February 1995 arXiv papers — page 9

Krzysztof M. Gorski, Bharat Ratra, Naoshi Sugiyama, Anthony J. Banday

Fourier analysis on a cut sky of the two-year COBE DMR 53 and 90 GHz sky maps (in galactic coordinates) is used to determine the normalisation of an open inflation model based on the cold dark matter scenario. The normalised model is compared to measures of large-scale structure in the universe. Although the DMR data alone does not provide sufficient discrim

Krzysztof M. Gorski, Radoslaw Stompor, Anthony J. Banday

The two-year COBE-DMR 53 and 90 GHz sky maps in both ecliptic and galactic coordinates, are used to determine the normalisation of inflationary, flat, dark matter dominated universe models. The appropriately normalized cold and mixed dark matter models, computed for a range of values of Omega_baryon and h, and several values of the hot to cold dark matter ab

K. Gorski, C. L. Bennett, A. J. Banday

The three papers summarize the methods employed by the COBE-DMR group to analyze the power spectrum of the two-year DMR anisotropy maps. Results for the slope and normalization of the power spectrum are presented and compared. The implications of these results for various dark matter-based structure formation models are also discussed.

J. H. Knapen, J. E. Beckman, I. Shlosman, R. F. Peletier

New optical and NIR K-band images of the inner 3 kpc region of the nearby Virgo spiral M100 (NGC 4321) display remarkable morphological changes with wavelength. While in the optical the light is dominated by a circumnuclear zone of enhanced star formation, the features in the 2.2\mum image correspond to a newly discovered kpc-size stellar bar, and a pair of

Max Tegmark

A new method for estimating the power spectrum $C_l$ from cosmic microwave background (CMB) maps was recently presented by the author and applied to the 2 year COBE data. It was found that the spectral resolution $Δl$ for COBE could be more than doubled at $l=15$, thereby revealing previously unresolved features in the power spectrum. Whereas that paper was

Gary Steigman, James. E. Felten

Nucleosynthesis in the standard hot big bang cosmology offers a successful account of the production of the light nuclides during the early evolution of the Universe. Consistency among the predicted and observed abundances of D, $^3$He, \hel4 and \li7 leads to restrictive lower and upper bounds to the present density of nucleons. In particular, the upper bou

Frederic A. Rasio

The minimum mass ratio for tidal stability of a contact binary containing two unevolved main-sequence stars is calculated to be $\qmin\simeq0.09$ in the case of a mostly radiative primary, and is higher if an appreciable fraction of the mass lies in a convective envelope. At least one observed system, AW UMa, has a mass ratio just below this value ($q=0.075$

Tal Alexander

A recently discovered inverse correlation between QSO redshift and long-term continuum variability timescales was suggested to be the signature of microlensing on cosmological scales (Hawkins 1993). A general theoretical method for calculating such correlations is presented and applied to various lensing scenarios in the framework of $Λ= 0$ Friedmann cosmolo

Lars Brostrom, Sven Mannervik, Peder Royen, Anders Wannstrom

The isotope shift between singly-charged ^<151>Eu and ^<153>Eu in the 4f^7(^8S^o)6s^9S_4-4f^7(^8S^o)6p_1/2>(J=4) transition at 4129 A has been measured using fast ion beam-laser technique. This Eu line has attracted interest in connection with efforts of obtaining a cosmochronometer based on observed Th/Eu abundance ratios. Knowledge of the isotope shift is

Helene Di Nella, Georges Paturel

From the Lyon-Meudon Extragalactic Database LEDA, we constructed a sample of 27,000 galaxies with radial velocities smaller than 15,000 km s$^{-1}$. From this first sample we selected the 5,683 largest galaxies which constitute a sample complete up to the diameter limit $D_{25}=1.6&#39;$. This sub-sample has been used to search for the most populated plane.

