Research archive

arXiv papers from June 2004

The most recent 100 records published that month. Open any paper for its original abstract, citation metadata, related research, and reading tools.

  1. L. K. Chavda, Abhijit L. Chavda

    We prove that the primordial black holes in the early universe did not decay until the gravity decoupled from the other interactions. Rabinowitz' two objections to the formation of Holeums are shown to be inapplicable. We show that primordial black holes having masses beween 8x10^18 GeV and 10^19 GeV formed gravitational bound states called Holeums when the

  2. Claude Ederer, Nicola A. Spaldin

    We analyze the coupling between the ferroelectric and magnetic order parameters in the magnetoelectric multiferroic BiFeO_3 using density functional theory within the local spin density approximation and the LSDA+U method. We show that weak ferromagnetism of the Dzyaloshinskii-Moriya type occurs in this material, and we analyze the coupling between the resul

  3. B. Aubert

    The branching fractions of the decays B->K*0,gamma and B->K*+,gamma are measured using a sample of 88 x 10^6 B\bar{B} events collected with the BaBar detector at the PEP-II asymmetric-energy e^+e^- collider. We find B(B->K*0,gamma) = 3.92 +/- 0.20 (stat) +/- 0.24 (syst) x 10^{-5} and B(B->K*_,gamma) = 3.87 +/- 0.28 (stat) +/- 0.26 (syst) x 10^{-5}. Our measu

  4. Jan Stark

    The Fermilab Tevatron (p pbar), operating at sqrt(s)=1.96 TeV, is a rich source of B hadrons. The large acceptance in terms of rapidity and transverse momentum of the charged particle tracking system and the muon system make the upgraded Run II D0 detector an excellent tool for B physics. In this article, we report on selected physics results based on the fi

  5. K. M. Shen, F. Ronning, D. H. Lu, W. S. Lee

    The evolution of Ca$_{2-x}$Na$_{x}$CuO$_{2}$Cl$_{2}$ from Mott insulator to superconductor was studied using angle-resolved photoemission spectroscopy. By measuring both the excitations near the Fermi energy as well as non-bonding states, we tracked the doping dependence of the electronic structure and the chemical potential with unprecedented precision. Our

  6. Yevgeniy Kovchegov

    We consider a multi-particle generalization of linear edge-reinforced random walk (ERRW). We observe that in absence of exchangeability, new techniques are needed in order to study the multi-particle model. We describe an unusual coupling construction associated with the two-point edge-reinforced process on Z and prove a form of recurrence: the two particles

  7. Dennis Zaritsky, Jason Harris, Ian B. Thompson, Eva K. Grebel

    We present our catalog of U, B, V, and I stellar photometry of the central 64 sq. deg. area of the Large Magellanic Cloud. Internal and external astrometric and photometric tests using existing optical photometry (U, B, and V from Massey's bright star catalog and I from the near-infrared sky survey DENIS) are used to confirm our observational uncertainty est

  8. Yevgeniy Kovchegov

    We introduce the mathematical theory of the particle systems that interact via permutations, where the transition rates are assigned not to the jumps from a site to a site, but to the permutations themselves. This permutation processes can be viewed as a generalization of the symmetric exclusion processes, where particles interact via transpositions. The dua

  9. Abigail G. Mitchell

    Rook polynomials are a powerful tool in the theory of restricted permutations. It is known that the rook polynomial of any board can be computed recursively, using a cell decomposition technique of Riordan. In this paper, we give a new decomposition theorem, which yields a more efficient algorithm for computing the rook polynomial. We show that, in the worst

  10. R. P. Panguluri, Changgan Zeng, H. H. Weitering, J. M. Sullivan

    Germanium-based alloys hold great promise for future spintronics applications, due to their potential for integration with conventional Si-based electronics. Mn5Ge3 exhibits strong ferromagnetism up to the Curie temperature Tc~295K. We use Point Contact Andreev Reflection (PCAR) spectroscopy to measure the spin polarization of Mn5Ge3 epilayers grown by solid

  11. Regina Demina

    CDF and D0 collaborations analyzed up to 200 pb-1 of the delivered data in search for different supersymmetry signatures, so far with negative results. We present results on searches for chargino and neutralino associated production, squarks and gluinos, sbottom quarks, gauge mediated SUSY breaking and long lived heavy particles.

