December 1996 arXiv papers — page 7

H. J. Haubold, A. M. Mathai

An introductory account is given of the understanding of the structure of the universe. At present the most plausible theory of the origin of the universe is that it formed from the explosion of an extremely hot and dense fireball several billion years ago. During the first few seconds after the big bang, the energy density was so great that only fundamental

A. A. Tseytlin

0-brane of type IIA string theory can be interpreted as a dimensional reduction of a gravitational wave in 11 dimensions. We observe that a similar interpretation applies also to the D-instanton background of type IIB theory: it can be viewed as a reduction (along one spatial and one time-like direction) of a wave in a 12-dimensional theory. The instanton ch

Victor T. Kim, Grigorii B. Pivovarov

A new framework for a high energy limit of quantum gauge field theories is introduced. Its potency is illustrated on a new derivation of the reggeization of the gluon.

Shamit Kachru, Eva Silverstein

We discuss the appearance of $E_8\times E_8$ gauge bosons in Banks, Fischler, Shenker, and Susskind's zero brane quantum mechanics approach to M theory, compactified on the interval $S^1/Z_2$. The necessary bound states of zero branes are proven to exist by a straightforward application of T-duality and heterotic $Spin(32)/Z_2$-Type I duality. We then st

Alexander Gromov

The Tolman-Bondi (TB) model is defined up to some transformation of a co-moving coordinate but the transformation is not fixed. The use of an arbitrary co-moving system of coordinates leads to the solution dependent on three functions $f, F, {\bf F}$ which are chosen independently in applications. The article studies the transformation rule which is given by

Charles H. Lineweaver, Domingos Barbosa

Recent cosmic microwave background (CMB) measurements over a large range of angular scales have become sensitive enough to provide interesting constraints on cosmological parameters within a restricted class of models. We use the CMB measurements to study inflation-based, cold dark matter (CDM) critical density universes. We explore the 4-dimensional paramet

Joel David Hamkins, Saharon Shelah

After small forcing, any < kappa-closed forcing will destroy the supercompactness, even the strong compactness, of kappa .

Mirna Džamonja, Saharon Shelah

We prove that club does not imply the existence of a Suslin tree, so answering a question of I. Juhasz.

Nikita Sidorov, Anatoly Vershik

We define a two-sided analog of Erdös measure on the space of two-sided expansions with respect to the powers of the golden ratio, or, equivalently, the Erdös measure on the 2-torus. We construct the transformation (goldenshift) preserving both Erdös and Lebesgue measures on $\Bbb T^2$ which is the induced automorphism with respect to the ordinary shift (or

Billy D. Jones, Robert J. Perry

Light-front Hamiltonian methods are being developed to attack bound-state problems in QCD. In this paper we advance the state of the art for these methods by computing the well-known Lamb shift in hydrogen starting from first principles of QED. There are obvious but significant qualitative differences between QED and QCD. In this paper, we discuss the simila

Carlos Castro

The exact quantum integrability aspects of a sector of the membrane is investigated. It is found that spherical membranes ( in the lightcone gauge) moving in flat target spacetime backgrounds admit a class of integrable solutions linked to $SU(\infty)$ SDYM equations ( dimensionally reduced to one temporal dimension) which, in turn, are related to Plebanski

H. Falomir

Functional determinants for Dirac operators on manifolds with boundary are considered. Ellipticity of boundary value problems is discussed in terms of the Calderon projector. The functional determinant for a Dirac operator on a bidimensional disk, in the presence of an Abelian gauge field, subject to global boundary conditions of the type introduced by Atiya

S. Moretti, K. Odagiri

In this paper we compare $H^+H^-$ and $W^+W^-$ into four-fermion production at centre-of-mass energies typical of LEP2 and somewhat larger. The theoretical framework considered is the Minimal Supersymmetric Standard Model. The interest in exploiting the $e^+e^-$ CERN collider at values of $\sqrt s$ greater than 192 GeV could come from the discovery of Supers

I. Halperin, M. Lublinsky

The inclusive nonleptonic transition rate of B meson in gluonic penguin channel is calculated in QCD using the heavy quark mass expansion. We found the branching ratio to be approximately 0.25%.

