March 2001 arXiv papers — page 7

K. Iwasawa, G. Matt, M. Guainazzi, A. C. Fabian

We present X-ray results on the ultraluminous infrared galaxy Arp220 obtained with BeppoSAX. The X-ray emission up to 10 keV is detected. No significant signal is detected with the PDS detector in the higher energy band. The 2-10 keV emission has a hard spectrum (photon-index of 1.7), similar to M82, and a luminosity of 1e41 erg/s. A population of X-ray bina

S. Aalto, S. Huettemeister, A. G. Polatidis

We have detected CO 1-0 emission along the tidal tail of the NGC 4194 (the Medusa) merger. It is the first CO detection in the optical tail of a minor merger. Emission is detected both in the centre of the tail and at its tip. The molecular mass in the 33'' Onsala 20m beam is estimated to be >= 8.5 x 10^7 M_{sun} which is at least 4% of the total mol

J. Sanchez Almeida

The equilibrium configuration of very small magnetic fluxtubes in an intergranular environment automatically produces kG magnetic field strengths. We argue that such process takes place in the Sun and complements the convective collapse (CC), which is traditionally invoked to explain the formation of kG magnetic concentrations in the solar photosphere. In pa

M. Heydari-Malayeri, V. Charmandaris, L. Deharveng, M. R. Rosa

High resolution imaging with the HST uncovers the so far hidden stellar content and the nebular features of the high excitation compact HII region N83B in the Large Magellanic Cloud (LMC). We discover that the HII region is powered by the most recent massive starburst in the OB association LH5 and the burst has created about 20 blue stars spread over ~30&#34

Paola Grandi, Laura Maraschi, C. Meg Urry, Giorgio Matt

We present a detailed X-ray study of the Broad Line Radio Galaxy 3C382, observed with the BeppoSAX satellite in a very bright state. The continuum emission is well modeled with a power law that steepens at high energies, with an e-folding energy of about 120 keV. At soft energies a clear excess of emission is detected, which can not be explained solely by th

O. Petruk

Evolution of adiabatic remnants of an aspherical supernova explosion in uniform medium are considered. Thermal X-ray emission of such remnants are investigated. It is shown that integral thermal X-ray characteristics (X-ray luminosity and spectrum) of the objects do not allow us to reveal the assymetry in the explosion because these characteristics are close

Yohko Tsuboi, Katsuji Koyama, Kenji Hamaguchi, Ken'ichi Tatematsu

We have observed the Orion Molecular Clouds 2 and 3 (OMC-2 and OMC-3) with the Chandra X-ray Observatory (CXO). The northern part of OMC-3 is found to be particularly rich in new X-ray features; four hard X-ray sources are located in and along the filament of cloud cores. Two sources coincide positionally with the sub$mm$-$mm$ dust condensations of MMS 2 and

Shoichi Ichinose

A solution with the pole configuration in six dimensions is analysed both analytically and numerically. It is a dimensional reduction model of Randall-Sundrum type. The soliton configuration is induced by the bulk Higgs mechanism. The boundary condition is systematically solved up to the 6th order. The Riemann curvature is finite everywhere. An exact solutio

Stefano Vidussi

In this note we prove that, for any integer n, there exist a smooth 4-manifold, homotopic to a K3 surface, defined by applying the link surgery method of Fintushel-Stern to a certain 2-component graph link, which admits n inequivalent symplectic structures Keywords: Symplectic topology of 4-manifolds; Seiberg-Witten theory

Geza Giedke, Barbara Kraus, Maciej Lewenstein, J. Ignacio Cirac

We derive a necessary and sufficient condition for the separability of tripartite three mode Gaussian states, that is easy to check for any such state. We give a classification of the separability properties of those systems and show how to determine for any state to which class it belongs. We show that there exist genuinely tripartite bound entangled states

T. A. Costi

We study the effect of a magnetic field on the conductance through a strongly interacting quantum dot by using the finite temperature extension of Wilson's numerical renormalization group method to dynamical quantities. The quantum dot has one active level for transport and is modelled by an Anderson impurity attached to left and right electron reservoir

Markus Debert, Mario Paschke, Andrzej Sitarz

We derive the Kac-Paljutkin finite-dimensional Hopf algebras as finite fibrations of the quantum double torus and generalize the construction for quantum multiple tori.

