March 2001 arXiv papers — page 22

F. M. Dunlop, P. A. Ferrari, L. R. G. Fontes

We study a symmetric randomly moving line interacting by exclusion with a wall. We show that the expectation of the position of the line at the origin when it starts attached to the wall satisfies the following bounds: c_1t^{1/4} \le\Eξ_t(0) \le c_2 t^{1/4}\log t The result is obtained by comparison with a ``free'' process, a random line that has the

Stefano Bellucci, Anton Galajinsky, Olaf Lechtenfeld

We reconsider the issue of embedding space-time fermions into the four-dimensional N=2 world-sheet supersymmetric string. A new heterotic theory is constructed, taking the right-movers from the N=4 topological extension of the conventional N=2 string but a c=0 conformal field theory supporting target-space supersymmetry for the left-moving sector. The global

Georgios Kofinas

A new moving domain wall solution is obtained for a flat 3-universe. This consists of a bulk metric depending on both time and the extra coordinate, plus a dynamically interacting domain wall, admitted by the metric and inhabited by the three-universe. The matter contents are cosmological constants on the domain wall and the bulk. The bulk space is shown to

Qaisar Shafi, Zurab Tavartkiladze

We discuss how a three-brane with an associated non-factorizable (warped) geometry can emerge from a five dimensional theory of gravity coupled to a complex scalar field. The system possesses a discrete $Z_2$ symmetry, whose spontaneous breaking yields an 'axionic' three-brane and a warped metric. Analytic solutions for the wall profile and warp fact

C. S. Simoes, J. R. Drugowich de Felicio

We revisit the short-time dynamics of 2D Ising model with three spin interactions in one direction and estimate the critical exponents $z,$ $θ,$ $β$ and $ν$. Taking properly into account the symmetry of the Hamiltonian we obtain results completely different from those obtained by Wang et al.. For the dynamic exponent $z$ our result coincides with that of the

F. Poli, N. Menci, E. Giallongo, A. Fontana

The galaxy Luminosity Function (LF) has been estimated in the rest frame B luminosity at 0<z<1.25 and at 1700 Å for 2.5<z<4.5 from deep multicolor surveys in the HDF-N, HDF-S, NTT-DF. The results have been compared with a recent version of galaxy formation models in the framework of hierarchical clustering in a flat Cold Dark Matter Universe with cosmologica

Karol Zyczkowski, Ingemar Bengtsson

Entanglement of any pure state of an N times N bi-partite quantum system may be characterized by the vector of coefficients arising by its Schmidt decomposition. We analyze various measures of entanglement derived from the generalized entropies of the vector of Schmidt coefficients. For N >= 3 they generate different ordering in the set of pure states and fo

B. Gorshunov, C. A. Kuntscher, P. Haas, M. Dressel

Far-infrared reflectivity studies on the polycrystalline intermetallic compound MgB_2 with a superconducting transition temperature T_c=39 K were performed at temperatures 20 K to 300 K. We observe a significant raise of the superconducting-to-normal state reflectivity ratio below 70 cm^{-1}, with a maximum at about 25-30 cm^{-1}, which gives a lower estimat

P. Szabo, P. Samuely, J. Kacmarcik, A. G. M. Jansen

We show that the interlayer transport in a two-dimensional superconductor can reveal a peak in the temperature as well as the magnetic field dependence of the resistivity near the superconducting transition. The magnetotransport experiment was performed on the highly anisotropic misfit-layer superconductor (LaSe)$_{1.14}$(NbSe$_2$) with critical tempertaure

Jonathan Granot, Arieh Konigl

We calculate the structure of a relativistic shock wave in which the internal energy of the shocked fluid is radiated away on a time scale much shorter than the characteristic shock propagation time. The shock is assumed to move through a uniformly magnetized, neutral plasma consisting of protons, electrons, and positrons, and allowance is made for the possi

A. L. Larsen, N. Sánchez

We study the properties of {\bf exact} (all level $k$) quantum coherent states in the context of string theory on a group manifold (WZWN models). Coherent states of WZWN models may help to solve the unitarity problem: Having positive norm, they consistently describe the very massive string states (otherwise excluded by the spin-level condition). These states

Markus Walzl, Ulf-G. Meißner

We calculate elastic electron-deuteron scattering in a chiral effective field theory approach for few-nucleon systems based on a modified Weinberg power counting. We construct the current operators and the deuteron wave function at next-to-leading (NLO) and next-to-next-to-leading (NNLO) order simultaneously within a projection formalism. The leading order c

