December 1999 arXiv papers — page 5

T. Kafka

An updated measurement of the atmospheric nu_mu/nu_e ratio-of-ratios, 0.68+-0.11+-0.06, has been obtained using a 4.6-kty exposure of the Soudan-2 iron tracking calorimeter. The L/E distributions have been analyzed for effects of nu_mu -> nu_x oscillations, and an allowed region in the Delta m^2 vs. sin^2 2 theta plane has been determined.

The CLEO Collaboration, S. J. Richichi

In a sample of 19 million produced B mesons, we have observed the decays B -> eta K* and improved our previous measurements of B -> eta'K. The branching fractions we measure for these decay modes are BR(B+ -> eta K*+) = (26.4 +9.6-8.2 +- 3.3) x $10^{-6}$, BR(B0 -> eta K*0) = (13.8 +5.5-4.6 +- 1.6) x $10^{-6}$, BR(B+ -> eta' K+) = (80 +10-9 +- 7) x $1

The SLD Collaboration, Kenji Abe

We have developed a new technique for inclusive reconstruction of the energy of B hadrons. The excellent efficiency and resolution of this technique allow us to make the most precise determination of the b-quark fragmentation function, using e+e- -> Z0 decays recorded in the SLD experiment at SLAC. We compared our measurement with the predictions of a number

Shane L. Larson, William A. Hiscock

Interacting white dwarf binary star systems, including helium cataclysmic variable (HeCV) systems, are expected to be strong sources of gravitational radiation, and should be detectable by proposed space-based laser interferometer gravitational wave observatories such as LISA. Several HeCV star systems are presently known and can be studied optically, which

Dieter Maison

We give arguments for the existence of ``radial excitations'' of gravitational global monopoles with any number of zeros of the Higgs field and present numerical results for solutions with up to two zeros. All these solutions possess a de Sitter like cosmological horizon, outside of which they become singular. In addition we study corresponding stati

Alberto Vecchio

Massive black hole binary systems are among the most interesting sources for the Laser Interferometer Space Antenna (LISA); gravitational radiation emitted during the last year of in-spiral could be detectable with a very large signal-to-noise ratio for sources at cosmological distance. Here we discuss the impact of LISA for astronomy and cosmology; we revie

V. N. Folomeev, V. Ts. Gurovich, I. V. Tokareva

The behaviour of the wave function of the Universe under the barrier for anisotropic cosmological Bianchi type IX model with account of influence of the scalar field is explored. In view of known difficulties with interpretation of multidimensional wave functions the method of reduction of such problems to one-dimensional is offered. For this purpose in fram

Michael Hess

A system is described that uses a mixed-level knowledge representation based on standard Horn Clause Logic to represent (part of) the meaning of natural language documents. A variable-depth search strategy is outlined that distinguishes between the different levels of abstraction in the knowledge representation to locate specific passages in the documents. A

Jin-Dong Kim, Sang-Zoo Lee, Hae-Chang Rim

We present a technique which complements Hidden Markov Models by incorporating some lexicalized states representing syntactically uncommon words. Our approach examines the distribution of transitions, selects the uncommon words, and makes lexicalized states for the words. We performed a part-of-speech tagging experiment on the Brown corpus to evaluate the re

Weiqun Peng, Paul M. Goldbart

Correlators describing the vulcanization transition are constructed and explored via a renormalization group approach. This approach is based on a minimal model that accounts for the thermal motion of constituents and the quenched random constraints imposed on their motion by crosslinks. Critical exponents associated with the correlators are obtained near si

Xiaoyu Xia, Peter G. Wolynes

A microscopically motivated theory of glassy dynamics based on an underlying random first order transition is developed to explain the magnitude of free energy barriers for glassy relaxation. A variety of empirical correlations embodied in the concept of liquid "fragility" are shown to be quantitatively explained by such a model. The near universalit

A. A. Koulakov

We study the exchange correction to the density of states in the three-dimensional metal near the Fermi energy. In the ballistic limit, when the distance to the Fermi level exceeds the inverse transport relaxation time $1/τ$, we find the correction linear in the distance from the Fermi level. By a large parameter $ε_{\rm F} τ$ this ballistic correction excee

Paola Gori-Giorgi, Francesco Sacchetti, Giovanni B. Bachelet

We discuss and clarify a simple and accurate interpolation scheme for the spin-resolved electron static structure factor (and corresponding pair correlation function) of the 3D unpolarized homogeneous electron gas which, along with some analytic properties of the spin-resolved pair-correlation functions, we have just published. We compare our results with th