V. P. Gusynin, I. A. Shovkovy

We predict the existence of the gapless Carlson-Goldman modes in the color-flavor locked color superconducting phase of dense QCD. These modes resemble Nambu-Goldstone modes of the superconducting phase below the critical temperature where the Anderson-Higgs mechanism takes place. These modes exist in the broken phase in the vicinity of the critical line. Th

U. V. Poulsen, K. Molmer

We propose to produce pulses of strongly squeezed light by Raman scattering of a strong laser pulse on a spin squeezed atomic sample. We prove that the emission is restricted to a single field mode which perfectly inherits the quantum correlations of the atomic system.

M. C. Land, L. P. Howitz

This paper examines the Stark effect, as a first order perturbation of manifestly covariant hydrogen-like bound states. These bound states are solutions to a relativistic Schrödinger equation with invariant evolution parameter, and represent mass eigenstates whose eigenvalues correspond to the well-known energy spectrum of the non-relativistic theory. In ana

Mark Nelkin

I give three different arguments for an upper critical dimension $d_{max}>3$ above which the 1941 Kolmogorov mean field theory becomes essentially exact, and anomalous scaling vanishes. The first argument concerns the number of degrees of freedom in a turbulent flow and indicates that $d_{max}=4$. The second argument is a naive estimate of dangerous fluctuat

Tahl Nowik

We classify all order one invariants of immersions of a closed orientable surface F into R^3, with values in an arbitrary Abelian group G. We show that for any F and G and any regular homotopy class A of immersions of F into R^3, the group of all order one invariants on A is isomorphic to G^\aleph_0 \oplus B \oplus B where G^\aleph_0 is the group of all func

Weimin Chen, Yongbin Ruan

In this article, we introduce the notion of good map and use it to establish Gromov-Witten theory for orbifolds.

Alain Connes, Henri Moscovici

We prove a cyclic cohomological analogue of Haefliger's van Est-type theorem for the groupoid of germs of diffeomorphisms of a manifold. The differentiable version of cyclic cohomology is associated to the algebra of transverse differential operators on that groupoid, which is shown to carry an intrinsic Hopf algebraic structure. We establish a canonical

J. Iliopoulos

We review the history of non-renormalisation theorems in global supersymmetry, as well as their importance in all attempts to apply supersymmetry to the real world.

J. B. Kogut, D. Toublan

We study the effects of small chemical potentials associated with the three light quark flavors in QCD. We use a low-energy effective field theory that solely relies on the symmetries of the QCD partition function. We find three different phases: a normal phase, a pion superfluid phase and a kaon superfluid phase. The two superfluid phases are separated by a

Y. Mambrini, G. Moultaka

We reconsider the Infrared Quasi Fixed Points which were studied recently in the literature in the context of the Baryon and Lepton number violating Minimal Supersymmetric Standard Model (hep-ph/0011274). The complete analysis requires further care and reveals more structure than what was previously shown. The formalism we develop here is quite general, and

Chun-xiu Liu, Zuo-tang Liang

We study the energy dependence of the contribution of pion exchange to large-rapidity-gap events in deep inelastic scattering. The results show that this contribution can be quite significant at low energy and that the LRG events observed by E665 collaboration in μXe and μD interactions at 490 $GeV$ can be reasonably well described in terms of meson exchange

Qing-hua Xu, Chun-xiu Liu, Zuo-tang Liang

We calculate the spin density matrix of the vector meson produced in e+e- annihilation at Z^0 pole. We show that the data imply a significant polarization for the antiquark which is created in the fragmentation process of the polarized initial quark and combines with the fragmenting quark to form the vector meson. The direction of polarization is opposite to

Zuo-tang Liang, Chun-xiu Liu

We point out that measuring longitudinal polarizations of different hyperons produced in lepton induced reactions are ideal to study the spin transfer of the fragtmenting quark to produced hadron in high energy hadronization processes. We briefly summarize the method used in calculating the hyperon polarizations in these processes, then present some of the r

Nguyen Anh Ky, Hoang Ngoc Long

Bilepton masses in the 3-3-1 models and the recently announced E821 experiment result are discussed. We get bounds on the bilepton masses 243 GeV $\leq M_Y \leq $ 357 GeV in the minimal model and 70 GeV $\leq M_Y \leq $ 115 GeV in the model with right-handed neutrinos.

