February 1994 arXiv papers — page 3

M. Knecht, B. Moussallam, J. Stern

The cross section for $γγ\toπ^0π^0$ and the pion polarizabilities are computed, within generalized chiral perturbation theory, in the full one loop approximation, {\it i.e.} up to and including order $O({p^5})$. The result depends on the parameter $α_{ππ}$ defining the tree level $π- π$ scattering amplitude and on an additional low energy constant. The latte

M. E. Pospelov

Schwinger operator method is applied for studying CP-odd pure gluonic effective Lagrangian in the Standard Model at three-loop level. The induced $θ$-term vanishes by the same reasons as EDMs of quark and W-boson to two-loop approximation. A simple way is found to demonstrate these cancellations. All other terms of the effective Lagrangian acquire non-vanish

Karl Svozil

Due to the nonvanishing average photon population of the squeezed vacuum state, finite corrections to the scattering matrix are obtained. The lowest order contribution to the electron mass shift for a one mode squeezed vacuum state is given by $δm(Ω,s)/m=α(2/π)(Ω/m)^2\sinh^2(s)$, where $Ω$ and $s$ stand for the mode frequency and the squeeze parameter and $α

B. A. Kniehl, A. Pilaftsis

We analyze the phenomenological implications for new electroweak physics in the Higgs sector in the framework of SU(2)_L x U(1)_Y theories that naturally predict heavy Majorana neutrinos. We calculate the one-loop Majorana-neutrino contributions to the decay rates of the Higgs boson into pairs of quarks and intermediate bosons and to its production cross sec

T. K. Kuo, Gye T. Park

We perform precision electroweak tests on the $Sp(6)_L \times U(1)_Y$ model. The purpose of the analysis is to delineate the model parameters such as the mixing angles of the extra gauge bosons present in this model. We find that the model is already constrained considerably by the present LEP data.

She-Sheng XUE

In the chirally-invariant context of the $U_{em}(1)$ gauge interaction and four-fermion interactions for ordinary and mirror fermions, the Schwinger-Dyson equation for the fermion self-energy function is studied on a lattice. We find that a sensible infrared limit can be defined on a critical surface, which is consistent with the critical line found in the c

Bernd Dahmen

A systematic method to obtain strong coupling expansions for scattering quantities in Hamiltonian lattice field theories is presented. I develop the conceptual ideas by means of the Hamiltonian field theory analogue of the Ising model, in $d$ space and one time dimension. The main result is a convergent series representation for the sacttering states and the

Tsutomu Momoi

We study low-lying states of the XY and Heisenberg antiferromagnets on a triangular lattice to clarify whether spontaneous symmetry breaking occurs at $T=0$ in the thermodynamic limit. Approximate forms of low-lying states are proposed, in which degrees of freedom of the sublattice magnetization and of the chirality are separated. It is shown that low-lying

Lin-Yuan Chen, Nigel Goldenfeld, Y. Oono

We study the propagation of uniformly translating fronts into a linearly unstable state, both analytically and numerically. We introduce a perturbative renormalization group (RG) approach to compute the change in the propagation speed when the fronts are perturbed by structural modification of their governing equations. This approach is successful when the f

W. R. Osborn, J. M. Yeomans

This paper discusses wetting and capillary condensation transitions on a line and a rectangular array of cylinders using an interface potential formalism. For a line of cylinders, there is a capillary condensation transition followed by complete wetting if the cylinders are sufficiently close together. Both transitions disappear as the cylinder separation is

J. G. Skibo, C. D. Dermer, R. L. Kinzer

We consider whether the hard X-ray and soft gamma-ray emission from Centaurus A is beamed radiation from the active nucleus which is Compton-scattered into our line-of-sight. We derive the spectrum and degree of polarization of scattered radiation when incident beamed radiation is scattered from a cold ($kT<<m_ec^2$) electron cloud moving with bulk relativis

Ben Dorman, R. W. O&#39;Connell, R. T. Rood

We present the case that populations of sdB/sdOB/sdO-type stars may be a common constituent of galactic stellar populations, responsible for the UV upturn (`UVX&#39;) observed in the spectra of spiral bulges and normal galaxy nuclei. Extreme Horizontal Branch stars with $\log g > 5$ and $\log \teff > 20,000K$ have emerged in the last few years as the most li

