September 1996 arXiv papers — page 3

M. Botje, M. Klein, C. Pascaud

The results are presented of a study of the accuracy one may achieve at HERA in measuring the strong coupling constant $α_s$ and the gluon distribution $xg(x,Q^{2})$ using future data of the structure function $F_{2}(x,Q^{2})$ which are estimated to be accurate at the few % level over the full accessible kinematic region down to $x \simeq 10^{-5}$ and up to

S. Dittmaier, D. Schildknecht

The most reliable prediction for the Higgs-boson mass, M_H, is obtained in a fit to the leptonic Z-resonance observables Gamma_l and swbar^2 combined with the W-boson mass, M_W, and top-quark mass, m_t, measurements. The corresponding bounds on M_H are independent of potential uncertainties related to R_b, R_c, and alpha_s(M_Z^2), and they are not significan

Frank Cuypers, Sacha Davidson

We define bileptons to be bosons coupling to a pair of leptons and construct the most general dimension four lagrangian involving scalar and vector bileptons. We concentrate on fields with lepton number 2, and derive model independent bounds on their masses and couplings from low-energy data. In addition, we study their signals in high energy experiments and

Tatsuo Kobayashi, Zhi-zhong Xing

We propose a simple but realistic pattern of quark mass matrices at the string scale, which can be derived from orbifold models of superstring theory with no use of gauge symmetries. This pattern is left-right symmetric and preserves the structural parallelism between up and down quark sectors. Its phenomenological consequences on flavor mixing and $CP$ viol

A. Mehta, J. Phillips, B. Waugh

The purposes and possibilities of future diffractive structure function measurements at HERA are presented. A review of the current range and accuracy of the measurement of $F_2^{D(3)}(β, x_p, Q^2)$ is presented and an estimate of the precision of future measurements is given. A feasibility study is performed on the measurement of the structure functions $F_

Laurent Lellouch

I present two recent pieces of work on semileptonic $B \to π, ρ$ decays where it is shown how lattice QCD calculations can be used to test heavy-quark symmetry and determine phenomenologically relevant quantities despite the limits on these calculations' kinematical reach. The study of semileptonic $B \to ρ$ decays was performed with the UKQCD Collaborat

Chao-Hsi Chang

With respect to the two theoretical approaches for estimating the hadronic productions of the mesons $B_c$ and $B_c^*$: the full $α_s^4$ calculation and the fragmentation approximation, with a thorough comparative study a quite remarkable conclusion may be drawn. In hadronic collisions the condition for the applicability of the fragmentation approximation is

M. Caselle, R. Fiore, F. Gliozzi, M. Hasenbusch

We test numerically the effective string description of the infrared limit of lattice gauge theories in the confining regime. We consider the 3d Z(2) lattice gauge theory, and we define ratios of Wilson loops such that the predictions of the effective string theory do not contain any adjustable parameters. In this way we are able to obtain a degree of accura

F. Gliozzi

In the dual superconductivity description of quark confinement the core of the flux tube connecting a quark pair belongs to a deconfined, hot phase. This can be checked in numerical experiments on 3D $Z_2$ gauge model. It is also pointed out that the Svetitsky-Yaffe conjecture provides analytic expressions for the distribution of the flux density around quar

Reza Mansouri, Ali Nayeri

Assuming the equivalence of FRW-cosmological models and their Newtonian counterparts, we propose using the Gauss law in arbitrary dimension a general relation between the Newtonian gravitational constant G and the gravitational coupling constant κ.

T. Shirafuji, G. G. L. Nashed, Y. Kobayashi

We study the problem of whether the active gravitational mass of an isolated system is equal to the total energy in the tetrad theory of gravitation. The superpotential is derived using the gravitational Lagrangian which is invariant under parity operation, and applied to an exact spherically symmetric solution. Its associated energy is found equal to the gr

Yadin Y. Goldschmidt

We study the effects of weak columnar and point disorder on the vortex-lattice phase transitions in high temperature superconductors. The combined effect of thermal fluctuations and of quenched disorder is investigated using a simplified cage model. For columnar disorder the problem maps into a quantum particle in a harmonic + random potential. We use the va

