August 1993 arXiv papers — page 3

H. Reinhardt, K. Langfeld

The classical Yang-Mills equations are solved for arbitrary semi-simple gauge groups in the Schwinger-Fock gauge. A new class of SU(N) instantons is presented which are not embeddings of SU(N-1) instantons but have non-trivial SU(N) color structure and carry winding number $n=N(N^{2}-1)/6$. Explicit configurations are given for SU(3) and SU(4) gauge groups.

Valeri V. Dvoeglazov, Sergei V. Khudyakov, Svyatoslav B. Salganik

Relativistic three-dimensional quasipotential (equal-time) equations are considered, which describe bound states of fermion and boson of spin S=0 or S=1. The spin structure of the interaction quasipotentials in such systems is studied, and corresponding partial-wave equation for the simplest case is obtained. Such equations can be used in calculations of ene

Youichi Yamada

We calculate the two-loop renormalization group equations for the running gaugino masses in general SUSY gauge models, improving our previous result. We also study its consequence to the unification of the gaugino masses in the SUSY SU(5) model. The two-loop correction to the one-loop relation $m_i(μ)\proptoα_i(μ)$ is found to be of the order of a few \%.

Nenad Manojlović, Bill Spence

We apply the inverse scattering method to the midi-superspace models that are characterized by a two-parameter Abelian group of motions with two spacelike Killing vectors. We present a formulation that simplifies the construction of the soliton solutions of Belinski\v i and Zakharov. Furthermore, it enables us to obtain the zero curvature formulation for the

J. J. Halliwell, M. E. Ortiz

This paper gives a brief description of the derivation of a composition law for the propagator of a relativistic particle, in a sum over histories quantization. The extension of this derivation to the problem of finding a composition law for quantum cosmology is also discussed. (For the proceedings of Journees Relativistes 93)

Leo Radzihovsky, Erwin Frey

We study the Langevin dynamics of flux lines of high--T$_c$ superconductors in the presence of random quenched pinning. The hydrodynamic theory for the densities is derived by starting with the microscopic model for the flux-line liquid. The dynamic functional is expressed as an expansion in the dynamic order parameter and the corresponding response field. W

Michael Strauss, Daniel Koranyi

All direct measurements of peculiar velocities of glaxies assume the Hubble law at low redshifts. However, it has been suggested by Segal et al (1993) that the correlation of redshifts and fluxes in a complete sample of IRAS galaxies is inconsistent with the Hubble law, and instead implies that redshifts are proportional to the square of distance at small re

Michael Strauss, Renyue Cen, Jeremiah Ostriker

The large-scale bulk flow implied by the measurements of distances to brightest cluster members within 15,000 km/s by Lauer and Postman has the potential to put strong constraints on, or to even rule out, various models of large-scale structure. Using PM simulations 400$h^{-1}$ Mpc on a side of five cosmological models (Standard CDM, Tilted CDM, HDM, $Ω= 0.3

David Thomas, David N. Schramm, Keith A. Olive, Grant J. Mathews

We investigate the possibility that inhomogeneous nucleosynthesis may eventually be used to explain the abundances of \li6, \be9 and B in population II stars. The present work differs from previous studies in that we have used a more extensive reaction network. It is demonstrated that in the simplest scenario the abundances of the light elements with $A\le7$

Kevin Krisciunas

I have noted a number of errors, most of them quite minor, in the {\em Encyclopedia of Cosmology} (New York and London: Garland), 1993, Norriss S. Hetherington, ed. The majority occur in my mathematically verbose article, ``Fundamental cosmological parameters". Some errata were passed on to me by Prof. Ralph Alpher. In the interests of accuracy, I feel t

R. Brussee

Define the Donaldson series of a simply connected 4-manifold by q(X) = \sum_d q_d(X)/d! Recently Kronheimer and Mroka have announced the result that the Donaldson series of so called simple 4-manifolds can be written as q(X) = e^{Q/2}\sum_{i=1}^p a_i e^{K_i} where $Q$ is the intersection form and the $K_i \in H^2(X,\Z)$ are the {\it Kronheimer-Mrowka classes

Jorma Louko, Donald M. Marolf

We investigate the space ${\cal M}$ of classical solutions to Witten's formulation of 2+1 gravity on the manifold ${\bf R} \times T^2$. ${\cal M}$ is connected, unlike the spaces of classical solutions in the cases where $T^2$ is replaced by a higher genus surface. Although ${\cal M}$ is neither Hausdorff nor a manifold, removing from ${\cal M}$ a set of

U. Ornik, R. M. Weiner, G. Wilk

A study of hadronic data up to TEVATRON energies in terms of relativistic hydrodynamics indicates an extended 1-dimensional stage of the expansion which suggests a jet like behaviour of the fireball along the collision axis.