Merab Gogberashvili

We consider the optical Sagnac effect, when the fictitious gravitational field simulates the reflections from the mirrors. It is shown that no contradiction exists between the conclusions of the laboratory and rotated observers. Because of acting of gravity-like Coriolis force the trajectories of co- and anti-rotating photons have different radii in the rota

Evgeny Sorkin, Tsvi Piran

We investigate the dynamical formation and evaporation of a spherically symmetric charged black hole. We study the self-consistent one loop order semiclassical back-reaction problem. To this end the mass-evaporation is modeled by an expectation value of the stress-energy tensor of a neutral massless scalar field, while the charge is not radiated away. We obs

L. Coffey

Recent SIS tunneling conductance measurements on a range of Bi2212 crystals with varying oxygen doping have revealed new information on the behavior of a dip feature in the tunneling conductance. Calculations presented here show that the observed variation in position of the dip can be generated in an Eliashberg formalism for a d-wave superconducting state b

Sandeep K. Joshi, Debendranath Sahoo, A. M. Jayannavar

We present a detailed analysis of the Aharonov-Bohm (AB) interference oscillations manifested through transmission of an electron in a mesoscopic ring with a magnetic impurity atom inserted in one of its arms. The spin polarization transport is also studied. The electron interacts with the impurity through the exchange interaction leading to exchange spin-fl

A. D. Chepelianskii, D. L. Shepelyansky

We study numerically and analytically the dynamics of charged particles on the Galton board, a regular lattice of disc scatters, in the presence of constant external force, magnetic field and friction. It is shown that under certain conditions friction leads to the appearance of a strange chaotic attractor. In this regime the average velocity and direction o

J. R. Thompson, M. Paranthaman, D. K. Christen, K. D. Sorge

Fine grained polycrystalline samples of MgB(2) superconductor were synthesized from the elements to contain < 5 % of impurity phases, according to X-ray powder diffractometry. The superconductive transition was sharp with a midpoint Tc = 38.5 K. The magnetization in the vortex state was studied as a function of applied field H, temperature T, and time t. Fro

A. G. Vanakaras, D. J. Photinos

We have used Monte Carlo NPT computer simulations to study a system of spherical fan shaped particles made of three hard discs fused along a common diameter. The calculated equation of state indicates a strong, entropy driven, first order transition from the isotropic phase to a layered phase that has the basic characteristics of the usual smectic A mesophas

A. Kohen, G. Deutscher

We have performed differential conductance versus voltage measurements of Au/MgB2 point contacts. We find that the dominant component in the conductance is due to Andreev reflection. The results are fitted to the theoretical model of BTK for an s-wave symmetry from which we extract the value of the order parameter (Delta) and its temperature dependence. From

R. Stehle, H. C. Spruit

We study the stability of poloidal magnetic fields anchored in a thin accretion disc. The two-dimensional hydrodynamics in the disc plane is followed by a grid-based numerical simulation including the vertically integrated magnetic forces. The 3--dimensional magnetic field outside the disc is calculated in a potential field approximation from the magnetic fl

K. G. Gayley, R. Ignace, S. P. Owocki

We examine the effects of optically thick line forces on orbiting circumstellar disks, such as occur around Be stars. For radially streaming radiation, line forces are only effective if there is a strong radial velocity gradient, as occurs, for example, in a line-driven stellar wind. However, within an orbiting disk, the radial shear of the azimuthal velocit

J. A. Combi, G. E. Romero, P. Benaglia, I. F. Mirabel

We report the results of a study of the radio surroundings of the superluminal microquasar GRO J1655-40. We have searched for extended continuum structures that might be indicative of the presence of a supernova remnant (SNR) associated with the formation of the compact object in the binary system. We also carried out HI-line observations of the region looki

Rafal Weron

A major issue in financial economics is the behavior of asset returns over long horizons. Various estimators of long range dependence have been proposed. Even though some have known asymptotic properties, it is important to test their accuracy by using simulated series of different lengths. We test R/S analysis, Detrended Fluctuation Analysis and periodogram

Teruyuki Kitabayashi, Masaki Yasue

In the minimal SU(3)_LxU(1)_N gauge model with a global L_e-L_mu-L_tau (=L&#39;) symmetry and a discrete Z_4 symmetry, it is found that the interplay between neutrinos and charged leptons contained in triplets of ψ^i=(ν^i_L, \ell^i_L, \ell^{ci}_L) (i=1,2,3) naturally leads to the large mixing angle (LMA) MSW solution. The model includes two (anti)sextet Higg