Alexander L. Fetter

I review recent theoretical treatments of a dilute interacting condensed Bose gas in a trap. Bogoliubov's classic results for a uniform condensate are generalized to include the effect of a trap, using the Gross-Pitaevskii formalism (for the condensate) and the Bogoliubov equations (for the linearized small-amplitude excitations of the condensate). Sever

George Kastrinakis

Based on a Fermi liquid model, we present several results on the normal state of the optimally doped and overdoped cuprate superconductors. Our main result is an analytic demonstration, backed by self-consistent numerical calculations, of the linear in temperature resistivity and linear in 1/(energy) optical conductivity, provided the interacting Fermi liqui

Johannes Kellendonk

We introduce a notion of equivalence on tilings which is formulated in terms of their local structure. We compare it with the known concept of locally deriving one tiling from another and show that two tilings of finite type are topologically equivalent whenever their associated groupoids are isomorphic.

R. Hlubina, S. Sorella, F. Guinea

Using an improved version of the projection quantum Monte Carlo technique, we study the square-lattice Hubbard model with nearest-neighbor hopping t and next-nearest-neighbor hopping t', by simulation of lattices with up to 20 X 20 sites. For a given R=2t'/t, we consider that filling which leads to a singular density of states of the noninteracting p

Eshel Ben-Jacob, Francisco Guinea, Ziv Hermon, Alexander Shnirman

We propose the existence and study the solitonic excitations in two kinds of samples in the fractional quantum Hall regime. One is a strip modulated by a one-dimensional array of gates. The other is made of two parallel strips coupled by a one-dimensional array of tunnel barriers. We predict the existence of integer charge solitons in the first case, and fra

D. L. Feder, C. Kallin

The Ginzburg-Landau (GL) equations for a d-wave superconductor are derived within the context of two microscopic lattice models used to describe the cuprates: the extended Hubbard model and the Antiferromagnetic-van Hove model. Both models have pairing on nearest-neighbour links, consistent with theories for d-wave superconductivity mediated by spin fluctuat

V. M. Malkin

The problem of intermittency in developed hydrodynamic turbulence is considered. Explicit formulae taking into account effects of finite size of the inertial range are presented for the whole set of intermittency exponents. The formulae fit pretty well experimental data whose apparent discrepancies are attributed to different sizes of the inertial ranges in

V. M. Lipunov, S. B. Popov

In this work we give detail consideration of the possible scenario of evolution of isolated neutron stars and determine some characteristics of X-ray pulsars from their spin period evolution (the paper containes more detailed abstract).

D. Galli, L. Stanghellini, M. Tosi, F. Palla

The discrepancy between the observed abundances of 3He in the ISM and those predicted by stellar and galactic chemical evolution remains largely unexplained. In this paper, we attempt to shed some light on this unsolved problem by presenting a quantitative comparison of the 3He abundances recently measured in six planetary nebulae (PNe) with the correspondin

N. Benitez, E. Martinez-Gonzalez, IFCA

We have studied the distribution of $B_J<20.5$ galaxies from the ROE/NRL COSMOS/UKST catalogue around two samples of $z>0.3$ QSOs with similar redshift distributions. The first sample is formed by 144 radio-loud QSOs from the Parkes Catalogue, and the other contains 167 optically selected QSOs extracted from the Large Bright Quasar Survey. It is found that t

Donald C. Ellison, Matthew G. Baring, Frank C. Jones

We have developed a Monte Carlo technique for self-consistently calculating the hydrodynamic structure of oblique, steady-state shocks, together with the first-order Fermi acceleration process and associated non-thermal particle distributions. This is the first internally consistent treatment of modified shocks that includes cross-field diffusion of particle

Stephen S. Eikenberry, Giovanni G. Fazio

We observed the galactic microquasar GRS1915+105 in the K ($2.2 μ$m) band on October 16 and 17, 1995 UTC using the COB infrared (IR) imager on the Kitt Peak National Observatory 2.1-m telescope with a 0.2-arcsec/pixel plate scale and under good ($\sim 0.7$-arcsec) seeing conditions. Using a neighboring star in the image frames to determine the point spread f

B. Czerny, H. J. Witt, P. T. Zycki

We discuss the optical/UV/Xray spectra of AGN within the frame of the corona model of Witt, Czerny and Zycki (1996). In this model both the disk and the corona accrete and release energy through the viscosity. The relative strength the the disk and the corona is therefore determined by the model. Translated into the spectra, this model allows to predict the