Wayne Hu, Douglas Scott, Joseph Silk

%The content of this replacement paper is identical to the original. %We have attempted to fix the postscript so that it will print out on %a larger number of printers. Using recent experimental limits on $μ$ distortions from COBE FIRAS, and the large lever-arm spanning the damping of sub-Jeans scale fluctuations to the scale of the COBE DMR fluctuations, we

Yuri V. Shtanov, Sergei A. Yushchenko

Conformally invariant GUT-like model including gravity based on Riemann - Cartan space-time $U_4$ is considered. Cosmological scenario that follows from the model is discussed and standard quantum gravitational formalism in the Arnowitt-Deser-Misner form is developed. General formalism is then illustrated on Bianchi-IX minisuperspace cosmological model. Wave

D. Comelli, C. Verzegnassi, F. M. Renard

We introduce and define operatively in a model independent way a new ``heavy&#34; b-vertexparameter, $η_b$, that can be derived from the measurement of a special polarization asymmetry for production of b-quarks on Z resonance. We show that the combination of the measurement of $η_b$ with that of a second and previously defined ``heavy&#34; b-vertex paramete

Fred Cooper, John Dawson, Harvey Shepard

Using a newly suggested algorithm of Gozzi, Reuter, and Thacker for calculating the excited states of one dimensional systems, we determine approximately the eigenvalues and eigenfunctions of the anharmonic oscillator, described by the Hamiltonian $H= p^2/2 + g x^4$. We use ground state post-gaussian trial wave functions of the form $Ψ(x) = N{\rm{exp}}[-b |x

J. Engel, S. Pittel, P. Vogel

We discuss and improve a recent treatment of the absorption of solar neutrinos by ${}^{127}$I, in connection with a proposed solar neutrino detector. With standard-solar-model fluxes and an in-medium value of -1.0 for the axial-vector coupling constant $g_A$, we obtain a ${}^8$B-neutrino cross section of 3.3$\times 10^{-42}$, about 50\% larger than in our pr

Erik J. Balder, Maria Girardi, Vincent Jalby

Necessary and sufficient oscillation conditions are given for a weakly convergent sequence (resp. relatively weakly compact set) in the Bochner-Lebesgue space $\l1$ to be norm convergent (resp. relatively norm compact), thus extending the known results for $\rl1$. Similarly, necessary and sufficient oscillation conditions are given to pass from weak to limit

Robert Rudd

This work describes the formulation of the manifestly ghost-free (spacetime) light-cone gauge for bosonic string theory with non-trivial spacetime metric, antisymmetric tensor, dilaton and tachyon fields. The action is a general two-dimensional sigma model, corresponding to a closed string theory with a second order action in the Polyakov picture. The spacet

Branko Urosevic

In this note we present an explicit procedure for the regularization of tree level amplitudes involving discrete states, using open string field theory. We show that there is a natural correspondence between the discrete states and off--shell states, later acting as a regularized version of the former. A general off-shell state corresponds to several physica

Louis Crane

We consider the implications of some simple assumptions about the nature of the quantum theory of gravity which are plausible for a class of possible theories I have been attempting to construct. The simple assumptions turn out to have surprizingly wide implications of a type one might call philosophical. The paper is short and nontechnical. ( This builds on

J. M. Aroca, H. Fort

We present the extension of the Lagrangian $loop$ representation in such a way to introduce matter fields. The partition function of lattice compact U(1) Gauge-Higgs model is expressed as a sum over closed as much as open surfaces. These surfaces correspond to world sheets of loop-like pure electric flux excitations and open electric flux tubes carrying matt

J. M. Aroca, H. Fort

We introduce in a natural and straigthforward way the $loop$ (Lagrangian) $representation$ for the partition function of pure compact lattice QED. The corresponding classical lattice loop action is proportional to the quadratic area of the loop world sheets. We discuss the parallelism between the $loop$ formulation of this model in terms of world sheets of l

Anjan Kundu

We translate effectively our earlier quantum constructions to the classical language and using Yang-Baxterisation of the Faddeev-Reshetikhin-Takhtajan algebra are able to construct Lax operators and associated $r$-matrices of classical integrable models. Thus new as well as known lattice systems of different classes are generated including new types of colle

J. Navarro-Salas, M. Navarro, C. F. Talavera, V. Aldaya

The quantization of the induced 2d-gravity on a compact spatial section is carried out in three different ways. In the three approaches the supermomentum constraint is solved at the classical level but they differ in the way the hamiltonian constraint is imposed. We compare these approaches establishing an isomorphism between the resulting Hilbert spaces.