Paul J. Steinhardt

Observational tests during the next decade may determine if the evolution of the Universe can be understood from fundamental physical principles, or if special initial conditions, coincidences, and new, untestable physical laws must be invoked. The inflationary model of the Universe is an important example of a predictive cosmological theory based on physica

C. A. Collins, L. Guzzo, R. C. Nichol, S. L. Lumsden

We present the redshifts of the galaxies and galaxy clusters which form the Edinburgh--Milano (EM) cluster redshift survey. A total of 777 galaxy redshifts have been measured in 94 clusters extracted from the digitised Edinburgh Durham Cluster Catalogue. We also present the radial velocity dispersions for 37 clusters. Observational and data reduction techniq

Masanori Kobayashi

A notion of duality of weight systems which corresponds to Batyrev&#39;s toric mirror symmetry is given. Explicit duality on the (1,1)-cohomology of K3 surfaces which are minimal models of toric hypersurfaces is constructed using monomial divisor mirror map of Aspinwall-Greene-Morrison. It is shown that Arnold&#39;s strange duality for exceptional unimodal s

Silas R. Beane

A general no-go theorem dampens hope that the cosmological constant problem can be solved by a local symmetry mechanism. The possibility is considered here that this no-go theorem can be avoided by a pseudo-symmetry. A simple macroscopic effective field theory is constructed which admits an enhanced pseudo-symmetry in the absence of a cosmological term. It i

Ehab Malkawi, C. --P. Yuan

We study large top quark mass effects on low energy physics in the chiral Lagrangian formulated electroweak theories. We show that these radiative corrections can be easily obtained from a set of Feynman diagrams involving only the scalar Goldstone bosons and the fermions when the contributions of the order $g$ (the weak coupling) are ignored. Using CERN LEP

Yoshinari Inoue

With respect to the Dirac operator and the conformally invariant Laplacian, an explicit description of the inverse Penrose transform on Riemannian twistor spaces is given. A Dolbeault representative of cohomology on the twistor space is constructed from a solution of the field equation on the base manifold.

Jorge Berger

After presenting possible motives for fighting against the second law of thermodynamics, several attempts to beat this law are analyzed. The second law wins, but an interesting interpretation of it emerges. This interpretation uses the notion of ``encoded order&#39;&#39; and claims that whether a system is or is not in thermodynamic equilibrium depends on th

Sandu Popescu

As is well known, quantum mechanical behavior cannot, in general, be simulated by a local hidden variables model. Most -if not all- the proofs of this incompatibility refer to the correlations which arise when each of two (or more) systems separated in space is subjected to a single ideal measurement. This setting is good enough to show contradictions betwee

L. Vaidman

In a recent article [D. Suter, Phys. Rev. {\bf A 51}, 45 (1995)] Suter has claimed to present an optical implementation of the quantum time-translation machine which ``shows all the features that the general concept predicts and also allows, besides the quantum mechanical, a classical description.&#39;&#39; It is argued that the experiment proposed and perfo

S. Nakamura, K. Muto, M. Oka, S. Takeuchi

A charge-symmetry-breaking nucleon-nucleon force due to the up-down quark mass difference is evaluated in the quark cluster model. It is applied to the shell-model calculation for the isovector mass shifts of isospin multiplets and the isospin-mixing matrix elements in 1s0d-shell nuclei. We find that the contribution of the quark mass difference effect is la

A. Moroianu, U. Semmelmann

We collect our recent results ([5] and [8]) and we get the equivalence of the three notions of the title under some conditions. We then use this equivalence in order to prove some consequences about Sasakian manifolds, complex almost contact structures and complex k-contact structures.

Gregor Erbach

We propose a bottom-up variant of Earley deduction. Bottom-up deduction is preferable to top-down deduction because it allows incremental processing (even for head-driven grammars), it is data-driven, no subsumption check is needed, and preference values attached to lexical items can be used to guide best-first search. We discuss the scanning step for bottom

Gregor Erbach

ProFIT is an extension of Standard Prolog with Features, Inheritance and Templates. ProFIT allows the programmer or grammar developer to declare an inheritance hierarchy, features and templates. Sorted feature terms can be used in ProFIT programs together with Prolog terms to provide a clearer description language for linguistic structures. ProFIT compiles a

Barbara Dietz, Jean-Pierre Eckmann, Claude-Alain Pillet, Uzy Smilansky

This paper reports the results of extensive numerical studies related to spectral properties of the Laplacian and the scattering matrix for planar domains (called billiards). There is a close connection between eigenvalues of the billiard Laplacian and the scattering phases, basically that every energy at which a scattering phase is $2π$ corresponds to an ei

H. J. Haubold, A. M. Mathai

Hydrostatic equilibrium and energy conservation determine the conditions in the gravitationally stabilized solar fusion reactor. We assume a matter density distribution varying non- linearly through the central region of the Sun. The analytic solutions of the differential equations of mass conservation, hydrostatic equilibrium, and energy conservation, toget