F. Larios, Ehab Malkawi, C. -P. Yuan

A study on effective anomalous interactions up to dimension 5 of the top quark with the electroweak gauge bosons is made in the non-linear Chiral Lagrangian approach. Bounds on the anomalous dimension four terms are obtained from their contribution to low energy data. Also, the potential contribution to the production of top quarks at hadron colliders (the T

Alberto S. Cattaneo

In the context of the Batalin-Vilkovisky formalism, a new observable for the Abelian BF theory is proposed whose vacuum expectation value is related to the Alexander-Conway polynomial. The three-dimensional case is analyzed explicitly, and it is proved to be anomaly free. Moreover, at the second order in perturbation theory, a new formula for the second coef

D. Blaschke, H. -P. Pavel, V. N. Pervushin, G. Röpke

We consider a mechanism to create the $η- η&#39;$ mass difference by the gluon anomaly in a squeezed vacuum. We find that the mass shift of the $η_0$ governing this mass difference is determined by the magnetic part of the gluon condensate. For the squeezed vacuum this magnetic part coincides with the total gluon condensate, so that we get a relation between

Elisabetta Sassaroli

Neutrino flavor oscillations are discussed in terms of two coupled Dirac fields. The interacting Lagrangian is diagonalized to obtain the exact eigenvalues and eigenfunctions. Flavor wave functions are then derived directly from the quantized neutrino fields. Probability density obtained by squaring these wave functions upon taking into account the neutrino

M. Rausch de Traubenberg, M. J. Slupinski

Non-trivial extensions of the three dimensional Poincaré algebra, beyond the supersymmetric one, are explicitly constructed. These algebraic structures are the natural three dimensional generalizations of fractional supersymmetry of order $F$ already considered in one and two dimensions. Representations of these algebras are exhibited, and unitarity is expli

Lapo Casetti, Monica Cerruti-Sola, Marco Pettini, E. G. D. Cohen

The Fermi-Pasta-Ulam $α$-model of harmonic oscillators with cubic anharmonic interactions is studied from a statistical mechanical point of view. Systems of N= 32 to 128 oscillators appear to be large enough to suggest statistical mechanical behavior. A key element has been a comparison of the maximum Lyapounov coefficient $λ_{max}$ of the FPU $α$-model and

E. W. N. Glover, D. J. Miller

We calculate the one-loop QCD corrections for the decay of an off-shell vector boson with vector couplings into two pairs of quarks of equal or unequal flavours keeping all orders in the number of colours. These matrix elements are relevant for the calculation of the next-to-leading order ${\cal O}(α_s^3)$ corrections to four jet production in electron-posit

J. C. Le Guillou, E. Moreno, C. Nunez, F. A. Schaposnik

We discuss non-Abelian bosonization of two and three dimensional fermions using a path-integral framework in which the bosonic action follows from the evaluation of the fermion determinant for the Dirac operator in the presence of a vector field. This naturally leads to the Wess-Zumino-Witten action for massless two-dimensional fermions and to a Chern-Simons

Matias Zaldarriaga, Uros Seljak

Using the formalism of spin-weighted functions we present an all-sky analysis of polarization in the Cosmic Microwave Background (CMB). Linear polarization is a second-rank symmetric and traceless tensor, which can be decomposed on a sphere into spin $\pm 2$ spherical harmonics. These are the analog of the spherical harmonics used in the temperature maps and

Anja Drewitz, Reinhard Leidl, Theodore W. Burkhardt, H. W. Diehl

The surface critical behavior of semi-infinite (a) binary alloys with a continuous order-disorder transition and (b) Ising antiferromagnets in the presence of a magnetic field is considered. In contrast to ferromagnets, the surface universality class of these systems depends on the orientation of the surface with respect to the crystal axes. There is ordinar

P. Anninos, K. Camarda, J. Libson, J. Massó

We have developed a general method for finding apparent horizons in 3D numerical relativity. Instead of solving for the partial differential equation describing the location of the apparent horizons, we expand the closed 2D surfaces in terms of symmetric trace--free tensors and solve for the expansion coefficients using a minimization procedure. Our method i

Guido Haak

We give a new proof of a theorem by M.P. do Carmo and M. Dajczer on helicoidal surfaces of constant mean curvature.