D. Loison, P. Simon

We consider the 2D $J_1-J_2$ classical XY model on a square lattice. In the frustrated phase corresponding to $J_2>J_1/2$, an Ising like order parameter emerges by an ``order due to disorder'' effect. This leads to a discrete $Z_2$ symmetry plus the U(1) global one. Using a powerful algorithm we show that the system undergoes two transitions at diffe

A. Morello, A. G. M. Jansen, R. S. Gonnelli, S. I. Vedeneev

We have measured the irreversible magnetization of an overdoped Bi$_2$Sr$_2$CuO$_6$ single crystal up to B=28 T and down to T=60 mK, and extracted the irreversibility line $B_{\rm irr}(T)$: the data can be interpreted in the whole temperature range as a 3D-anisotropic vortex lattice melting line with Lindemann number $c_{\rm L}=0.13$. We also briefly discuss

R. S. Gonnelli, V. A. Stepanov, A. Morello, G. A. Ummarino

In this work, we present the results of precise measurements of the resistivity of YNi$_2$B$_2$C single crystals with $T_{\rm c}$ = 15.5 K as a function of the temperature, and analyze the experimental data in the framework of the Bloch-Grüneisen theory and electron-phonon coupling. The transport electron-phonon spectral function that best fits the resistivi

R. S. Gonnelli, V. A. Stepanov, A. Morello, G. A. Ummarino

We have measured the ab-plane resistivity of La$_{2-x}$Sr$_x$CuO$_4$ single crystals with small Sr content (x=0.052 $÷$ 0.075) between 4.2 and 300 K by using the AC Van der Pauw technique. As recently suggested by Ichikawa et al., the deviation from the linearity of the $ρ_{\mathrm{ab}}(T)$ curve starting at a temperature T$_{\mathrm{ch}}$ can be interpreted

G. A. Ummarino, R. S. Gonnelli

In this work, we discuss the results of the direct solution of the Eliashberg equations with finite bandwidth, in the cases of s- and d-wave symmetry for the pair wave function and in the presence of scattering from impurities. We show that the reduction of the critical temperature $T_{\mathrm{c}}$ due to the finite bandwidth depends on the value of the band

G. A. Ummarino, R. S. Gonnelli, D. Daghero

The real-axis direct solution of the Eliashberg equations for the retarded electron-boson interaction in the half-filling case and in the presence of impurities is obtained for six different symmetries of the order parameter: $s$, $s+\mathrm{i}d$, $s+d$, $d$, anisotropic-$s$ and extended-$s$. The spectral function is assumed to contain an isotropic part $α_{

G. M. Minkov, S. A. Negashev, O. E. Rut, A. V. Germanenko

It is shown that a new kind of information can be extracted from the Fourier transform of negative magnetoresistance in 2D semiconductor structures. The procedure proposed provides the information on the area distribution function of closed paths and on the area dependence of the average length of closed paths. Based on this line of attack the method of anal

G. M. Minkov, A. V. Germanenko, V. A. Larionova, S. A. Negashev

Statistics of closed paths in two-dimensional (2D) systems, which just determines the interference quantum correction to conductivity and anomalous magnetoconductance, has been studied by computer simulation of a particle motion over the plane with randomly distributed scatterers. Both ballistic and diffusion regimes have been considered. The results of simu

Werner Fettes, Thomas Husslein, Ingo Morgenstern

The CuO-planes of high-T_c superconductors were found to consist of geometric stripes with alternating superconducting and antiferromagnetic areas. Here we will investigate the repulsive Hubbard model of striped clusters as a possible microscopic description of the superconducting elements. The focus of our attention lies on the superconducting properties. W

C. E. Creffield, J. H. Jefferson, S. Sarkar, D. L. Tipton

The low-energy eigenstates of two interacting electrons in a square quantum dot in a magnetic field are determined by numerical diagonalization. In the strong correlation regime, the low-energy eigenstates show Aharonov-Bohm type oscillations, which decrease in amplitude as the field increases. These oscillations, including the decrease in amplitude, may be

E. Pazy, B. Laikhtman

We treat a tunneling electron coupled to acoustical phonons through a realistic electron phonon interaction: deformation potential and piezoelectric, in two or three-dimensional tunneling configurations. Making use of slowness of the phonon system compared to electron tunneling, and using a Green function method for imaginary time, we are able to calculate t