Keith A. Clay, Stephen D. Ellis

The O(alpha_s^2) contribution to the Energy-Energy Correlation function (EEC) of e+e- -> hadrons is calculated to high precision and the results are shown to be larger than previously reported. The consistency with the leading logarithm approximation and the accurate cancellation of infrared singularities exhibited by the new calculation suggest that it is r

Francesco Mauri, Roberto Car

We present a first-principles study of excitonic self-trapping in diamond. Our calculation provides evidence for self-trapping of the 1s core exciton and gives a coherent interpretation of recent experimental X-ray absorption and emission data. Self-trapping does not occur in the case of a single valence exciton. We predict, however, that self-trapping shoul

M. B. Voloshin

The QCD sum rules for moments of production cross section of $b \overline b$ states in $e^+\,e^-$ annihilation are extremely sensitive to the values of $m_b$ and $α_s$ for moments of large order $n$. This enables one to extract from the existing data on $Υ$ resonances the values of these parameters with a high precision by using a non-relativistic expansion

Y. Alhassid, H. Attias

This paper establishes the universality of parametric correlations of eigenfunctions in chaotic and weakly disordered systems. We demonstrate this universality in the framework of the gaussian random matrix process and obtain predictions for a number of parametric correlators, one of them analytically. We present numerical evidence from different models that

J. -P. Eckmann, C. -A. Pillet

For a bounded open domain $Ω\in \real^2$ with connected complement and piecewise smooth boundary, we consider the Dirichlet Laplacian $-\DO$ on $Ω$ and the S-matrix on the complement $Ω^c$. Using the restriction $A_E$ of $(-Δ-E)^{-1}$ to the boundary of $Ω$, we establish that $A_{E_0}^{-1/2}A_EA_{E_0}^{-1/2}-1$ is trace class when $E_0$ is negative and give

C. J. Pethick, Vesteinn Thorsson

A brief review is given of neutrino emission processes in dense matter, with particular emphasis on recent developments. These include direct Urca processes for nucleons and hyperons, which can give rise to rapid energy loss from the stellar core without exotic matter, and the effect of band structure on neutrino bremsstrahlung from electrons in the crust, w

Mihir P. Worah

We propose a model based on the gauge group $SU(4)\times SU(2)_L\times SU(2)_R$ where the Dirac masses of all the known fermions are generated as one-loop radiative corrections. We are able to generate realistic quark and lepton masses and mixings without a large hierarchy of Yukawa couplings or extra symmetries. The neutrino masses, which are see-saw suppre

Dmitri Pogosyan, Alexei Starobinsky

Mixed cold-hot dark matter cosmological models (CHDM) with $Ω_{tot}=1$, approximately flat initial spectrum of adiabatic perturbations and 1, 2 or 3 types of massive neutrinos are compared and tested using recent observational data. The models with 2 or 3 neutrino types of equal mass permit as the best fit larger values of both the Hubble constant ($H_0\le 6

Olaf Bechmann, Olaf Lechtenfeld

Einstein gravity minimally coupled to a self-interacting scalar field is investigated in the static and isotropic situation. We explicitly construct in partially closed form a new black-hole solution with exponentially decaying scalar hair. The symmetric interaction potential has both signs and a triple-well shape with a smooth but non-analytic minimum at va

M. Asorey, F. Falceto

We show that regularization of gauge theories by higher covariant derivatives and gauge invariant Pauli-Villars regulators is a consistent method if the Pauli-Villars vector fields are considered in a covariant in the regulating Pauli-Villars fields is pathological and the original Slavnov proposal in covariant Landau gauge is not correct because of the appe

A. Aurilia, A. Smailagic, E. Spallucci

We discuss a model of a conformal p-brane interacting with the world volume metric and connection. The purpose of the model is to suggest a mechanism by which gravity coupled to p-branes leads to the formation of structure rather than homogeneity in spacetime. Furthermore, we show that the formation of structure is accompanied by the appearance of a multival

Carla Buzano, Alessandro Pelizzola

The phase diagram of the Blume--Capel model on a semi--infinite simple cubic lattice with a (100) free surface is studied in the pair approximation of the cluster variation method. Six main topologies are found, of which two are new, due to the occurrence of a first order surface transition in the phase with ordered bulk, separating two phases with large and

Alessandro Pelizzola

The crossover behavior of the semi--infinite three dimensional Ising model is investigated by means of Padé approximant analysis of cluster variation method results. We give estimates for ordinary critical as well as for multicritical exponents, which are in very good agreement with extensive Monte Carlo simulations.