Axel Gross, Michel Bockstedte, Matthias Scheffler

Ab initio molecular dynamics calculations of deuterium desorbing from Si(100) have been performed in order to monitor the energy redistribution among the various D$_2$ and silicon degrees of freedom during the desorption process. The calculations show that a considerable part of the potential energy at the transition state to desorption is transferred to the

P. H. Damgaard, P. E. Haagensen

We analyze the way in which duality constrains the exact beta function and correlation length in single-coupling spin systems. A consistency condition we propose shows very concisely the relation between self-dual points and phase transitions, and implies that the correlation length must be duality invariant. These ideas are then tested on the 2-d Ising mode

Dan Edidin, William Graham

This is a revised and shortened version of our paper &#34;Equivariant intersection theory&#34; (alg-geom/9603008). In particular, the sections on Riemann-Roch and localization are omitted. They will appear in separate papers, at which time alg-geom/9603008 will become obsolete. We have intsead added a section of examples, and have include a calculation of th

Uros Seljak, Matias Zaldarriaga

Using spin-weighted decomposition of polarization in the Cosmic Microwave Background (CMB) we show that a particular combination of Stokes $Q$ and $U$ parameters vanishes for primordial fluctuations generated by scalar modes, but does not for those generated by primordial gravity waves. Because of this gravity wave detection is not limited by cosmic variance

Rainer Dick

We examine consequences of the stabilization of the dilaton through the axion. An estimate of the resulting dilaton potential yields a relation between the axion parameter $m_a f_{PQ}$ and the average instanton radius, and predicts the ratio between the dilaton mass $m_ϕ$ and the axion mass $m_a$. If we identify the string axion with a Peccei--Quinn axion, t

Naoki Enomoto, Masanori Ichioka, Kazushige Machida

The Ginzburg Landau theory for d_{x^2-y^2}-wave superconductors is constructed, by starting from the Gor&#39;kov equation with including correction terms up to the next order of ln(T_c/T). Some of the non-local correction terms are found to break the cylindrical symmetry and lead to the fourfold symmetric core structure, reflecting the internal degree of fre

A. P. Isaev

Some aspects of differential and integral calculi on generalized grassmann (paragrassmann) algebras are considered. The integration over paragrassmann variables is applied to evaluate the partition function for the $Z_{p+1}$ Potts model on a chain. Finite dimensional paragrassmann representations for $GL_{q}(2)$ are constructed.

R. Coutinho, B. Fernandez

We consider a diffusive Coupled Map Lattice (CML) for which the local map is piece-wise affine and has two stable fixed points. By introducing a spatio-temporal coding, we prove the one-to-one correspondence between the set of global orbits and the set of admissible codes. This relationship is applied to the study of the (uniform) fronts&#39; dynamics. It is

J. Adam,, H. Arenhoevel

The intrinsic electromagnetic nuclear meson exchange charge and current operators arising from a separation of the center-of-mass motion are derived for a one-boson-exchange model for the nuclear interaction with scalar, pseudoscalar and vector meson exchange including leading order relativistic terms. Explicit expressions for the meson exchange operators co

M. S. Fayache, Y. Y. Sharon, L. Zamick

We address some properties of the quadrupole-quadrupole ($Q \cdot Q$) interaction in nuclear studies. We first consider how to restore $SU(3)$ symmetry even though we use only coordinate and not momentum terms. Using the Hamiltonian $H=\sum_i (p^2/2m + m/2 ω^2 r_i^2) -χ\sum_{i < j}Q(i) \cdot Q(j) - χ/2 \sum_i Q(i) \cdot Q(i)$ with $Q_μ=r^2 Y_{2,μ}$, we find

Ziwei Lin

Open charm production at the initial and the pre-equilibrium stages in nuclear collisions is studied. The pre-equilibrium contribution to open charm production in $A+A$ collisions at $\sqrt s=200 AGeV$ is shown to be very sensitive to correlations between momenta and space-time coordinates of the minijets produced after the initial collision. A minimal corre

A. Kley, M. Scheffler

The diffusivity of Ga and Al adatoms on the (2x4) reconstructed GaAs(001) surface are evaluated using detailed ab initio total energy calculations of the potential energy surface together with transition state theory. A strong diffusion anisotropy is found, with the direction of fastest diffusion being parallel to the surface As-dimer orientation. In contras