Ilia Gogoladze

We investigate the SU(N) supersymmetric Grand Unified Theories with ``custodial symmetry&#39;&#39; mechanism to explane the doublet-triplet hierarchy. We show that in such type of SU(7) SUSY theory intermediate scale appears naturally and the correct value for sin^2(θ)_W is predicted via vector-like matter superfields splitting. The unification appears to be

D. Bodeker, P. John, M. Laine, M. G. Schmidt

We calculate the finite temperature 2-loop effective potential in the MSSM with stop condensation, using a 3-dimensional effective theory. We find that in a part of the parameter space, a two-stage electroweak phase transition appears possible. The first stage would be the formation of a stop condensate, and the second stage is the transition to the standard

Jonathan Bagger, Uriel Nauenberg, Xerxes Tata, Andrew White

We summarize the results obtained by the Supersymmetry Working Group at the 1996 Snowmass Workshop.

B. Jegerlehner

We investigate the application of Krylov space methods to the solution of shifted linear systems of the form (A+σ) x - b = 0 for several values of σsimultaneously, using only as many matrix-vector operations as the solution of a single system requires. We find a suitable description of the problem, allowing us to understand known algorithms in a common frame

B. Jegerlehner

We report on several improvements of the local bosonic algorithm proposed by M. Luescher. We find that preconditioning and over-relaxation works very well. A detailed comparison between the bosonic and the Kramers-algorithms shows comparable performance for the physical situation examined.

I. M. Barbour, S. E. Morrison, John B. Kogut

We present a method of simulating lattice QCD at nonzero chemical potential in the chiral limit. By adding a weak four-fermi interaction to the standard staggered fermion SU(3) QCD action, we produce an algorithm in which the limit of massless fermions is well-behaved and physical. Using configurations at zero chemical potential, and an exact fugacity expans

L. A. Hamel, L. Lessard, L. Rainville, B. Sur

We discuss the operation principle of a detector based on superheated droplets of Freon-12 and its feasibility for the search of weakly interacting cold dark matter particles. In particular we are interested in a neutralino search experiment in the mass range from 10 to 10^4 GeV/c^2 and with a sensitivity of better than 10^-2 events/kg/d. We show that our ne

J. M. Pons, D. C. Salisbury, L. C. Shepley

We study spacetime diffeomorphisms in Hamiltonian and Lagrangian formalisms of generally covariant systems. We show that the gauge group for such a system is characterized by having generators which are projectable under the Legendre map. The gauge group is found to be much larger than the original group of spacetime diffeomorphisms, since its generators mus

Arvind Borde, Alexander Vilenkin

We review here some recent results that show that inflationary cosmological models must contain initial singularities. We also present a new singularity theorem. The question of the initial singularity re-emerges in inflationary cosmology because inflation is known to be generically future-eternal. It is natural to ask, therefore, if inflationary models can

Jorge Berger, Jacob Rubinstein

We study the Little-Parks effect for mesoscopic loops with very nonuniform thickness. The results follow the trend of the phase diagram obtained for almost uniform thickness. In particular, the singly-connected state is stable on a line segment delimited by two critical points. Most of this study considers loops with piecewise constant thickness; in this cas

J. W. Wadsley, J. Richard Bond

Our understanding of the Lyman-$α$ forest has received a great boost with the advent of the Keck Telescope and large 3D hydrodynamical simulations. We present new simulations using the SPH technique with a P^3MG (Particle-Particle Particle-MultiGrid) non-periodic gravity solver. Our method employs a high resolution (1 kpc) inner volume, essential for capturi

F. K. Sutaria, J. A. Sheikh, A. Ray

We use the Relativistic Mean Field (RMF) method to calculate properties of neutron rich, usually deformed nuclei, important for equation of state calculations and which have significant abundance in the early stages of stellar collapse. We compare the results of our microscopic calculations with existing cold nuclear equations of state based on macroscopic l

Colin Denniston, Chao Tang

We study and compare the critical properties of the two-dimensional (2D) XY model in a transverse magnetic field with magnetic filling factors f=1/3 and f=2/5. In addition to the spin waves, the low energy excitations of the system consist of various domain walls between degenerate ground states. The lowest energy domain wall has a similar structure for both

