November 1996 arXiv papers — page 8

Suzanne Talon, Jean-Paul Zahn, Andre Maeder, Georges Meynet

We describe the main-sequence evolution of a rotating 9 $M_\odot$ star. Its interior rotation profile is determined by the redistribution of angular momentum through the meridian circulation and through the shear turbulence generated by the differential rotation; the possible effect of internal waves is neglected. We examine the mixing of chemicals produced

R. Donato, L. Peliti, M. Serva

Altruistic behaviour is disadvantageous for the individual while is advantageous for its group. If the target of the selection is the individual, one would expect the selection process to lead to populations formed by wholly homogeneous groups, made up of either altruistic or egoistic individuals, where the winning choice depends on the balance beetwen group

Vernon Barger, Ashok Das, Chung Kao

The electric dipole moment of the muon ($d_μ$) is evaluated in a two Higgs doublet model with a softly broken discrete symmetry. The leading contributions from both one loop and two loop diagrams are considered. For $\tanβ\equiv |v_2|/|v_1|$ close to one, contributions from two loop diagrams involving the $t$ quark and the $W$ boson dominate; while for $\tan

Juan Maldacena

It has been observed recently that many properties of some near extremal black holes can be described in terms of bound states of D-branes. Using a non-renormalization theorem we argue that the D-brane description is the correct quantum gravity description of the black hole at low energies. The low energy theory includes the black hole degrees of freedom tha

R. Flume, M. Magro, L. O'Raifeartaigh, I. Sachs

The low energy effective Lagrangian for $N\es 2$ supersymmetric Yang-Mills theory, proposed by Seiberg and Witten is shown to be the unique solution, assuming only that supersymmetry is unbroken and that the number of strong-coupling singularities is finite. Duality is then a consequence rather than an input.

Ziqiang Wang

Quasi-one-dimensional quantum antiferromagnets formed by a d-dimensional hypercubic lattice of weakly coupled spin-1/2 antiferromagnetic Heisenberg chains are studied by combining exact results in one-dimension and renormalization group analyses of the interchain correlations. It is shown that d-dimensional magnetic long-range order develops at zero-temperat

Dorit Aharonov, Michael Ben-Or

We define formally decohered quantum computers (using density matrices), and present a simulation of them by a probabalistic classical Turing Machine. We study the slowdown of the simulation for two cases: (1) sequential quantum computers, or quantum Turing machines(QTM), and (2) parallel quantum computers, or quantum circuits. This paper shows that the comp

D. Aharonov, M. Ben-Or, R. Impagliazzo, N. Nisan

Noisy computation and reversible computation have been studied separately, and it is known that they are as powerful as unrestricted computation. We study the case where both noise and reversibility are combined and show that the combined model is weaker than unrestricted computation. In our noisy reversible circuits, each wire is flipped with probability p

J. Dobaczewski, J. Dudek

We describe the code HFODD which solves the nuclear Skyrme-Hartree-Fock problem by using the deformed Cartesian harmonic oscillator basis. The user has a possibility of choosing among various symmetries of the nuclear HF problem for rotating or non-rotating nuclei; they vary from the non-axial parity-invariant nuclear shapes, through those also breaking the

J. Dobaczewski, J. Dudek

We describe a method of solving the nuclear Skyrme-Hartree-Fock problem by using a deformed Cartesian harmonic oscillator basis. The complete list of expressions required to calculate local densities, total energy, and self-consistent fields is presented, and an implementation of the self-consistent symmetries is discussed. Formulas to calculate matrix eleme

A. Peter, W. Cassing, J. M. Hauser, M. H. Thoma

We investigate the convergence properties of the cluster expansion of equal-time Green functions in scalar theories with quartic self-coupling in (0+1), (1+1), and (2+1) space-time dimensions. The computations are carried out within the equal-time correlation dynamics approach. We find that the cluster expansion shows good convergence as long as the system i

Sayan Kar

We demonstrate, by a simple analysis, that cosmological line elements related by scale factor duality also exhibit a duality with respect to the conservation/violation of the Weak Energy Condition (WEC) by the matter that acts as the source in the one-loop beta function equations for the metric coupling written explicitly in the form of the Einstein equation