M. Ebrahim Fouladvand, H. Woo Lee

Within the formalism of martix product ansatz, we study a two-species asymmetric exclusion process with backward and forward site-ordered sequential update. This model describes a two-way traffic flow with a dynamical impurity and shows a phase transition between the free flow and the traffic jam. We investigate characteristics of this jamming and examine si

Boris N. Shalaev

Non-linear d-dimensional vector $σ$-models are studied in the large N-limit. It is found that a two-point correlation function obeys a standard Schrodinger equation for a free quantum particle moving in the $δ$-function quantum well. The threshold problem for bound states in this equation is shown to be equivalent to a critical behavior of these models above

Yigal Meir

Recently, a simple non-interacting-electron model, combining local quantum tunneling via quantum point contacts and global classical percolation, has been introduced in order to describe the observed ``metal-insulator transition'' in two dimensions [1]. Here, based upon that model, a two-species-percolation scaling theory is introduced and compared t

Burkhard Doliwa, Andreas Heuer

We examine the dynamics of hard spheres and discs at high packing fractions in two and three dimensions, modeling the simplest systems exhibiting a glass transition. As it is well known, cooperativity and dynamic heterogeneity arise as central features when approaching the glass transition from the liquid phase, so an understanding of their underlying physic

Y. Kopelevich, P. Esquinazi, J. H. S. Torres, S. Moehlecke

We have identified ferromagnetic- and superconducting-like magnetization hysteresis loops in highly oriented pyrolytic graphite samples below and above room temperature. We also found that both behaviors are very sensitive to low-temperature -- as compared to the sample synthesis temperature -- heat treatment. The possible contribution of magnetic impurities

B. Pannetier, H. Courtois

The Andreev Reflection is the key mechanism for the superconducting proximity effect. It provides phase correlations in a system of non-interacting electrons at mesoscopic scales, i.e. over distances much larger than the microscopic lengths : Fermi wavelength and elastic electron mean free path. This field of research has attracted an increasing interest in

C. W. Chu, Y. Y. Xue, R. L. Meng, J. Cmaidalka

We have systematically investigated the magnetic, electrical, and structural properties of RuSr2GdCu2O8, in which a long-range ferromagnetic order and superconductivity have been previously reported to coexist. Based on the reversible magnetization results, we conclude that the bulk Meissner state does not exist in this compound and that the condensation ene

Matthias Bartelmann, Peter Schneider

We review theory and applications of weak gravitational lensing. After summarising Friedmann-Lemaitre cosmological models, we present the formalism of gravitational lensing and light propagation in arbitrary space-times. We discuss how weak-lensing effects can be measured. The formalism is then applied to reconstructions of galaxy-cluster mass distributions,

A. Loinger

The modern apparatuses for the detection of the gravity waves are devised with the purpose to exploit the geodesic deviation generated by them. But the pseudo energy-momentum of these waves cannot exert any physical action on the apparatuses.

K. Hurley, C. Kouveliotou, T. Cline, D. Cole

We analyze 426 observations of the bursting pulsar GRO J1744-28 by Ulysses and BATSE. Triangulating each burst, and statistically combining the triangulation annuli, we obtain a 3 sigma error ellipse whose area is 532 sq. arcsec. The accuracy of this statistical method has been independently verified with observations of the soft gamma repeater SGR1900+14. T

Jacek Guzik, Uros Seljak, Matias Zaldarriaga

Matter inhomogeneities along the line of sight deflect the cosmic microwave background (CMB) photons originating at the last scattering surface at redshift $z \sim 1100$. These distortions modify the pattern of CMB polarization. We identify specific combinations of Stokes $Q$ and $U$ parameters that correspond to spin 0,$\pm 2$ variables and can be used to r

D. Calzetti, C. A. Tremonti, T. M. Heckman, C. Leitherer

The interplay between the ISM and the massive stars formed in clusters and, more generally, in recent events of star formation is reviewed via the global effects each has on the other. The pre-existing environment affects the properties of the massive stars, the duration of the star-forming event and could potentially affect the IMF. The collective effect of

Peter Messmer, Arnold O. Benz

The minimum and the mean bandwidth of individual narrowband spikes in two events in decimetric radio waves is determined by means of multi-resolution analysis. Spikes of a few tens of millisecond duration occur at decimetric/microwave wavelength in the particle acceleration phase of solar flares. A first method determines the dominant spike bandwidth scale b