J. Hietarinta, T. Kuusela, B. Malomed

We consider the propagation of a shock wave (SW) in the damped Toda lattice. The SW is a moving boundary between two semi-infinite lattice domains with different densities. A steadily moving SW may exist if the damping in the lattice is represented by an ``inner&#39;&#39; friction, which is a discrete analog of the second viscosity in hydrodynamics. The prob

Chong-Sun Chu, Bruno Zumino

The vector fields of the quantum Lie algebra are described for the quantum groups $GL_q(N), SL_q(N)$ and $SO_q(N)$ as pseudodifferential operators on the linear quantum spaces covariant under the corresponding quantum group. Their expressions are simple and compact. It is pointed out that these vector fields satisfy certain characteristic polynomial identiti

Terry Gannon

The characters $χ_μ$ of nontwisted affine algebras at fixed level define in a natural way a representation $R$ of the modular group $SL_2(Z)$. The matrices in the image $R(SL_2(Z))$ are called the Kac-Peterson modular matrices, and describe the modular behaviour of the characters. In this paper we consider all levels of $(A_{r_1}\oplus\cdots\oplus A_{r_s})^{

Rajeev K. Puri, E. Lehmann, Amand Faessler, S. W. Huang

The covariant and non-covariant Quantum Molecular Dynamics models are applied to investigate possible relativistic effects in heavy ion collisions at SIS energies. These relativistic effects which arise due to the full covariant treatment of the dynamics are studied at bombarding energies E$_{lab.}$ = 50, 250, 500, 750, 1000, 1250, 1500, 1750 and 2000 MeV/nu

E. Lehmann, Rajeev K. Puri, Amand Faessler, G. Batko

Heavy ion collisions at intermediate energies are studied by using a new RQMD code, which is a covariant generalization of the QMD approach. We show that this new implementation is able to produce the same results in the nonrelativistic limit (i.e. 50MeV/nucl.) as the non-covariant QMD. Such a comparison is not available in the literature. At higher energies

Rajeev K. Puri, E. Lehmann, Amand Faessler, S. W. Huang

Non-equilibrium effects are studied using a full Lorentz-invariant formalism. Our analysis shows that in reactions considered here, no global or local equilibrium is reached. The heavier masses are found to be equilibrated more than the lighter systems. The local temperature is extracted using hot Thomas Fermi formalism generalized for the case of two interp

Rajeev K. Puri, E. Lehmann, Amand Faessler, S. W. Huang

We analyze relativistic effects in transverse momentum using Quantum Molecular Dynamics [QMD] and its covariant extension Relativistic Quantum Molecular Dynamics [RQMD]. The strength of the relativistic effects is found to increase with the bombarding energy and with an averaged impact parameter. The variation in the intensity of the relativistic effects wit

A. A. Usmani, Steven C. Pieper, Q. N. Usmani

Variational Monte Carlo calculations have been made for the $_{ Λ}^{17}$O hypernucleus using realistic two- and three-baryon interactions. A two pion exchange potential with spin- and space-exchange components is used for the $Λ$N potential. Three-body two-pion exchange and strongly repulsive dispersive $Λ$NN interactions are also included. The trial wave fu

S. Soff, S. A. Bass, C. Hartnack, H. Stoecker

We investigate the disappearance of collective flow in the reaction plane in heavy-ion collisions within a microscopic model (QMD). A systematic study of the impact parameter dependence is performed for the system Ca+Ca. The balance energy strongly increases with impact parameter. Momentum dependent interactions reduce the balance energies for intermediate i

M. M. Sharma, G. Lalazissis, J. König, P. Ring

The isospin dependence of the spin-orbit potential is investigated for an effective Skyrme-like energy functional suitable for density dependent Hartree-Fock calculations. The magnitude of the isospin dependence is obtained from a fit to experimental data on finite spherical nuclei. It is found to be close to that of relativistic Hartree models. Consequently

G. I. Lykasov, M. N. Sergeenko

Resubmitted as hep-ph/9502316. Removed from hep-th. Incorrigibly inept submitter publicly excoriated.