Udo Ornik, M. Pluemer, D. Strottman

We show that a system described by an equation of state which contains a high number of degrees of freedom (resonances) can create a considerable amount of superfluid (condensed) pions through the decay of short-lived resonances, if baryon number and entropy are large and the dense matter decouples from chemical equilibrium earlier than from thermal equilibr

Metin Arik, Gokhan Unel, Muhittin Mungan

Considering a multi-dimensional $q$-oscillator invariant under the (non quantum) group $U(n)$, we construct a $q$-deformed Levi-Civita epsilon tensor from the inner product states. The invariance of this $q$-epsilon tensor is shown to yield the quantum group $SL_{q}(n)$ and establishes the relationship of the $U(n)$ invariant $q$-oscillator to quantum groups

G. K. Savvidy, F. J. Wegner

We formulate a new geometrical string on the euclidean lattice. It is possible to find such spin systems with local interaction which reproduce the same surface dynamics.In the three-dimensional case this spin system is a usual Ising ferromagnet with additional diagonal antiferromagnetic interaction and with specially adjusted coupling constants. In the four

J. Rembielinski

A new deformation of the of the Poincaré group and of the Minkowski space-time is given. From the mathematical point of view this deformation is rather quantum-braided group. Global and local structure of this quantum-braided Poincaré group is investigated. A kind of ``quantum metrics'' is introduced in the $q$-Minkowski space.

Zhong-Qi Ma, An-Ying Dai

A new solution of the Yang-Baxter equation, that is related to the adjoint representation of the quantum enveloping algebra $U_{q}B_{2}$, is obtained by fusion formulas from a non-standard solution.

Konstantinos Anagnostopoulos, Mark Bowick, Paul Coddington, Marco Falcioni

We present the results of an extension of our previous work on large-scale simulations of dynamically triangulated toroidal random surfaces embedded in $R^3$ with extrinsic curvature. We find that the extrinsic-curvature specific heat peak ceases to grow on lattices with more than 576 nodes and that the location of the peak $\lam_c$ also stabilizes. The evid

M. B. Gay Ducati

A QCD-Pomeron composed by two non-perturbative gluons with a dynamically generated mass, is constructed in a gauge invariant way. The gluon propagator is infrared-finite. The model properly describes data on elastic scattering, exclusive $ρ$ production in deep inelastic scattering (DIS) and the $J/Ψ$-nucleon total cross-section in terms of a single gluon mas

S. Okubo

Some experimental tests are suggested for possible CP-violations for decays of $B^\pm$ bosons. Especially, a detailed comparison of decays $B^+ \rightarrow D^0 π^+ π^+ π^-$ and $B^- \rightarrow \overline{D^0} π^- π^- π^+$ will lead to tests of not only CP, but also C, and P invariances.

Felix Schlumpf

We investigate the predictive power of a relativistic quark model formulated on the light-front. The nucleon electromagnetic form factors, the semileptonic weak decays of the hyperons and the magnetic moments of both baryon octet and decuplet are calculated and found to be in excellent agreement with experiment.

Minos Axenides, Andrei Johansen, Holger Bech Nielsen

In the minimal model of electroweak interactions we carefully investigate the spectrum of the massive euclidean \dop \ in three, four and five dimensions ($D$) in the presence of \tly \ nontrivial \exl \ fields. More specifically we study the cases of the \inst \ ($D=4$), \sp \ ($D=3$) as well as that of the ($D=5$) \dop \ that pertains to the existence of t

Jishnu Dey, Lauro Tomio, Mira Dey

Recent Deep Inelastic data leads to an up-down quark asymmetry of the nucleon sea. Explanations of the flavour asymmetry and the di-lepton production in proton-nucleus collisions call for a temperature $T \approx 100$ MeV in a statistical model. This T may be conjectured as being due to the Fulling-Davies-Unruh effect. But it is not possible to fit the struc