V. M. Alekseyev, S. N. Cherepnya, L. V. Fil&#39;kov, V. L. Kashevarov

The possibility of obsevation of supernarrow dibaryons with symmetric wave function in reactions $γ+d to π^+ +γ+nn$ and $γ+d to π^- +γ+pp$ is studied. These dibaryons satisfy the condition $(-1)^{T+S}P=+1$ (where T is the isospin, S is the internal spin and P is the dibaryon parity) and their decay into two nucleons is suppressed by the Pauly principle. In t

A. R. Rastegar, M. R. Rahimi Tabar, P. Hawaii

We investigate the exact results of the Navier-Stokes equations using the methods developed by Polyakov. It is shown that when the velocity field and the density are not independent, the Burgers equation is obtained leading to exact N-point generating functions of velocity field. Our results show that, the operator product expansion has to be generalized bot

N. Nakagawa, T. S. Komatsu

We discovered numerically a scaling law obeyed by the amplitude of collective mo tion in large populations of chaotic elements. Our analysis strongly suggests that such populations generically exhibit collective motion in the presence of interaction, however weak it may be. A phase diagram for the collective motion, which is characterized by peculiar structu

L. Turban, F. Igloi

Off-diagonal profiles of local densities (e.g. order parameter or energy density) are calculated at the bulk critical point, by conformal methods, for different types of boundary conditions (free, fixed and mixed). Such profiles, which are defined by a non-vanishing matrix element of the appropriate operator between the ground state and the corresponding low

F. Bonechi, R. Giachetti, R. Maciocco, E. Sorace

In this report we give an intrinsic treatment of the results we developed in a previous work connecting the differential calculi on Hopf algebras to the Drinfeld double. In the first place we recover that bicovariant bimodules are in one to one correspondence with the Drinfeld double representations; we then introduce a Hochschild cohomology of the algebra o

F. Simkovic, J. Schwieger, M. Veselsky, G. Pantis

Using the renormalized quasiparticle random phase approximation (RQRPA), we calculate the light neutrino mass mediated mode of neutrinoless double beta decay of Ge76, Mo100, Te128 and Te130. Our results indicate that the simple quasiboson approximation is not good enough to study the neutrinoless double beta decay, because its solutions collapse for physical

G. Pantis, F. Simkovic, J. D. Vergados, Amand Faessler

We have investigated the role of proton-neutron pairing in the context of the Quasiparticle Random Phase approximation formalism. This way the neutrinoless double beta decay matrix elements of the experimentally interesting A= 48, 76, 82, 96, 100, 116, 128, 130 and 136 systems have been calculated. We have found that the inclusion of proton-neutron pairing i

M. A. Walton

The Demazure character formula is applied to the Verlinde formula for affine fusion rules. We follow Littelmann&#39;s derivation of a generalized Littlewood-Richardson rule from Demazure characters. A combinatorial rule for affine fusions does not result, however. Only a modified version of the Littlewood-Richardson rule is obtained that computes an (old) up

M. Reuter

Liouville field theory is quantized by means of a Wilsonian effective action and its associated exact renormalization group equation. For $c<1$, an approximate solution of this equation is obtained by truncating the space of all action functionals. The Ward identities resulting from the Weyl invariance of the theory are used in order to select a specific uni

Martin Cederwall

A couple of issues concerning the effective dynamics of D-branes in string theory are discussed. Primarily, I am concerned with linearization of the actions by introduction of non-propagating fields and a full super- and kappa-symmetric description of D-branes.

A. Djouadi, P. Gambino, S. Heinemeyer, W. Hollik

We calculate the two-loop QCD correction to the scalar quark contributions to the electroweak gauge-boson self-energies at zero momentum-transfer in the supersymmetric extension of the Standard Model. We then derive the $O(α_s)$ correction to the contribution of the scalar top and bottom quark loops to the rho parameter, which is the most sizable supersymmet

A. Djouadi, V. Driesen, W. Hollik, J. I. Illana

We analyze the contribution of the SUSY particles to the coupling of the lightest Higgs boson to two photons in supersymmetric theories. We discuss to what extent these contributions can be large enough to allow for a discrimination between the lightest SUSY and the standard Higgs particles in the decoupling limit where all other Higgs bosons are very heavy