  12. Eli Dwek

    The extinction curve derived from ISO mid-infrared (IR) observations of the Galactic center (GC) exhibits a surprisingly flat behavior in the ~ 3 to 8 micron region, contrary to the deep minimum expected from standard interstellar dust models consisting of bare silicate and graphite dust particles. We show that this extinction is likely caused by the presenc

  13. Frank Calegari

    We prove R = T theorems for certain reducible residual Galois representations. We answer in the positive a question of Gross and Lubin on whether certain Hecke algebras T are discrete valuation rings. In order to prove these results we determine (using the theory of Breuil modules) when two finite flat group schemes G and H of order p over an arbitrarily tam

  14. Ronald J. Allen

    Young massive stars produce Far-UV photons which dissociate the molecular gas on the surfaces of their parent molecular clouds. Of the many dissociation products which result from this ``back-reaction'', atomic hydrogen \HI is one of the easiest to observe through its radio 21-cm hyperfine line emission. In this paper I first review the physics of this proce

  15. T. Binoth

    We discuss algebraic/numeric methods to compute one-loop corrections for multiparticle/jet production cross sections. By using efficient reduction algorithms a compact expression for the ggg\gamma\gamma -> 0 amplitude is obtained. Further a numerical approach for 6-point 1-loop diagrams is presented.

  16. Katherine M. Benson, Tom Imbo

    Symmetry breaking can produce ``Alice'' strings, which alter scattered charges and carry monopole number and charge when twisted into loops. Alice behavior arises algebraically, when strings obstruct unbroken symmetries -- a fragile criterion. We give a topological criterion, compelling Alice behavior or deforming it away. Our criterion, that \pi_o(H) acts n

  17. R. Mauersberger, U. Ott, C. Henkel, J. Cernicharo

    The J=2-1 and 3-2 rotational lines of the rare isotopomer C36S and the J=5-4 and 6-5 transitions of Si36S were detected in the carbon star IRC+10216 (CW Leo). These are the first detections of 36S bearing molecules in a star and the first spectroscopic detection of Si36S. From a comparison of 34S and 36S bearing isotopomers, th 34S/36S isotopic ratio is 107(

  18. Jean-Philippe Jourdan

    For a smooth manifold A, we consider the ordered configuration space F_k(AxR) of k distinct points in AxR. We obtain an explicit homotopy construction of the configuration space F_k(AxR) and of the (k-2)-fold suspension of F_k(A). Under certain conditions, we then show that the homotopy types of these two spaces depend only on the homotopy type of A. ----- P

  19. M. Gronau, J. Zupan

    Defining a most economical parametrization of time-dependent B-> rho^\pm pi^\mp decays, including a measurable phase alpha_{eff} which equals the weak phase alpha in the limit of vanishing penguin amplitudes, we propose two ways for determining alpha in this processes. We explain the limitation of one method, assuming only that two relevant tree amplitudes f

  20. G. L. Kane, Brent D. Nelson, Lian-Tao Wang, Ting T. Wang

    We study the implications for the minimal supersymmetric standard model (MSSM) of the absence of a direct discovery of a Higgs boson at LEP. First we exhibit 15 physically different ways in which one or more Higgs bosons lighter than the LEP limit could still exist. For each of these cases -- as well as the case that the lightest Higgs eigenstate is at, or s

  21. Dimitri Veras, Philip J. Armitage

    The significant orbital eccentricities of most giant extrasolar planets may have their origin in the gravitational dynamics of initially unstable multiple planet systems. In this work, we explore the dynamics of two close planets on inclined orbits through both analytical techniques and extensive numerical scattering experiments. We derive a criterion for tw

  22. Boris Y. Rubinstein

    Explicit expressions for restricted partition function $W(s,{\bf d}^m)$ and its quasiperiodic components $W_j(s,{\bf d}^m)$ (called Sylvester waves) for a set of positive integers ${\bf d}^m = \{d_1, d_2, ..., d_m\}$ are derived. The formulas are represented in a form of a finite sum over Bernoulli polynomials of higher order with periodic coefficients.