Dennis Bonatsos, C. Daskaloyannis, P. Kolokotronis, D. Lenis

The symmetry algebra of the two-dimensional quantum harmonic oscillator with rational ratio of frequencies is identified as a non-linear extension of the u(2) algebra. The finite dimensional representation modules of this algebra are studied and the energy eigenvalues are determined using algebraic methods of general applicability to quantum superintegrable

D. Pirjol

The structure function of a heavy quark in a heavy hadron in electroproduction is calculated from QCD. Its deviation from the parton model prediction (a delta function) is shown to be governed by a shape function, similar to the one recently proposed by Neubert and Bigi {\em et al.} to describe the end-point behaviour of the lepton spectrum in semileptonic $

Naoya Hata

Vacuum oscillations are considered for the combined solar neutrino observations, including the Kamiokande II spectrum data and incorporating theoretical uncertainties and their correlations. Despite the conceptual difficulty of the fine tuning between the neutrino parameters and the Sun-Earth distance, 2-flavor vacuum oscillations provide phenomenologically

Chi-Keung Chow, Mark B. Wise

The spectrum of excited $Λ_Q$-type heavy baryons is considered in the large $N_c$ limit. The universal form factors for $Λ_b$ semileptonic decay to excited charmed baryons are calculated in the large $N_c$ limit. We find that the Bjorken sum rule (for the slope of the Isgur--Wise function) and Voloshin sum rule (for the mass of the light degrees of freedom)

Zhenping Li, Zhujun Li

In this paper, we show what we can learn from the CEBAF experiments on spin-structure functions, and the transition from the Drell-Hearn-Gerasimov sum rule in the real photon limit to the spin dependent sum rules in the deep inelastic scattering, and how the asymmetry $A_1(x,Q^2)$ approaches the scaling limit in the resonance region. The spin structure funct

S. G. Kovalenko

A modification of the standard model of electroweak interactions with the nonlocal Higgs sector is proposed. Proper form of nonlocality makes Higgs particles unobservable after the electroweak symmetry breaking. They appear only as a virtual state because their propagator is an entire function. We discuss some specific consequences of this approach comparing

P. A. Henning

Within a relativistic real-time Green&#39;s function formalism, a quantum transport equation for the phase-space distribution function is derived without a quasi-particle approximation. Dissipation is due to a nonzero spectral width, and can be separated into time-local and memory effects.

Michael Creutz, Ivan Horvath

In a Hamiltonian formalism we study chiral symmetry for lattice Fermions formulated in terms of Shockley surface states bound to a wall in an extra spatial dimension. For hadronic physics this provides a natural scheme for taking quark masses to zero without requiring a precise tuning of parameters. We illustrate the chiral anomaly as a flow of states in thi

Guillermo A. Mena Marugan

We determine the wavefunction that corresponds to the exponential of the Chern-Simons action in a family of gravitational models provided with cosmological constant whose non-perturbative canonical quantization is completely known. We show that this wavefunction does not represent a proper quantum state, because it is not normalizable with respect to the uni

Piotr T. Chrusciel

Various assumptions underlying the uniqueness theorems for black holes are discussed. Some new results are described, and various unsatisfactory features of the present theory are stressed.

Marco Cavaglià, Vittorio de Alfaro, Alexandre T. Filippov

We discuss how to fix the gauge in the canonical treatment of Lagrangians, with finite number of degrees of freedom, endowed with time reparametrization invariance. The motion can then be described by an effective Hamiltonian acting on the gauge shell canonical space. The system is then suited for quantization. We apply this treatment to the case of a Robert

Rudolf A. Römer, Bill Sutherland

We present an exact calculation of the Luttinger liquid relation for the one-dimensional, two-component SC model in the interaction strength range $-1<s<0$ by appropriately varying the limits of the integral Bethe Ansatz equations. The result is confirmed by numerical and conformal methods. By a related study of the transport properties of the SC model, we c

Stefan Kettemann, Konstantin B. Efetov

A dynamic response to a magnetic field in a long disordered cylinder is considered. We show that, although at high frequencies conduction is classical in all directions, the low frequency behavior corresponds to localization in the longitudinal direction and to a diamagnetic dynamic persistent current in the transversal one. The current density does not vani

