September 2002 arXiv papers — page 13

Sven Soff, Steffen A. Bass, David H. Hardtke, Sergey Y. Panitkin

We present calculations of two-pion and two-kaon correlation functions in relativistic heavy ion collisions from a relativistic transport model that includes explicitly a first-order phase transition from a thermalized quark-gluon plasma to a hadron gas. We compare the obtained correlation radii with recent data from RHIC. The predicted R_side radii agree wi

Jeremy Schiff

An analog of the lattice KdV equation of Nijhoff et al. is constructed on a hexagonal lattice. The resulting system of difference equations exhibits soliton solutions with interesting local structure: there is a nontrivial phase shift on moving between adjacent lattice sites, with the magnitude of the shift tending to zero in the continuum limit.

Jeremy Schiff

A study is presented of fully discretized lattice equations associated with the KdV hierarchy. Loop group methods give a systematic way of constructing discretizations of the equations in the hierarchy. The lattice KdV system of Nijhoff et al. arises from the lowest order discretization of the trivial, lowest order equation in the hierarchy, b_t=b_x. Two new

Giovanni Gallavotti, Lamberto Rondoni, Enrico Segre

We perform numerical experiments to study the Lyapunov spectra of dynamical systems associated with the Navier--Stokes (NS) equation in two spatial dimensions truncated over the Fourier basis. Recently new equations, called GNS equations, have been introduced and conjectured to be equivalent to the NS equations at large Reynolds numbers. The Lyapunov spectra

B. Cessac, Ph. Blanchard, T. Krueger, J. L. Meunier

We introduce a dissipative version of the Zhang's model of Self-Organized Criticality, where a parameter allows to tune the local energy dissipation. We analyze the main dynamical features of the model and relate in particular the Lyapunov spectrum with the transport properties in the stationary regime. We develop a thermodynamic formalism where we defin

N. Ono, T. Ikegami

It has been pointed out that if an autocatalytic cycle produces primitive membrane chemicals, it can compose a self-maintaining proto cell. Moreover, it is known that a proto cell can divide itself spontaneously as it grows. An unsolved problem is how such a catalytic system can evolve in the pre-cellular environment. Here we examine, as the first step, the

Sandip Kar, Suman Kumar Banik, Deb Shankar Ray

The Fisher and Burgers' equations with finite memory transport, describing reaction-diffusion and convection-diffusion processes, respectively have recently attracted a lot of attention in the context of chemical kinetics, mathematical biology and turbulence. We show here that they admit exact solutions. While the speed of the traveling wavefront is depe

Michael J Gruber

We study Schroedinger operators with periodic magnetic field in Euclidean 2-space, in the case of irrational magnetic flux. Positive measure Cantor spectrum is generically expected in the presence of an electric potential. We show that, even without electric potential, the spectrum has positive measure if the magnetic field is a perturbation of a constant on

V. V. Varlamov

General solutions of relativistic wave equations are studied in terms of the functions on the Lorentz group. A close relationship between hyperspherical functions and matrix elements of irreducible representations of the Lorentz group is established. A generalization of the Gel'fand-Yaglom formalism for higher-spin equations is given. It is shown that a

M. Duetsch, K. -H. Rehren

Motivated by structural issues in the AdS-CFT correspondence, the theory of generalized free fields is reconsidered. A stress-energy tensor for the generalized free field is constructed as a limit of Wightman fields. Although this limit is singular, it fulfils the requirements of a conserved local density for the Poincar'e generators. An explicit "ho

Greg Kuperberg

Fusion categories are fundamental objects in quantum algebra, but their definition is narrow in some respects. By definition a fusion category must be k-linear for some field k, and every simple object V is strongly simple, meaning that (V) = k. We prove that linearity follows automatically from semisimplicity: Every connected, finite, semisimple, rigid, mon

Eric S. Egge, Toufik Mansour

We use combinatorial and generating function techniques to enumerate various sets of involutions which avoid 231 or contain 231 exactly once. Interestingly, many of these enumerations can be given in terms of $k$-generalized Fibonacci numbers.