Krzysztof Pachucki

Relativistic corrections to the hyperfine splitting are calculated for the triplet $2^3S_1$ state of the helium isotope He$^3$. High precision variational wave functions are employed, where the electron-electron correlations are well accounted for. Due to the unknown nuclear structure a comparison with the experimental result is performed via He$^{3+}$ hyper

Tara E. Brendle, Hessam Hamidi-Tehrani

Formanek and Procesi have demonstrated that Aut(F_n) is not linear for n >2. Their technique is to construct nonlinear groups of a special form, which we call FP-groups, and then to embed a special type of automorphism group, which we call a poison group, in Aut(F_n), from which they build an FP-group. We first prove that poison groups cannot be embedded in

T. Becher, H. Leutwyler

We derive a representation for the pion nucleon scattering amplitude that is valid to the fourth order of the chiral expansion. To obtain the correct analytic structure of the singularities in the low energy region, we have performed the calculation in a relativistic framework (infrared regularization). The result can be written in terms of functions of a si

H. P. De Oliveira, S. E. Jorás

Warm inflation is an interesting possibility of describing the early universe, whose basic feature is the absence, at least in principle, of a preheating or reheating phase. Here we analyze the dynamics of warm inflation generalizing the usual slow-roll parameters that are useful for characterizing the inflationary phase. We study the evolution of entropy an

Rajendra Bhandari

We analyse a recently reported neutron interference experiment to measure a geometric phase and attempt to bring out the inadequacy of the ``phase modulo 2π&#34; approach to the geometric phase. A modified neutron interferometer experiment to observe 2nπphase changes of topological origin resulting from closed circuits around singularities in the parameter s

Stefano Mancini, Vladimir I. Man&#39;ko

We study the dissipative dynamics of deformed coherent states superposition. We find that such kind of superposition can be more robust against decoherence than the usual Schrodinger cat states.

D. A. Trifonov, S. G. Donev

The proposition 1 is incomplete. In some of the examples D(a,b) may not obey the triangle inequality. The paper is withdrawn for further elaboration.

M. Bender, W. Nazarewicz, P. -G. Reinhard

Quantum stabilization of superheavy elements is quantified in terms of the shell-correction energy. We compute the shell correction using self-consistent nuclear models: the non-relativistic Skyrme-Hartree-Fock approach and the relativistic mean-field model, for a number of parametrizations. All the forces applied predict a broad valley of shell stabilizatio

Zixiang Zhou, Wen-Xiu Ma, Ruguang Zhou

For the Davey-Stewartson I equation, which is an integrable equation in 1+2 dimensions, we have already found its Lax pair in 1+1 dimensional form by nonlinear constraints. This paper deals with the second nonlinearization of this 1+1 dimensional system to get three 1+0 dimensional Hamiltonian systems with a constraint of Neumann type. The full set of involu

U. Frisch, J. Bec

This is a review of selected work on the one- and multi-dimensional random Burgers equation (burgulence) with emphasis on questions generally asked for incompressible Navier--Stokes turbulence, such as the law of decay of the energy and the pdf of velocity gradients. Most of the material is devoted to decaying (unforced) burgulence. For more details see the

M. Lagraa

From the quantum analog of the Iwasawa decomposition of $SL(2,C)$ group and the correspondence between quantum $SL(2,C)$ and Lorentz groups we deduce the different properties of the Hopf algebra representing the boost of particles in noncommutative special relativity. The representation of the boost in the Hilbert space states is investigated and the additio

Pavel Exner, David Krejcirik

It has been shown recently that a nonrelativistic quantum particle constrained to a hard-wall layer of constant width built over a geodesically complete simply connected noncompact curved surface can have bound states provided the surface is not a plane. In this paper we study the weak-coupling asymptotics of these bound states, i.e. the situation when the s

Saharon Shelah

If kappa is strongly compact, lambda > kappa is regular, then (2^{< lambda})^+ --> (lambda+eta)^2_theta holds for eta,theta<kappa.