A. H. MacDonald, Shou-Cheng Zhang

We study the collective excitation spectra of double-layer quantum-Hall systems using the single mode approximation. The double-layer in-phase density excitations are similar to those of a single-layer system. For out-of-phase density excitations, however, both inter-Landau-level and intra-Landau-level double-layer modes have finite dipole oscillator strengt

P. Sitko

We find, in the Hartree-Fock approximation, the ground-state energy of anyons with no Coulomb interaction in the case when the external magnetic field precisely cancels the average statistical field. From the point of view of the fractional quantum Hall effect statistics transmutations to {\it superfermions} at filling fractions $ν=1/2p$ are not energeticall

M. Smock, H. W. Diehl, D. P. Landau

The universal, scaled order parameter profiles $P_{\pm}(z/ξ)$ for critical adsorption of a fluid or fluid mixture onto a wall or interface, and for the extraordinary transition of the semi-infinite Ising model, are discussed theoretically, where $z$ is the distance from the interface, $ξ(T)$ is the bulk correlation length, and the subscript $+$ ($-$) refers

J. Merikoski, H. Hakkinen, M. Manninen, J. Timonen

The structure of the Cu(110) surface is studied at high temperatures using a combination of lattice-gas Monte Carlo and molecular dynamics methods with identical many-atom interactions derived from the effective medium theory. The anisotropic six-vertex model is used in the interpretation of the lattice-gas results. We find a clear roughening transition arou

Jian-Sheng WANG

An efficient algorithm for random sequential adsorption of hard discs in two dimensions is implemented. A precise value for the coverage is obtained: theta(infty) = 0.547069. The asymptotic law theta(t) = theta(infty) - ct^{-1/2} is verified to a high accuracy. Pair correlation function is analyzed.

David N. Spergel, Ue-Li Pen

(To appear in Nuclear Physics B Supplements Proceedings section) This talk will explore the evolution of topological defects in an open universe. The rapid expansion of the universe in an open model slows defects and suppresses the generation of CBR fluctuations at large angular scale as does the altered relationship between angle and length in an open unive

Atsushi Moriwaki

Let K be a number field, O_K the ring of integers of K and X a stable curve over O_K of genus g >= 2. In this note, we will prove a strict inequality ( (K_{X/S})^2 / [K : Q] ) > Height_{Fal}(J(X_K)), where $K_{X/S}$ is the canonically metrized dualizing sheaf of X over S = Spec(O_K) and Height_{Fal}(J(X_K)) is the Faltings modular height of the Jacobian of X

B. Sriram Shastry

We summarize recent work showing that the $1/r^2$ model of interacting particles in 1-dimension is a universal Hamiltonian for quantum chaotic systems. The problem is analyzed in terms of random matrices and of the evolution of their eigenvalues under changes of parameters. The robustness of bulk space-time correlations of a many particle system to changing

Xiangdong Ji, Zheng-Kun Zhu

We examine the physics content of fragmentation functions for inclusive hadron production in a quark jet and argue that it can be calculated in low energy effective theories. As an example, we present a calculation of $u$-quark fragmentation to $π^+$ and $π^-$ mesons in the lowest order in the chiral quark model. The comparison between our result and experim

M. Chertkov, G. Falkovich, I. Kolokolov, V. Lebedev

Steady statistics of a passive scalar advected by a random two-dimensional flow of an incompressible fluid is described in the range of scales between the correlation length of the flow and the diffusion scale. That corresponds to the so-called Batchelor regime where the velocity is replaced by its large-scale gradient. The probability distribution of the sc

A. Mikovic

We investigate nonperturbative canonical quantization of two dimensional dilaton gravity theories with an emphasis on the CGHS model. We use an approach where a canonical transformation is constructed such that the constraints take a quadratic form. The required canonical transformation is obtained by using a method based on the Bäcklund transformation from

H. J. Schulz, T. A. L. Ziman, D. Poilblanc

We have performed a numerical investigation of the ground state properties of the frustrated quantum Heisenberg antiferromagnet on the square lattice (``$J_1-J_2$ model&#39;&#39;), using exact diagonalization of finite clusters with 16, 20, 32, and 36 sites. Using a finite-size scaling analysis we obtain results for a number of physical properties: magnetic