Axel Gross, Matthias Scheffler

The interaction of hydrogen with many transition metal surfaces is characterized by a coexistence of activated with non-activated paths to adsorption with a broad distribution of barrier heights. By performing six-dimensional quantum dynamical and classical molecular dynamics calculations using the same potential energy surface derived from ``ab initio&#39;&

P. Alippi, P. M. Marcus, M. Scheffler

Paths of tetragonal states between two phases of a material, such as bcc and fcc, are called Bain paths. Two simple Bain paths can be defined in terms of special imposed stresses, one of which applies directly to strained epitaxial films. Each path goes far into the range of nonlinear elasticity and reaches a range of structural parameters in which the struc

Alessio Filippetti, Vincenzo Fiorentini

Prediction criteria for surface reconstructions are discussed, with reference to ab initio calculations of the (110)-$1\times 2$ missing-row and (100)-$5\times 1$ quasi-hexagonal reconstructions of Ir and Rh.

J. Neugebauer, C. G. Van de Walle

We have calculated formation energies and position of the defect levels for all native defects and for a variety of donor and acceptor impurities employing first-principles total-energy calculations. An analysis of the numerical results gives direct insight into defect concentrations and impurity solubility with respect to growth parameters (temperature, che

Hans J. Haubold, Arak Mathai Mathai

Nuclear reactions govern major aspects of the chemical evolution of galaxies and stars. Analytic study of the reaction rates and reaction probability integrals is attempted here. Exact expressions for the reaction rates and reaction probability integrals for nuclear reactions in the cases of nonresonant, modified nonresonant, screened nonresonant and resonan

David M. Kaplan, David A. Lowe, Juan M. Maldacena, Andrew Strominger

String theory is used to compute the microscopic entropy for several examples of black holes in compactifications with $N=2$ supersymmetry. Agreement with the Bekenstein-Hawking entropy and the moduli-independent $N=2$ area formula is found in all cases.

Mikhail S. Volkov

The dynamics of small perturbations around sphaleron and black hole solutions in the Einstein-Yang-Mills theory for the gauge group $SU(2)$ is investigated. The perturbations can be split into the two independent sectors in accordance with their parity; each sector contains negative modes. The even-parity negative modes are shown to correspond to the negativ

Mikhail S. Volkov

An exactly solvable sphaleron model in $3+1$ spacetime dimensions is described

Dan Radu Grigore

Trivial second-order Lagrangians are studied and a complete description of the dependence on the second-order derivatives is given. This extends previous work of Olver and others. In particular, this description involves some polynomial expressions called hyper-Jacobians. There exists some linear dependencies between these polynomials which are elucidated fo

Z. Horváth, R. L. Karp, L. Palla

The equivalence of several $SL(3)$ sigma models and their special Abelian duals is investigated in the two loop order of perturbation theory. The investigation is based on extracting and comparing various $β$ functions of the original and dual models. The role of the discrete global symmetries is emphasized.

Walter Dittrich, Holger Gies

In this letter we study (2+1)-dimensional QED. The first part contains the computation of the flavor symmetry-breaking condensate and its relation to the trace of the energy-momentum tensor, while the second part is concerned with the computation of the effective action allowing for non-constant static external magnetic fields. We do not find that space deri

Peter Arnold, Dam Son, Laurence G. Yaffe

The rate per unit volume for anomalous electroweak baryon number violation at high temperatures, in the symmetric phase, has been estimated in the literature to be $O(\alpha_W^4 T^4)$ based on simple scaling arguments. We argue that damping effects in the plasma suppress the rate by an extra power of $\alpha_W$ to give $O(\alpha_W^5 T^4)$. We show how to und

Christopher Kolda, John March-Russell

We consider the low-energy signatures of, and high-energy motivations for, scenarios of semi-perturbative gauge coupling unification. Such scenarios can leave striking imprints on the low-energy sparticle spectrum, including novel gaugino mass ratios (including $M_2/M_1\approx1$), substantial compression of the intra-generational squark-to-slepton mass ratio