Markus A. Luty, Rabindra N. Mohapatra

We present a class of supersymmetric models with complete generations of composite quarks and leptons using recent non-perturbative results for the low energy dynamics of supersymmetric QCD. In these models, the quarks arise as composite "mesons" and the leptons emerge as composite "baryons." The quark and lepton flavor symmetries are linked

E. I. Guendelman, A. B. Kaganovich

We develop the principle of nongravitating vacuum energy, which is implemented by changing the measure of integration from $\sqrt{-g}d^{D}x$ to an integration in an internal space of $D$ scalar fields $ϕ_{a}$. As a consequence of such a choice of the measure, the matter Lagrangian $L_{m}$ can be changed by adding a constant while no cosmological term is indu

A. Retter, E. M. Leibowitz, E. O. Ofek

We present results of 32 nights of CCD photometry of V1974 Cygni, from the years 1994 and 1995. We verify the presence of two distinct periodicities in the light curve: 0.0812585 day~1.95 hours and 0.0849767 d~2.04 hr. We establish that the shorter periodicity is the orbital period of the underlying binary system. The longer period oscillates with an average

R. H. Méndez, T. Soffner

We have developed a new procedure for the generation of a planetary nebula luminosity function (PNLF), improving on previous work. The procedure is based, as before, on an exponential central star mass distribution, on H-burning post-AGB evolutionary tracks, and on the avoidance of nebular models for the calculation of nebular fluxes. We have added new post-

Robert H. Kraichnan

An isotropic passive scalar field $T$ advected by a rapidly-varying velocity field is studied. The tail of the probability distribution $P(θ,r)$ for the difference $θ$ in $T$ across an inertial-range distance $r$ is found to be Gaussian. Scaling exponents of moments of $θ$ increase as $\sqrt{n}$ or faster at large order $n$, if a mean dissipation conditioned

A. Langari, V. Karimipour

Inspired by the superblock method of White, we introduce a simple modification of the standard Renormalization Group (RG) technique for the study of quantum lattice systems. Our method which takes into account the effect of Boundary Conditions(BC), may be regarded as a simple way for obtaining first estimates of many properties of quantum lattice systems. By

Yűji Ohta

Three dimensional topological field theories associated with the three dimensional version of Abelian and non-Abelian Seiberg-Witten monopoles are presented. These three dimensional monopole equations are obtained by a dimensional reduction of the four dimensional ones. The starting actions to be considered are Gaussian types with random auxiliary fields. As

Chungsik Song, Volker Koch

We calculate characteristic time scales for chemical equilibration of pions in hot hadronic matter using an effective chiral Lagrangian. We find that inelastic processes involving the vector and axial vector mesons reduce the chemical equilibration time by a factor of $\sim 10$ compared to the result previously calculated in chiral perturbation theory. For a

Andrew Steane

Active stabilisation of a quantum system is the active suppression of noise (such as decoherence) in the system, without disrupting its unitary evolution. Quantum error correction suggests the possibility of achieving this, but only if the recovery network can suppress more noise than it introduces. A general method of constructing such networks is proposed,

E. E. W. Bruins

A review of neutron form factor measurements is given. We focus on recent measurements of the neutron magnetic form factor $G_M^n$, and discuss in detail our measurements of this quantity at momentum transfers Q^2=0.1-0.6 (GeV/c)^2.

Ioannis Giannakis

Two-dimensional gravity in the light-cone gauge was shown to exhibit an underlying sl(2,R) current algebra. It is the purpose of this note to offer a possible explanation about the origin of this important algebra. The essential point is that two-dimensional gravity is governed by a topological field theory. The gauge group is sl(2,R) and it is this enhanced

Subir Mohan

We find that for second and weakly first order electroweak phase transition (EWPT) the mere presence of non-zero Majorana masses for left-handed neutrinos is sufficient to ensure the destruction of any existing baryon (lepton) asymmetry. Even if the EWPT is strongly first order, a baryon asymmetry generated before EWPT is seen to only barely survive, to the

Ken Sasaki

The pinch technique (PT) is applied to obtain the gauge-independent resummed gluon self-energy in a hot Yang-Mills gas. Calculation is performed at one- loop level in linear gauges which preserve rotational invariance and the res ummed propagators and vertices are used. The effective gluon self-energy, w hich is obtained as the sum of the resummed gluon self

E. E. W. Bruins

In 1995, the HERMES experiment at DESY (Hamburg, Germany) has taken its first data, using the 27.5 GeV polarised HERA positron beam impinging on a longitudinally polarised internal $^3$He target. Preliminary results from the semi-inclusive physics program are presented.