Sam Krucker, Arnold O. Benz

Temporary enhancements of the coronal emission measure in a quiet region have been shown to constitute a significant energy input. Here some relatively large events are studied for simultaneous brightenings in transition region lines and in radio emission. Associated emissions are discussed and tested for characteristics known from full-sized impulsive flare

R. Neuhaeuser, W. Brandner, A. Eckart, E. Guenther

We show that {\em ground-based} direct imaging detection of extra-solar planets is possible with current technology. As an example, we present evidence for a possible planetary companion to the young T Tauri star 1RXSJ104230.3$-$334014 (=TWA-7), discovered by ROSAT as a member of the nearby TW Hya association. In an HST NICMOS F160W image, an object is detec

O. V. Verkhodanov, A. I. Kopylov, Yu. N. Parijskij, N. S. Soboleva

The structure of the radio source RC B1146+052 of the ``Cold'' catalogue is investigated by data of the MIT-GB-VLA survey at 4850 MHz. This source belongs to the steep spectrum radio sources subsample of the RC catalogue. Its spectral index is $α$ = -1.04. The optical image of this source obtained with 6m telescope is analysed. The radio source cente

A. P. Jones, L. d'Hendecourt

In this paper we pursue the natural consequences of the structure of nanodiamonds and their surface relaxation and reconstruction to surfaces exhibiting sp2 carbon atoms. We show that in the interstellar radiation field nanodiamonds can be stochastically heated to temperatures as high as 1000 K and give rise to discrete emission bands associated with the sur

David Langlois, Alain Riazuelo

We examine the consequences of the existence of correlated mixtures of adiabatic and isocurvature perturbations on the CMB and large scale structure. In particular, we consider the four types of ``elementary'' totally correlated hybrid initial conditions, where only one of the four matter species (photons, baryons, neutrinos, CDM) deviates from adiab

G. R. Knapp, M. Crosas, K. Young, Z. Ivezic

Atomic carbon has been detected in the envelopes of three carbon-rich evolved stars: HD 44179 (=AFGL 915, the `Red Rectangle'); HD 56126; and, tentatively, the carbon star V Hya. This brings to seven the number of evolved star envelopes in which CI has been detected. Upper limits were found for several other stars, including R CrB. CI was not detected in

I. Negueruela, P. Reig, J. S. Clark

We present low and intermediate resolution spectroscopy of the optical counterpart to the recently discovered pulsating X-ray source 1WGA J1958.2+3232. The presence of strong HI, HeI and HeII emission lines together with the absence of absorption features rules out the possibility that the object is a massive star, as had recently been suggested. The observe

Tapas K. Das, Sandip K. Chakrabarti

We compute mass outflow rates from accretion disks around compact objects, such as neutron stars and black holes. These computations are done using combinations of exact transonic inflow and outflow solutions which may or may not form standing shock waves. Assuming that the bulk of the outflow is from the effective boundary layers of these objects, we find t

I. G. Irastorza, S. Cebrian, E. Garcia, D. Gonzalez

A calculation of the expected signal due to Primakov coherent conversion of solar axions into photons via Bragg scattering in several solid-state detectors is presented and compared with present and future experimental sensitivities. The axion window m_a > 0.03 eV (not accessible at present by other techniques) could be explored in the foreseeable future wit

Cristina C. Popescu, Ulrich Hopp

We present a spectrophotometric catalogue of 90 emission-line galaxies (ELGs) discovered during an objective - prism survey that aimed to search for dwarf galaxies within the voids (Popescu et al. 1996, 1998). The paper presents line ratios, equivalent widths and absolute fluxes for the emission-lines seen in the spectra of the galaxies. A list of newly disc

A. Burkert, Th. Naab

N-body simulations of major spiral-spiral mergers with different mass ratios q <= 4:1 are presented. All mergers lead to spheroidal stellar systems with de Vaucouleurs-like surface density profiles, resembling elliptical galaxies. The internal dynamical structure of the remnants does however depend critically on the adopted mass ratio. Equal-mass mergers wit

M. Feroci, C. L. Bianco, F. Lazzarotto, A. Mattei

The BeppoSAX Gamma Ray Burst Monitor (GRBM) is triggered any time a statistically significant counting excess is simultaneously revealed by at least two of its four independent detectors. Several spurious effects, including highly ionizing particles crossing two detectors, are recorded as onboard triggers. In fact, a large number of false triggers is detecte