Abdelhak Djouadi

I briefly review the Higgs sector in the Standard Model and in its minimal supersymmetric extension. After summarizing the properties of the Higgs bosons, I will discuss the prospects for discovering these particles at the present colliders LEP2 and Tevatron, and at the next generation colliders LHC and a high--energy $e^+e^-$ linear collider. The possibilit

A. Ukawa

Recent developments in finite-temperature studies of lattice QCD are reviewed. Topics include (i) tests of improved actions for the pure gauge system, (ii) scaling study of the two-flavor chiral transition and restoration of $U_A(1)$ symmetry with the Kogut-Susskind quark action, (iii) present understanding of the finite-temperature phase structure for the W

S. Aoki, T. Kaneda, A. Ukawa, T. Umemura

We present further analyses of the finite-temperature phase structure of lattice QCD with the Wilson quark action based on spontaneous breakdown of parity-flavor symmetry. Results are reported on (i) an explicit demonstration of spontaneous breakdown of parity-flavor symmetry beyond the critical line, (ii) phase structure and order of chiral transition for t

J. Piekarewicz, J. R. Shepard

We employ a plaquette basis-generated by coupling the four spins in a $2\times2$ lattice to a well-defined total angular momentum-for the study of Heisenberg ladders with antiferromagnetic coupling. Matrix elements of the Hamiltonian in this basis are evaluated using standard techniques in angular-momentum (Racah) algebra. We show by exact diagonalization of

I. L. Aleiner, L. I. Glazman

We study the Coulomb blockade in a chaotic cavity connected to a lead by a perfectly transmitting quantum channel. In contrast to the previous theories, we show that the quantum fluctuations of charge, resulting from the perfect transmission, do not destroy the Coulomb blockade completely. The oscillatory dependence of all the observable characteristics on t

C. Micheletti, A. B. Harris, J. M. Yeomans

We consider the neutral, one-dimensional Falicov-Kimball model at zero temperature in the limit of a large electron--ion attractive potential, U. By calculating the general n-ion interaction terms to leading order in 1/U we argue that the ground-state of the model exhibits the behavior of a complete devil&#39;s staircase.

T. Aste, K. Y. Szeto, W. Y. Tam

We investigate the statistical properties of two dimensional random cellular systems (froths) in term of their shell structure. The froth is analyzed as a system of concentric layers of cells around a given central cell. We derive exact analytical relations for the topological properties of the sets of cells belonging to these layers. Experimental observatio

Uwe Gunsenheimer, A. D. Zaikin

Nonequilibrium effects and their impact on a charge transport in superconducting ballistic weak links biased by an ac voltage are investigated within the framework of the Keldysh technique. We demonstrate that the microwave field destroys the phase coherence during the multiple Andreev reflection cycle and leads to the effective cooling of subgap quasipartic

Hiroshi Takano, Masaru Onoda, Ikuo Ichinose, Tetsuo Matsui

We study a dissipative gauge theory of nonrelativistic fermions in 2+1 dimensions at zero temperature by the Wilsonian renormalization-group method. In this theory, we incorporate in the fermion propagator a new term of the form $ i κ\cdot\sign(ω)$ (where $κ$ is a parameter and $ω$ is the fermion frequency), which is usually induced by impurity effects. In t

P. A. Crowell, F. W. Van Keuls, J. D. Reppy

We have studied 4He films adsorbed in two porous glasses, aerogel and Vycor, using high precision torsional oscillator and DC calorimetry techniques. Our investigation focused on the onset of superfluidity at low temperatures as the 4He coverage is increased. Torsional oscillator measurements of the 4He-aerogel system were used to determine the superfluid de

M. B. Isichenko

The evolution of an initial perturbation in Vlasov plasma is studied in the intrinsically nonlinear long-time limit dominated by the effects of particle trapping. After the possible transient linear exponential Landau damping, the evolution enters into a universal regime with an algebraically damped electric field, $E\propto1/t$. The trick used for the Vlaso