V. A. Saleev

Based on a perturbative theory of quantum chromodynamics and non-relativistic quark model, associated $J/ψ$ plus open charm photoproduction on charm quarks in a proton via partonic subprocess $γc\to J/ψc$ is discussed. It is shown that the value and energy dependence of the cross section for such process remarkably depends on the choice of charm distribution

Rouzbeh Allahverdi, Bruce A. Campbell, Keith A. Olive

We consider an extension of the supersymmetric standard model which includes singlet Higgs superfield representations (in three generations) to generate neutrino masses via the see-saw mechanism. The resulting theory may then exhibit R-parity violation in the couplings of the singlets, inducing $R$-parity violating effective interactions among the standard m

Mirjam Cvetic

We study supersymmetric (extreme) domain walls in four-dimensional (4d) N=1 supergravity theories with a general dilaton coupling $α> 0$. Type I walls, which are static, planar (say, in ($x,y$) plane) configurations, interpolate between Minkowski space-time and a vacuum with a varying dilaton field. We classify their global space-time with respect to the val

Hong-Jian He, Zhaoming Qiu, Chia-Hsiung Tze

A precise formulation of $U(1)$ local gauge invariance in QED is presented, which clearly shows that the gauge coupling associated with the unphysical longitudinal photon field is non-observable and actually has an arbitrary value. We then re-examine the Dirac quantization condition and find that its derivation involves solely the unphysical longitudinal cou

Tomasz Nowicki, Sebastian van Strien

In this paper we shall show that there exists L_0 such that for each even integer L >= L_0 there exists $c_1 \in \rz$ for which the Julia set of $z --> z^L + c_1$ has positive Lebesgue measure. This solves an old problem. Editor&#39;s note: In 1997, it was shown by Xavier Buff that there was a serious flaw in the argument, leaving a gap in the proof. Current

Jose M. Gracia-Bondia, Joseph C. Varilly

Systematic use of the infinite-dimensional spin representation simplifies and rigorizes several questions in Quantum Field Theory. This representation permutes ``Gaussian&#39;&#39; elements in the fermion Fock space, and is necessarily projective: we compute its cocycle at the group level, and obtain Schwinger terms and anomalies from infinitesimal versions

Matthias Blau, George Thompson

Motivated by some questions in the path integral approach to (topological) gauge theories, we are led to address the following question: given a smooth map from a manifold $M$ to a compact group $G$, is it possible to smoothly `diagonalize&#39; it, i.e.~conjugate it into a map to a maximal torus $T$ of $G$? We analyze the local and global obstructions and gi

Yutaka Hosotani

We re-examine three-dimensional gauge theory with a Chern-Simons term in which the Lorentz invariance is spontaneously broken by dynamical generation of a magnetic field. A non-vanishing magnetic field leads, through the Nambu-Goldstone theorem, to the decrease of zero-point energies of photons, which accounts for a major part of the mechanism. The asymmetri

Uwe Grimm

Explicit expressions for three series of $R$ matrices which are related to a ``dilute&#39;&#39; generalisation of the Birman--Wenzl--Murakami are presented. Of those, one series is equivalent to the quantum $R$ matrices of the $D^{(2)}_{n+1}$ generalised Toda systems whereas the remaining two series appear to be new.

J. M. F. Labastida, M. Mariño

Polynomial invariants corresponding to the fundamental representation of the gauge group $SU(N)$ are computed for arbitrary torus knots and links in the framework of Chern-Simons gauge theory making use of knot operators. As a result, a formula for the HOMFLY polynomial for arbitrary torus links is presented.

Takanori Sugihara, Masayuki Matsuzaki, Masanobu Yahiro

Two-dimensional SU($N$) gauge theory is accurately analyzed with the light-front Tamm-Dancoff approximation, both numerically and analytically. The light-front Einstein-Schrödinger equation for mesonic mass reduces to the &#39;t Hooft equation in the large $N$ limit, $g^2N$ fixed, where $g$ is the coupling constant. Hadronic masses are numerically obtained i

Krzysztof Gawedzki

We compute, by free field techniques, the scalar product of the SU(2) Chern-Simons states on genus > 1 surfaces. The result is a finite-dimensional integral over positions of ``screening charges&#39;&#39; and one complex modular parameter. It uses an effective description of the CS states closely related to the one worked out by Bertram. The scalar product f