Eric Sven Ristad, Robert G. Thomas

A statistical language model assigns probability to strings of arbitrary length. Unfortunately, it is not possible to gather reliable statistics on strings of arbitrary length from a finite corpus. Therefore, a statistical language model must decide that each symbol in a string depends on at most a small, finite number of other symbols in the string. In this

L. J. Greenhill, S. P. Ellingsen, R. P. Norris, R. G. Gough

The water maser lines in the nucleus of the Circinus galaxy vary on time scales as short as a few minutes, at least two orders of magnitude less than for other Galactic or extragalactic water masers. The amplitude of one line more than doubled in about 10 minutes. The intensity changes cannot be attributed easily to a mechanism of intrinsic fluctuations. The

G. M. Fuller, Y. -Z. Qian

Neutrinos emitted from near the surface of the hot proto-neutron star produced by a supernova explosion may be subject to significant gravitational redshift at late times. Electron antineutrinos decouple deeper in the gravitational potential well of the neutron star than do the electron neutrinos, so that the electron antineutrinos experience a larger redshi

Peter M. Magyar

We give a new construction of the Bott-Samelson variety $Z$ as the closure of a $B$-orbit in a product of flag varieties $(G/B)^l$. This also gives an embedding of the projective coordinate ring of the variety into the function ring of a Borel subgroup: $\CC[Z] \subset \CC[B]$. In the case of the general linear group $G = GL(n)$, this identifies $Z$ as a con

R. Shankar, G. Murthy

We address the problem of separating the short-distance, high-energy physics of cyclotron motion from the long- distance, low-energy physics within the Lowest Landau Level in field theoretic treatments of the Fractional Quantum Hall Effect. We illustrate our method for the case $ν=1/2$. By a sequence of field transformations we go from electrons to fermions

Jaemo Park

We present orientifold and F-theory duals of the heterotic string compactification constructed by Chaudhuri, Hockney and Lykken (CHL) which has the maximal supersymmetry but gauge group of reduced rank. The 8-dimensional dual is given by the Type IIA orientifold on the Möbius band. We show the non-trivial monodromy on the base induces non-simply laced gauge

Shekhar Garde, Gerhard Hummer, Angel E. Garcia, Michael E. Paulaitis

An information theory model is used to construct a molecular explanation why hydrophobic solvation entropies measured in calorimetry of protein unfolding converge at a common temperature. The entropy convergence follows from the weak temperature dependence of occupancy fluctuations for molecular-scale volumes in water. The macroscopic expression of the contr

Robert Bartnik

The structure of the full Einstein equations in a coordinate gauge based on expanding null hypersurfaces foliated by metric 2-spheres is explored. The simple form of the resulting equations has many applications -- in the present paper we describe the structure of timelike boundary conditions; the matching problem across null hypersurfaces; and the propagati

Urs Achim Wiedemann, Ulrich Heinz

We study the effect of resonance decays on intensity interferometry for heavy ion collisions. Collective expansion of the source leads to a dependence of the two-particle correlation function on the pair momentum K. This opens the possibility to reconstruct the dynamics of the source from the K-dependence of the measured HBT radii. Here we address the questi

L. Houra-Yaou, P. Kessler, J. Parisi, F. Murgia

Starting from a bound-state model of weakly bound quarks for ($q \bar{q}$) mesons, we derive a formalism for computing the production or decay of such mesons, whatever the value of their internal orbital angular momentum L. That approach appears as a natural generalization of the Brodsky-Lepage formalism (valid only for L=0) that has been widely used in rece

Joseph N. Ginocchio

We study a new type of collective motion with alpha-particle type of correlations and show that it may be relevant for N $\sim$ Z nuclei.