Andrew Gould, Jordi Miralda-Escude

We propose that relative variability on short time-scales of the multiple images of a lensed quasar, after removal of the time delay, may be caused by hot spots or other moving structures in the accretion disk crossing microlens caustics caused by stellar mass objects in the lensing galaxy. Such variability has been reported in the two images of 0957+561. Th

Marek Kutschera

The equation of state of hadronic matter in neutron stars is briefly reviewed. Uncertainties regarding the stiffness and composition of hadronic matter are discussed. Importance of poorly known short range interactions of nucleons and hyperons is emphasized. Condensation of meson fields and the role of subhadronic degrees of freedom is considered. Empirical

Michael P Reisenberger, Carlo Rovelli

We derive a spacetime formulation of quantum general relativity from (hamiltonian) loop quantum gravity. In particular, we study the quantum propagator that evolves the 3-geometry in proper time. We show that the perturbation expansion of this operator is finite and computable order by order. By giving a graphical representation a&#39; la Feynman of this exp

M. A. Nowak, R. V. Wagoner, M. C. Begelman, D. E. Lehr

The Rossi X-ray Timing Explorer (RXTE) has made feasible for the first time the search for high-frequency (~ 100 Hz) periodic features in black hole candidate (BHC) systems. Such a feature, with a 67 Hz frequency, recently has been discovered in the BHC GRS 1915+105 (Morgan, Remillard, & Greiner). This feature is weak (rms variability ~0.3%-1.6%), stable in

Masayasu Harada, Akihiro Shibata

We study the temperature dependence of the pion decay constant and rho-meson mass in the hidden local symmetry model at one loop. Using the standard imaginary time formalism, we include the thermal effect of rho meson as well as that of pion. We show that the pion gives a dominant contribution to the pion decay constant and rho-meson contribution slightly de

Tom Banks, Nathan Seiberg, Stephen Shenker

Various aspects of branes in the recently proposed matrix model for M theory are discussed. A careful analysis of the supersymmetry algebra of the matrix model uncovers some central charges which can be activated only in the large $N$ limit. We identify the states with non-zero charges as branes of different dimensions.

Daniel Duffy, Adriana Moreo

Quantum Monte Carlo results for the specific heat c of the two dimensional Hubbard model are presented. At half-filling it was observed that $c \sim T^2$ at very low temperatures. Two distinct features were also identified: a low temperature peak related to the spin degrees of freedom and a higher temperature broad peak related to the charge degrees of freed

Luis M. A. Bettencourt, Pablo Laguna, Richard A. Matzner

We perform the numerical field evolution for the collision of two Abelian type I cosmic strings. We present evidence that, for collisions at small but characteristic relative velocities and angles, these cosmic strings do not exchange ends and separate. Rather, local higher winding number bound states are formed close to the collision point, which promote mu

Jochen Rau

We show that dissipative transport and renormalization can be described in a single theoretical framework. The appropriate mathematical tool is the Nakajima-Zwanzig projection technique. We illustrate our result in the case of interacting quantum gases, where we use the Nakajima-Zwanzig approach to investigate the renormalization group flow of the effective

Riccardo Guida, Nicodemo Magnoli

The most relevant thermal perturbation of the continuous d=2 minimal conformal theory with c=7/10 (Tricritical Ising Model) is treated here. This model describes the scaling region of the phi^6 universality class near the tricritical point. The problematic IR divergences of the naive perturbative expansion around conformal theories are dealt within the OPE a

J. Nassalski

New experimental results on the spin dependent structure functions g_1 and g_2 which are determined from deep-inelastic scattering experiments at CERN, SLAC and DESY are reported. These results are used to evaluate the Bjorken sum rule and the singlet axial charge a_0. Results are discussed in the framework of next-to-leading order perturbative QCD. The role

Juergen Tolksdorf

In this article we show in some detail how the full action functional of the standard model of elementary particle physics can be described within the geometrical setting of generalized Dirac operators. We thereby introduce a new model building kit for (a certain class of) gauge invariant theories which provides a unified geometrical description of Einstein&

Gary T. Horowitz, Joseph Polchinski

For most black holes in string theory, the Schwarzschild radius in string units decreases as the string coupling is reduced. We formulate a correspondence principle, which states that (i) when the size of the horizon drops below the size of a string, the typical black hole state becomes a typical state of strings and D-branes with the same charges, and (ii)

A. V. Smilga

We give a review of modern theoretical understanding of the physics of QCD at finite temperature. Three temperature regions are studied in details: the low temperature region where the system presents a rarefied pion gas and its properties are described by chiral perturbation theory, the high temperature region where the system is adequately described in ter

A. Kuniba, K. C. Misra, M. Okado, T. Takagi

We review the path realization of Demazure crystals and discuss Demazure characters in the light of symmetric functions.