Wenhua Zhao

Let $f=(f_1, f_2)$ be a regular sequence of affine curves in $\bC^2$. Under some reduction conditions achieved by composing with some polynomial automorphisms of $\bC^2$, we show that the intersection number of curves $(f_i)$ in $\bC^2$ equals to the coefficient of the leading term $x^{n-1}$ in $g_2$, where $n=°f_i$ $(i=1, 2)$ and $(g_1, g_2)$ is the unique

Victoria Gould

A subsemigroup S of a semigroup Q is a local left order in Q if, for every maximal subgroup H of Q, the intersection of S with H is a local left order in the sense of group theory. That is, every q in H can be written as a#b for some a,b in the intersection of S with H, where here a# denotes the group inverse of a in H. On the other hand, S is a left order i

Ian M. Aberbach

Let (R,m) -> (S,n) be a flat local homomorphism of excellent local rings. We investigate the conditions under which the weak or strong F-regularity of R passes to S. We show that is suffices that the closed fiber S/mS be Gorenstein and either F-finite (if R and S have a common test element), or F-rational (otherwise).

Johannes Kellendonk, Mark V Lawson

We study the universal groups of inverse semigroups associated with point sets and with tilings. We focus our attention on two classes of examples. The first class consists of point sets which are obtained by a cut and projection scheme (so-called model sets). Here we introduce another inverse semigroup which is given in terms of the defining data of the pro

Mario Catalani

Determinants and symmetric functions of the eigenvalues of matrices characterizing stochastic processes with indepedent increments. Relationships with Fibonacci numbers are derived.

John B. Little

In a recent paper, I. Selesnick and C.S. Burrus developed a design method for maximally flat FIR low-pass digital filters with reduced group delay. Their approach leads to a system of polynomial equations depending on three integer design parameters $K,L,M$. In certain cases (their ``Region I''), Selesnick and Burrus were able to derive solutions usi

Nikita Sidorov

Given $β\in(1,2)$, a $β$-expansion of a real $x$ is a power series in base $β$ with coefficients 0 and 1 whose sum equals $x$. The aim of this note is to study certain problems related to the universality and combinatorics of $β$-expansions. Our main result is that for any $β\in(1,2)$ and a.e. $x\in (0,1)$ there always exists a universal $β$-expansion of $x$

Nuno Martins, Ricardo Severino, J. Sousa Ramos

We compute the $K$-groups for the Cuntz-Krieger algebras $\mathcal{O}_{A_{\mathcal{K}(f_μ)}}$, where $A_{\mathcal{K}(f_μ)}$ is the Markov transition matrix arising from the \textit{kneading sequence }$\mathcal{K} (f_μ)$ of the one-parameter family of real quadratic maps $f_μ$.

Hartmut Fuehr

Given a representation of a unimodular locally compact group, we discuss criteria for associated coherent state expansions in terms of the commuting algebra. It turns out that for those representations that admit such expansions there exists a unique finite trace on the commuting algebra such that the admissible vectors are precisely the tracial vectors for

Yuri I. Manin

Talk at the meeting of the German Mathematical Society and the Cantor Medal Award Ceremony

Martin B. Einhorn, Finn Larsen

We discuss interacting quantum field theory in de Sitter space and argue that the Mottola-Allen vacuum ambiguity is an artifact of free field theory. The nature of the nonthermality of the MA-vacua is also clarified. We propose analyticity of correlation functions as a fundamental requirement of quantum field theory in curved spacetimes. In de Sitter space,

Thomas Quella

We construct the boundary WZNW functional for symmetry breaking D-branes on a group manifold which are localized along a product of a number of twisted conjugacy classes and which preserve an action of an arbitrary continuous subgroup. These branes provide a geometric interpretation for the algebraic formulation of constructing D-branes developed recently in

G. Delfino, P. Mosconi, G. Mussardo

The two-dimensional ghost systems with negative integral central charge received much attention in the last years for their role in a number of applications and in connection with logarithmic conformal field theory. We consider the free massive bosonic and fermionic ghost systems and concentrate on the non-trivial sectors containing the disorder operators. A

J. W. Moffat

It is generally believed that inflationary cosmology explains the isotropy, large scale homogeneity and flatness as well as predicting the deviations from homogeneity of our universe. We show that this is not the only cosmology which can explain successfully these features of the universe. We consider anew and modify a model in which local Lorentz invariance

Ehud Fuchs, Michael Kroyter, Alon Marcus

We find a new subalgebra of the star product in the matter sector. Its elements are squeezed states whose matrices commute with (K_1)^2. This subalgebra contains a large set of projectors. The states are represented by their eigenvalues and we find a mapping between the eigenvalues representation and other known representations. The sliver is naturally in th