Victor M. Villalba

In this article the particle creation process of scalar and spin 1/2 particles in a spatially open cosmological model associated with a universe filled by radiation and dustlike matter. The Klein-Gordon and Dirac equations are solved via separation of variables. After comparing the{\it \ in }and% {\it \ out} vacua, we obtain that the number of created partic

David Valls-Gabaud, Thomas Zannias

By a combination of analytical and numerical methods, the density profile of a momentarily at rest spherical star is varied, and the corresponding response in the area of the spherical shells is monitored. It is shown that the inner apparent horizon (if it exists) must lie within or at most on the star's surface, while no such restriction is found for th

Jose' Riera, Elbio Dagotto

A method of cluster diagonalization in a systematically expanded Hilbert space is described. We discuss some applications of this procedure to models of high-T_c superconductors, like the t - J and one and three bands Hubbard models in two dimensions. The results obtained with this method are compared against results obtained with other techniques dealing wi

R. N. Henriksen, D. Valls-Gabaud

We propose that the prevalence of bipolarity in Young Stellar Objects is due to the fine tuning that is required for spherical accretion of an ambient medium onto a central node.It is shown that there are two steady modes that are more likely than radial accretion, each of which is associated with a hyperbolic central point in the meridional stream lines, an

R. N. Mohapatra, S. Nussinov, X. Zhang

We point out that, in the left-right symmetric model of weak interaction, if $ν_τ$ mass is in the keV to MeV range, there is a strong correlation between rare decays such as $τ\rightarrow 3 μ, τ\rightarrow 3 e$ and the $ν_τ$ mass. In particular, we point out that a large range of $ν_τ$ masses are forbidden by the cosmological constraints on $m_{ν_τ}$ in comb

A. Saa

Through the analyses of volume-forms in differentiable manifolds, it is shown that the usual way of defining minimal action principles for field theory on curved space-times is not appropriate on non-riemannian manifolds. An alternative approach, based in a new volume-form, is proposed and confronted with the standard one. The new volume element is explicitl

H. Aratyn, L. A. Ferreira, J. F. Gomes, A. H. Zimerman

We construct infinite sets of local conserved charges for the conformal affine Toda model. The technique involves the abelianization of the two-dimensional gauge potentials satisfying the zero-curvature form of the equations of motion. We find two infinite sets of chiral charges and apart from two lowest spin charges all the remaining ones do not possess chi

Philip Candelas, Xenia de la Ossa, Anamaria Font, Sheldon Katz

We study, by means of mirror symmetry, the quantum geometry of the Kähler-class parameters of a number of Calabi-Yau manifolds that have $b_{11}=2$. Our main interest lies in the structure of the moduli space and in the loci corresponding to singular models. This structure is considerably richer when there are two parameters than in the various one-parameter

C. H. M. van Antwerpen, I. R. Afnan

A covariant, unitary and gauge invariant theory for pion photoproduction on a single nucleon is presented. To achieve gauge invariance at the operator level one needs to include both the $πN$ and $γπN$ thresholds. The final amplitude can be written in terms of a distorted wave in the final $πN$ channel provided one includes additional diagrams to the standar

\Mary K. Gaillard, Vidyut Jain

We extend earlier calculations of the one-loop contributions to the effective bose Lagrangian in supergravity coupled to chiral matter. We evaluate all logarithmically divergent contributions for arbitrary background scalar fields and space-time metric. We show that, with a judicious choice of gauge fixing and of the definition of the action expansion, much

M. Hossein Partovi

Leading corrections to Planck's formula and photon thermodynamics arising from the pair-mediated photon-photon interaction are calculated. This interaction is attractive and causes an increase in occupation number for all modes. Possible consequences, including the role of the cosmic photon gas in structure formation, are considered.

J. A. Dixon

The established results concerning the BRS cohomology of supersymmetric theories in four space-time dimensions are briefly reviewed. The current status of knowledge concerning supersymmetry anomalies and the possibility that supersymmetry breaks itself through anomalies in local composite operators is then discussed. It turns out that the simplest allowable

S. Massar

Local modes and local particles are defined at any point in curved space time as those that most resemble Minkowsky modes at that point. It is shown that the renormalised stress tensor is the difference of energy between the physical vacuum and that defined by these local modes.