M. Feroci, K. Hurley, R. Duncan, C. Thompson

The extraordinary giant flare of 1998 August 27 from SGR 1900+14 was the most intense event ever detected from this or any other cosmic source (even more intense than the famous March 5th 1979 event). It was longer than any previous burst from SGR1900+14 by more than one order of magnitude, and it displayed the same 5.16-s periodicity in hard X-rays that was

Avishay Gal-Yam, Dan Maoz

Supernovae (SNe) play a critical role in the metal enrichment of the intra-cluster medium (ICM) in galaxy clusters. Not only are SNe the main source for metals, but they may also supply the energy to eject enriched gas from galaxies by winds. However, measurements of SN rates in galaxy clusters have not been published to date. We have initiated a program to

D. Georgobiani, A. G. Kosovichev, R. Nigam, A. Nordlund

We use the three-dimensional hydrodynamic code of Stein and Nordlund to realistically simulate the upper layers of the solar convection zone in order to study physical characteristics of solar oscillations. Our first result is that the properties of oscillation modes in the simulation closely match the observed properties. Recent observations from SOHO/MDI a

S. E. Woosley

A variety of arguments suggest that the most common form of gamma-ray bursts (GRBs), those longer than a few seconds, involve the formation of black holes in supernova-like events. Two kinds of ``collapsar&#39;&#39; models are discussed, those in which the black hole forms promptly - a second or so after iron core collapse - and those in which formation occu

G. K. Leontaris, N. E. Mavromatos

Using conformal field theory methods we construct a metric that describes the distortion of space-time surrounding a D(irichlet)-brane (solitonic) defect after being struck by another D-brane. By viewing our four-dimensional universe as such a struck brane, embedded in a five-dimensional space-time, we argue on the appearance of a band of massive Kaluza-Klei

J. Goeres, D. Goldhaber-Gordon, S. Heemeyer, M. A. Kastner

We have observed asymmetric Fano resonances in the conductance of a single electron transistor resulting from interference between a resonant and a nonresonant path through the system. The resonant component shows all the features typical of quantum dots, but the origin of the non-resonant path is unclear. A unique feature of this experimental system, compar

Joshua A. Faber, Frederic A. Rasio

We present the first results from our Post-Newtonian (PN) Smoothed Particle Hydrodynamics (SPH) code, which has been used to study the coalescence of binary neutron star (NS) systems. The Lagrangian particle-based code incorporates consistently all lowest-order (1PN) relativistic effects, as well as gravitational radiation reaction, the lowest-order dissipat

C. P. Burgess, J. Matias, M. Pospelov

We show how to systematically analyze what may be inferred should a new scalar particle be discovered in collider experiments. Our approach is systematic in the sense that we perform the analysis in a manner which minimizes apriori theoretical assumptions as to the nature of the scalar particle. For instance, we do not immediately make the common assumption

Theodore Voronov

The complex of "stable forms" on supermanifolds is studied. Stable forms on $M$ are represented by certain Lagrangians of "copaths" (formal systems of equations, which may or may not specify actual surfaces) on $M\times\mathbb R^D$. Changes of $D$ give rise to stability isomorphisms. The Cartan--de Rham complex made of stable forms extends both in positive a

M. Freund, M. Lindner, S. T. Petcov, A. Romanino

Assuming three-neutrino mixing, we study the capabilities of very long baseline neutrino oscillation experiments to verify and test the MSW effect and to measure the lepton mixing angle theta_13. We suppose that intense neutrino and antineutrino beams will become available in so-called neutrino factories. We find that the most promising and statistically sig

Kan Chen, Per Bak

The forest fire model is a reaction-diffusion model where energy, in the form of trees, is injected uniformly, and burned (dissipated) locally. We show that the spatial distribution of fires forms a novel geometric structure where the fractal dimension varies continuously with the length scale. In the three dimensional model, the dimensions varies from zero

T. Blazek, S. Raby, K. Tobe

In a previous paper we analyzed fermion masses (focusing on neutrino masses and mixing angles) in an SO(10) SUSY GUT with U(2)$\timesU(1)^n$ family symmetry. The model is &#34;natural&#34; containing all operators in the Lagrangian consistent with the states and their charges. With minimal family symmetry breaking vevs the model is also predictive giving a u

