanning subgraphs in $\varepsilon$-regular graphs. Our

Gabor N. Sarkozy, Stanley Selkow

A Hamiltonian graph $G$ of order $n$ is $k$-ordered, $2\leq k \leq n$, if for every sequence $v_1, v_2, \ldots ,v_k$ of $k$ distinct vertices of $G$, there exists a Hamiltonian cycle that encounters $v_1, v_2, \ldots , v_k$ in this order. In this paper, answering a question of Ng and Schultz, we give a sharp bound for the minimum degree guaranteeing that a g

M. Bershadsky, A. Johansen, T. Pantev, V. Sadov

We consider geometric engineering of N=1 supersymmetric QFTs with matter in terms of a local model for compactification of F-theory on Calabi-Yau fourfold. By bringing 3-branes near 7-branes we engineer N=1 supersymmetric $SU(N_c)$ gauge theory with $N_f$ flavors in the fundamental. We identify the Higgs branch of this system with the instanton moduli space

Igor R. Klebanov, Michael Krasnitz

We perform the classical gravity calculations of the fixed scalar absorption cross-sections by D=5 black holes with three charges and by D=4 black holes with four charges. We obtain analytic results for the cases where the energy and the left and right moving temperatures are sufficiently low but have arbitrary ratios. In D=5 the greybody factor is in perfec

T. Fugleberg, A. Zhitnitsky

We demonstrate in two minisuperspace models that a perturbation expansion of quasiclassical Euclidean gravity has a factorial dependence on the order of the term at large orders. This behavior indicates that the expansion is an asymptotic series which is suggestive of an effective field theory. The series may or may not be Borel summable depending on the cla

A. Belavin, A. Fring

The conjecture that the states of the fermionic quasi-particles in minimal conformal field theories are eigenstates of the integrals of motion to certain eigenvalues is checked and shown to be correct only for the Ising model.