Chanju Kim, Choonkyu Lee

Galilean transformation relates a physical system under mutually perpendicular uniform magnetic and electric fields to that under uniform magnetic field only. This allows a complete specification of quantum states in the former case in terms of those for the latter. Based on this observation, we consider the Hall effect and the behavior of a neutral composit

Myron Bander, H. R. Rubinstein

Superconducting cosmic strings may be viewed as wires of thickness $1/Λ$ with $Λ=10^{16}$ TeV. We show that the weak interactions will spread out the current to distances $r= (1/M_Z)\ln (I/M_Z)$, where $I$ is the magnitude of the current in the string. Consequences for the scattering of light by these strings is presented.

E. Laenen, S. Riemersma, J. Smith, W. L. van Neerven

We present the complete NLO QCD analysis of the photon structure functions $F_2^γ(x,Q^2)$ and $F_L^γ(x,Q^2)$ for a real photon target. In particular we study the heavy flavor content of the structure functions which is due to two different production mechanisms, namely collisions of a virtual photon with a real photon, and with a parton. We observe that the

E. Laenen, E. Levin, A. G. Shuvaev

The anomalous dimensions of high-twist operators in deeply inelastic scattering ($γ_{2n}$) are calculated in the limit when the moment variable $N \rightarrow 1$ (or $x_B\rightarrow 0$) and at large $Q^2$ (the double logarithmic approximation) in perturbative QCD. We find that the value of $γ_{2n}(N-1)$ in this approximation behaves as ${N_c α_S \over π(N-1)

M. Hossein Partovi

The feasibility of detecting the photon-photon interaction using Fabry-Perot type laser interferometers developed for gravity wave detection is demonstrated. An ``external'' laser beam, serving as a refractive medium, is alternatively fed into the cavities of the interferometer and made to collide with the ``internal'' beams thereby inducing

Tom Banks, David B. Kaplan, Ann E. Nelson

We provide a taxonomy of dynamical supersymmetry breaking theories, and discuss the cosmological implications of the various types of models. Models in which supersymmetry breaking is produced by chiral superfields which only have interactions of gravitational strength (\eg\ string theory moduli) are inconsistent with standard big bang nucleosynthesis unless

M. Drees, M. M. Nojiri

We study the decays of a scalar \stst\ bound state \sigst, where \st\ is the lighter stop eigenstate. If \st\ has no tree--level 2--body decays, the dominant decay modes of \sigst\ are $gg$ or, if $m_h < \mst \ll \mstt$, a pair of light scalar Higgs bosons $h$. The best signal for \sigst\ production at hadron colliders is probably its decay into two photons.

Guido Nolte, Jutta Kunz

We calculate the minimal energy path over the sphaleron barrier in the pre\-sen\-ce of fermions, assuming that the fermions of a doublet are degenerate in mass. This allows for spherically symmetric ansätze for the fields, when the mixing angle dependence is neglected. While light fermions have little influence on the barrier, the presence of heavy fermions

C. S. Lam

Methods to apply the spinor helicity technique and string reorganization to multiloop amplitudes using the Feynman- and Schwinger-parameter representations are reviewed and expanded.

Adam F. Falk, Michael Luke, Martin J. Savage

We discuss nonperturbative contributions to the inclusive rare $B$ decays $B\to X_sγ$ and $B\to X_s\ell^+\ell^-$. We employ an operator product expansion and the heavy quark effective theory to compute the leading corrections to the decay rate found in the free quark decay model, which is exact in the limit $m_b\to\infty$. These corrections are of relative o

A. P. Kostyuk, A. P. Kobushkin, N. M. Chepilko, T. Okazaki

It is proved that the quantum-mechanical consideration of global breathing of a hedgehog-like field configuration leads to the dynamically stable soliton solutions in the nonlinear sigma-model without the Skyrme term. Such solutions exist only when chiral symmetry of the model is broken.