Ashok Das, Marcelo Hott

We study the Wess-Zumino theory on ${\bf R}^3 \times S^1$ where a spatial coordinate is compactified. We show that when the bosonic and fermionic fields satisfy the same boundary condition, the theory does not develop a vacuum energy or tadpoles. We work out the two point functions at one loop and show that their forms are consistent with the nonrenormalizat

M. Asorey, F. Falceto, J. L. Lopez, G. Luzon

In the presence of Chern-Simons interactions the wave functionals of physical states in 2+1-dimensional gauge theories vanish at anumber of nodal points. We show that those nodes are located at some classical configurations which carry a non-trivial magnetic charge. In abelian gauge theories this fact explains why magnetic monopoles are suppressed by Chern-S

M. Martellini, M. Spreafico, K. Yoshida

We discuss the so called gauge invariant quantization of anomalous gauge field theory, originally due to Faddeev and Shatashvili. It is pointed out that the further non invariance of relevant path integral measures poses a problem when one tries to translate it to BRST formalism. The method by which we propose to get around of this problem introduces certain

B. Enriquez

We study the soliton-type solutions of the system introduced by B. Feigin and the author in in [EF]. We show that it reduces to a top-like system, and we study the behaviour of the solutions at the lattice infinity. We compute the scattering of the solitons and study some periodic solutions of the system.

Andrea Cappelli, Carlo A. Trugenberger, Guillermo R. Zemba

In this paper, we pursue our analysis of the W-infinity symmetry of the low-energy edge excitations of incompressible quantum Hall fluids. These excitations are described by (1+1)-dimensional effective field theories, which are built by representations of the W-infinity algebra. Generic W-infinity theories predict many more fluids than the few, stable ones f

Rolf Tarrach

Triviality and Landau poles are often greeted as harbingers of new physics at 1 TeV. After briefly reviewing the ideas behind this, a model of singular quantum mechanics is introduced. Its ultraviolet structure, as well as some features of its vacuum, related to triviality, very much parallel $λϕ^4$. The model is solvable, exactly and perturbatively, in any

Sigurd Schelstraete, Henri Verschelde

We present a simple technique that allows to generate Feynman diagrams for vector models with interactions of order $2n$ and similar models (Gross-Neveu, Thirring model), using a bootstrap equation that uses only the free field value of the energy as an input. The method allows to find the diagrams to, in principle, arbitrarily high order and applies to both

H. Arodz

The well-known idea to construct domain wall type solutions of field equations by means of an expansion in the width of the domain wall is reexamined. We observe that the problem involves singular perturbations. Hilbert-Chapman-Enskog method is used to construct a consistent perturbative expansion. We obtain the solutions to the second order in the width wit

S. Dimopoulos

A few topics beyond the standard model are reviewed.

Srubabati Goswami, Kamales Kar, Amitava Raychaudhuri

The role of matter enhanced resonant neutrino oscillations in reviving a stalled shock in a type-II supernova through delayed neutrino heating is investigated. The extent of neutrino heating is estimated for the allowed possibility of complete flavour conversion self-consistently with the changes in nuclear equilibrium. The average internal energy per nucleo

Seyong Kim, D. K. Sinclair

We present the first direct evidence that quenched QCD differs from full QCD in the chiral ($m_q \rightarrow 0$) limit, as predicted by chiral perturbation theory, from our quenched lattice QCD simulations at $β= 6/g^2 = 6.0$. We measured the spectrum of light hadrons on $16^3 \times 64$, $24^3 \times 64$ and $32^3 \times 64$, using staggered quarks of masse

Ingemar Bengtsson

Riemannian geometry in four dimensions, including Einstein&#39;s equations, can be described by means of a connection that annihilates a triad of two-forms (rather than a tetrad of vector fields). Our treatment of the conformal factor of the metric differs from the original presentation of this result, due to &#39;tHooft. In the action the conformal factor n

D. Burghelea, L. Friedlander, T. Kappeler, P. McDonald

For a closed Riemannian manifold we extend the definition of analytic and Reidemeister torsion associated to an orthogonal representation of fundamental group on a Hilbert module of finite type over a finite von Neumann algebra. If the representation is of determinant class we prove, generalizing the Cheeger-Müller theorem, that the analytic and Reidemeister