  23. Jay Strader, Jean P. Brodie

    We present a principal components analysis (PCA) of high-quality Lick/IDS absorption-line measurements for 11 indices in the wavelength range 4100-5400 Ang for 39 Galactic globular clusters (GCs). Only the first principal component appears to be physically significant. We find that there is a tight linear relationship between this first component (PC1) and G

  24. the STAR Collaboration, J. Adams

    Correlations in the hadron distributions produced in relativistic Au+Au collisions are studied in the discrete wavelet expansion method. The analysis is performed in the space of pseudorapidity (|eta| < 1) and azimuth (full 2 pi) in bins of transverse momentum (p_t) from 0.14 < p_t < 2.1 GeV/c. In peripheral Au+Au collisions a correlation structure ascribed

  25. Zhengfeng Ji, Runyao Duan, Mingsheng Ying

    We prove, in a multipartite setting, that it's always feasible to exactly transform a genuinely $m$-partite entangled state with sufficient many copies to any other $m$-partite state via local quantum operation and classical communication. This result affirms the comparability of multipartite pure entangled states.

  26. J C Brown, J P Cassinelli, Q Li, A F Kholtygin

    The hot star wind momentum problem \eta = mdot*vinfty/(L/c) >> 1 is revisited, and it is shown that the conventional belief, that it can be solved by a combination of clumping of the wind and multiple scattering of photons, is not self-consistent for optically thick clumps. Clumping does reduce the mass loss rate mdot, and hence the momentum supply, required

  27. William E. Baylis

    A century after its formulation by Einstein, it is time to incorporate special relativity early in the physics curriculum. The approach advocated here employs a simple algebraic extension of vector formalism that generates Minkowski spacetime, displays covariant symmetries, and enables calculations of boosts and spatial rotations without matrices or tensors.

  28. Constantin V. Usenko

    The Wigner function of quantum systems is an effective instrument to construct the approximate classical description of the systems for which the classical approximation is possible. During the last time, the Wigner function formalism is applied as well to seek indications of specific quantum properties of quantum systems leading to impossibility of the clas

  29. A. M. Zagoskin, M. Grajcar, A. N. Omelyanchouk

    We predict a novel effect in a quantum two-level system (TLS) coupled to a resonant cavity. By bringing the TLS in and out of resonance with the cavity by a series of $N$ rectangular bias pulses (the length of the $m$th pulse scaling as $1/\sqrt{m}$), we will coherently excite the $N$-photon state, $|N,$ of the cavity only if the TLS was initially in an appr

  30. Charles P. Boyer, Krzysztof Galicki, Paola Matzeu

    We study eta-Einstein geometry as a class of distinguished Riemannian metrics on contact metric manifolds. In particular, we use a previous solution of the Calabi problem for Sasakian geometry to prove the existence of eta-Einstein structures on many different compact manifolds, including exotic spheres. We also relate these results to the existence of Einst

  31. Yaakov S. Weinstein, Timothy F. Havel, Joseph Emerson, Nicolas Boulant

    The results of quantum process tomography on a three-qubit nuclear magnetic resonance quantum information processor are presented, and shown to be consistent with a detailed model of the system-plus-apparatus used for the experiments. The quantum operation studied was the quantum Fourier transform, which is important in several quantum algorithms and poses a