L. Snobl

We construct modular spaces of all 6-dimensional real semisimple Drinfeld doubles, i.e. the sets of all possible decompositions of the Lie algebra of the Drinfeld double into Manin triples. These modular spaces are significantly different from the known one for Abelian Drinfeld double, since some of these Drinfeld doubles allow decomposition into several non

A. Gardestig, A. P. Szczepaniak, J. T. Londergan

A model for deeply virtual Compton scattering, based on analytical light-cone hadron wave functions is presented and studied at energies currently accessible at Jefferson Laboratory and DESY. It is shown that poles and perpendicular vector components play an important role at Q^2 < 10 GeV^2. A Q^2 suppressed diagram has to be included at these low energies,

Andreas S. Kronfeld

After reviewing some of the mathematical foundations and numerical difficulties facing lattice QCD, I review the status of several calculations relevant to experimental high-energy physics. The topics considered are moments of structure functions, which may prove relevant to search for new phenomena at the LHC, and several aspects of flavor physics, which ar

Michael Gronau, Dan Pirjol, Daniel Wyler

We point out that the decays of B mesons into a vector meson and an axial-vector meson can distinguish between left and right-handed polarized mesons, in contrast to decays into two vector mesons. Measurements in B0 -> D*-a1+ are proposed for testing factorization and the V-A structure of the weak b -> c current, and for resolving a discrete ambiguity in 2β+

Markus Diehl, Otto Nachtmann, Felix Nagel

The sensitivity of optimal integrated observables to electroweak triple gauge couplings is investigated for the process e-e+ -> W-W+ -> 4 fermions at future linear colliders. By a suitable reparameterisation of the couplings we achieve that all 28 coupling parameters have uncorrelated statistical errors and are naturally normalised for this process. Discrete

V. Cirigliano, M. Knecht, H. Neufeld, H. Pichl

Within the framework of chiral perturbation theory with virtual photons and leptons, we present an updated analysis of the pionic beta decay including all electromagnetic contributions of order e**2 p**2. We discuss the extraction of the Cabibbo-Kobayashi-Maskawa matrix element |Vud| from experimental data. The method employed here is consistent with the ana

Peter Minkowski, Wolfgang Ochs

In our phenomenological analysis of the spectroscopy of light scalar mesons we do not find compelling evidence for the existence of the low mass κ(900) or σ(600) states nor for f_0(1370) as single resonance. If the f_0(980) and and f_0(1500) are taken as members of the q qbar nonet there remains a broad object formed by f_0(400-1200) and f_0(1370) which is a

A. Pich, J. Portoles

We study a model-independent parameterization of the vector pion form factor that arises from the constraints of analyticity and unitarity. Our description should be suitable up to s^(1/2) ~ 1.2 GeV and allows a model-independent determination of the mass of the rho(770) resonance. We analyse the experimental data on tau^- -> pion^- pion^0 nu_tau and e^+ e^-

Peter Minkowski, Wolfgang Ochs

The hypothesis that there exists a nonet of scalars mainly composed of a valence quark-antiquark pair and mixed according to near singlet-octet separation : f_0 (980) singlet, a_0^{+,0,-} (980), K^{* +,0}_0 (1430), \bar K^{* -,0}_0 (1430), f_0 (1500) octet, is put to further tests from the three body decays D^{\pm}, D_{s}^{\pm} -> PS^{\pm} pi^+ pi^- with PS^

Sandhya Choubey, Abhijit Bandyopadhyay, Srubabati Goswami, D. P. Roy

We study the implication of the first neutral current (NC) data from SNO. We perform model independent and model dependent analyses of the solar neutrino data. The inclusion of the first SNO NC data in the model independent analysis determines the allowed ranges of $^{8}{B}$ flux normalization and the $ν_e$ survival probability more precisely than what was p

H. J. Pirner

We give an overview of the current theoretical status of proper time renormalization group flow equations applied to QCD. These equations give the evolution of coupling constants in an effective QCD Lagrangian as a function of an infra-red cut-off parameter. This parameter characterizes the resolution with which the system is looked at. Decreasing resolution

A. Ferroglia, G. Passarino, M. Passera, S. Uccirati

A detailed investigation is presented of a set of algorithms which form the basis for a fast and reliable numerical integration of one-loop multi-leg (up to six) Feynman diagrams, with special attention to the behavior around (possibly) singular points in phase space. No particular restriction is imposed on kinematics, and complex masses (poles) are allowed.