Rüdiger Göbel, Saharon Shelah, Simone Wallutis

We discuss the lattice of cotorsion theories for abelian groups. First we show that the sublattice of the well-studied rational cotorsion theories can be identified with the well-known lattice of types. Using a recently developed method for making Ext vanish we also prove that any power set together with the ordinary set inclusion (and thus any poset) can be

Joerg Brendle, Saharon Shelah

Say that a function pi:n^{<omega}-->n (henceforth called a predictor) k-constantly predicts a real x in n^omega if for almost all intervals I of length k, there is i in I such that x(i)=pi (x restriction i). We study the k-constant prediction number v_n^const(k), that is, the size of the least family of predictors needed to k --constantly predict all reals,

William Duke, Arpad Toth

In this paper we will give a global description of the Frobenius for the division fields of an elliptic curve E which is strictly analogous to the cyclotomic case. This is then applied to determine the splitting of a prime p in subfields of such a division field. Such fields include a large class of non-solvable quintic extensions and our application provide

Helmut Prodinger

A certain functional-difference equation that Runyon encountered when analyzing a queuing system was solved in a combined effort of Morrison, Carlitz, and Riordan. We simplify that analysis by exclusively using generating functions, in particular the kernel method, and the Lagrange inversion formula.

Sei-Hoon Moon

We consider a brane world residing in the interior region inside the horizon of extreme black branes. In this picture, the size of the horizon can be interpreted as the compactification size. The large mass hierarchy is simply translated into the large horizon size, which is provided by the magnitude of charges carried by the black branes. Hence, the macrosc

Yoshinobu Kuramashi

We present a GUT-model-independent calculation of hadron matrix elements for all dimension-six operators associated with baryon number violating processes using lattice QCD. Our results cover all the matrix elements required to estimate the partial lifetimes of (proton,neutron)$\to$($π,K,η$) +(${\bar ν},e^+,μ^+$) decay modes. We point out the necessity of di

Davison E. Soper

I discuss how to sample the space of parton momenta in order to best perform the numerical integrations that lead to a calculation of three jet cross sections and similar observables in electron-positron annihilation.

Christoph Jurecka, Wolfram Brenig

We present a bond-operator mean field theory for the Kondo lattice model at half filling in two (2D) and three (3D) dimensions. A continuous quantum phase transition from an antiferromagnetic to a spin-gapped singlet ground state is found at J/t=1.505 (1.833) in 2D (3D). Additionally we evaluate the quasiparticle dispersions as well as the staggered magnetic

P. K. Karahaliou, A. G. Vanakaras, D. J. Photinos

The order parameters for the phenomenological description of the smectic-{\it A} to smectic-{\it C} phase transition are formulated on the basis of molecular symmetry and structure. It is shown that, unless the long molecular axis is an axis of two-fold or higher rotational symmetry, the ordering of the molecules in the smectic-{\it C} phase gives rise to mo

Tatsuaki Wada, Tomotoshi Nishino

A brief review of the interaction-round-a-face (IRF) density-matrix renormalization-group (DMRG) method. We have demonstrated the numerical superiority of IRF-DMRG method applied to SU(2) invariant quantum spin chains over the conventional DMRG. The ground state energy densities and the gap energies of both $S = 1$ and $S = 2$ spin chains can be calculated u

Jun Lei, Jones T. K. Wan, K. W. Yu, Hong Sun

Recent experiments revealed that the dielectric dispersion spectrum of fission yeast cells in a suspension was mainly composed of two sub-dispersions. The low-frequency sub-dispersion depended on the cell length, whereas the high-frequency one was independent of it. The cell shape effect was qualitatively simulated by an ellipsoidal cell model. However, the

A. B. Sushkov, B. R. Jones, J. L. Musfeldt, Y. J. Wang

We report the far-infrared spectra of the molecular nanomagnet Mn_12-acetate (Mn_12) as a function of temperature (5-300 K) and magnetic field (0-17 T). The large number of observed vibrational modes is related to the low symmetry of the molecule, and they are grouped together in clusters. Analysis of the mode character based on molecular dynamics simulation

G. Soto, J. A. Diaz, R. Machorro, A. Reyes-Serrato

Beryllium nitride thin films were grown on silicon substrates by laser ablating a beryllium foil in molecular nitrogen ambient. The composition and chemical state were determined with Auger (AES), X-Ray photoelectron (XPS) and energy loss (EELS) spectroscopies. A low absorption coefficient in the visible region, and an optical bandgap of 3.8 eV, determined b