P. Chandra, L. B. Ioffe, D. Sherrington

We present an analytic study of a periodic Josephson array with long-range interactions in a transverse magnetic field. We find that this system exhibits a first-order transition into a phase characterized by an extensive number of states separated by barriers that scale with the system size; the associated discontinuity is small in the limit of weak applied

Y. M. Vilk, A. -M. S. Tremblay

It is shown that it is possible to quantitatively explain quantum Monte Carlo results for the Green&#39;s function of the two-dimensional Hubbard model in the weak to intermediate coupling regime. The analytic approach includes vertex corrections in a paramagnon-like self-energy. All parameters are determined self-consistently. This approach clearly shows th

Dmitri B. Chklovskii

I study the structure of the two-dimensional electron gas edge in the quantum Hall regime using the composite fermion approach. The electron density distribution and the composite fermion energy spectrum are obtained numerically in Hartree approximation for bulk filling factors $ν=1,1/3,2/3,1/5$. For a very sharp edge of the $ν=1$ state the one-electron pict

Miles Osborne

When parsing unrestricted language, wide-covering grammars often undergenerate. Undergeneration can be tackled either by sentence correction, or by grammar correction. This thesis concentrates upon automatic grammar correction (or machine learning of grammar) as a solution to the problem of undergeneration. Broadly speaking, grammar correction approaches can

R. Aurich, J. Marklof

This paper is devoted to the quantum chaology of three-dimensional systems. A trace formula is derived for compact polyhedral billiards which tessellate the three-dimensional hyperbolic space of constant negative curvature. The exact trace formula is compared with Gutzwiller&#39;s semiclassical periodic-orbit theory in three dimensions, and applied to a tetr

Michael J. Tripicco, Roger A. Bell, Ben Dorman, Beth Hufnagel

We have computed 8, 10, and 12 Gyr isochrones and physically consistent models of zero-age red horizontal branch stars for stellar masses between 0.55 and 1.3~\msun, all at [Fe/H] $=+0.15$. Comparison to the NGC 6791 BVI photometry of Kałużny & Udalski (1992) and Montgomery, Janes & Phelps (1994) yields an age of $10.0\pm0.5$ Gyr at an apparent distance modu

A. Campos, G. Yepes, A. Klypin, G. Murante

We use the moments of counts of neighbors as given by the Generalized Correlation Integrals, to study the clustering properties of Dark Matter Halos (DH) in Cold Dark Matter (CDM) and Cold+Hot Dark Matter (CHDM) models. We compare the results with those found in the CfA and SSRS galaxy catalogs. We show that if we apply the analysis in redshift space, both m

Matthew Colless

A re-analysis of Lauer \& Postman&#39;s (1994; LP) finding that the Abell cluster inertial frame (ACIF), defined by the 119 Abell clusters within 15,000 km/s, is moving at almost 700 km/s with respect to the cosmic microwave background. Such a motion is inconsistent with most cosmological models at a confidence level of 95% or higher. We obtain an exact expr

Xingming Chen, Marek A. Abramowicz, Jean-Pierre Lasota, Ramesh Narayan

We provide a unified description of thermal equilibria of black hole accretion disks, including the newly-discovered advection-dominated solutions. We classify the solutions on the basis of optical depth and importance of advection cooling. We demonstrate that only four physically distinct topological types of equilibria exist. Two of the types correspond to

Xingming Chen

Cold optically thick accretion disks with hot coronae and radial advection have been investigated. Within the framework of $α$-viscosity models, we assume that all the mass accretion and angular momentum transport take place in the cold disk, but that a fraction of the gravitational energy released is dissipated in the corona. Both the coronal energy dissipa

Matthias Steinmetz

SPH hydrodynamical simulations of the formation of galaxies are presented including the effects of an UV background radiation field. Based on a talk presented at the 17th Texas Symposium on Relativistic Astrophysics held in Munich, December 1994.

Arnaud Beauville

The title is self-explanatory.