Hiroaki Sugiyama

Allowed regions on the m_l - cos{2θ_{12}} plane are extracted from results of neutrinoless double beta decay experiments. It is shown that 0.05 eV (0 eV) < m_l < 1.85 eV is obtained for the normal (inverted) hierarchy by using the LMA best fit parameters and the 0νββresult announced late last year, which is 0.05 eV < <m>_ββ< 0.84 eV with +/- 50% uncertainty

Alejandro Cabo

In this note, it is argued that the mass matrix for the six quarks can be generated in first approximation by introducing fermion condensates on the same lines as was done before for gluons, within the modified perturbative expansion for QCD proposed in former works. Thus, the results point in the direction of the conjectured link of the approximate `Democra

C. C. Barros, M. R. Robilotta

We evaluate the long range part of the hyperon form factors and their contribution to elastic pion-hyperon scattering.

J. Fleischer, T. Hahn, W. Hollik, T. Riemann

Electroweak one-loop radiative corrections to the process e^+ e^- -> t tbar are revisited. Two groups from Karlsruhe and Bielefeld/Zeuthen performed independent calculations of both (virtual and soft) QED contributions and weak virtual corrections. For the angular distribution an agreement of at least eight digits for the weak corrections and of at least sev

H. Hansen, G. Chanfray, D. Davesne, P. Schuck

An application of a self-consistent version of RPA to quantum field theory with broken symmetry is presented. Although our approach can be applied to any bosonic field theory, we specifically study the $ϕ^4$ theory in 1+1 dimensions. We show that standard RPA approach leads to an instability which can be removed when going to a superior version,i.e. the reno

George T. Fleming, Daniel R. Nelson, Gregory W. Kilcup

Last year, we reported our first results on the determination of Gasser-Leutwyler coefficients using partially quenched lattice QCD with three flavors of dynamical staggered quarks. We give an update on our progress in determining two of these coefficients, including an exhaustive effort to estimate all sources of systematic error. At this conference, we hav

Simon Hands, David N. Walters

We present results of numerical simulations of the 3+1d Nambu - Jona-Lasinio model with a non-zero baryon chemical potential mu, with particular emphasis on the superfluid diquark condensate and associated susceptibilities. The results, when extrapolated to the zero diquark source limit, are consistent with the existence of a non-zero BCS condensate at high

J. Greensite, S. Olejnik

We discuss two issues related to the physics of center vortices in pure SU(N) lattice gauge theory at large N: (1) Center vortices are stable classical solutions of the Wilson action, as well as of a wide class of improved lattice actions, for any N > 4. (2) The natural scaling of k-string tensions at large N, in the vortex picture of confinement, is σ(k)=k

V. G. Bornyakov, S. M. Morozov, M. I. Polikarpov

We study propagators of diagonal and off-diagonal gluons in the momentum space in maximal abelian gauge of SU(2) lattice gauge theory. Remaining U(1) degrees of freedom are fixed using Landau gauge. We find substantial difference between the propagator of the diagonal and the off-diagonal gluon in the infrared region. The propagator of the off-diagonal gluon

The OPAL collaboration, G. Abbiendi

Charged particle momentum distributions are studied in the reaction e+e- -> hadrons, using data collected with the OPAL detector at centre-of-mass energies from 192 GeV to 209 GeV. The data correspond to an average centre-of- mass energy of 201.7 GeV and a total integrated luminosity of 433 pb-1. The measured distributions and derived quantities, in combinat

Mario D. Leberig

One of the important goals of the COMPASS experiment is the determination of the gluonic contribution to the spin of the nucleon. By using the photon gluon fusion (PGF) process in polarised deep inelastic scattering direct access to the gluon polarisation can be obtained. The PGF is selected via the detection of open charm or high $p_T$ hadron pairs. In 2001

Ian C. Brock

I present a small selection of the many QCD studies that have been performed at HERA. I concentrate on results that have been made available in the past year. Results are presented on the QCD description of the parton density functions, determinations of alpha_S, jets and heavy flavour production. Where possible comparisons are made with next to leading orde

Giampiero Mancinelli

We report on preliminary results of searches for penguin mediated B decays based on 20.7 fb^{-1} of data collected at the Y(4S) peak with the BABAR detector at PEP-II. The following branching fractions have been measured: BR(B+ --> phi K+) = (7.7^{+1.6}_{-1.4} +- 0.8)*10^{-6}, BR(B0 --> phi K0) = (8.1^{+3.1}_{-2.5} +- 0.8)*10^{-6}, BR(B+ --> phi K*+) = (9.7^