A. B. Sushkov, J. L. Musfeldt, S. A. Crooker, J. Jegoudez

We report polarized optical reflectance studies of α&#39;-NaV2O5 as a function of temperature (4-45 K) and magnetic field (0-60 T). Rung directed electronic structure changes, as measured by near-infrared reflectance ratios ΔR(H)=R(H)/R(H=0 T), are especially sensitive to the phase boundaries. We employ these changes to map out an H-T phase diagram. Topologi

F. Pereira Dos Santos, J. Leonard, Junmin Wang, C. J. Barrelet

We have observed a Bose-Einstein Condensate in a dilute gas of $^4$He in the $2^3S_1$ metastable state. We find a critical temperature of $(4.7\pm0.5) μ$K and a typical number of atoms at the threshold of $8\times10^6$. The maximum number of atoms in our condensate is about $5\times10^5$. An approximate value for the scattering length $a=(16\pm8)$ nm is meas

Jorge A. Combi, Gustavo E. Romero, Paula Benaglia, Justin L. Jonas

We report on the discovery of a shell-type supernova remnant in the southern sky. It is a large (8*8), low-brightness source with a nonthermal radio spectrum, which requires background filtering to isolate it from the diffuse background emission of the Galaxy. Three 3EG gamma-ray sources are spatially correlated with the radio structure. We have made 21-cm l

Alister W. Graham, W. J. G. de Blok

We present observational evidence for a galaxy `Type&#39; dependence to the location of a spiral galaxy&#39;s disk parameters in the mu_0-log(h) (central disk surface-brightness - disk scale-length) plane. With a sample of ~40 Low Surface Brightness galaxies (both bulge- and disk-dominated) and ~80 High Surface Brightness galaxies, the early-type disk galaxi

David M. Palmer

SGR 1900+14 had a brief episode of exceedingly rapid spindown immediately following its 1998 Aug. 27 superburst. On a timescale of hours, it increased its period by a part in 10^4. The corresponding Pdot ~ 10^{-8} is orders of magnitude higher than the typical quiescent rate of Pdot ~ 6x10^{-11}.

Robin Stevens, Mark Lacy

In this paper we describe a set of models to predict the colours of galaxies over a wide range of redshifts. We present example output from the simulations, and discuss their application to the selection of galaxies at high redshifts, particularly through identification of the Lyman break. Additionally we consider the optimal choices of filters for selection

Andreas Schweitzer, John E. Gizis, Peter H. Hauschildt, France Allard

We present analyses of high resolution and medium resolution spectra of early L dwarfs. We used our latest set of model atmospheres to reproduce and analyze the observed features. We can model the optical flux and the atomic line profiles with the best accuracy to date. The models used to reproduce the observations include dust condensation and dust opacitie

Michio Watanabe, David B. Haviland

We have measured the current-voltage characteristics of small-capacitance single Josephson junctions at low temperatures (T < 0.04 K), where the strength of the coupling between the single junction and the electromagnetic environment was controlled with one-dimensional arrays of dc SQUIDs. We have clearly observed Coulomb blockade of Cooper-pair tunneling an

Adriano H. Cerqueira, Elisabete M. de Gouveia Dal Pino

(Abridged) We here investigate, by means of fully 3-D Smoothed Particle Magnetohydrodynamic numerical simulations, the effects of magnetic fields on overdense, radiatively cooling, pulsed jets, using different initial magnetic field topologies and strengths ($B \simeq 260 μ$G-0). The relative differences that have been previously detected in 2-D simulations

Charles Mielke, John Singleton, Moon-Sun Nam, Neil Harrison

The Fermi surface topology of the organic superconductor \lbets has been determined using the Shubnikov-de Haas and magnetic breakdown effects and angle-dependent magnetoresistance oscillations. The former experiments were carried out in pulsed fields of up to 60 T, whereas the latter employed quasistatic fields of up to 30 T. All of these data show that the

A. Pinzul, A. Stern

We construct a Dirac operator on the quantum sphere $S^2_q$ which is covariant under the action of $SU_q(2)$. It reduces to Watamuras&#39; Dirac operator on the fuzzy sphere when $q\to 1$. We argue that our Dirac operator may be useful in constructing $SU_q(2)$ invariant field theories on $S^2_q$ following the Connes-Lott approach to noncommutative geometry.