Max Tegmark

The power spectrum estimated from a galaxy redshift survey is the real spectrum convolved with a window function, so when estimating the power on very large scales (for small k), it is important that this window function be as narrow as possible. A method that achieves this is presented. The optimal estimate of P(k) is found to be the Fourier transform of th

TED JACOBSON, GUNGWON KANG, ROBERT C. MYERS

We discuss some recent results on black hole thermodynamics within the context of effective gravitational actions including higher-curvature interactions. Wald&#39;s derivation of the First Law demonstrates that black hole entropy can always be expressed as a local geometric density integrated over a space-like cross-section of the horizon. In certain cases,

Orfeu Bertolami, Juan Garcia-Bellido

We study the phenomenological consequences of the recently proposed idea of a running gravitational coupling on macroscopic scales. When applied to the rotation curves of galaxies, we find that their flatness requires the presence of baryonic dark matter. Bounds on the variation of the gravitational coupling from primordial nucleosynthesis and the change of

E. S. Moreira, Jnr.

Representations of the Klein-Gordon and Dirac propagators are determined in a $N$ dimensional conical background for massive fields twisted by an arbitrary angle $2πσ$. The Dirac propagator is shown to be obtained from the Klein-Gordon propagator twisted by angles $2πσ\pm {\cal D}/2$ where ${\cal D}$ is the cone deficit angle. Vacuum expectation values are d

R. Piorno Schiavon, C. Batalha, B. Barbuy

The inferred effective temperatures (T$_{\rm eff}$) and surface gravities of T Tauri stars (TTS) are usually contaminated by the presence of a non stellar continuum emission (veiling) and the strong chromospheric activity characteristic of these objects. In this work, we develop a method to determine T$_{\rm eff}$&#39;s and surface gravities (log$\,g$) of a

B. C. Allanach, S. F. King

We calculate quark and lepton masses and quark mixing angles in the framework of a supersymmetric SU(4)$\otimes$SU(2)$_L\otimes$SU(2)$_R$ model where the gauge group is broken at 10$^{16}$ GeV. The model predicts third family top-bottom-tau Yukawa unification, as in minimal SO(10). The other smaller Yukawa couplings are assumed to arise from non-renormalisab

Anders W. Sandvik, Andrey V. Chubukov, Subir Sachdev

We analyze quantum Monte Carlo data in the vicinity of the quantum transition between a Neel state and a quantum paramagnet in a two-layer, square lattice spin 1/2 Heisenberg antiferromagnet. The real-space correlation function and the universal amplitude ratio of the structure factor and the dynamic susceptibility show clear evidence of quantum critical beh

Mihir Arjunwadkar, D. G. Kanhere, G. Baskaran, Rahul Basu

One of the most debated issues related to high-$T_c$ superconductivity is the symmetry of the Cooper pair or the gap function. In this report, we present numerical results regarding the gap function in strongly correlated electron systems using $t-J$ and Hubbard models in one and two dimensions. To this end, we use exact diagonalization to study the ground s

G. Baskaran, D. G. Kanhere, Mihir Arjunwadkar, Rahul Basu

Electron correlation in cuprates leads to a global constraint $\sum_{\bf k} Δ_{\bf k} = 0$ on the gap function $Δ_{\bf k}$ resulting in a gap nodal surface. We give physical arguments supported by numerical results and discuss some experimental results to argue that correlations also lead to a local constraint on charge fluctuations in ${\bf k}$-space close

M. Alexandrov, M. Kontsevich, A. Schwarz, O. Zaboronsky

In Batalin-Vilkovisky formalism a classical mechanical system is specified by means of a solution to the {\sl classical master equation}. Geometrically such a solution can be considered as a $QP$-manifold, i.e. a super\m equipped with an odd vector field $Q$ obeying $\{Q,Q\}=0$ and with $Q$-invariant odd symplectic structure. We study geometry of $QP$-manifo

Christopher Jarzynski

The study of wavepacket revivals is extended to the case of Hamiltonians which are made time-dependent through the adiabatic cycling of some parameters. It is shown that the quantal geometric phase (Berry&#39;s phase) causes the revived packet to be displaced along the classical trajectory, by an amount equal to the classical geometric phase (Hannay&#39;s an

Aephraim M. Steinberg

It is argued that there is a sensible way to define conditional probabilities in quantum mechanics, assuming only Bayes&#39;s theorem and standard quantum theory. These probabilities are equivalent to the ``weak measurement&#39;&#39; predictions due to Aharonov {\it et al.}, and hence describe the outcomes of real measurements made on subensembles. In partic