M. Sioli

The MACRO experiment detected more than 300000 multiple muon events. We analysed these events to measure the distribution of the separation of underground TeV muons (decoherence function), up to a distance of 70 meters. On a subsample of very high multiplicity events, we performed two independent analyses, based on the study of the spatial structure of the b

Alexei Raspereza

This paper shortly reports on the results of Higgs boson searches performed at LEP and Tevatron. No signal is found and limits on the mass and couplings of the Higgs boson are derived. Interpreting the data in the framework of the Standard Model, the 95% C.L. lower limit of 114.4 GeV on the Higgs boson mass is obtained.

R. Chan, M. F. A. da Silva, Jaime F. Villas da Rocha

A class of solutions to Einstein field equations is studied, which represents gravitational collapse of thick spherical shells made of self-similar and shear-free fluid with heat flow. It is shown that such shells satisfy all the energy conditions, and the corresponding collapse always forms naked singularities.

I. G. Dymnikova, M. L. Fil&#39;chenkov

We consider the quantum birth of a hot FRW universe from a vacuum-dominated quantum fluctuation with admixture of radiation and strings, which correspond to quantum tunnelling from a discrete energy level with a non-zero temperature. The presence of strings with the equation of state $p=-ε/3$ mimics a positive curvature term which makes it possible, in the c

V. B. Braginsky, S. E. Strigin, S. P. Vyatchanin

We present the analysis of a nonlinear effect of parametric oscillatory instability in power recycled LIGO interferometer with the Fabry-Perot (FP) cavities in the arms. The basis for this effect is the excitation of the additional (Stokes) optical mode and the mirror elastic mode, when the optical energy stored in the main FP cavity main mode exceeds the ce

Paul Prekop, Mark Burnett

Context and context-awareness provides computing environments with the ability to usefully adapt the services or information they provide. It is the ability to implicitly sense and automatically derive the user needs that separates context-aware applications from traditionally designed applications, and this makes them more attentive, responsive, and aware o

J. C. Campuzano, M. R. Norman, M. Randeria

We review angle resolved photoemission spectroscopy (ARPES) results on the high Tc superconductors, focusing primarily on results obtained on the quasi-two dimensional cuprate Bi2Sr2CaCu2O8 and its single layer counterpart Bi2Sr2CuO6. The topics treated include the basics of photoemission and methodologies for analyzing spectra, normal state electronic struc

Gemunu H. Gunaratne, Joseph L. McCauley

A new theory for pricing options of a stock is presented. It is based on the assumption that while successive variations in return are uncorrelated, the frequency with which a stock is traded depends on the value of the return. The solution to the Fokker-Planck equation is shown to be an asymmetric exponential distribution, similar to those observed in intra

Y. Moreno, R. Pastor-Satorras, A. Vazquez, A. Vespignani

We study the tolerance to congestion failures in communication networks with scale-free topology. The traffic load carried by each damaged element in the network must be partly or totally redistributed among the remaining elements. Overloaded elements might fail on their turn, triggering the occurrence of failure cascades able to isolate large parts of the n

B. Grabiec, M. Matlak

We investigate superconducting systems with the use of the phenomenological Landau&#39;s theory of second order phase transitions, including into the considerations the critical behaviour of the chemical potential. We derive in this way a variety of new thermodynamical relations at the critical point. Twelve basic relations connect critical jumps of differen

Olivier Deloubriere, Henk Hilhorst, Uwe C. Tauber

We consider diffusion-limited reactions A_i + A_j -> 0 (1 <= i < j <= q) in d space dimensions. For q > 2 and d >= 2 we argue that the asymptotic density decay for such mutual annihilation processes with equal rates and initial densities is the same as for single-species pair annihilation A + A -> 0. In d = 1, however, particle segregation occurs for all q <

M. Matlak, B. Grabiec

We consider systems which exhibit typical critical dependence of the specific heat: $Δc\varpropto (T_C-T)^{-γ}$ ($T<T_C$); $Δc\varpropto (T-T_C)^{-γ^{\prime}}$ ($T>T_C$) where $γ$,$γ^{\prime}$ are critical exponents ($γ=α$ for $Δc=Δc_{p,N},$ $γ=\barα$ for $Δc=Δc_{V,N}$), as well as, the case when $Δc\varpropto (\ln \mid T_C-T\mid)^a$ ($% a=\frac 13$, uniaxia