Joseph Christensen, Terrence Draper, Craig McNeile

We compute the perturbative renormalization factors required to match to the continuum Isgur-Wise function, calculated using lattice Heavy Quark Effective Theory. The velocity, mass, wavefunction and current renormalizations are calculated for both the forward difference and backward difference actions for a variety of velocities. Subtleties are clarified re

Kari Enqvist, John McDonald

We consider the evolution of the Affleck-Dine scalar during D-term and F-term inflation and solve the combined slow-roll equations of motion. We show that for a typical case, where both the Affleck-Dine scalar and inflaton initially have large values, in D-term inflation the Affleck-Dine scalar is driven to a fixed value, with only a very slight dependence o

D. Petz, M. Mosonyi

In this paper the quantum source coding theorem is obtained for a completely ergodic source. This results extends Shannon&#39;s classical theorem as well as Schumacher&#39;s quantum noiseless coding theorem for memoryless sources. The control of the memory effects requires earlier results of Hiai and Petz on high probability subspaces.

S. Arunagiri

The paper has been withdrawn due to numerical error.

Bastian Bergerhoff, Johannes Manus, Juergen Reingruber

We formulate the thermal renormalization group, an implementation of the Wilsonian RG in the real-time (CTP) formulation of finite temperature field theory, for fermionic fields. Using a model with scalar and fermionic degrees of freedom which should describe the two-flavor chiral phase-transition, we discuss the mechanism behind fermion decoupling and unive

Abdelhak Djouadi, Michael Spira

We analyze the next-to-leading order SUSY-QCD corrections to the production of Higgs particles at hadron colliders in supersymmetric extensions of the Standard Model. Besides the standard QCD corrections due to gluon exchange and emission, genuine supersymmetric corrections due to the virtual exchange of squarks and gluinos are present. At both the Tevatron

Hannu Kurki-Suonio, Elina Sihvola

We consider the effect of a small-scale matter-antimatter domain structure on big bang nucleosynthesis and place upper limits on the amount of antimatter in the early universe. For small domains, which annihilate before nucleosynthesis, this limit comes from underproduction of He-4. For larger domains, the limit comes from He-3 overproduction. Most of the He

G. Mangano, G. Miele

We propose a new mechanism producing a non-vanishing lepton number asymmetry, based on decays of heavy Majorana neutrinos. If they are produced out of equilibrium, as occurs in preheating scenario, and are superpositions of mass eigenstates rapidly decaying, their decay rates contains interference terms provided the mass differences $Δm$ are small compared t

Fabio Gavarini

Let R be an integral domain, let a non-zero h in R be such that k := R/hR is a field, and let HA be the category of torsionless (or flat) Hopf algebras over R. We call H in HA a &#34;quantized function algebra&#34; (=QFA), resp. &#34;quantized restricted universal enveloping algebras&#34; (=QrUEA), at h if - roughly speaking - H/hH is the function algebra of

Thibault Damour

I review some recent work (done in collaboration with G. Veneziano) which clarifies the existence of a correspondence between self-gravitating fundamental string states and Schwarzschild black holes. The main result is a detailed calculation showing that self-gravity causes a typical string state of mass M to shrink, as the string coupling g^2 increases, dow

I. Goldman, R. Mohapatra, S. Nussinov

We show, that SN1987A can serve as an astrophysical laboratory for testing the viability of the assertion that a new massive neutral fermion is implied by the KARMEN data. We show that a wide range of the parameters characterizing the proposed particle is ruled out by the above constraints making this interpretation very unlikely.

R Maartens, D Wands, B Bassett, I Heard

We consider slow-roll inflation in the context of recently proposed four-dimensional effective gravity induced on the world-volume of a three-brane in five-dimensional Einstein gravity. We find significant modifications of the simplest chaotic inflationary scenario when the five-dimensional Planck scale is below about 10^{17} GeV. We use the comoving curvatu

H. Eberl, K. Hidaka, S. Kraml, W. Majerotto

We improve the calculation of the supersymmetric $O(α_s)$ QCD corrections to the decays of Higgs bosons into quarks and squarks in the Minimal Supersymmetric Standard Model. In the on-shell renormalization scheme these corrections can be very large, which makes the perturbative expansion unreliable. This is especially serious for decays into bottom quarks an

E. Athanassoula, E. Fady, J. -C. Lambert, A. Bosma

In N-body simulations the force calculated between particles representing a given mass distribution is usually softened, to diminish the effect of graininess. In this paper we study the effect of such a smoothing, with the aim of finding an optimal value of the softening parameter. As already shown by Merritt (1996), for too small a softening the estimates o