A. B. Larionov, W. Cassing, S. Leupold, U. Mosel

We study the pion production in heavy-ion collisions at SIS energies within the coupled resonance BUU model. The standard calculation overpredicts the pion multiplicity in the central Au+Au collision at 1 A GeV by about a factor of 2, which is interpreted as a signature for the quenching of the resonance production/absorption in nucleon-nucleon collisions at

Urs Ledermann

We study the dimensional crossover from 1D to 2D in half-filled and lightly doped, weakly interacting N-leg Hubbard ladders. In this case, the Hubbard ladders are equivalent to a N-band model. Using renormalization group techniques, we find, that the half-filled ladders exhibit (in the spin-sector) an odd-even effect only below a crossover energy E_{c}\propt

Thibault Damour

We generalize to the case of spinning black holes a recently introduced ``effective one-body&#39;&#39; approach to the general relativistic dynamics of binary systems. The combination of the effective one-body approach, and of a Padé definition of some crucial effective radial functions, is shown to define a dynamics with much improved post-Newtonian converg

M. Sun, S. S. Murray, M. Markevitch, A. Vikhlinin

We present here \chandra observations of the rich cluster of galaxies A2256. In addition to the known cool subcluster, a new structure was resolved 2$&#39;$ east of the peak of the main cluster. Its position is roughtly at the center of a low-brightness radio halo. Spectral analysis shows that the &#34;shoulder&#34; has high iron abundance ($\sim$ 1). We sug

W. J. G. de Blok, Stacy S. McGaugh, Albert Bosma, Vera C. Rubin

We derive the mass density profiles of dark matter halos that are implied by high spatial resolution rotation curves of low surface brightness galaxies. We find that at small radii, the mass density distribution is dominated by a nearly constant density core with a core radius of a few kpc. For rho(r) ~ r^a, the distribution of inner slopes a is strongly pea

Itzhak Bars, Cemsinan Deliduman

All possible interactions of a point particle with background electromagnetic, gravitational and higher-spin fields is considered in the two-time physics worldline formalism in (d,2) dimensions. This system has a counterpart in a recent formulation of two-time physics in non-commutative field theory with local Sp(2) symmetry. In either the worldline or field

Varoujan Gorjian, Jean L. Turner, Sara C. Beck

Hidden from optical view in the starburst region of the dwarf galaxy NGC 5253 lies an intense radio source with an unusual spectrum which could be interpreted variously as nebular gas ionized by a young stellar cluster or nonthermal emission from a radio supernova or an AGN. We have obtained 11.7 and 18.7 micron images of this region at the Keck Telescope an

Ben Moore

I explore several possible solutions to the ``missing satellites&#39;&#39; problem that challenges the collisionless cold dark matter model.

C. Skornia, J. von Zanthier, G. S. Agarwal, E. Werner

We demonstrate the existence of new nonclassical correlations in the radiation of two atoms, which are coherently driven by a continuous laser source. The photon-photon-correlations of the fluorescence light show a spatial interferene pattern not present in a classical treatment. A feature of the new phenomenon is, that bunched and antibunched light is emitt

B. Nilsson

It is possible to fabricate mesoscopic structures where at least one of the dimensions is of the order of de Broglie wavelength for cold electrons. By using semiconductors, composed of more than one material combined with a metal slip-gate, two-dimensional quantum tubes may be built. We present a method for predicting the transmission of low-temperature elec

Karl Hess, Walter Philipp

We analyze the assumptions that are made in the proofs of Bell-type inequalities for the results of Einstein-Podolsky-Rosen type of experiments. We find that the introduction of time-like random variables permits the construction of a broader mathematical model which accounts for all correlations of variables that are contained in the time dependent paramete

Konrad Banaszek, Alfred B. U&#39;Ren, Ian A. Walmsley

We report the observation of correlated photon pairs generated by spontaneous parametric down-conversion in a quasi-phase matched KTiOPO4 nonlinear waveguide. The highest ratio of coincidence to single photon count rates observed in the 830 nm wavelength region exceeds 18%. This makes nonlinear waveguides a promising source of correlated photons for metrolog

A. Acin, D. Bruss, M. Lewenstein, A. Sanpera

We introduce a classification of mixed three-qubit states, in which we define the classes of separable, biseparable, W- and GHZ-states. These classes are successively embedded into each other. We show that contrary to pure W-type states, the mixed W-class is not of measure zero. We construct witness operators that detect the class of a mixed state. We discus

He-Shan Song, Dong Mi, Ling Zhou, Chong Li

A doubled q-Fock space is constructed by introducing an idle mode system dual to the physical one under consideration. The quantum entanglements of photons in the squeezed states and thermal states based on the doubled q-Fock space are discussed.