M. Benmerrouche, Nimai C. Mukhopadhyay, J. -F. Zhang

We analyze the existing data on electroproduction of eta mesons in the region of W~1.5GeV, and extract an electrostrong form factor for the N*(1535) electroexcitation and decay into the eta-N channel, which is found to be relatively insensitive to the uncertainties of the effective Lagrangian approach. this extracted quantity is of interest in the QCD descri

A. Parreño, A. Ramos, C. Bennhold

The nonmesonic weak decay of $Λ$ hypernuclei is studied in a shell model framework. A complete strangeness-changing weak $ΛN \to NN$ transition potential, based on one boson exchange, is constructed by including the exchange of the pseudoscalar mesons $π$, K, $η$ as well as the vector mesons $ρ, ω$, and K$^*$, whose weak coupling constants are obtained from

Japheth Wood

We extend a recent result of McKenzie, and show that it is an undecidable problem to determine if 4 appears in the typeset of a finitely generated, locally finite variety.

Saharon Shelah

We show the consistency of ZFC +''there is no NWD-ultrafilter on omega'', which means: for every non principle ultrafilter D on the set of natural numbers, there is a function f from the set of natural numbers to the reals, such that for some nowhere dense set A of reals, the set {n: f(n) in A} is not in D. This answers a question of van Douw

Edson de Faria

In this paper we establish $C^2$ a-priori bounds for the scaling ratios of critical circle mappings in a form that gives also a compactness property for the renormalization operator.

R. Flume, L. O'Raifeartaigh, I. Sachs

Talk presented by the second author at the Inaugural Coference of the Asia Pacific Center for Theoretical Physics, Seoul, June 1996. The purpose of this note is to give a resume of the Seiberg-Witten theory in the simplest possible mathematical terms.

P. R. Johnson

Exact solutions to the quantum S-matrices for solitons in simply-laced affine Toda field theories are obtained, except for certain factors of simple type which remain undetermined in some cases. These are found by postulating solutions which are consistent with the semi-classical limit, $\hbar\rightarrow 0$, and the known time delays for a classical two soli

Raymond Stora

Equivariant cohomology is suggested as an alternative algebraic framework for the definition of topological field theories constructed by E. Witten circa 1988. It also enlightens the classical Faddeev Popov gauge fixing procedure.

Raymond Stora

La fixation de jauge est définie comme l'opération permettant d'exprimer une intégrale sur un espace d'orbite comme intégrale sur le fibré principal correspondant. Quand la fibre est non compacte cette opération met en jeu une classe de cohomologie à support compact -ou à décroissance rapide- de celle-ci. La symétrie de Slavnov est l'expressi

Raymond Stora

Equivariant cohomology is a mathematical framework particularly well adapted to a kinematical understanding of topological gauge theories of the cohomological type. It also sheds some light on gauge fixing, a necessary field theory operation connected with the non compactness of the gauge group. The respective roles of fields and observables are emphasized t

C. Becchi, S. Giusto, C. Imbimbo

We parametrize the gauge-fixing freedom in choosing the Lagrangian of a topological gauge theory. We compute the gauge-fixing dependence of correlators of equivariant operators when the compactified moduli space has a non-empty boundary and verify that only a subset of these has a gauge independent meaning. We analyze in detail a simple example of such anoma

M. G. Olsson

A common pattern of large orbital and radial excitations in heavy-light and light-light mesons is demonstrated. Within a general potential model the Regge slopes of the light degrees of freedom for these mesons are shown to be in the ratio of two. The possibility of ``tower'' degeneracy occurs only with pure scalar confinement.

Pierre Sikivie

Contents: 1. The strong CP problem 2. Dark matter axions 3. The cavity detector of galactic halo axions 4. The phase space structure of cold dark matter halos

P. Kroll

The proton form factor, two-photon annihilations into $p\bar{p}$ as well as exclusive charmonium decays are critically examined. It will be argued that the standard perturbative QCD analysis of these reactions fails, i.e. the need for additional contributions can convincingly be demonstrated. Possible dynamical mechanisms such as colour-octet admixtures to t

Frank Cuypers

We investigate the incidence of several systematic effects on the $Z'$ discovery limits of the NLC. These include the initial state radiation and the systematic errors due to the imperfect polarization measurement, the finite detector angular resolution and the uncertainty on the integrated luminosity. We focus on three reactions involving leptonic coupl