S. Uchiyama

We model measuring processes of a single spin-1/2 object and of a pair of spin-1/2 objects in the EPR-Bohm state by systems of differential equations. Our model is a local model with hidden-variables of the EPR-Bohm Gedankenexperiment. Although there is no dynamical interaction between a pair of spin-1/2 objects, the model can reproduce approximately the qua

J. A. de Azcarraga, F. Rodenas

An introduction to quantum groups and non-commutative differential calculus (Lecture at the III Workshop on Differential Geometry, Granada, September 1994)

T. -S. H. Lee

It is shown that the threshold productions of $π^0 pp$, $π^+ np$ and $π^+ d$ from $pp$ collisions can be consistently described by a model consisting of a pion s-wave rescattering and $N\bar N$ pair-terms of heavy-meson exchanges. The large difference between $σ^{tot} (pp\rightarrowπ^+ d)$ and $σ^{tot} (pp\rightarrowπ^+ np)$ is understood from the orthogonal

V. Thorsson, M. Prakash, T. Tatsumi, C. J. Pethick

We consider the rate at which energy is emitted by neutrinos from the dense interior of neutron stars containing a Bose condensate of pions or kaons. The rates obtained are larger, by a factor of 2, than those found earlier, and are consistent with those found for the direct Urca processes.

Vesteinn Thorsson, Andreas Wirzba

Chiral effective lagrangians may differ in their prediction of meson-nucleon scattering amplitudes off-meson-mass-shell, but must yield identical S-matrix elements. We argue that the effective meson mass in nuclear matter obtained from chiral effective lagrangians is also unique. Off-mass-shell amplitudes obtained using the PCAC choice of pion field must the

Shin Muroya, Hiroki Nakamura, Mikio Namiki

We numerically analyze recent high energy heavy-ion collision experiments based on a hydrodynamical model with phase transition and discuss a systematic change of initial state of QGP-fluid depending on colliding-nuclei&#39;s mass. In a previous paper, we formulated a (3+1)-dimensional hydrodynamical model for quark-gluon plasma with phase transition and dis

R. Nojarov, Amand Faessler, M. Dingfelder

All the orbital M1 excitations, at both low and high energies, obtained from a rotationally invariant QRPA, represent the fragmented scissors mode. The high-energy M1 strength is almost purely orbital and resides in the region of the isovector giant quadrupole resonance. In heavy deformed nuclei the high-energy scissors mode is strongly fragmented between 17

Thomas Jech, Saharon Shelah

It is unprovable that every complete subalgebra of a countably closed complete Boolean algebra is countably closed.

A. Kehagias, J. Madore, J. Mourad, G. Zoupanos

A modification of Kaluza-Klein theory is proposed which is general enough to admit an arbitrary finite noncommutative internal geometry. It is shown that the existence of a non-trival extension to the total geometry of a linear connection on space-time places severe restrictions on the structure of the noncommutative factor. A counter-example is given.

J. S. Dowker, J. S. Apps

Functional determinants for the scalar Laplacian on spherical caps and slices, flat balls, shells and generalised cylinders are evaluated in two, three and four dimensions using conformal techniques. Both Dirichlet and Robin boundary conditions are allowed for. Some effects of non-smooth boundaries are discussed; in particular the 3-hemiball and the 3-hemish

Jean-Marc DAUL

We propose a matrix-model derivation of the scaling exponents of the critical and tricritical q-states Potts model coupled to gravity on a sphere. In close analogy with the $O(n)$ model, we reduce the determination of the one-loop-to-vacuum expectation to the resolution of algebraic equations; and find the explicit scaling law for the case q=3.

Ofer Aharony

Recently Seiberg has conjectured a duality symmetry connecting different theories of the supersymmetric QCD type. We provide support for this conjecture by analyzing a flat direction of the theory along which the two dual theories go over to the same theory in the IR.

Jacques Distler

In these lecture notes, I review the ``linear sigma model&#34; approach to (0,2) string vacua. My aim is to provide the reader with a toolkit for studying a very broad class of (0,2) superconformal field theories with the requisite properties to be candidate string vacua. These lectures were delivered at the 1994 Trieste Summer School.

S. Skorik, H. Saleur

We present a complete study of boundary bound states and related boundary S-matrices for the sine-Gordon model with Dirichlet boundary conditions. Our approach is based partly on the bootstrap procedure, and partly on the explicit solution of the inhomogeneous XXZ model with boundary magnetic field and of the boundary Thirring model. We identify boundary bou