R. Gomez-Medina, P. San Jose, A. Garcia-Martin, M. Lester

A theoretical analysis of electromagnetic forces on neutral particles in an hollow waveguide is presented. We show that the effective scattering cross section of a very small (Rayleigh) particle can be strongly modified inside a waveguide. The coupling of the scattered dipolar field with the waveguide modes induce a resonant enhanced backscattering state of

P. Pieranski, S. Przybyl, A. Stasiak

The most tight conformations of prime knots are found with the use of the SONO algorithm. Their curvature and torsion profiles are calculated. Symmetry of the knots is analysed. Connections with the physics of polymers are discussed.

F. Arias de Saavedra, G. Co&#39;, A. Fabrocini

We study the properties of hypernuclei containing one lambda hyperon in the framework of the correlated basis function theory with Jastrow correlations. Fermi hypernetted chain integral equations are derived and used to evaluate energies and one-body densities of lambda hypernuclei having a doubly closed shell nucleonic core in the jj coupling scheme, from C

Piotr Zgliczynski

Using ODE-methods and trapping regions derived by Mattingly and Sinai we give a new proof of the existence and uniqueness of solutions to Navier-Stokes equations with periodic boundary conditions on the plane.

Martin Markl

In [math.AT/9907138] we proved that strongly homotopy algebras are homotopy invariant concepts in the category of chain complexes. Our arguments were based on the fact that strongly homotopy algebras are algebras over minimal cofibrant operads and on the principle that algebras over cofibrant operads are homotopy invariant. In our approach, algebraic models

N. F. Benschop

A suggestion is put forward regarding a partial proof of FLT(case1), which is elegant and simple enough to have caused Fermat&#39;s enthusiastic remark in the margin of his Bachet edition of Diophantus&#39; &#34;Arithmetica&#34;. It is based on an extension of Fermat&#39;s Small Theorem (FST) to mod p^k for any k>0, and the cubic roots of 1 mod p^k for prime

F. Camia, E. De Santis, C. M. Newman

We analyze clustering and (local) recurrence of a standard Markov process model of spatial domain coarsening. The continuous time process, whose state space consists of assignments of +1 or -1 to each site in ${\bf Z}^2$, is the zero-temperature limit of the stochastic homogeneous Ising ferromagnet (with Glauber dynamics): the initial state is chosen uniform

T. Haines, B. C. Ngo

The special fiber of the local model of a PEL Shimura variety with Iwahori-type level structure admits a cellular decomposition. The set of strata is in a natural way a finite subset of the affine Weyl group determined by the Shimura data. In this paper, we generalize and give a new proof of a theorem of Kottwitz and Rapoport concerning the description of th

T. Haines, B. C. Ngo

Kottwitz conjectured a formula for the (semi-simple) trace of Frobenius on the nearby cycles for the local model of a Shimura variety with Iwahori-type level structure. In this paper, we prove his conjecture in the linear and symplectic cases by adapting an argument of Gaitsgory, who proved an analogous theorem in the equal characteristic case.

David L. desJardins, Michael E. Zieve

Let f(x) be a polynomial with integer coefficients, let n be a positive integer, and let p be an odd prime. Then the mapping x-->f(x) sends Z/p^n into Z/p^n. We study the topological structure of this mapping.

Christophe Mourougane

We extend to any simply connected Kähler manifold with non-positive sectional curvature some conditions for interpolation in $\mathbb{C}$ and in the unit disk given by Berndtsson, Ortega-Cerdà and Seip. The main tool is a comparison theorem for the Hessian in Kähler geometry due to Greene, Wu and Siu, Yau.

Anton Malkin

The role of Spaltenstein varieties in the tensor product for GL is explained. In particular a direct (non-combinatorial) proof of the fact that the number of irreducible components of a Spaltenstein variety is equal to a Littlewood-Richardson coefficient (i.e. certain tensor product multiplicity) is obtained.