R. D. Peccei

These notes contain some of the material I presented at TASI 96 on the comparison of the standard model with precision electroweak data. After a physical accounting of the dominant electroweak radiative corrections, including the effects of initial state bremsstrahlung, I examine how data from LEP and the SLC provides a clear test of the standard model. Appa

U. Baur, M. Demarteau

We present an overview of the present status and prospects for progress in electroweak measurements at future collider experiments leading to precision tests of the Standard Model of Electroweak Interactions. Special attention is paid to the measurement of the W mass, the effective weak mixing angle, and the determination of the top quark mass. Their constra

Martin Lüscher, Stefan Sint, Rainer Sommer, Hartmut Wittig

A finite-size technique is employed to compute the normalization constant $Z_A$ of the isovector axial current in lattice QCD. The calculation is carried out in the quenched approximation for values of the bare gauge coupling $g_0$ ranging from 0 to 1. In the lattice action and the lattice expression for the axial current we include the counterterms required

Slawek Tkaczyk

Charmonium and bottomonium production is studied using $μ^+μ^-$ data samples collected by the CDF and D0 experiments during the 1992-96 p-pbar collider run at the Fermilab Tevatron. The inclusive cross sections as a function of the transverse momentum of reconstructed quarkonium states are measured. The results are compared with theoretical predictions, whic

Leon Balents, Matthew P. A. Fisher

We consider the effects of Coulomb interactions on single-wall carbon nanotubes using an on-site Hubbard interaction, u. For the (N,N) armchair tubes the low energy theory is shown to be identical to a 2-chain Hubbard model at half-filling, with an effective interaction u_N = u/N. Umklapp scattering leads to gaps in the spectrum of charge and spin excitation

Yong Baek Kim, A. J. Millis

The transresistance (i.e. the voltage induced in one layer by a current in another) between composite fermions in double-layers of half-filled Landau levels is shown to be dominated by scattering due to singular gauge field fluctuations arising from the antisymmetric combination of density fluctuations in two layers. The drag rate is found to be proportional

Ron Miller, Rob Phillips, Glenn Beltz, Michael Ortiz

Cohesive zone models provide an illuminating and tractable way to include constitutive nonlinearity into continuum models of defects. Powerful insights have been gained by studying both dislocations and cracks using such analyses. Recent work has shown that as a result of the locality assumption present in such cohesive zone models, significant errors can be

P. Dai, M. Yethiraj, H. A. Mook, T. B. Lindemer

Polarized and unpolarized triple-axis spectrometry has been used to study an underdoped YBa_2Cu3O6.6. Our results indicate that spin excitations in the superconducting state are essentially the same as those in the fully doped material except that the unusual 41 meV resonance is observed at 34.8 meV. The normal state spin excitations are characterized by a w

Vijay B. Shenoy, Rob Phillips

The interaction of screw dislocations with an applied stress is studied using atomistic simulations in conjunction with a continuum treatment of the role played by the far field boundary condition. A finite cell of atoms is used to consider the response of dislocations to an applied stress and this introduces an additional force on the dislocation due to the

M. J. P. Gingras, C. V. Stager, N. P. Raju, B. D. Gaulin

Some frustrated pyrochlore antiferromagnets, such as Y2Mo2O7, show a spin-freezing transition and magnetic irreversibilities below a temperature Tf similar to what is observed nonlinear magnetization measurements on Y2Mo2O7 that provide strong evidence that there is an underlying thermodynamic phase transition at Tf, which is characterized by critical expone

A. M. Rudin, I. L. Aleiner, L. I. Glazman

We study tunneling into interacting disordered two-dimensional electron gas in a non-quantizing magnetic field, which does not cause the standard de Haas-- van Alphen oscillations. Interaction induces a new type of oscillations in the tunneling density of states with the characteristic period of cyclotron quantum.