M. Suzuki

The new BES measurement on the two-body decays of J/psi and psi&#39; into an axial-vector meson and a pseudoscalar meson is analyzed with the axial-K mixing including the one-photon annihilation contribution. A somewhat puzzling pattern of the K_1^+ K^- decay channels can be understood with no tight constraint on the mixing angle. The branching fractions of

K. Daum, S. Riemersma, B. W. Harris, E. Laenen

We present theoretical and experimental considerations pertaining to deeply inelastic heavy-flavour production at HERA. The various theoretical uncertainties in the cross section calculation are discussed. Cuts are imposed to determine the fraction of charm production accessible to the detectors. The production of charm at asymptotic $Q^2$ and bottom product

Maria Krawczyk

Present data do not rule out a light neutral Higgs particle with mass below 40--50 GeV in the framework of 2HDM with $ tan β\sim $ 20-30. The promising possibility of searching for a light Higgs particle in such a scenario in photoproduction at HERA collider is discussed. For the MSSM there is only a very small chance to observe the Higgs sector, and only fo

Maria Krawczyk

Present data do not rule out the light neutral Higgs particle $h$ or $A$ with mass below 40--50 GeV in the framework of the general 2HDM (&#34;Model II&#34;). The recent limits from LEP I on the parameters of the model, based on the Bjorken process $Z \to Z h$, Higgs pair production $Z \to A h$ and the Yukawa process $Z \to f {\bar f} A$ ($f= b$ quark or $τ$

Roberto Ugoccioni

Results are presented from calculations carried out in the discrete QCD model, concerning multiplicity distributions in rapidity intervals and fluctuations.

Marco Aurelio Diaz

If the lightest chargino is discovered at LEP2, the measurement of its mass and cross section together with the mass of the lightest neutralino, enables the determination of the parameters that define the theory and the entire supersymmetric and Higgs spectrum. Within this context, we: (i) study the effect of the one--loop tadpoles in the minimization condit

D. Cocolicchio, L. Telesca

The phenomenological features of the mixing in the neutral pseudoscalar mesons K0-K0bar can be illustrated in the classical framework of mechanics and by means of electromagnetic coupled circuits. The time-reversed not-invariant processes and the related phenomenon of CP-nonconservation can be induced by dissipative effects which yield a not vanishing imagin

Sean Gavin

Measurements of $ψ$ and $ψ&#39;$ production from experiment NA50 at the CERN SPS are compared to predictions based on a hadronic model of charmonium suppression by Vogt and myself. Data on centrality dependence and total cross sections are in good accord with our predictions. Uncertainties in theoretical quanities such as NA50&#39;s $L$ parameter are discuss

S. Groote, J. G. Körner, O. I. Yakovlev

We derive QCD sum rules for heavy baryons at leading order in $1/m_Q$ and at next-to-leading order in $α_s$. The calculation involves the evaluation of four different perturbative three-loop diagrams which determine the $α_s$-corrections to the Wilson coefficients of the leading term in the Operator Product Expansion (OPE). From the sum rules we obtain estim

E. Maina, R. Pittau, M. Pizzio

QCD one-loop corrections to the semileptonic process $e^+ e^- \to μ^- \bar ν_μu \bar d$ are computed. We compare the exact calculation with a ``naive&#39;&#39; approach to strong radiative corrections which has been widely used in the literature and discuss the phenomenological relevance of QCD contributions for LEP2 and NLC physics.

H. Leutwyler

Lecture Notes, Summer School on Masses of Fundamental Particles, Cargese, 1996. In the first part, some qualitative aspects the mass pattern are discussed, concerning the breaking of isospin and eightfold way symmetries. The second part deals with the chiral perturbation theory results for the masses of the pseudoscalar octet, which lead to very stringent co

H. Leutwyler

The implications of the hidden, spontaneously broken symmetry for the properties of the sound waves of a solid are analyzed. Although the discussion does not go beyond standard wisdom, it presents some of the known results from a different perspective. In particular, I argue that, as a consequence of the hidden symmetry, the equations of motion for a sound w

H. Leutwyler

Lecture Notes, Summer School on Effective Theories and Fundamental Interactions, Erice, 1996. The application of effective field theory methods to the low energy structure of QCD is discussed. I emphasize the universal structure of the corresponding effective Lagrangian and then discuss the physics of the effective coupling constants. The implications of the