Anton Malkin

Let g be a simple simply laced Lie algebra. In this paper two families of varieties associated to the Dynkin graph of g are described: ``tensor product&#39;&#39; and ``multiplicity&#39;&#39; varieties. These varieties are closely related to Nakajima&#39;s quiver varieties and should play an important role in the geometric constructions of tensor products and

Rutwig Campoamor, Jose Maria Ancochea

We introduce the product by generators of complex nilpotent Lie algebras, which is a commutative product obtained from a central extension of the direct sum of Lie algebras. We show that the product preserves also the characteristic nilpotence provided that the multiplied algebras are $S$-algebras. In particular, this shows the existence of nonsplit characte

Stefaan Vaes, Leonid Vainerman

In the framework of locally compact quantum groups, we study cocycle actions. We develop the cocycle bicrossed product construction, starting from a matched pair of locally compact quantum groups. We define exact sequences and establish a one-to-one correspondence between cocycle bicrossed products and cleft extensions. In this way, we obtain new examples of

Ichiro Oda

We propose a new mechanism for trapping bulk gauge field, giving rise to a massless photon on a flat Minkowski 3-brane in the Randall-Sundrum model in five space-time dimensions. The mechanism we propose employs the topological Higgs mechansim where a topological term and a 3-form gauge potential play an important role. This new mechanism might be considered

H. Falomir, K. Kirsten, K. Rébora

We consider a dielectric medium with an ultraviolet behavior as it follows from the Drude model. Compared with dilute models, this has the advantage that, for large frequencies, two different media behave the same way. As a result one expects the Casimir energy to contain less divergencies than for the dilute media approximation. We show that the Casimir ene

L. O. Chekhov, A. K. Khizhnyakov

The explicit form of non-Abelian noncommutative supersymmetric (SUSY) chiral anomaly is calculated, the Wess-Zumino consistency condition is verified and the correspondence of the Yang-Mills sector to the previously obtained results is shown. We generalize the Seiberg-Witten map to the case of N=1 SUSY Yang-Mills theory and calculations up to the second orde

Stephen G. Naculich, Howard J. Schnitzer, Niclas Wyllard

We find the classical supersymmetric vacuum states of a class of N = 1* field theories obtained by mass deforming superconformal models with simple gauge groups and N = 4 or N =2 supersymmetry. In particular, new classical vacuum states for mass-deformed N = 4 models with Sp(2N) and SO(N) gauge symmetry are found. We also derive the classical vacua for vario

M. de Innocentis, R. S. Ward

We study static solutions of the Skyrme model on the two-sphere of radius L, for various choices of potential. The high-density Skyrmion phase corresponds to the ratio beta=L/(size of Skyrmion) being small, whereas the low-density phase corresponds to beta being large. The transition between these two phases, and in particular the behaviour of a relevant ord

Heinrich Saller

Interactions and particles in the standard model are characterized by the action of internal and external symmetry groups. The four symmetry regimes involved are related to each other in the context of induced group representations. In addition to Wigner&#39;s induced representations of external Poincaré group operations, parametrized by energy-momenta, and

Patricia Ball, Markus Lazar

Wandzura-Wilczek (WW) relations between matrix-elements of bilocal light-ray operators have recently regained interest in connection with off-forward scattering processes. Originally derived for matrix elements over leading-twist operators, their generalization to off-forward and exclusive processes gets complicated by the presence of higher-twist operators

H. V. Klapdor-Kleingrothaus, B. Majorovits

The GENIUS proposal is described and some of it&#39;s physics potential is outlined. Also in the light of the contradictive results from the DAMA and CDMS experiments the Genius TF, a new experimental setup is proposed. The Genius TF could probe the DAMA evidence region using the WIMP nucleus recoil signal and WIMP annual modulation signature simultaneously.

A. I. Davydychev, A. G. Grozin

We calculate the HQET quark-gluon vertex at one loop, for arbitrary external momenta, in an arbitrary covariant gauge and space-time dimension. Relevant results and algorithms for the three-point HQET integrals are presented. We also show how one can obtain the HQET limit directly from QCD results for the quark-gluon vertex.

H. V. Klapdor-Kleingrothaus, L. Baudis, A. Dietz, G. Heusser

The status of dark matter search with the HDMS experiment is reviewed. After one year of running the HDMS prototype detector in the Gran Sasso Underground Laboratory, the inner crystal of the detector has been replaced with a HPGe crystal of enriched 73Ge. The results of the operation of the HDMS prototype detector are discussed.