F. Despa

In the present paper, the dielectric behaviour of the PbLixNb3xZr0.51Ti0.49-4xO3 ( PLNZT) system is analyzed. It is shown that the decrease in the dielectric constant with respect to an increase of the impurity content may be due to an aggregation trend of the interacting off-centre dipoles rather than due to cooperative phenomena which renormalizes the dipo

C. P. Burgess, C. A. Lutken

We construct the c-function whose gradient determines the RG flow of the conductivities (sigma_xy and sigma_xx) for a quantum Hall system, subject to two assumptions. (1) We take the flow to be invariant with respect to the infinite discrete symmetry group, recently proposed by several workers to explain the `superuniversality' of the delocalization expo

Marc Kamionkowski, Arthur Kosowsky, Albert Stebbins

We present a formalism for analyzing a full-sky temperature and polarization map of the cosmic microwave background. Temperature maps are analyzed by expanding over the set of spherical harmonics to give multipole moments of the two-point correlation function. Polarization, which is described by a second-rank tensor, can be treated analogously by expanding i

Harald Riffert, Pawan Kumar, W. K. Huchtmeier

We have mapped two molecular clouds at (l, b) = (3.2 degrees, + 0.3 degrees) and (l, b) = (5.4 degrees, -0.5 degrees) in 21-cm line and continuum emission. These clouds show unusually large velocity dispersions of more than 100 km/s (FWHM) which has also been seen in $^{12}$CO, $^{13}$CO, and CS emissions. This dispersion is roughly an order of magnitude lar

Martin Krockenberger, Dimitar D. Sasselov, Robert W. Noyes

We develop a formulation of the Baade-Wesselink method which uses the Fourier coefficients of the observables. We derive an explicit, analytic expression to determine the mean radius from each Fourier order. The simplicity of this method allows us to derive the uncertainty in the mean radius due to measurement errors. Using simulations and a recent dataset w

C. Motch, F. Haberl, K. Dennerl, M. Pakull

We report the discovery of several new OB/X-ray accreting binary candidates. These massive systems were found by cross-correlating in position SIMBAD OB star catalogues with the part of the ROSAT all-sky survey located at low galactic latitudes (|b| < 20d) and selecting the early type stars which apparently displayed the most significant excess of X-ray emis

J. Borissova, M. Catelan, N. Spassova, A. V. Sweigart

BV CCD photometry of the central (1.5 arcmin x 2.0 arcmin) part of the mildly concentrated outer-halo globular cluster NGC 6229 is presented. The data reduction in such a crowded field was based on a wavelet transform analysis. Our larger dataset extends the previous results by Carney et al. (1991, AJ, 101, 1699) for the outer and less crowded fields of the

Tina Christensen, Lars Petersen, Peter Gammelgaard

We propose an empirical sulphur abundance determination method based on the strong sulphur emission lines, [S II] 6716, 6731 and [S III] 9069, 9531 in H II regions. From a compilation of literature data we have made a calibration of sulphur abundance versus ([S II] + [S III])/Hbeta, similar to what has been widely used for the more easily observable iso-elec

G. A. Tammann, M. Federspiel

Six independent methods yield a Virgo cluster modulus of (m-M)=31.66+/- 0.08. This inserted into the Hubble diagram of clusters, whose relative distances to the Virgo cluster are known, gives H_0=54+/-4. The result is independent of any observed or inferred velocity of the Virgo cluster and holds out 10 000 km/s. An analogous use of the Fornax cluster is not

Bo Qin, Xiang-Ping Wu, Zhenlong Zou

The signature of the self-microlensing in compact binaries (white dwarfs, neutron stars and black holes) is a flare with the characteristic time of typically a few minutes. The probability of detecting these microlensing events can be as high as $1/50$ for a flux sensitivity of $Δm=0.01$ in magnitude. The discovery of the self-microlensing by binaries would

Hélène Esnault

We give a construction of algebraic differential characters, receiving classes of algebraic bundles with connection, lifitng the Chern-Simons invariants defined with S. Bloch, the classes in the Chow group and the analytic secondary invariants if the variety is defined over the field of complex numbers.

Maximo Banados, Andres Gomberoff

We examine Carlip&#39;s derivation of the 2+1 Minkowskian black hole entropy. A simplified derivation of the boundary action -valid for any value of the level k- is given.