Stephan Haas, Jose Riera, Elbio Dagotto

The one-dimensional XXZ model is studied in the presence of disorder in the Heisenberg Exchange Integral. Recent predictions obtained from renormalization group calculations are investigated numerically using a Lanczos algorithm on chains of up to 18 sites. It is found that in the presence of strong X-Y-symmetric random exchange couplings, a ``random singlet

M. Alouani, J. W. Wilkins, R. C. Albers, J. M. Wills

Local-density-approximation calculations are used to show that the metal-metal distance along the chains controls the charge-density wave (CDW) in halogen-bridged transition-metal linear-chain (MX) compounds. The strength of the CDW can be understood in terms of a two band Su-Schrieffer-Heeger model if a hard-core ion-ion repulsion potential is also added. W

Michael Luke, Martin J. Savage

Using recent results for nonperturbative contributions to the $B$ and $D$ meson inclusive semileptonic widths, a model independent extraction of $\vbc$, $m_c$ and $m_b$ is made from the experimentally measured $B$ and $D$ lifetimes and semileptonic branching ratios. Constraining the parameters of the HQET at $\CO(1/m_Q^2)$ by the $D$ semileptonic width, $\vb

E. Bunn, M. White, M. Srednicki, D. Scott

We present results on the consistency of standard cold dark matter (CDM) models with both the COBE normalization and the data from the 4th channel of the 9-point South Pole scan. We find that CDM models are consistent with both experiments, a conclusion which is at odds with some other analyses. This is partly due to our careful treatment of the temperature

Christian Grosche

The incorporation of two- and three-dimensional $δ$-function perturbations into the path-integral formalism is discussed. In contrast to the one-dimensional case, a regularization procedure is needed due to the divergence of the Green-function $G^{(V)}(\vec x,\vec y;E)$, ($\vec x,\vec y\in\bbbr^2,\bbbr^3$) for $\vec x=\vec y$, corresponding to a potential pr

Christian Grosche

Invited talk given at the ``International Workshop on `Symmetry Methods in Physics&#39; in memory of Ya.\ A.\ Smorodinsky, 5--10 July 1993, Dubna, Russia; to appear in the proceedings. In this contribution I present further results on steps towards a Table of Feynman Path Integrals. Whereas the usual path integral solutions of the harmonic oscillator (Gaussi

I. Jack, D. R. T. Jones, J. Panvel

We derive an explicit, exactly conformally invariant form for the action for the non-abelian Toda field theory. We demonstrate that the conformal invariance conditions, expressed in terms of the $β$-functions of the theory, are satisfied to all orders, and we use our results to obtain a value for the central charge agreeing with previous calculations.

Boris Feigin, A. V. Stoyanovsky

We give a new interpretation and proof of the &#34;quasi-particle&#34; type character formulas for integrable representations of the simply-laced affine Kac-Moody algebras through a new &#34;semi-infinite&#34; construction of such representations. We compare formulas of this kind to other formulas obtained using the geometry of the corresponding flag manifol

N. Di Bartolomeo

An effective lagrangian incorporating both chiral and heavy quark symmetries and describing the low momentum interactions of heavy mesons and light scalar and vector resonances is presented. Using some available data and assuming nearest pole dominance for the form factors we can calculate, at the leading order in chiral and heavy quark expansion, semilepton

A. Blotz, M. Praszalowicz, K. Goeke

We examine $O(1/\Ne)$ rotational corrections to axial couplings \gt~ and \go~ in the framework of the semibosonized SU(3) Nambu--Jona-Lasinio model. A novelty is due to the observation that the rotational (cranking) velocity and the rotation matrix itself do not commute within semiclassical quantization scheme. If time ordering in the quark loop is maintaine

H. Y. Cheng, C. Y. Cheung, G. L. Lin, Y. C. Lin

In earlier publications we have analyzed the strong and radiative decays of heavy hadrons in a formalism which incorporates both heavy-quark and chiral symmetries. In particular, we have derived a heavy-hadron chiral Lagrangian whose coupling constants are related by the heavy-quark flavor-spin symmetry arising from the QCD Lagrangian with infinitely massive

Eran Yehudai, Stephen Godfrey, K. Andrew Peterson

We study single top production in high energy $eγ$ collisions. The process $eγ\toνb\bar t$ can serve as a unique tool for measuring the $Wtb$ coupling. We show that allowing for realistic luminosity and backgrounds, the size of this coupling can be determined to within 10 (5)\% in an $eγ$ collider built around a 500 (1000) GeV $e^+e^-$ collider.

Beverly K. Berger

To assess the validity of the Belinskii, Khalatnikov, and Lifshitz (BKL) approximation to Mixmaster dynamics, it would be useful to evaluate the BKL discrete parameters as a byproduct of the numerical solution of Einstein&#39;s equations. An algorithm to do this and results for a typical trajectory are presented.