H. V. Klapdor-Kleingrothaus, H. Paes, A. Yu. Smirnov

We discuss the possibility of reconstructing the neutrino mass spectrum from the complementary processes of neutrino oscillations and double beta decay in view of the new data of Super-Kamiokande presented at the Neutrino2000 conference. Since the large mixing angle solution is favored, now, the prospects to observe double beta decay and provide informations

H. V. Klapdor-Kleingrothaus

Double beta decay is indispensable to solve the question of the neutrino mass matrix together with neutrino oscillation experiments. The most sensitive experiment since eight years - the Heidelberg-Moscow experiment in Gran-Sasso - already now, with the experimental limit of < m_ν> < 0.26 eV excludes degenerate neutrino mass scenarios allowing neutrinos as h

W. Cassing, L. A. Kondratyuk, G. I. Lykasov, M. V. Rzjanin

We calculate open charm production in $Pb+Pb$ reactions at SPS energies within the HSD transport approach - which is based on string, quark, diquark ($q, \bar{q}, qq, \bar{q}\bar{q}$) and hadronic degrees of freedom - including the production of open charm pairs from secondary &#39;meson&#39;-&#39;baryon&#39; (or quark-diquark and antiquark-diquark) collisio

Jihn E. Kim

There is the scale problem in the Randall-Sundrum models. Regarding this, I review the works done with B. S. Kyae and H. M. Lee. In a supersymmetric generalization in the RSI model, we discuss that the $μ$ parameter can be obtained by an intermediate scale brane. In addition, we also discuss the cosmological constant problem with a self-tuning solution in th

F. Yuasa, T. Kaneko, T. Ishikawa

We present a Feynman graph selection tool {\tt grcsel}, which is an interpreter written in C language. In the framework of {\tt GRACE}, it enables us to get a subset of Feynman graphs according to given conditions.

Subhash Rajpoot

It is shown that a minimal extension of the standard model with leptons that transform as singlets under the SU(2) symmetry of weak interactions can explain the recently reported derivation in the measured value of the anomalous magnetic moment of the muon from that expected in the standard model.

Seungwon Baek, Dilip Kumar Ghosh, Xiao-Gang He, W-Y. P. Hwang

In this paper we study non-commutative (NC) QED signatures at photon colliders through pair production of charged leptons $(\ell^+ \ell^-)$ and charged scalars $(H^+ H^-)$. The NC corrections for the fermion pair production can be easily obtained since NC QED with fermions has been extensively studied in the literature. NC QED with scalars is less studied. T

F. Arneodo

The final phase of the ICARUS physics program requires a sensitive mass of liquid Argon of 5000 tons or more. The T600 detector stands today as the first living proof that such large detector can be built and that liquid Argon imaging technology can be implemented on such large scales. After the successful completion of a series of technical tests to be perf

Friedrich W. Hehl, Yuri N. Obukhov

We complete a metric-free axiomatic framework for electrodynamics by introducing the appropriate energy-momentum current Sigma of the electromagnetic field. We start from the Lorentz force density and motivate the form of Sigma. Then we postulate it (fourth axiom) and discuss its properties. In particular, it is found that Sigma is traceless and invariant un

Scott H. Hawley, Matthew W. Choptuik

We present a brief synopsis of related work (gr-qc/0007039), describing a study of black hole threshold phenomena for a self-gravitating, massive complex scalar field in spherical symmetry. We construct Type I critical solutions dynamically by tuning a one-parameter family of initial data consisting of a boson star and a massless real scalar field, and numer

P. Simon, I. Affleck

We study the persistent currents induced by the Aharonov-Bohm effect in a closed ring which either embeds or is directly side coupled to a quantum dot at Kondo resonance. We predict that in both cases, the persistent current is very sensitive to the ratio between the length of the ring and the size of the Kondo screening cloud which appears as a fundamental

Eugene B. Kolomeisky, T. J. Newman, J. P. Straley

Using the example of the Davydov soliton - a large acoustic polaron in one dimension - we demonstrate that the electron wave function can be fissioned in two or more long-lived, well-localized and spatially arbitrarily far separated fragments. The phenomenon of wave function splitting is a result of the electron-medium interaction, and takes place under a va

Carsten Honerkamp

We compare the one-loop renormalization group flow to strong coupling of the electronic interactions in the two-dimensional t-t&#39;-Hubbard model with t&#39;=-0.3t for band fillings smaller and larger than half-filling. Using a numerical N-patch scheme (N=32...96) we show that in the electron-doped case with decreasing electron density there is a rapid tran