S. U. Park

The simple algebras of a dressed operator, which is composed of a dressing and a residual operators, are averaged following a proper statistics of the dressing one. In the Bose-Einstein statistics, a (fermionic) Calogero-Vasiliev oscillator, $q$-boson (fermion), and (fermionic) $su_q(1,1)$ are obtained for each bosonic (fermionic) residual operator. In the F

Michael I. Eides, Howard Grotch, Peter Pebler

The radiative correction to the Lamb shift of order $α^{2}(Zα)^5m$ induced by the light by light scattering insertion in external photons is obtained. The new contribution turns out to be equal to $-0.122(2)α^2(Zα)^5/(πn^3)(m_r/m)^3m$. Combining this contribution with our previous results we obtain the complete correction of order $α^{2}(Zα)^5m$ induced by a

J. Ohnemus, T. F. Walsh, P. M. Zerwas

Non--strongly interacting supersymmetric particles -- sleptons, charginos, neutral\-inos, and charged Higgs bosons -- are difficult to detect at the Large Hadron Collider. We therefore examine the possibility of producing particles of this type in virtual $γγ$ collisions at the LHC. Since photons can be emitted from protons which do not break up in the radia

Hong-Jian He, Zhaoming Qiu, Chia-Hsiung Tze

We enlarge the local gauge invariance of QED from $~U(1)_A~$ to $~U(1)_A \times U(1)_Θ~$ by introducing another unphysical pure gauge field $~Θ~$ with an independent, unphysical gauge coupling $~\tilde{e}~$. This pure gauge field can be gauge-transformed away and the resulting theory is {\it identical to} standard QED. We then re-examine the Dirac quantizati

Haim Goldberg

It is shown that, in a theory where the dilaton is coupled to a Yang-Mills gauge field which enters a confining phase at scale Λ, the dilaton may grow a mass $m_{dilaton}\sim Λ^2/m_{Pl}\sim (m_{SUSY}^2 m_{Pl})^{1/3}\sim 10^8\ \mbox{GeV}. $ This allows ample time for decay before the electroweak era if $m_{SUSY}\simeq 1\ \mbox{TeV},$ and circumvents cosmologi

J. Lopez, D. Nanopoulos, A. Zichichi

Review to appear in Progress in Particle and Nuclear Physics. Contents: {1}Introduction}{1} {2}High precision LEP data and convergence of couplings: physics is not Euclidean geometry}{2} {3}Interconnections between the measured quantities due to Unification}{7} {4}The origin of $M_{SUSY}$ and why it should be abandoned: masses and spectra are needed}{13} {5}

Geert Jan van Oldenborgh, Paula. J. Franzini, Arianna Borrelli

We present an efficient generator for the process e+e- to 4 fermions + gamma through off-shell W pairs. It is based on a massless matrix element with leading order(m^2) corrections. Only the resonant WW graphs are included. We have tested it against a matrix element without these approximations and found agreement to within ~1% at LEPII energies.

E. Kh. Akhmedov

Recent results of atmospheric neutrino experiments are reviewed and their possible interpretations are discussed, main emphasis being put on the neutrino oscillation hypothesis.

H. Aoki

We evaluate the eigenvalues of Dirac operator in the background of instanton-anti-instanton configuration (I-$\bar{\rm I}$), in a simple (1+0)-dimensional model, and find that quasi-zero-mode disappears for the closely localized I-$\bar{\rm I}$ configurations. This result suggests that the configurations which are dominant at high energy in the valley method

Kari Enqvist, Poul Olesen

Non-abelian gauge theories may have a ferromagnet-like vacuum with a non-zero magnetic field, which also exists at finite temperature. We argue that the formation of the ferromagnet-like vacuum at GUT scales gives rise to a Maxwell magnetic field imprinted on the comoving plasma, and that it is energetically favourable to align the field in different correla

Christoph Best, Andreas Schaefer

We investigate the description of statistical field theories using Daubechies&#39; orthonormal compact wavelets on a lattice. A simple variational approach is used to extend mean field theory and make predictions for the fluctuation strengths of wavelet coefficients and thus for the correlation function. The results are compared to Monte Carlo simulations. W

Kieran Mullen, H. T. C. Stoof, Mats Wallin, S. M. Girvin

We develop a theory for a novel state of ${}^4$He films, that possesses off diagonal order (as in the superfluid state), as well as hexatic or bond orientational order. Within our description, both the hexatic and superfluid transitions are still of the Kosterlitz-Thouless type, but the superfluid stiffness is sensitive to the hexatic transition. We briefly

M. Chertkov, Y. V. Fyodorov, I. Kolokolov

The letter presents new field-theoretical approach to 2D passive scalar problem. The Gaussian form of the distribution for the Lyapunov exponent is derived and its parameters are found explicitly.