Nimai C. Mukhopadhyay, K. Junker

We utilize precise weak interaction experiments on atomic muon capture and beta decay in the A = 3 nuclei, and take into account the effects of nuclear &#34;anomalous thresholds&#34; to extract the pseudoscalar pi-^3He-^3H coupling parameter, G^{eff}(m_π^2) = 45.8+- 2.4. This is an order of magnitude improvement in precision over that from the use of pion-nu

Jorge G. Hirsch, Peter O. Hess, Osvaldo Civitarese

An exactly solvable model suitable for the description of single and double-beta decay processes of the Fermi-type is introduced. The model is equivalent to the exact shell-model treatment of protons and neutrons in a single j-shell. Exact eigenvalues and eigenvectors are compared to those corresponding to the hamiltonian in the quasiparticle basis (qp) and

Sourav Sarkar, Pradip Roy, Jane Alam, Sibaji Raha

The effects of dissipation on the space time evolution of matter formed in ultra-relativistic heavy ion collision is discussed. The thermal photon spectra for RHIC and LHC energies with viscous flow is considered. The effects of viscosity in the thermal single photon spectra is seen to be important in QGP phase as compared to the hadronic phase. Recently ava

by D. H. Lu, A. W. Thomas, A. G. Williams

We study the γ^* N -> Δtransition amplitudes in a recoil corrected cloudy bag model approach. A modified Peierls-Thouless projection method is used to construct the Galilean invariant baryon states. The pionic contribution is found to be significant. The effect of the recoil correction is to reduce the magnitude of the transition amplitudes at small momentum

Steven G. Krantz, Song-Ying Li

We construct a special plurisubharmonic defining function for a smoothly bounded strictly pseudoconvex domain so that the determinant of the complex Hessian vanishes to high order on the boundary. This construction, coupled with regularity of solutions of complex Monge-Ampere equation and the reflection principle, enables us to give a new proof of the Feffer

A. A. Andrianov, R. Soldati

We study the renormalizable abelian vector-field models in the presence of the Wess-Zumino interaction with the pseudoscalar matter. The renormalizability is achieved by supplementing the standard kinetic term of vector fields with higher derivatives. The appearance of fourth power of momentum in the vector-field propagator leads to the super-renormalizable

Franco Ferrari

In this paper the Maxwell field theory is considered on the $Z_n$ symmetric algebraic curves. As a first result, a large family of nondegenerate metrics is derived for general curves. This allows to treat many differential equations arising in quantum mechanics and field theory on Riemann surfaces as differential equations on the complex sphere. The examples

Matej Pavsic

The theory of the usual, constrained p-branes is embedded into a larger theory in which there is no constraints. In the latter theory the Fock-Schwinger proper time formalism is extended from point-particles to p-branes which can be considered as a points in an infinite dimensional space M. The quantization appears to be straightforward and elegant. The conv

E. Corrigan, Z-M Sheng

The classical integrability the O(N) nonlinear sigma model on a half-line is examined, and the existence of an infinity of conserved charges in involution is established for the free boundary condition. For the case N=3 other possible boundary conditions are considered briefly.