P. Ziherl, Randall D. Kamien

We propose a heuristic explanation for the numerous non-close-packed crystal structures observed in various colloidal systems. By developing an analogy between soap froths and the soft coronas of fuzzy colloids, we provide a geometrical interpretation of the free energy of soft spheres. Within this picture, we show that the close-packing rule associated with

Zhi-Feng Huang, Sorin Solomon

We study the finite-size effects in some scaling systems, and show that the finite number of agents N leads to a cut-off in the upper value of the Pareto law for the relative individual wealth. The exponent $α$ of the Pareto law obtained in stochastic multiplicative market models is crucially affected by the fact that N is always finite in real systems. We s

C. Petrovic, P. G. Pagliuso, M. F. Hundley, R. Movshovich

We report the observation of heavy-fermion superconducitivity in CeCoIn5 at Tc =2.3 K. When compared to the pressure-induced Tc of its cubic relative CeIn3 (Tc ~200 mK), the Tc of CeCoIn5 is remarkably high. We suggest that this difference may arise from magnetically mediated superconductivity in the layered crystal structure of CeCoIn5 .

J. C. Phillips, J. Jung

Filamentary high-temperature superconductivity (HTSC) theory differs fundamentally from continuous HTSC theories because it emphasizes self-organized, discrete dopant networks and does not make the effective medium approximation (EMA). Analysis of neutron and infrared (especially with c-axis polarization) vibrational spectra, primarily for YBa2Cu3O(6+x), wit

Dmitrii S. Golubev, Andrei D. Zaikin

We report on a quantitative comparison between our theory of quantum dephasing at low temperatures and some recent experimental results [D. Natelson {\it et al.}, Phys. Rev. Lett. {\bf 86}, 1821 (2001); A.B. Gougam {\it et al.}, J. Low Temp. Phys. {\bf 118}, 447 (2000); F. Pierre {\it et al.} cond-mat/0012038].

Wei-Guo Yin, Hai-Qing Lin, Chang-De Gong

We study single hole motion in LaMnO$_3$ using the classical approximation for JT lattice distortions, a modified Lang-Firsov approximation for dynamical breathing-mode phonons, and the self-consistent Born approximation (verified by exact diagonalization) for hole-orbital-excitation scattering. We show that in the realistic parameter space for LaMnO$_3$, qu

W. N. Kang, Kijoon H. P. Kim, Hyeong-Jin Kim, Eun-Mi Choi

We report fluctuation magnetoconductance in a MgB2 superconductor prepared under a high pressure of 3 GPa. This excess magnetoconductance, $Δσ(H)$, follows the three-dimensional scaling function for the critical fluctuations proposed by Ullah and Dorsey. This feature is inferred to originate from the isotropic nature of the MgB2 compound.

O. Entin-Wohlman, A. Aharony, Y. Levinson

The magnetic character of the ground-state of two electrons on a double quantum dot, connected in series to left and right single-channel leads, is considered. By solving exactly for the spectrum of the two interacting electrons, it is found that the coupling to the continuum of propagating states on the leads, in conjunction with the electron-electron inter

Sudha Srivastava, Shankar P. Das

We analyze results for the Boson Peak from the neutron time of flight spectroscopy data on Ge-As-Se, and Raman spectra data on m-TCP and OTP, using a recent mode coupling model that takes into account the coupling of density fluctuations with vibrational modes in presence of defects in the supercooled state. From the experimental results for different materi

N. I. Medvedeva, A. L. Ivanovskii, J. E. Medvedeva, A. J. Freeman

First principles FLMTO-GGA electronic structure calculations of the new medium-$T_C$ superconductor (MTSC) $MgB_2$ and related diborides indicate that superconductivity in these compounds is related to the the existence of $p_{x,y}$-band holes at the $Γ$ point. Based on these calculations, we explain the absence of medium-$T_C$ superconductivity for $BeB_2$,

Miyuki K. Shimamura, Tetso Deguchi

We discuss the entropy of a circular polymer under a topological constraint. We call it the {\it topological entropy} of the polymer, in short. A ring polymer does not change its topology (knot type) under any thermal fluctuations. Through numerical simulations using some knot invariants, we show that the topological entropy of a stiff ring polymer with a fi

Gennady Y. Chitov, Andrew J. Millis

We calculate using perturbative calculations and Ward identities the basic parameters of the Fermi Liquid: the scattering vertex, the Landau interaction function, the effective mass, specific heat, and physical susceptibilities for a model of two-dimensional (2D) fermions with a short ranged interaction at non-zero temperature. The leading temperature depend