M. Wintel, H. U. Everts, W. Apel

We study the topological defects in the classical Heisenberg antiferromagnet in two dimensions on a triangular lattice (HAFT). While the topological analysis of the order parameter space indicates that the defects are of $Z_2$ type, consideration of the energy leads us to a description of the low--energy stationary points of the action in terms of $\pm$ vort

J. Richard Bond

The natural outcome of theoretical calculations of microwave background anisotropy is the angular power spectrum ${\cal C}_\ell$ as a function of multipole number $\ell$. Experimental ${\cal C}_\ell$&#39;s are needed for direct comparison. Estimation procedures using statistics linear in the pixel amplitudes as well as the conventional but less useful quadra

K. Mannheim, R. Schlickeiser

We present convenient formulae for the energy losses of energetic atomic nuclei over the entire energy range relevant to the physics of cosmic rays. Results are applied to a leaky-box equation with a complete loss term. Thereby we derive the equilibrium spectrum of cosmic rays in various types of galaxies. We emphasize a spectral break energy at 450 MeV inde

J. Richard Bond, Richard L. Davis, Paul J. Steinhardt

The CMB anisotropy depends sensitively upon the slope and amplitude of primordial density and gravitational wave fluctuations, the baryon density, the Hubble constant, the cosmological constant, the ionization history, {\it etc.} We report on recent work showing how well multi-scale measurements of the anisotropy power spectrum can resolve these factors. We

Paolo Salucci, Massimo Persic

We estimate the contribution of galaxies to the cosmological density Omega_0 including also their extended dark halos. We find Omega_gal< 0.1, so implying that the matter in galaxies cannot by itself close the Universe but marginally could be baryonic. (latex file)two figures available upon request).

Ue-Li Pen

(accepted for publication in the Ap.J.) I present a general classification of self-similar solutions to the equations of gravitational hydrodynamics that contain many previous results as special cases. For cold flows with spherical symmetry, the solution space can be classified into several regions of behavior similar to the Bondi solutions for steady flow.

Ludmil Katzarkov

In this paper, using Gromov-Jost-Korevaar-Schoen technique of harmonic maps to nonpositively curved targets, we study the representations of the fundamental groups of quasiprojective varieties. As an application of the above considerations we give a proof of a weak version of the Shafarevich Conjecture.

Gerald B. Cleaver, Philip J. Rosenthal

The implications of string theory for understanding the dimension of uncompactified spacetime are investigated. Using recent ideas in string cosmology, a new model is proposed to explain why three spatial dimensions grew large. Unlike the original work of Brandenberger and Vafa, this paradigm uses the theory of random walks. A computer model is developed to

David Seibert, Che Ming Ko

We derive classically an expression for a hadron width in a two-phase region of hadron gas and quark-gluon plasma (QGP). The presence of QGP gives hadrons larger widths than they would have in a pure hadron gas. We find that the $ϕ$ width observed in a central Au+Au collision at $\sqrt{s}=200$ GeV/nucleon is a few MeV greater than the width in a pure hadron

K. Varga, Y. Suzuki, Y. Ohbayasi

The neutron halo structure of $^{6}$He and of $^{8}$He is studied in a microscopic three-body and five-body model, respectively. Various cluster arrangements are included to embody a variety of correlations between the clusters. The intercluster wave function is determined with the stochastic variational method. The $^{6}$He and $^{8}$He energies are reprodu

Saharon Shelah, Lee Stanley

We lay the combinatorial foundations for [ShSt:340] by setting up and proving the essential properties of the coding apparatus for singular cardinals. We also prove another result concerning the coding apparatus for inaccessible cardinals.

Peter Komjath, Saharon Shelah

We describe some (countably many) classes K^{n,e} of finite graphs and prove that if lambda^{aleph_0}= lambda then every lambda^+-chromatic graph of cardinal lambda^+ contains, for some n, e, all members of K^{n,e} as subgraphs. On the other hand, it is consistent for every regular infinite cardinal kappa that there is a kappa^+-chromatic graph on kappa^+ th

E. Elizalde, S. D. Odintsov, A. Romeo, Yu. I. Shil&#39;nov

The Schwinger-Dyson equations in the ladder approximation for $2D$ induced gravity coupled to fermions on a flat background are obtained in conformal gauge. A numerical study of these equations shows the possiblity of chiral symmetry breaking in this theory.