Arlen Anderson

The use of $\sum \exp(iS[x])$ as the generic form for a sum over histories in configuration space is discussed critically and placed in its proper context. The standard derivation of the sum over paths by discretizing the paths is reviewed, and it is shown that the form $\sum \exp(iS[x])$ is justified only for Schrodinger-type systems which are at most secon

J. K. Freericks, D. J. Scalapino

Weak-coupling expansions (conserving approximations) are carried out for the attractive Holstein and Hubbard models (on an infinite-dimensional hypercubic lattice) that include all bandstructure and vertex correction effects. Quantum fluctuations are found to renormalize transition temperatures by factors of order unity, but may be incorporated into the supe

O. -G. Richter, P. D. Sackett, L. S. Sparke

We present the results of a neutral hydrogen survey conducted with the Green Bank 140-foot radio telescope of 47 northern objects in the polar-ring galaxy atlas of Whitmore \etal\ (1990). We detected 39 of these above our detection limit of 1.7 \hbox{Jy\CDOT\KMS}; the average measured flux of 21 Jy\CDOT\KMS\ corresponds to an average neutral hydrogen mass of

Hans-Walter Rix, George Lake

If the dark matter in galactic halos is made up of compact, macroscopic objects (MO), such as black holes with $M_\MO >>M_{stars}$, gravitational scattering will lead to kinematic heating of the stars. Observational constraints on the amount of heating in the disk of the Milky Way put upper limits on $M_\MO \ltorder 10^{6.3}\msun $. We find limits that are t

C. Ordóñez y J. M Pons

A Lagrangian treatment of the quantization of first class Hamiltonian systems with constraints and Hamiltonian linear and quadratic in the momenta respectively is performed. The ``first reduce and then quantize&#39;&#39; and the ``first quantize and then reduce&#39;&#39; (Dirac&#39;s) methods are compared. A new source of ambiguities in this latter approach

Gary T. Horowitz, Dean L. Welch

We consider solutions to low energy string theory which have a horizon and a spacelike symmetry. Each of these solutions has a geometrically different dual description. We show that the dual solution has a horizon with exactly the same Hawking temperature (surface gravity) and entropy (area) as the original solution.

C. Ordóñez, J. París, J. M. Pons, R. Toldrà

The equivalence between the covariant and the non-covariant version of a constrained system is shown to hold after quantization in the framework of the field-antifield formalism. Our study covers the cases of Electromagnetism and Yang-Mills fields and sheds light on some aspects of the Faddeev-Popov method, for both the coratiant and non-covariant approaches

M. J. Duff

In 1973 two Salam protégés (Derek Capper and the author) discovered that the conformal invariance under Weyl rescalings of the metric tensor $g_{μν}(x)\rightarrowΩ^2(x)g_{μν}(x)$ displayed by classical massless field systems in interaction with gravity no longer survives in the quantum theory. Since then these Weyl anomalies have found a variety of applicati

W. Mödritsch

The critical dimension of the bosonic string in the harmonic and the deDonder gauge may be calculated from the time ordered product of two energy momentum tensors. We show that recently found ambiguities within that method in nonconformal gauges can be resolved by a treatment respecting background covariance.

N. A. Kivel, A. S. Stepanenko, A. N. Vasil&#39;ev

Using knowledge of the explicit $n$ dependence of the RG functions and expressions of critical exponents in the framework of large $N$ expansion in the Gross Neveu model we derive RG functions in 4- and 5-loop approximation.

Shahn Majid, Martin Markl

We introduce an associative glueing operation $\oplus_q$ on the space of solutions of the Quantum Yang-Baxter Equations of Hecke type. The corresponding glueing operations for the associated quantum groups and quantum vector spaces are also found. The former involves $2\times 2$ quantum matrices whose entries are themselves square or rectangular quantum matr

B. K. Chung, K. G. Joo, Soonkeon Nam

We give a unified view of the relation between the $SL(2)$ KdV, the mKdV, and the Ur-KdV equations through the Fr\'{e}chet derivatives and their inverses. For this we introduce a new procedure of obtaining the Ur-KdV equation, where we require that it has no non-local operators. We extend this method to the $SL(3)$ KdV equation, i.e., Boussinesq(Bsq) equatio

Esko Keski-Vakkuri

We study the entropy generation and particle production in scalar quantum field theory in expanding spacetimes with many-particle mixed initial states. The recently proposed coarse-grained entropy approach by Brandenberger et. al. is applied to systems which may have a non-zero initial entropy. We find that although the the particle production is amplified a