S. V. Shulga, S. -L. Drechsler, H. Eschrig, H. Rosner

The upper critical field Hc2(T) for MgB2 is analyzed in terms of single and multi-band Eliashberg models. The relatively high value of Hc2(0) in the range of 14 to 18 Tesla can be understood, if a strongly coupled subgroup of heavy quasiparticles is involved in the superconductivity. The sizable coupling to both low- and high-frequency bosons is essential. T

Mun Dae Kim, Chul Koo Kim, Kyun Nahm, Chang-Mo Ryu

The Kondo effect in a Luttinger liquid is studied using the renormalization group method. By renormalizing the boson fields, scaling equations to the second order for an arbitrary Luttinger interaction are obtained. For the ferromagnetic Kondo coupling, a spin bound state(triplet) can be realized without invoking a nearest neighbor spin interaction in agreem

R. Reigada, A. Sarmiento, K. Lindenberg

We use temperature tuning to control signal propagation in simple one-dimensional arrays of masses connected by hard anharmonic springs and with no local potentials. In our numerical model a sustained signal is applied at one site of a chain immersed in a thermal environment and the signal-to-noise ratio is measured at each oscillator. We show that raising t

T. Sharpee, M. I. Dykman, P. M. Platzman

We show that, in a magnetic field parallel to the 2D electron layer, strong electron correlations change the rate of tunneling from the layer exponentially. It results in a specific density dependence of the escape rate. The mechanism is a dynamical Mossbauer-type recoil, in which the Hall momentum of the tunneling electron is partly transferred to the whole

Uwe R. Fischer, Nils Schopohl

We derive electromagnetomotive force fields for charged particles moving in a rotating Hall sample, satisfying a twofold U(1) gauge invariance principle. It is then argued that the phase coherence property of quantization of the line integral of total collective particle momentum into multiples of Planck&#39;s quantum of action is solely responsible for quan

Oliver Czoske, Jean-Paul Kneib, Genevieve Soucail, Terry Bridges

We present the catalogue of a wide-field CFHT/WHT spectroscopic survey of the lensing cluster Cl0024+1654 at z=0.395. This catalogue contains 618 new spectra, of which 581 have identified redshifts. Adding redshifts available from the literature, the final catalogue contains data for 687 objects with redshifts identified for 650 of them. 295 galaxies have re

S. L. Dubovsky, D. S. Gorbunov

We consider a possibility to explain the observed suppression of the second acoustic peak in the anisotropy spectrum of the Cosmic Microwave Background (CMB) by interaction between a fraction of non-baryonic Cold Dark Matter (CDM) and normal baryonic matter. This scenario does not require any modifications in the standard Big Bang Nucleosynthesis (BBN). We e

Shoko Sakai, Barry Madore

We report the detection of upper main sequence stars and red giant branch stars in the halo of an amorphous galaxy, NGC3077. The observations were made using Wide Field Planetary Camera~2 on board the Hubble Space Telescope. The red giant branch luminosity function in I-band shows a sudden discontinuity at I = 24.0 +- 0.1 mag. Identifying this with the tip o

B. Stecklum, O. Fischer, S. Klose, R. Mundt

Based on near-infrared polarimetric observations we constrain the degree of linear polarization of the afterglow light of GRB 000301C to less than 30% 1.8 days after the burst.

C. Bruens, J. Kerp, A. Pagels

We present deep HI observations of the compact high-velocity cloud HVC125+41-207 using the 100-m Effelsberg telescope. Our goal was in particular to study the warm neutral medium (WNM) in detail. The Effelsberg data reveal a two phase core/halo structure - one component with a velocity width of FWHM approx 5 km/s (Westerbork data show FWHM approx 2 km/s, Bra

C. Maxia, L. Testi, R. Cesaroni, C. M. Walmsley

We present high angular resolution interferometric observations of the 3 and 1.3mm continuum emission, and HCO+(1-0) and SiO(2-1)v=0 lines, obtained with the Owens Valley Radio Observatory millimeter-wave array, toward two hot cores (HCs) associated with two well known ultracompact (UC) HII regions: G29.96-0.02 and G31.41+0.31. These HCs are believed to host

P. Picozza, A. Morselli

The direct detection of annihilation products in cosmic rays offer an alternative way to search for dark matter particles candidates. Here we will see in particular that the study of the spectrum of antiproton and positrons offer good possibilities to perform this search and we will review our experimental effort in this direction.