Kari Enqvist

The equilibration of the right-helicity states $ν_+$ of light Dirac-neutrinos is discussed. I point out that the $ν_+$ production rate is enhanced by weak gauge boson pole effects so that the right-helicity component of $ν_τ$ is brought into equilibrium at $T\simeq 10$ GeV independently of the initial abundance, provided $m_{ν_τ}\gsim 10$ keV. Neutrino spin

Greg Anderson, Diego Castano, Antonio Riotto

We quantify the extent to which naturalness is lost as experimental lower bounds on the Higgs boson mass increase, and we compute the natural upper bound on the lightest supersymmetric Higgs boson mass. We find that it would be unnatural for the mass of the lightest supersymmetric Higgs boson to saturate it&#39;s maximal upper bound. In the absence of signif

Yoshiharu Kawamura, Tatsuo Kobayashi, Tohru Komatsu

We study flat directions and soft scalar masses using a $Z_3$ orbifold model with $SU(3) \times SU(2) \times U(1)$ gauge group and extra gauge symmetries including an anomalous $U(1)$ symmetry. Soft scalar masses contain $D$-term contributions and particle mixing effects after symmetry breaking and they are parametrized by a few number of parameters. Some sp

Thomas G. Rizzo

The capability of the NLC in the $γe$ collider mode to probe the CP-conserving $γWW$ and $γZZ$ anomalous couplings through the use of the polarization asymmetry is examined. When combined with other measurements, very strong constraints on both varieties of anomalous couplings can be obtained. We show that these bounds are complementary to those that can be

L. A. T. Bauerdick, A. Glazov, M. Klein

A study is presented of a possible future measurement of the longitudinal structure function $F_{L}(x,Q^{2})$ with different proton beam energies at HERA.

D. D. Sarma, S. R. Barman, H. Kajueter, G. Kotliar

We present experimental photoemission and inverse photoemission spectra of SrTiO$_{3- δ}$ representing electron doped $d^0$ systems. Photoemission spectra in presence of electron doping exhibit prominent features arising from electron correlation effects, while the inverse photoemssion spectra are dominated by spectral features explainable within single-part

Herve Castella

A one-dimensional tight-binding Hamiltonian describes the evolution of a single impurity interacting locally with $N$ electrons. The impurity spectral function has a power-law singularity $A(ω)\propto\midω-ω_0\mid^{-1+β}$ with the same exponent $β$ that characterizes the logarithmic decay of the quasiparticle weight $Z$ with the number of electrons $N$, $Z\p

Nikolai Brilliantov, Peter Strizhak

We revealed a right-left asymmetry of the inter-well mean first passage times for the Brownian particles in a ratchet potential under internal white noise. We showed analytically and numerically that this asymmetry gives rise to the following phenomena: (i) nonstationary transport; (ii) localization or ultraslow (Sinai) diffusion for ratchets with a disorder

D. Khomskii, W. Geertsma, M. Mostovoy

The microscopic description of the spin-Peierls transition in pure and doped CuGeO_3 is developed taking into account realistic details of crystal structure. It it shown that the presence of side-groups (here Ge) strongly influences superexchange along Cu-O-Cu path, making it antiferromagnetic. Nearest-neighbour and next-nearest neighbour exchange constants

Boris V. Svistunov

We study the effect of commensurability (integer filling factor) on the superfluid (SF) - Bose-glass (BG) transition in a one-dimensional disordered system in the limit of weak disorder, when the effect is most pronounced and, on the other hand, may be traced via the renormalization-group analysis. The equation for the SF-BG phase boundary demonstrating the

Hualin Shi, Wei-Mou Zheng

The Bose gas in an external potential is studied by means of the local density approximation. An analytical result is derived for the dependence of the critical temperature of Bose-Einstein condensation on the mutual interaction in a generic power-law potential.