Gianfranco Pradisi

We discuss the open descendants of diagonal irrational $Z_3$ orbifolds, starting from the $c=2$ case and analyzing six-dimensional and four-dimensional models. As recently argued, their consistency is linked to the presence of geometric discrete moduli. The different classes of open descendants, related to different resolutions of the fixed-point ambiguities

P. Azaria, P. Lecheminant

We study a class of one-dimensional models consisting of a frustrated (N+1)-leg spin ladder, its asymmetric doped version as a special example of a Luttinger liquid in an active environment, and the N-channel Kondo-Heisenberg model away from half-filling. It is shown that these models exhibit a critical phase with generally a non-integer central charge and b

Takeshi Chiba, Takahiro Okabe, Masahide Yamaguchi

Recently, a novel class of models for inflation has been found in which the inflationary dynamics is driven solely by (non-canonical) kinetic terms rather than by potential terms. As an obvious extension, we show that a scalar field with non-canonical kinetic terms alone behaves like an energy component which is time-varying and has negative pressure present

Hiroaki Kodama, Jun-Ichi Sumi

The chiral phase structure of the Nambu-Jona-Lasinio/Gross-Neveu model at finite temperature T and finite chemical potential μis investigated using (Wilsonian) Non-Perturbative Renormalization Group (NPRG). In the large N_c limit, the solutions of NPRG with various cutoff schemes are shown. For a sufficiently large ultra-violet cutoff, NPRG results coincide

D. Voigt, B. T. Wolschrijn, R. Jansen, N. Bhattacharya

We report a direct observation of radiation pressure, exerted on cold rubidium atoms while bouncing on an evanescent-wave atom mirror. We analyze the radiation pressure by imaging the motion of the atoms after the bounce. The number of absorbed photons is measured for laser detunings ranging from {190 MHz} to {1.4 GHz} and for angles from {0.9 mrad} to {24 m

L. Bonora, M. Rinaldi

We deal with the problem of diffeomorphism anomaly in theories with branes. In particular we thoroughly analyze the problem of the residual chiral anomaly of a five-brane immersed in M-theory, paying attention to its global formulation in the five-brane world-volume. We conclude that the anomaly can be canceled by a {\it local} counterterm in the five-brane

Kicheon Kang, Sung-Chul Shin

An interacting quantum dot inserted in a mesoscopic ring is investigated. A variational ansatz is employed to describe the ground state of the system in the presence of the Aharonov-Bohm flux. It is shown that, for even number of electrons with the energy level spacing smaller than the Kondo temperature, the persistent current has a value similar to that of

Jin-Hwan Cho, Min Kyu Kim, Dong Youp Suh

Let $H$ be a closed normal subgroup of a compact Lie group $G$ such that $G/H$ is connected. This paper provides a necessary and sufficient condition for every complex representation of $H$ to be extendible to $G$, and also for every complex $G$-vector bundle over the homogeneous space $G/H$ to be trivial. In particular, we show that the condition holds when

W. A. Watters, K. J. Joshi, F. A. Rasio

We present the results of Monte Carlo simulations for the dynamical evolution of star clusters containing two stellar populations with individual masses m1 and m2 > m1, and total masses M1 and M2 < M1. We use both King and Plummer model initial conditions and we perform simulations for a wide range of individual and total mass ratios, m2/m1 and M2/M1. We ign

L. A. Kalyakin

Small perturbation of the Liouville equation under singular initial data is considered. An asymptotics of the singular solution is constructed by the method which is similar to Bogolubov -- Krylov one. The main object is an asymptotics of the singular lines.

Jeff P Barnes, Warren S Warren

Criteria are given by which dissipative evolution can transfer populations and coherences between quantum subspaces, without a loss of coherence. This results in a form of quantum error correction that is implemented by the joint evolution of a system and a cold bath. It requires no external intervention and, in principal, no ancilla. An example of a system

Marek Czachor

A new scheme of field quantization is proposed. Instead of associating with different frequencies different oscillators we begin with a single oscillator that can exist in a superposition of different frequencies. The idea is applied to the electromagnetic radiation field. Using the standard Dirac-type mode-quantization of the electromagnetic field we obtain

V. P. Dmitriyev

1. Connection between integration and differentiation/ Gauss theorem. Coordinate-free definitions: gradient, divergence, curl. Stokes theorem. 2. Elements of continuum mechanics/ Continuity equation. Stress tensor. Euler equation. Hydrodynamics. Elasticity.