Shadow J. Q. Robinson, Larry Zamick

In a previous work we studied the effects of setting all two body T=0 matrix elements to zero in shell model calculations for $^{43}$Ti ($^{43}$Sc) and $^{44}$Ti. The results for $^{44}$Ti were surprisingly good despite the severity of this approximation. In this approximation degeneracies arose in the T=1/2 I=$({1/2})^-_1$ and $({13/2})^-_1$ states in $^{43

S. L. Dubovsky

We consider a class of models with infinite extra dimension, where bulk space does not possess SO(1,3) invariance, but Lorentz invariance emerges as an approximate symmetry of the low-energy effective theory. In these models, the maximum attainable speeds of the graviton, gauge bosons and scalar particles are automatically equal to each other and smaller tha

Roya Zandi, Joseph Rudnick

We investigate the mechanical stability of a segment of DNA wrapped around a histone in the nucleosome configuration. The assumption underlying this investigation is that the proper model for this packaging arrangement is that of an elastic rod that is free to twist and that writhes subject to mechanical constraints. We find that the number of constraints re

Robert Korus, Stanislaw Mrowczynski

The event-by-event p_T-fluctuations in proton-proton and central Pb-Pb collisions, which have been experimentally studied by means of the so-called Phi-measure, are analyzed. The contribution due to the correlation which couples the average p_T to the event multiplicity is computed. The correlation appears to be far too weak to explain the preliminary experi

V. A. Petrov, A. V. Prokudin, S. M. Troshin, N. E. Tyurin

Interest and problems in the studies of diffraction at LHC are highlighted. Predictions for the global characteristics of proton-proton interactions at the LHC energy are given. Potential discoveries of the antishadow scattering mode and diffractive scattering conjugated with high--$E_T$ jets are discussed.

M. Zetenyi, Gy. Wolf

We study the production of dileptons in relativistic nucleon-nucleon collisions. Additionally to the traditional dilepton production channels (vector meson decays, meson and Delta(1232) Dalitz decays) we included in our model as new dilepton sources the Dalitz decay of higher unflavored baryon resonances with spin<=5/2 and mass<=2.25 GeV/c^2. The contributio

D. M. Asner, CLEO Collaboration

We have searched for the charmless hadronic decay of B0 mesons into two neutral pions. Using 9.13fb^-1 taken at the Upsilon(4S) with the CLEO detector, we obtain an improved upper limit for the branching fraction BR(B0-->pi0pi0) < 5.7*10^-6 at the 90% confidence level.

Boris Kors, Dieter Lust, Andre Miemiec

We analyze certain brane bound states in M-theory and their descendants in type IIA string theory, all involving 3-form or 2-form background fluxes. Among them are configurations which represent NCYM, NCOS and ODp-theories in the scaling limit of OM-theory. In particular, we show how the conditions for the embedding to preserve supersymmetry are modified by

Hans Peter Nilles, Marco Peloso, Lorenzo Sorbo

We provide the formalism for the quantization of systems of coupled bosonic and fermionic fields in a time dependent classical background. The occupation numbers of the particle eigenstates can be clearly defined and computed, through a generalization of the standard procedure valid for a single field in which Bogolyubov coefficients are employed. We apply o

I. Jack, D. R. T. Jones, R. Wild

We consider the renormalisation of a softly-broken supersymmetric theory with singlet fields and a superpotential with a linear term. We show that there exist exact beta-functions for both the linear term in the superpotential and the associated linear term in the Lagrangian. We also construct exact renormalisation group invariant trajectories for these term

PACS Collaboration, A. Ali Khan, S. Aoki, R. Burkhalter

We present results of a first study of equation of state in finite-temperature QCD with two flavors of Wilson-type quarks. Simulations are made on lattices with temporal size $N_t=4$ and 6, using an RG-improved action for the gluon sector and a meanfield-improved clover action for the quark sector. The lines of constant physics corresponding to fixed values

Tommy Ohlsson, Hakan Snellman

In this paper, we discuss the evolution operator and the transition probabilities expressed as functions of the vacuum mass squared differences, the vacuum mixing angles, and the matter density parameter for three flavor neutrino oscillations in matter of varying density in the plane wave approximation. The applications of this to neutrino oscillations in a