J. D. Monnier

Optical interferometers increasingly use single-mode fibers as spatial filters to convert varying wavefront distortion into intensity fluctuations which can be monitored for accurate calibration of fringe amplitudes. Here I propose using an asymmetric coupler to allow the photometric intensities of each telescope beam to be measured at the same time as the f

O. Kotov, E. Churazov, M. Gilfanov

It is shown that the energy dependence of the time lags in Cygnus X-1 excludes any significant contribution of the standard reflected component to the observed lags. The conclusion is valid in the 0.1--10 Hz frequency range where time lags have been detected with high enough significance. In fact the data hint that reflected component is working in opposite

D. C. Gabuzda, A. B. Pushkarev, N. N. Garnich

We present the results of simultaneous VLBA polarisation observations of the BL Lacertae object 0820+225 at 5, 8, and 15 GHz, together with earlier images at 5 GHz. This source has an unusually rich total intensity and polarisation structure compared to other objects with comparable redshifts. The magnetic field in the inner part of the complex and highly tw

L. Wisotzki, B. Kuhlbrodt, K. Jahnke

We report on results from H band imaging observations of a complete sample of high-luminosity low-redshift QSOs. The luminosity function of QSO hosts is similar in shape to that of normal galaxies, although offset in normalisation by a factor of 10^(-4). This supports the hypothesis that the parent population of quasars is identical to the general population

Ferdinando Patat, Enrico Cappellaro, John Danziger, Paolo A. Mazzali

We present and discuss the photometric and spectroscopic evolution of the peculiar SN1998bw, associated with GRB980425, through an analysis of optical and near IR data collected at ESO-La Silla. The spectroscopic data, spanning the period from day -9 to day +376 (relative to B maximum), have shown that this SN was unprecedented, although somewhat similar to

V. Mueller, S. Arbabi-Bidgoli

We have analyzed the size distribution of voids in 2D slices of the Las Campanas Redshift Survey (LCRS). The characteristic sizes show a scaling $D = D_0 + νλ$ with the mean galaxy separation $λ$. Comparison with mock samples of the LCRS in 2D and 3D, using various simulations, cosmologies and galaxy identification schemes, gives a similar scaling, but with

R. T. Gangadhara, Y. Gupta

We have analyzed high-quality single pulse data of PSR B0329+54 at 325 MHz and 606 MHz to study the structure of the emission beam. Using the window-threshold technique, which is suitable for detecting weak emission components, we have detected 4 additional emission components in the pulse window. Three of these are new components and the fourth is a confirm

G. Bono, F. Caputo, M. Marconi

We present a new set of Cepheid, full amplitude, nonlinear, convective models which are pulsationally unstable in the second overtone (SO). Hydrodynamical models were constructed by adopting a chemical composition typical for Cepheids in the Small Magellanic Cloud (SMC) and stellar masses ranging from 3.25 to 4 solar masses. Predicted phi{21} Fourier paramet

K. Vogt, P. Mohr, M. Babilon, J. Enders

The nucleosynthesis of heavy neutron-deficient nuclei in a stellar photon bath at the temperatures relevant for the astrophysical gamma process was investigated. In order to derive (gamma,n) cross sections and reaction rates, the stellar photon bath was simulated by the superposition of several bremsstrahlung spectra with different endpoint energies. As a fi

Noam Soker

We derive the conditions for a backflow toward the central star(s) of circumstellar material to occur during the post-asymptotic giant branch (AGB) phase. The backflowing material may be accreted by the post-AGB star and/or its companion, if such exists. Such a backflow may play a significant role in shaping the descendant planetary nebula, by, among other t

Alessandro Chieffi, Inma Dominguez, Marco Limongi, Oscar Straniero

New stellar models with mass ranging between 4 and 8 Mo, Z=0 and Y=0.23 are presented. The models have been evolved from the pre Main Sequence up to the Asymptotic Giant Branch (AGB). At variance with previous claims, we find that these updated stellar models do experience thermal pulses in the AGB phase. In particular we show that: a) in models with mass la

Jun-ichiro Kishine, Patrick A. Lee, Xiao-Gang Wen

We have studied a single vortex with the staggered flux (SF) core based on the SU(2) slave-boson theory of high $T_c$ superconductors. We find that whereas the center in the vortex core is a SF state, as one moves away from the core center, a correlated staggered modulation of the hopping amplitude $χ$ and pairing amplitude $Δ$ becomes predominant. We predic