S. Kümmel, T. Berkus, P. -G. Reinhard, M. Brack

The static electric dipole polarizability of $\mathrm{Na_N}$ clusters with even N has been calculated in a collective, axially averaged and a three-dimensional, finite-field approach for $2\le N \le 20$, including the ionic structure of the clusters. The validity of a collective model for the static response of small systems is demonstrated. Our density func

J. Ortner

Relativistic tunnel ionization of atoms by intense, elliptically polarized light is considered. The relativistic version of the Landau-Dykhne formula is employed. The general analytical expression is obtained for the relativistic photoelectron spectra. The most probable angle of electron emission, the angular distribution near this angle, the position of the

S. Drozdz, J. Okolowicz, M. Ploszajczak, I. Rotter

Various global characteristics of the coupling between the bound and scattering states are explicitly studied based on realistic Shell Model Embedded in the Continuum. In particular, such characteristics are related to those of the scattering ensemble. It is found that in the region of higher density of states the coupling to continuum is largely consistent

N. Kaiser

We calculate in (two-loop) chiral perturbation theory the local NN-potentials generated by the three-pion exchange diagrams proportional to g_A^4 and g_A^6. Surprisingly, we find that the total isoscalar central $3π$-exchange potential vanishes identically. The individually largest $3π$-exchange potentials are of isoscalar spin-spin, isovector central and is

J. Caro Ramon, N. Kaiser, S. Wetzel, W. Weise

We extend our recent non-perturbative chiral SU(3) coupled channel approach to pion- and photon-induced $η$- and $K$-meson production off protons by including all strong and electromagnetic p-wave multipoles. We identify the p-wave amplitudes of the next-to-leading order SU(3) chiral meson-baryon Lagrangian with a coupled channel potential which is iterated

P. Banerjee, R. Shyam

We investigate the structure of the neutron rich nucleus ^{19}C through studies of its breakup in the Coulomb field of target nuclei. The breakup amplitude is calculated within an adiabatic treatment of the projectile excitation, which allows the use of the realistic wave functions for the relative motion between the fragments in the ground state of the proj

A. Delfino, T. Frederico, M. S. Hussein, Lauro Tomio

It is shown that the three-body non-Borromean halo nuclei like ^{12}Be, ^{18}C, ^{20}C have p-wave virtual states with energy of about 1.6 times the corresponding neutron-core binding energy. We use a renormalizable model that guarantees the general validity of our results in the context of short range interactions.

J. Smyrski, P. Wuestner, A. Budzanowski, H. Dombrowski

The production of eta mesons has been measured in the proton-proton interaction close to the reaction threshold using the COSY-11 internal facility at the cooler synchrotron COSY. Total cross sections were determined for eight different excess energies in the range from 0.5 MeV to 5.4 MeV. The energy dependence of the total cross section is well described by

M. N. Andronenko, L. N. Andronenko, W. Neubert, D. M. Seliverstov

Nuclear temperatures obtained from inclusive measurements of double isotopic yield ratios of fragments produced in 1 GeV p + A collisions amount to about 4 MeV nearly independent from the target mass.

S. Y. Panitkin

First measurements of the beam energy dependence of the two proton correlation function in central Au+Au collisions are performed by the E895 Collaboration at the BNL AGS. The imaging technique of Brown-Danielewicz is used in order to extract information about the proton source at freeze-out. Measured correlation functions and sources do not exhibit signific

Pieter Moree, Peter Stevenhagen

For integer a let us consider the sequence X_a={x_0,x_1,x_2,...} defined by x_0=a, x_1=1 and, for n>=1, x_{n+1}=x_n+x_{n-1}. We say that a prime p divides X_a if p divides at least one term of the sequence. It is easy to see that every prime p divides X_1, the sequence of Fibonacci numbers. Lagarias, using a technique involving the computation of degrees of

Ruediger Goebel, Jose L. Rodriguez, Saharon Shelah

A group homomorphism eta:H-->G is called a localization of H if every homomorphism phi:H-->G can be `extended uniquely&#39; to a homomorphism Phi:G-->G in the sense that Phi eta=phi. Libman showed that a localization of a finite group need not be finite. This is exemplified by a well-known representation A_n-->SO_{n-1}(R) of the alternating group A_n, which