P. Martinez-Samper, H. Suderow, S. Vieira, J. P. Brison

We present scanning tunneling spectroscopy and microscopy measurements at low temperatures in the borocarbide materials RNi2B2C (R=Y, Lu). The characteristic strong coupling structure due to the pairing interaction is unambiguously resolved in the superconducting density of states. It is located at the superconducting gap plus the energy corresponding to a p

S. Salem-Sugui,, Mark Friesen, A. D. Alvarenga, F. G. Gandra

We have performed a magnetic study of a bulk metallic sample of Nb with critical temperature $T_{c}=8.5$ K. Magnetization versus temperature (M {\it vs} T) data obtained for fixed magnetic fields above 1 kOe show a superconducting transition which becomes broader as the field is increased. The data are interpreted in terms of the diamagnetic lowest Landau le

D. H. E. Gross

Equilibrium statistics of Hamiltonian systems is correctly described by the microcanonical ensemble, whereas canonical ones fail in the most interesting, mostly inhomogeneous, situations like phase separations or away from the thermodynamic ``limit&#39;&#39; (e.g. self-gravitating systems and small quantum systems). A new derivation of the Second Law is pres

I. Baladie, A. Buzdin

The theoretical description of the thermodynamic properties of ferromagnetic/superconductor/ferromagnetic (F/S/F) systems of nanoscopic scale is proposed. Their superconducting characteristics strongly depend on the mutual orientation of the ferromagnetic layers. In addition, depending on the transparency of S/F interfaces, the superconducting critical tempe

A. E. Hansen, A. Kristensen, H. Bruus

Detailed experimental studies of the conductance of mesoscopic GaAs devices in the few-mode regime reveal a novel thermal effect: for temperatures up to at least 10 K the measured gate characteristics, i.e. conductance $G$ versus gate voltage $V_g$, exhibit a systematic downward shift in gate voltage with increasing temperature. The effect is &#39;universal&

Toshimasa Fujisawa, David Guy Austing, Yasuhiro Tokura, Yoshiro Hirayama

The strength of radiative transitions in atoms is governed by selection rules. Spectroscopic studies of allowed transitions in hydrogen and helium provided crucial evidence for the Bohr&#39;s model of an atom. Forbidden transitions, which are actually allowed by higher-order processes or other mechanisms, indicate how well the quantum numbers describe the sy

S. I. Shevchenko

It is shown that in a magnetic field the vortices in superfluid electron-hole systems carry a real electrical charge. The charge value depends on the relation between the magnetic length and the Bohr radiuses of electrons and holes. In double layer systems at equal electron and hole filling factors in the case of the electron and hole Bohr radiuses much larg

T. Fukui

We study a Dirac fermion model with a random vector field, especially paying attention to a strong disorder regime. Applying the bosonization techniques, we first derive an equivalent sine-Gordon model, and next average over the random vector field using the replica trick. The operator product expansion based on the replica action leads to scaling equations

Brandon P. van Zyl, Rajat K. Bhaduri, Akira Suzuki, Matthias Brack

We present closed analytical expressions for the particle and kinetic energy spatial densities at finite temperatures for a system of noninteracting fermions (bosons) trapped in a d-dimensional harmonic oscillator potential. For d=2 and 3, exact expressions for the N-particle densities are used to calculate perturbatively the temperature dependence of the sp

P. Quemerais, J. -L. Raimbault, S. Fratini

On doping polar dielectrics, such as the cuprates or liquid ammonia, the long range polarization leads to the formation of bound states (polarons or solvated electrons). However, the exact role of such entities in the metal-insulator transition (MIT) still remains unclear. We suggest that the driving mechanism of the MIT is a polarization catastrophe that oc

G. Trambly de Laissardière, D. Nguyen-Manh, D. Mayou

The effect on the electronic structure of an indirect Mn-Mn interaction mediated by the valence states and the sp-d hybridisation is presented. In Al(rich)-Mn phases related to quasicrystals (Al12Mn, o-Al6Mn, alpha-Al9Mn2Si), this indirect interaction creates a Hume-Rothery pseudogap in the density of states together with a minimisation of the band energy. I

S. H. Naqib, J. R. Cooper, J. L. Tallon, C. Panagopoulos

The effects of planar hole concentration, p, and in-plane disorder, Zn (y), on the DC resistivity, r(T), of sintered samples of Y_{1-x}Ca_xBa_2(Cu_{1-y}Zn_y)_3O_{7-d} were investigated over a wide doping range by changing both the oxygen deficiency (d) and Ca content (x). From the r(T,p) data we extracted characteristic crossover temperatures on the underdop