Y. Imamura, T. Watari, T. Yanagida

The conventional supersymmetric grand unified theories suffer from two serious problems, the large mass splitting between doublet and triplet Higgs multiplets, and the too long lifetime of the proton. A unification model based on a semi-simple group SU(5)_{GUT} \times U(3)_H has been proposed to solve both of the problems simultaneously. Although the propose

V. G. Arkhipkin, I. V. Timofeev

Spatial and temporal evolution is studied of two powerful short laser pulses having different wavelengths and interacting with a dense three-level Lambda-type optical medium under coherent population trapping. A general case of unequal oscillator strengths of the transitions is considered. Durations of the probe pulse and the coupling pulse $T_{1,2}$ ($T_2>T

A. Dmitriev, M. Dyakonov, R. Jullien

The classical two-dimensional problem of non-interacting electrons scattered by short-range impurity centers in the presence of magnetic field is investigated both analytically and numerically. A strong magnetoresistance exists in such a system, due to freely circling electrons, which are not taken into account by the Boltzmann-Drude approach. A parabolic ma

Deon Solomons, Peter Dunsby, George Ellis

Many cosmological scenarios envisage either a bounce of the universe at early times, or collapse of matter locally to form a black hole which re-expands into a new expanding universe region. Energy conditions preclude this happening for ordinary matter in general relativistic universes, but scalar or dilatonic fields can violate some of these conditions, and

B. Lucini, M. Teper

We calculate the string tension, K, and some of the lightest glueball masses, M, in 3+1 dimensional SU(N) lattice gauge theories for N=2,3,4,5 . From the continuum extrapolation of the lattice values, we find that the mass ratios, M/sqrt(K), appear to show a rapid approach to the large-N limit, and, indeed, can be described all the way down to SU(2) using ju

C. Terrier, D. Babic, C. Strunk, T. Nussbaumer

We study the influence of a DC bias voltage V on quantum interference corrections to the measured differential conductance in metallic mesoscopic wires and rings. The amplitude of both universal conductance fluctuations (UCF) and Aharonov-Bohm effect (ABE) is enhanced several times for voltages larger than the Thouless energy. The enhancement persists even i

E. Z. Kurmaev, I. I. Lyakhovskaya, J. Kortus, A. Moewes

Measurements of x-ray emission and absorption spectra of the constituents of MgB$_2$ are presented. The results obtained are in good agreement with calculated x-ray spectra, with dipole matrix elements taken into account. The comparison of x-ray emission spectra of graphite, AlB$_2$, and MgB$_2$ in the binding energy scale supports the idea of charge transfe

G. F. Giudice, A. Riotto, I. Tkachev

Many models of supersymmetry breaking, in the context of either supergravity or superstring theories, predict the presence of particles with Planck-suppressed couplings and masses around the weak scale. These particles are generically called moduli. The excessive production of moduli in the early Universe jeopardizes the successful predictions of nucleosynth

C. Fuchs, Amand Faessler, M. El-Shabshiry

The properties of nucleon-nucleon scattering inside dense nuclear matter are investigated. We use the relativistic Brueckner-Hartree-Fock model to determine on-shell and half off-shell in-medium transition amplitudes and cross sections. At finite densities the on-shell cross sections are generally suppressed. This reduction is, however, less pronounced than

C. A. Kuntscher, S. Schuppler, P. Haas, B. Gorshunov

Resistivity, optical, and angle-resolved photoemission experiments reveal unusual one-dimensional electronic properties of highly anisotropic SrNbO$_{3.41}$. Along the conducting chain direction we find an extremely small energy gap of only a few meV at the Fermi level. A discussion in terms of typical 1D instabilities (Peierls, Mott-Hubbard) shows that neit

R. Casadio, A. Gruppuso

Discrete symmetries are studied in warped space-times with one extra dimension. In particular, we analyze the compatibility of five- and four-dimensional charge conjugation, parity, time reversal and the orbifold symmetry Z_2 with localization of fermions on the four-dimensional brane-world and Lorentz invariance. We then show that, when a suitable topologic

Eric Gawiser, Arthur M. Wolfe, Jason X. Prochaska, Kenneth M. Lanzetta

We report the first observations of the clustering environment of damped Lyman alpha absorption systems at z=4. Color selection and photometric redshifts were used to select 44 candidate Lyman-break galaxies brighter than I_AB=25.5 from deep BRI images of the 35 sq. arcmin field containing the quasar BR 0951-04. Multislit spectroscopy of 35 candidate galaxie