F. Pisano, V. Pleitez

The ratio $Δm_K/m_K$ within the standard model with 3 generations is calculated as a function of the CP nonconserving phase $δ_{13}$ and the quark masses $m_c,m_t$ assuming the current values of the Cabibbo-Kobayashi-Maskawa mixing angles. We have found that varying $δ_{13}$ and $m_c$ within the allowed range, not all the values for the top quark mass fit th

J. Garriga

Nucleation rates for tunneling processes in Minkowski and de Sitter space are investigated, taking into account one loop prefactors. In particular, we con- sider the creation of membranes by an antisymmetric tensor field, analogous to Schwinger pair production. This can be viewed as a model for the decay of false (or true) vacuum at zero temperature, in the

Marcelo Gleiser

The evolution of spherically symmetric unstable scalar field configurations (``bubbles&#39;&#39;) is examined for both symmetric (SDWP) and asymmetric (ADWP) double-well potentials. Bubbles with initial static energies $E_0\la E_{\rm crit}$, where $E_{\rm crit}$ is some critical value, shrink in a time scale determined by their linear dimension, or ``radius&

M. V. Libanov, V. A. Rubakov, S. V. Troitsky

We consider the tree amplitudes of production of $n_2$ scalar particles by $n_1$ particles of another kind, where both initial and final particles are at rest and on mass shell, in a model of two scalar fields with $O(2)$ symmetric interaction and unequal masses. We find that these amplitudes are zero except for the lowest possible $n_1$ and $n_2$, and that

Riccardo Capovilla

In this note we examine some recently proposed solutions of the linearized vacuum Einstein equations. We show that such solutions are {\it not} symmetries of the Einstein equations, because of a crucial integrability condition.

Heiko Leschhorn, Lei-Han Tang

We study the critical behavior of a driven interface in a medium with random pinning forces by analyzing spatial and temporal correlations in a lattice model recently proposed by Sneppen [Phys. Rev. Lett. {\bf 69}, 3539 (1992)]. The static and dynamic behavior of the model is related to the properties of directed percolation. We show that, due to the interpl

B. T. Jannuzi, P. S. Smith, R. Elston

We discuss the optical polarization properties of X-ray selected BL Lacertae objects (XSBLs) as determined from three years of monitoring 37 BL Lac objects and candidates. The observed objects include a complete X-ray flux limited sample drawn from the EMS Survey. The majority of the XSBLs classi- fied solely on the appearance of their spectra are members of

Scott Dodelson, Jay Jubas

Early reionization changes the pattern of anisotropies expected in the cosmic microwave background. To explore these changes, we derive from first principles the equations governing anisotropies, focusing on the interactions of photons with electrons. Vishniac (1987) claimed that second order terms can be large in a re-ionized Universe, so we derive equation

Peter Komjath, Saharon Shelah

We show that there is always a uniformly antisymmetric f:A-> {0,1} if A subset R is countable. We prove that the continuum hypothesis is equivalent to the statement that there is an f:R-> omega with |S_x| <= 1 for every x in R. If the continuum is at least aleph_n then there exists a point x such that S_x has at least 2^n-1 elements. We also show that there

Peter Komjath, Saharon Shelah

We give some existence/nonexistence statements on universal graphs, which under GCH give a necessary and sufficient condition for the existence of a universal graph of size lambda with no K(kappa), namely, if either kappa is finite or cf(kappa)>cf(lambda). (Here K(kappa) denotes the complete graph on kappa vertices.) The special case when lambda^{< kappa}= l

Lorenz Halbeisen, Saharon Shelah

In this paper, we consider certain cardinals in ZF (set theory without AC, the Axiom of Choice). In ZFC (set theory with AC), given any cardinals C and D, either C <= D or D <= C. However, in ZF this is no longer so. For a given infinite set A consider Seq(A), the set of all sequences of A without repetition. We compare |Seq(A)|, the cardinality of this set,

Shmuel Lifsches, Saharon Shelah

Gurevich and Shelah have shown that Peano Arithmetic cannot be interpreted in the monadic second-order theory of short chains (hence, in the monadic second-order theory of the real line). We show here that it is consistent that there is no interpretation even in the monadic second-order theory of all chains.