Mitsuhiro Kato, Tomoharu Okada

Possible Dirichlet boundary states for WZW models with untwisted affine super Kac-Moody symmetry are classified for all compact simple Lie groups. They are obtained by inner- and outer-automorphism of the group. D-brane world-volume turns out to be a group manifold of a symmetric subgroup, so that the moduli space of D-brane is a irreducible Riemannian symme

Phillial Oh

We discuss the recent developments in the generalized continuous Heisenberg ferromagnet model formulated as a nonrelativistic field theory defined on the target space of the coadjoint orbits. Hermitian symmetric spaces are special because they provide completely integrable field theories in 1+1 dimension and self-dual Chern-Simons solitons and vortices in 2+

Frederick T. Hawes, Tom Sizer, Anthony G. Williams

We study renormalized quenched strong-coupling QED in four dimensions in arbitrary covariant gauge, in the Dyson-Schwinger equation formalism. Above the chiral critical coupling, we show that there is no finite chiral limit. This behaviour is found to be independent of the detailed choice of proper vertex, provided that the vertex is consistent with the Ward

Amand Faessler, Sergey Kovalenko, Fedor Simkovic, Joerg Schwieger

We present a new contribution of the R-parity violating supersymmetry (SUSY) to neutrinoless double beta decay via the pion exchange between decaying neutrons. The pion coupling to the final state electrons is induced by the R-parity violating SUSY interactions. We have found this pion-exchange mechanism to dominate over the conventional two-nucleon one. The

Jon Pumplin

The two gluon exchange model of the pomeron is used to compute the photoproduction reaction $γp \to Z^0 p$. The predicted cross section is too small to be observed at HERA, but may be detectable at an eventual Next Linear Collider.

Glennys R. Farrar

The tree-level-massless gaugino scenario predicts that the lighter chargino mass is less than m_W and that gluino and lightest neutralino masses are $\lsi 1$ GeV. In this case the dominant decay mode of charginos and non-LSP neutralinos is generically to three jets. The excess of &#34;4j&#34; events with total invariant mass $\sim 105$ GeV observed in LEP ru

Glennys R. Farrar

The gluonic widths of four leading glueball candidates are determined from their production in radiative quarkonium decays, allowing quantitative estimation of their glue content. Lattice predictions for the scalar and tensor channels seem to be in reasonable agareement with present data (allowing for mixing with $q \bar{q}$ states). However there is a glueb

P. Nason, B. R. Webber

We estimate the non-perturbative power-suppressed corrections to heavy flavour fragmentation and correlation functions in e^+e^- annihilation, using a model based on the analysis of one-loop Feynman graphs containing a massive gluon. This approach corresponds to the study of infrared renormalons in the large-n_f limit of QCD, or to the assumption of an infra

Valery A. Khoze, W. J. Stirling

Significant colour interference effects are expected in V(=gamma,W,Z)+jet production at hadron colliders. These directly influence the hadronic antenna patterns and can provide a valuable diagnostic tool for probing the nature of the underlying parton subprocesses. Motivated by these ideas, we present quantitative predictions for the distributions of soft pa

N. G. Uraltsev

I review the status of the modern theoretical approach to weak decays of heavy flavor hadrons based on the 1/m_Q expansion in QCD. The qualitative features are explained and the subtleties in simultaneously incorporating perturbative and power-suppressed effects are addressed. A few topical phenomenological applications are discussed in quantitative detail.

Michael Melles

In this thesis exact results on O(alpha^2) single bremsstrahlung corrections to low angle Bhabha scattering at LEP/SLC energies are given. The calculation represents the last outstanding theoretical second order subleading electroweak contribution for that process, needed to determine the experimental luminosity at second generation LEP detectors below the 0

Giovanni Landi, Carlo Rovelli

The eigenvalues of the Dirac operator on a curved spacetime are diffeomorphism-invariant functions of the geometry. They form an infinite set of ``observables&#39;&#39; for general relativity. Recent work of Chamseddine and Connes suggests that they can be taken as variables for an invariant description of the gravitational field&#39;s dynamics. We compute t

O. V. Dolgov, H. J. Kaufmann, E. K. H. Salje, Y. Yagil

The normal state optical response of La_{2-x}Sr_xCuO_4 is found to be consistent with a simple multi-component model, based on free carriers with strong electron-phonon interaction, localized polaronic states near 0.15 eV and a mid-infrared band at 0.5 eV. Normal state reflectance and absorbance of La_{1.83}Sr_{0.17}CuO_4 are investigated and their temperatu

M. Auslender

Long-time asymptotic of field-field correlator for radiation propagated through a medium composed of random point-like scatterers is studied using Bete-Salpeter equation. It is shown that for plane source the fluctuation intensity (zero spatial moment of the correlator) obeys a power-logarithmic stretched exponential decay law, the exponent and preexponent b