Yu Zhu, Qing-feng Sun, Tsung-han Lin

We report on a new type of Fano effect, named as Andreev-Fano effect, in a hybrid normal-metal / superconductor (N/S) interferometer embedded with a quantum dot. Compared with the conventional Fano effect, Andreev-Fano effect has some new features related to the characteristics of Andreev reflection. In the linear response regime, the line shape is the squar

F. Capurro, M. Polini, M. P. Tosi

The imaginary part of the exchange-correlation kernel in the longitudinal current-current response function of a quasi-onedimensional Fermi liquid is evaluated by an approximate decoupling in the equation of motion for the current density, which accounts for processes of excitation of two particle-hole pairs. The two-pair spectrum determines the intrinsic da

F. Venturini, Q. -M. Zhang, R. Hackl, A. Lucarelli

Raman and Infrared (IR) spectra of an underdoped La_{1.90}Sr_{0.10}CuO_{4} single crystal have been measured as a function of temperature. Both techniques provide unconventional low-energy spectra. The IR conductivity exhibits features peaked at finite frequencies which do not have a counterpart in the Raman response. Below approximately 100 K a transfer of

Ugo Bastolla, Markus Porto, H. Eduardo Roman, Michele Vendruscolo

We simulate neutral evolution of proteins imposing conservation of the thermodynamic stability of the native state in the framework of an effective model of folding thermodynamics. This procedure generates evolutionary trajectories in sequence space which share two universal features for all of the examined proteins. First, the number of neutral mutations fl

A. Yu. Kasumov, D. V. Klinov

Debates about conductivity of DNAs have been recently renewed due to contradictory results of direct measurements by use of electrical contacts to molecules. In several works it was discovered that double-stranded (ds)DNAs are conductors: metals or semiconductors [1-6]. However in other works [7] the absence of DNAs conductivity has been observed even for th

Arne Soulier, Tim Halpin-Healy

We explore a generalized Seceder Model with variable size selection groups and higher dimensional genotypes, uncovering its well-defined mean-field limiting behavior. Mapping to a discrete, deterministic version, we pin down the upper critical size of the multiplet selection group, characterize all relevant dynamically stable fixed points, and provide a comp

M. Mezard, F. Ricci-Tersenghi, R. Zecchina

We derive analytical solutions for p-spin models with finite connectivity at zero temperature. These models are the statistical mechanics equivalent of p-XORSAT problems in theoretical computer science. We give a full characterization of the phase diagram: location of the phase transitions (static and dynamic), together with a description of the clustering p

Horst Meyer

A discussion is presented on the crossover of the susceptibility from mean-field to Ising critical behavior upon approaching the critical point from below and from above Tc, both for He3 and Xe. Fits of the experimental susceptibility data are made to curves from Monte Carlo simulations, and the corresponding Ginzburg numbers Gi for each measured property i

R. Lynne Allen, Gary Bernstein, Renu Malhotra

Almost all of the $>600$ known Kuiper belt objects (KBOs) have been discovered within 50 AU of the Sun. One possible explanation for the observed lack of KBOs beyond 50 AU is that the distant Kuiper belt is dynamically very cold, and thus thin enough on the sky to have slipped between previous deep survey fields. We have completed a survey designed to search

P. Hoeflich

Parallel computing has turned out to be the enabling technology to solve complex physical systems. However, the transition from shared memory, vector computers to massively parallel, distributed memory systems and, recently, to hybrid systems poses new challenges to the scientist. We want to present a cook-book (with a very strong, personal bias) based on ou

Marc Davis, Sandra M. Faber, Jeffrey A. Newman, Andrew C. Phillips

The DEIMOS spectrograph has now been installed on the Keck-II telescope and commissioning is nearly complete. The DEEP2 Redshift Survey, which will take approximately 120 nights at the Keck Observatory over a three year period and has been designed to utilize the power of DEIMOS, began in the summer of 2002. The multiplexing power and high efficiency of DEIM

Howard E. Bond, Don L. Pollacco, Ronald F. Webbink

WeBo 1 (PN G135.6+01.0), a previously unrecognized planetary nebula with a remarkable thin-ring morphology, was discovered serendipitously on Digitized Sky Survey images. The central star is found to be a late-type giant with overabundances of carbon and s-process elements. The giant is chromospherically active and photometrically variable, with a probable p