Renling Jin, Saharon Shelah

By an omega_1 --tree we mean a tree of power omega_1 and height omega_1. We call an omega_1 --tree a Jech--Kunen tree if it has kappa --many branches for some kappa strictly between omega_1 and 2^{omega_1}. In this paper we construct the models of CH plus 2^{omega_1}> omega_2, in which there are Jech--Kunen trees and there are no Kurepa trees.

Saharon Shelah

Let T be the family of open subsets of a topological space (not necessarily Hausdorff or even T_0). We prove that if T has a countable base and is not countable, then T has cardinality at least continuum.

Garvin Melles, Saharon Shelah

A model M of cardinality lambda is said to have the small index property if for every G subseteq Aut(M) such that [Aut(M):G] <= lambda there is an A subseteq M with |A|< lambda such that Aut_A(M) subseteq G. We show that if M^* is a saturated model of an unsuperstable theory of cardinality > Th(M), then M^* has the small index property.

Reinhard Diestel, Saharon Shelah, Juris Steprāns

A graph is called dominating if its vertices can be labelled with integers in such a way that for every function f: omega-> omega the graph contains a ray whose sequence of labels eventually exceeds f. We obtain a characterization of these graphs by producing a small family of dominating graphs with the property that every dominating graph must contain some

Saharon Shelah, Juris Steprāns

It is shown to be consistent that there is a non-trivial autohomeomorphism of beta N while all such autohomeomorphisms are trivial on some open set. The model used is one due to Velickovic in which, coincidentally, Martin&#39;s Axiom also holds.

Paul C. Eklof, Alan H. Mekler, Saharon Shelah

It is proved consistent with either CH or the negation of CH that there is an aleph_1-separable group of cardinality aleph_1 which does not have a coherent system of projections. It had previously been shown that it is consistent with not CH that every aleph_1-separable group of cardinality aleph_1 does have a coherent system of projections.

Saharon Shelah

We prove the consistency of ``CH + 2^{aleph_1} is arbitrarily large + 2^{aleph_1} not-> (omega_1 x omega)^2_2&#39;&#39;. If fact, we can get 2^{aleph_1} not-> [omega_1 x omega]^2_{aleph_0}. In addition to this theorem, we give generalizations to other cardinals.

Paul C. Eklof, Saharon Shelah

We consider the question of which valuation domains (of cardinality aleph_1) have non-standard uniserial modules. We show that a criterion conjectured by Osofsky is independent of ZFC + GCH.

Alan H. Mekler, Saharon Shelah

A canary tree is a tree of cardinality the continuum which has no uncountable branch, but gains a branch whenever a stationary set is destroyed (without adding reals). Canary trees are important in infinitary model theory. The existence of a canary tree is independent of ZFC + GCH.

Samir D. Mathur

We study the model of massless $1+1$ electrodynamics with nonconstant coupling, introduced by Peet, Susskind and Thorlacius as the `charge hole&#39;. But we take the boundary of the strong coupling region to be first timelike, then spacelike for a distance $X$, and then timelike again (to mimic the structure of a black hole). For an incident charge pulse ent

Ann E. Nelson, Lisa Randall

We show that if there are only two Higgs doublets in the supersymmetric standard model, large $\tanβ$ requires a fine tuning in the parameters of the Lagrangian of order ($1/\tanβ$), which cannot be explained by any approximate symmetry. With an extended Higgs sector, large $\tanβ$ can be natural. We give an explicit example with four doublets in which it is

M. J. Herrero, E. Ruiz Morales

The most general chiral Lagrangian for electroweak interactions with the complete set of $SU(2)_L\times U(1)_Y$ invariant operators up to dimension four is considered. The two-point and three-point functions with external gauge fields are derived from this effective chiral Lagrangian to one-loop order in a generic $R_ξ$-gauge. The same set of Green&#39;s fun

Paul H. Frampton, Plamen I. Krastev, James T. Liu

In the 331 model, lepton number may be explicitly broken by trilinear scalar self couplings. This leads to neutrino masses proportional to the cube of the corresponding charged lepton mass, with consequences for solar neutrinos and for hot dark matter.

B. Feigin, S. Parkhomenko

In this paper we investigate one Wakimoto-type construction of affine Kac-Moody algebras. We obtain a version of the regular representation, on which the affine algebra acts from the left and from the right with the sum of levels equal to minus two dual Coxeter numbers.