V. B. Derjagin, A. N. Leznov, A. S. Sorin

A new integrable N=2 supersymmetric f-Toda mapping in (1|2) superspace, acting like the symmetry transformation of N=2 supersymmetric NLS hierarchy, is proposed. The first two Hamiltonian structures and the recursion operator connecting all evolution systems and Hamiltonian structures of the N=2 super-NLS hierarchy are constructed in explicit form using only

A. A. Tseytlin

We comment on the structure of intersecting black p-brane solutions in string theory explaining how known solutions can be obtained from Schwarzschild solution simply by sequences of boosts and dualities. This implies, in particular, that dimensional reduction in all internal world-volume directions including time leads to a metric (related by analytic conti

Toby Falk, Keith A. Olive, Leszek Roszkowski, Anupam Singh

Flat directions in the Minimal Supersymmetric Standard Model (MSSM) can become unstable due to radiative corrections, and the global minimum of the (zero temperature) potential can lie at large values of the squark and/or slepton fields. Here we show that, in inflationary models of early cosmology, the universe is very likely to be in the domain of attractio

R. Aguirre, M. Schvellinger

A self-consistent description of the MIT bag parameters as functions of the nuclear matter density is presented. The subnuclear degrees of freedom are treated in the Quark-Meson Coupling Model, considering the equilibrium conditions for the bag in the nuclear medium. The hadronic interaction is described in the framework of the quantum field theory of hadron

B. Yurke, A. N. Pargellis, S. N. Majumdar, C. Sire

Using a twisted nematic liquid crystal system exhibiting planar Ising model dynamics, we have measured the scaling exponent $θ$ which characterizes the time evolution, $p(t) \sim t^{-θ}$, of the probability p(t) that the local order parameter has not switched its state by the time t. For 0.4 seconds to 200 seconds following the phase quench, the system exhib

Sang Pyo Kim

Using both the Born-Oppenheimer idea and the de Broglie-Bohm interpretation of wavefunction we represent in a different way the semiclassical quantum gravity from the Wheeler-DeWitt equation in an oscillating regime which can preserve completely the unitary quantum evolution of a matter field at the expense of a nonlinear gravitational field equation, but ha

Dorit Aharonov, Michael Ben-Or

Recently Shor showed how to perform fault tolerant quantum computation when the error probability is logarithmically small. We improve this bound and describe fault tolerant quantum computation when the error probability is smaller than some constant threshold. The cost is polylogarithmic in time and space, and no measurements are used during the quantum com

Timothy J. Hollowood

It is shown how monopoles and dyons decay on curves of marginal stability in the moduli space of vacua at weak coupling in pure N=2 gauge theory with arbitrary gauge group. The analysis involves a semi-classical treatment of the monopole and rests on the fact that the monopole moduli space spaces for a magnetic charge vector equal to a non-simple root enlarg

U. G. Mitreuter, J. M. Pawlowski, A. Wipf

A simple derivation of the free energy and expectation values of Polyakov-loops in $QCD_2$ via path integral methods is given. In the chosen gauge (which can be generalized to 4 dimensions) without Gribov-copies the Fadeev-Popov determinant and the integration over the space component of the gauge field cancel exactly and we are left only with an integration

D. Jido, M. Oka

The masses of the flavor octet and singlet baryons with negative parity and spin 1/2 are calculated using the QCD sum rule. We find that the chiral symmetry breaking vacuum condensates cause the mass splitting of the positive and negative baryons. The present sum rule reproduces the observed masses of these baryons within 10%, and predicts the mass of the ex

Vipul Periwal

It is shown that the world-line can be eliminated in the matrix quantum mechanics conjectured by Banks, Fischler, Shenker and Susskind to describe the light-cone physics of M theory. The resulting matrix model has a form that suggests origins in the reduction to a point of a Yang-Mills theory. The reduction of the Nishino-Sezgin 10+2 dimensional supersymmetr

M. C. Ashworth

For many years coherent states have been a useful tool for understanding fundamental questions in quantum mechanics. Recently, there has been work on developing a consistent way of including constraints into the phase space path integral that naturally arises in coherent state quantization. This new approach has many advantages over other approaches, includi

S. Nussinov

We suggest scattering experiments which implement the concept of ``protective measurements&#39;&#39; allowing the measurement of the complete wave function even when only one quantum system (rather than an ensemble) is available. Such scattering experiments require massive, slow, projectiles with kinetic energies lower than the first excitation of the system

A. S. Holevo

It is shown that the capacity of a classical-quantum channel with arbitrary (possibly mixed) states equals to the maximum of the entropy bound with respect to all apriori distributions. This completes the recent result of Hausladen, Jozsa, Schumacher, Westmoreland and Wooters, who proved the equality for the pure state channel.