Mark Lauer

The goal of this thesis is to advance the exploration of the statistical language learning design space. In pursuit of that goal, the thesis makes two main theoretical contributions: (i) it identifies a new class of designs by specifying an architecture for natural language analysis in which probabilities are given to semantic forms rather than to more super

Holger Schanz, Bernd Esser

The relation between the dynamical properties of a coupled quasiparticle-oscillator system in the mixed quantum-classical and fully quantized descriptions is investigated. The system is considered to serve as a model system for applying a stepwise quantization. Features of the nonlinear dynamics of the mixed description such as the presence of a separatrix s

Romeel Davé, Doug Hellinger, Joel Primack, Richard Nolthenius

A new class of geometric statistics for analyzing galaxy catalogs is presented. Filament statistics quantify filamentarity and planarity in large scale structure in a manner consistent with catalog visualizations. These statistics are based on sequences of spatial links which follow local high-density structures. From these link sequences we compute the disc

Lifan Wang, J. Craig Wheeler, Peter Hoeflich

We present broad-band and spectropolarimetry of the Type Ia SN 1996X obtained on April 14, 1996 (UT), and broad-band polarimetry of SN 1996X on May 22,1996, when the supernova was about a week before and 4 weeks after optical maximum, respectively. The Stokes parameters derived from the broad-band polarimetry are consistent with zero polarization. The spectr

Mark W. Sincell

Motivated by recent reports of strongly correlated radio and X-ray variability in 3C279 (Grandi, etal 1995), we have computed the relative amplitudes of variations in the synchrotron flux at $ν$ and the self-Compton X-ray flux at 1 keV ($R(ν)$) for a homogeneous sphere of relativistic electrons orbiting in a tangled magnetic field. Relative to synchrotron se

T. J. Bridges, K. M. Ashman, S. E. Zepf, D. Carter

We have obtained spectra for globular cluster candidates in M104 with LDSS-2 on the William Herschel Telescope, confirming 34 objects as M104 globular clusters. We find a cluster velocity dispersion of $\sim$ 260 km/sec, and the Projected Mass Estimator gives a mass of 5.0 (3.5,6.7) $\times 10^{11}$ M$_\odot$ for M104 within a projected radius of $\sim 330^{

Z. Loska, B. Czerny

We analyse the data from the optical/IUE observational campaign of the Seyfert galaxy NGC 5548 in the context of 10 phenomenological models. On the basis of the optical/UV data as well as constraints from the X-ray observations we can favour one model of the nucleus: an accretion disc with an inner radius cutoff surrounded by a hot corona. The second accepta

Dan Maoz

I review what we have learned about the BLR from reverberation mapping, point to some problems and complications that have emerged, and outline some future directions.

L. Masperi, S. Savaglio

A numerical calculation of properties of finite absorbers and of intergalactic medium based on photoionization equilibrium is performed to confront alternative UV sources in addition to quasars. It is seen that a spectrum including a large peak around the HI ionization energy due to decaying neutrinos is too soft in the region up to the HeI edge to explain t

Eric L. Sandquist, Michael Bolte, Lars Hernquist

We use smoothed-particle hydrodynamics to examine differences between direct collisions of single stars and binary star mergers in their roles as possible blue straggler star formation mechanisms. We find in all cases that core helium in the progenitor stars is largely retained in the core of the remnant, almost independent of the type of interaction or the

Somnath Bharadwaj

We have considered linear two point correlations of the form $1/{x^γ}$ which are known to have a self-similar behaviour in a $Ω=1$ universe. We investigate under what conditions the non-linear corrections, calculated using the Zel&#39;dovich approximation, have the same self-similar behaviour. We find that the scaling properties of the non-linear corrections

I. A. Taimanov

This paper is a survey on relations between secant identities and soliton equations and applications of soliton equations to problems of algebraic geometry, i.e., the Riemann-Schottky problem and its analogues. A short introduction into the analytic theory of theta functions is also given.

Michael Aizenman

In critical percolation models, in a large cube there will typically be more than one cluster of comparable diameter. In 2D, the probability of $k>>1$ spanning clusters is of the order $e^{-αk^{2}}$. In dimensions d>6, when $η= 0$ the spanning clusters proliferate: for $L\to \infty$ the spanning probability tends to one, and there typically are $ \approx L^{

A. Signer, L. Dixon

We calculate the rate for $e^+e^-$ annihilation into four jets at next-to-leading order in perturbative QCD, but omitting terms that are suppressed by one or more powers of $1/\Nc^2$, where $\Nc$ is the number of colors. The $\cO(α_s^3)$ corrections depend strongly on the jet resolution parameter $\ycut$ and on the clustering and recombination schemes, and t