Edward W. Thommes, Jack J. Lissauer

A planetary system may undergo significant radial rearrangement during the early part of its lifetime. Planet migration can come about through interaction with the surrounding planetesimal disk and the gas disk--while the latter is still present--as well as through planet-planet interactions. We review the major proposed migration mechanisms in the context o

C. Vignali, D. M. Alexander, F. E. Bauer, W. N. Brandt

Understanding the nature of Extremely Red Objects [EROs; (I-K)>=4] is one of the most challenging issues in observational cosmology. Here we report on the X-ray constraints provided by the 2 Ms Chandra Deep Field-North Survey (CDF-N). X-ray emission has been detected from 11 out of 36 EROs (approx 30%). Five of these have hard X-ray emission and appear to be

Dae-Sik Moon, Stephen S. Eikenberry, Ira M. Wasserman

We present Rossi X-ray Timing Explorer observations of the X-ray pulsar SMC X-1. The source is highly variable on short time scales (< 1 h), exhibiting apparent X-ray flares occupying a significant fraction (~3 %) of the total observing time, with a recurrence time of ~100 s. The flares seem to occur over all binary orbital phases, and correlate with the ove

Dusan Keres, Min S. Yun, J. S. Young

We derive a non-parametric CO luminosity function using a FIR and an optical B-band selected sample of the galaxies included in the FCRAO Extragalactic CO Survey. The FIR selected sample is defined using the IRAS Bright Galaxy Surveys (BGS; IRAS 60 micron flux density >= 5.24 Jy). Although our CO sample is not complete, the normalization using the BGS reprod

Jason Pruet, S. E. Woosley, R. D. Hoffman

We follow the nuclear reactions that occur in the accretion disks of stellar mass black holes that are accreting at a very high rate, 0.01 to 1 solar masses per second, as is realized in many current models for gamma-ray bursts (GRBs). The degree of neutronization in the disk is a sensitive function of the accretion rate, black hole mass, Kerr parameter, and

Rachel S. Somerville

In this paper, I discuss the capabilities and limitations of an 8-10 meter ultraviolet/optical telescope in space, the proposed successor to the Hubble Space Telescope, in the context of galaxy studies. The exquisite spatial resolution and excellent sensitivity of such a facility would open up new possibilities for the study of nearby dwarf galaxies ($z \la

Rachel S. Somerville

We investigate the properties of a galaxy similar to the Milky Way within the context of standard disk formation theory in a LCDM universe. Using the standard assumption that baryons conserve specific angular momentum when they collapse, we conclude that the mean properties of the model galaxies are in good agreement with the Milky Way and other similar spir

V. F. Dmitriev, V. V. Flambaum

We discuss limits on variation of $(m_q/Λ_{QCD})$. The results are obtained by studying $n-α$-interaction during Big Bang, Oklo natural nuclear reactor data and limits on variation of the proton $g$-factor from quasar absorpion spectra.

A. Grazian, S. Cristiani, A. Omizzolo

The AERQS is a project aimed at the construction of an all-sky statistically well-defined sample of local (z < 0.3) and bright (R < 15.5) QSOs. Present uncertainties on the theoretical modeling of the QSO evolution are to be ascribed to the relatively small number of objects observed in this magnitude and redshift domain. We are filling this gap with a sampl

Frederic Bournaud, Francoise Combes

Formation scenarios for polar ring galaxies are studied through N-body simulatio ns that are compared with existing observations. It is shown that polar rings ar e likely to be formed by tidal accretion of the polar material from a gas rich d onor galaxy. The distribution of dark matter in polar ring galaxies is studied: dark halos seem to be flattened towar

David L. Block, Frederic Bournaud, Francoise Combes, Ivanio Puerari

The distribution of gravitational torques and bar strengths in the local Universe is derived from a detailed study of 163 galaxies observed in the near-infrared. The results are compared with numerical models for spiral galaxy evolution. It is found that the observed distribution of torques can be accounted for only with external accretion of gas onto spiral

Matthew K. Browning, Jason Tumlinson, J. Michael Shull

We have developed a code that models the formation, destruction, radiative transfer, and vibrational/rotational excitation of H_2 in a detailed fashion. We discuss how such codes, together with FUSE observations of H_2 in diffuse and translucent lines of sight, may be used to infer various physical parameters. We illustrate the effects of changes in the majo