Dmitri B. Chklovskii, Bertrand I. Halperin

We consider the possibility of creating an adiabatic transition through a narrow neck, or point contact, between two different quantized Hall states that have the same number of edge modes, such as ν=1 and ν=1/3. We apply both the composite fermion and the Luttinger liquid formalism to analyze the transition. We suggest that using such adiabatic junctions on

Juan Garcia-Bellido, Andrei Linde

We propose a new version of the hybrid inflation scenario that produces a significantly tilted n>1 spectrum of curvature perturbations. This may happen in supersymmetric models where the inflaton field acquires a mass proportional to the Hubble constant, and in the models where this field non-minimally couples to gravity. A large tilt of the spectrum in this

William H. Waller, Theodore P. Stecher, Ultraviolet Imaging Telescope Science Team

When viewed from above the Earth&#39;s atmosphere, the nighttime ultraviolet sky background is profoundly dark - up to 100 times fainter than the equivalent visible background as measured by groundbased telescopes. Because the UV background is so faint, its measured strength and spatial distribution remain controversial topics. Estimates range from a few hun

F. Palla, D. Galli

We consider the problem of the apparent lack of old T Tauri stars in low-mass star forming regions in the framework of the standard model of low-mass star formation. We argue that the similarity between molecular cloud lifetime and ambipolar diffusion timescale implies that star formation does not take place instantaneously, nor at a constant rate. We conclu

Edward W. Kolb

In this lecture I will review some recent progress in improving the accuracy of the calculation of density perturbations resulting from inflation.

J. H. Knapen

New high resolution, high sensitivity WSRT HI synthesis observations of the spiral galaxy NGC 3631 are presented. In the total atomic hydrogen map, the spiral arms are well distinguished from the interarm regions, while the sensitivity allows detection of HI in all but a few isolated regions of the areas between the spiral arms. Most of the atomic hydrogen i

A. Cappi, L. Ciotti, B. Lanzoni, C. Maraston

In the first contribution the basic problems posed by the existence of the Fundamental Plane (FP), and its relations with the Virial Theorem are discussed. Various possibilities are presented that can produce the observed uniform departure from homology and/or from a constant stellar mass-to-light ratio. The role of orbital anisotropy and its relation with t

Graham R. Vincent, Mark Hindmarsh, Mairi Sakellariadou

We examine the scaling properties of an evolving network of strings in Minkowski spacetime and study the evolution of length scales in terms of a 3-scale model proposed by Austin, Copeland and Kibble (ACK). We find good qualitative and some quantitative agreement between the model and our simulations. We also investigate small-scale structure by altering the

A. Fuente, J. Martin-Pintado

We have detected CO+ toward the photon-dominated region (PDR) associated with the reflection nebula NGC 7023. This is the first detection of CO+ in the vicinity of a Be star. A CO+ column density of ~ 3E11 cm-2 has been derived toward the PDR peak. We have, however, not detected CO+ in a well shielded clump of the adjacent molecular cloud, where the CO+/HCO+

Brad K. Gibson, Jeremy R. Mould

Halo initial mass functions (IMFs), heavily-biased toward white dwarf (WD) precursors (i.e. 1->8 M_sun), have been suggested as a suitable mechanism for explaining microlensing statistics along the line of sight to the LMC. Such IMFs can apparently be invoked without violating the observed present-day WD luminosity function. By employing a simple chemical ev

Brad K. Gibson, Francesca Matteucci

Recent observational evidence for steep dwarf galaxy luminosity functions in several rich clusters has led to speculation that their precursors may be the source of the majority of gas and metals inferred from intracluster medium (ICM) x-ray observations. Their deposition into the ICM is presumed to occur through early supernovae-driven winds, the resultant

Brad K. Gibson, Francesca Matteucci

The enrichment of the intracluster medium (ICM) of galaxy clusters, within the framework of the supernovae-driven wind model for elliptical galaxies, has been considered under two extreme assumptions regarding the binding energy-mass-radius relations. Unless the binding energy at the time of wind commencement, for a given galactic mass, was a factor of appro