E. Elizalde, Yu. Kubyshin

Possible experimental manifestations of the contribution of heavy Kaluza-Klein particles, within a simple scalar model in six dimensions with spherical compactification, are studied. The approach is based on the assumption that the inverse radius $L^{-1}$ of the space of extra dimensions is of the order of the scale of the supersymmetry breaking $M_{SUSY} \s

Alexander Vilenkin

Inflation can occur in the cores of topological defects, where the scalar field is forced to stay near the maximum of its potential. This topological inflation does not require fine-tuning of the initial conditions.

T. J. Hollowood

An exact expression for the mass-gap, the ratio of the physical particle mass to the $Λ$-parameter, is found for the principal chiral sigma models associated to all the classical Lie algebras. The calculation is based on a comparison of the free-energy in the presence of a source coupling to a conserved charge of the theory computed in two ways: via the ther

A. Zadra, E. Abdalla

We review the relation between the matrix model and Liouville approaches to two-dimensional gravity as elaborated by Moore, Seiberg and Staudacher. Then, based on the supersymmetric Liouville formulation and the discrete eigenvalue model proposed by Alvarez-Gaumé, Itoyama, Mañes and Zadra, we extend the previous relation to the supersymmetric case. The minis

Gregory Keaton

Recently it was proposed that the constituent quark is a topological soliton. I investigate this soliton, calculating its mass, radius, magnetic moment, color magnetic moment, and spin structure function. Within the approximations used, the magnetic moments and spin structure function cannot simultaneously be made to agree with the constituent quark model. S

K. S. Babu, S. M. Barr

It is shown that a natural gauge hierarchy and doublet-triplet splitting can be achieved in SO(10) using the Dimopoulos-Wilczek mechanism. Artificial cancellations (fine-tuning) and arbitrary forms of the superpotential are avoided, the superpotential being the most general compatible with a symmetry. It is shown by example that the Dimopoulos-Wilczek mechan

J. F. Nieves, P. B. Pal

The zero momentum limit of thermal self-energies calculated in perturbation theory depends on the order in which the time and the space components of the momentum are taken to zero. We show that this is an artifact of the perturbative calculation, and in fact the limit is well-defined when higher orders of the perturbation expansion are properly taken into a

N. G. Deshpande, E. Keith

We investigate the status of predictive fermion mass ansatzes which make use of the grand unification scale conditions $m_e=m_d/3$, $m_μ=3m_s$, and $\mid V_{cb}\mid =\sqrt{m_{c}/m_{t}}$ in non-supersymmetric SO(10) grand unification. The gauge symmetry below an intermediate symmetry breaking scale $M_I$ is assumed to be that of the standard model with either

Thomas Mannel, Matthias Neubert

We apply the operator product expansion to resum the leading nonperturbative corrections to the endpoint region of the lepton spectrum in inclusive semileptonic $B\to X_q\,\ell\,\barν$ decays, taking into account a finite quark mass $m_q$ in the final state. We show that both for $b\to c$ and $b\to u$ transitions, it is consistent to describe these effects b

Christian F. Wöhler, Edward Shuryak

Feynman diagrams in the instanton background are used for the calculation of the tunneling amplitude, up to the two-loops order. Some mistakes made in the previous works are corrected. The same method is applied to the next-order corrections to the ground state wave function.

T. Shigetani, K. Suzuki, H. Toki

The pion structure function is studied in the Nambu and Jona-Lasinio (NJL) model. We calculate the forward scattering amplitude of a virtual photon from a pion target in the Bjorken limit, and obtain valence quark distributions of the pion at the low energy hadronic scale, where the NJL model is supposed to work. The calculated distribution functions are evo

Tao Huang, Bo-Qiang Ma, Qi-Xing Shen

Several general constraints are suggested to analyze the pionic valence-state wave function. It is found that the present model wave functions used in light-cone formalism of perturbative quantum chromodynamics have failed these requirements to fit the pionic form factor data and the reasonable valence-state structure function which does not exceed the pioni