J. K. Breslin, C. A. Holmes, G. J. Milburn

We show how a nonlinear chaotic system, the parametrically kicked nonlinear oscillator, may be realised in the dynamics of a trapped, laser-cooled ion, interacting with a sequence of standing wave pulses. Unlike the original optical scheme [G.J.Milburn and C.A.Holmes, Phys. Rev A, 44, p4704, (1991)], the trapped ion enables strongly quantum dynamics with min

Vyacheslav Artamonov, Alexander Totok

Action of finite-dimensional Hopf algebra $H$ on commutative $k-$algebra $A$ is considered. As a generalization of the well-known fact for finite groups S. Montgomery raised a problem in 1993 whether $A$ is integral over subalgebra of invariants $A^H$. Recently some new results were obtained. Using the properties of coradical filtration of pointed Hopf algeb

Reinhard Häring-Oldenburg

Braid groups may be defined for every Coxeter diagram. Artin&#39;s braid group is of type A. Analogs of Temperley-Lieb, Hecke and Birman-Wenzl algebras exist for B-type. Our general hypothethis is that the braid group of B-type replaces Artin&#39;s braid group in most physical applications if the model is equipped with a nontrivial boundary. Solutions of a P

Aric Hagberg, Ehud Meron

We derive a new set of kinematic equations for front motion in two-dimensional bistable media. The equations generalize the geometric approach by complementing the equation for the front curvature with an order parameter equation associated with a nonequilibrium Ising-Bloch bifurcation. The resulting equations capture the core structure of spiral waves and s

C. A. Bertulani

Nuclear reaction cross sections are usually very small in typical astrophysical environments. It has been one of the major challenges of experimental nuclear astrophysics to assess the magnitude of these cross sections in the laboratory. For a successful experiment high luminosity beams are needed. Increasing the target width, one also increases the reaction

C. M. Ko, G. Q. Li

The change of hadron properties in dense matter based on various theoretical approaches are reviewed. Incorporating these medium effects in the relativistic transport model, which treats consistently the change of hadron masses and energies in dense matter via the scalar and vector fields, heavy-ion collisions at energies available from SIS/GSI, AGS/BNL, and

F. Ritz, H. Goeller, T. Wilbois, H. Arenhoevel

The influence of relativistic contributions to deuteron electrodisintegration is systematically studied in various kinematic regions of energy and momentum transfer. As theoretical framework the equation-of-motion and the unitarily equivalent S-matrix approaches are used. In a (p/M)-expansion, all leading order relativistic $π$-exchange contributions consist

G. Baur, C. A. Bertulani

We critically discuss the recently developed quantum-mechanical equivalent photon spectrum by Benesh et al. We point out that the key point, the strong absorption in heavy ion collisions, is not treated adequately. Conclusions drawn from such a spectrum are invalid. Equivalent photon spectra appropriate for heavy ions, have been given before in quantal as we

Antoine Van Proeyen

The essential elements in the construction of the couplings of vector multiplets to supergravity using the conformal approach are repeated. This approach leads automatically to the basic quantities on which the symplectic transformations, the basic tools for duality transformations, are defined. A recent theorem about the existence of a basis allowing for a

Alexandros Kehagias

We construct solitonic string solutions of N=2 four-dimensional heterotic models of rank three, four and five. These finite energy configurations have constant dilaton while the moduli fields vary over space-time with jumps at the location of the string cores consistent with the T-duality groups SL(2,Z), SL(2,Z) X SL(2,Z) and Sp(4,Z). The solutions are expre

Paul Mansfield, Marcos Sampaio

The leading short-time behaviour of the Yang-Mills Schroedinger functional is obtained within a local expansion in the fields.