  32. B. Kocsis, G. Palla, J. Cserti

    We study the energy level structure of two-dimensional charged particles in inhomogeneous magnetic fields. In particular, for magnetic anti-dots the magnetic field is zero inside the dot and constant outside. Such a device can be fabricated with present-day technology. We present detailed semiclassical studies of such magnetic anti-dot systems and provide a

  33. J. Kowalski-Glikman, Lee Smolin

    We describe an extension of special relativity characterized by {\it three} invariant scales, the speed of light, $c$, a mass, $\kappa$ and a length $R$. This is defined by a non-linear extension of the Poincare algerbra, $\cal A$, which we describe here. For $R\to \infty$, $\cal A$ becomes the Snyder presentation of the $\kappa$-Poincare algebra, while for

  34. Si-Qi Liu, Youjin Zhang

    We prove in this paper the quasitriviality of a class of deformations of the one component bihamiltonian structures of hydrodynamic type.

  35. T. Mizuno, T. Kamae, G. Godfrey, T. Handa

    Cosmic-ray background fluxes were modeled based on existing measurements and theories and are presented here. The model, originally developed for the Gamma-ray Large Area Space Telescope (GLAST) Balloon Experiment, covers the entire solid angle (${\rm 4\pi sr}$), the sensitive energy range of the instrument (${\rm \sim 10 MeV to 100 GeV}$) and abundant compo

  36. Chia-Chen Chang, Gun Sang Jeon, Jainendra K. Jain

    When two-dimensional electrons are subjected to a very strong magnetic field, they are believed to form a triangular Wigner crystal. We demonstrate that, in the entire crystal phase, this crystal is very well represented by a composite-fermion-crystal wave function, revealing that it is not a simple Hartree-Fock crystal of electrons but an inherently quantum

  37. T. Shi, Z. Song, C. P. Sun

    We make a novel observation about the decoherence phenomenon of the fermion in the Witten's supersymmetric (SUSY) quantum mechanical model. It is shown that, when the bosonic partner in the SUNY model is unobservable in a certain energy scale, the quantum coherence meant by the superposition of fermion states can not be preserved for a long time due to the q

  38. STAR Collaboration, J. Adams

    We present the first measurements of charge-dependent correlations on angular difference variables $\eta_1 - \eta_2$ (pseudorapidity) and $\phi_1 - \phi_2$ (azimuth) for primary charged hadrons with transverse momentum $0.15 \leq p_t \leq 2$ GeV/$c$ and $|\eta| \leq 1.3$ from Au-Au collisions at $\sqrt{s_{NN}} = 130$ GeV. We observe correlation structures no

  39. Stefano Maghini, Alberto Santambrogio, Daniela Zanon

    We compute the two-point function of Konishi-like operators up to one-loop order, in N=4 supersymmetric Yang-Mills theory. We work perturbatively in N=1 superspace. We find the expression expected on the basis of superconformal invariance and determine the normalization of the correlator and the anomalous dimension of the operators to order g^2 in the coupli

  40. S. Fujii, H. Kamada, R. Okamoto, K. Suzuki

    Binding energies of ^{3}H, ^{4}He, and ^{16}O are calculated, using low-momentum nucleon-nucleon interactions (V_{low-k}) for a wide range of the cutoff momentum \Lambda. In addition, single-particle energies in nuclei around ^{16}O are computed. The dependence of the binding energies and the single-particle energies in these nuclei on the cutoff momentum \L

  41. Valentin Deaconu

    Given a compact space X and two commuting continuous open surjective maps sigma_1, sigma_2 : X --> X, we construct certain C*-algebras that reflect the dynamics of the N^2-action. When the maps sigma_1, sigma_2 are local homeomorphisms, these are groupoid algebras, but in general, we will use a Cuntz-Pimsner algebra associated to a product system of Hilbert

  42. V. Rotger, A. Skorobogatov, A. Yafaev

    We show how to construct counter-examples to the Hasse principle over the field of rational numbers on Atkin-Lehner quotients of Shimura curves and on twisted forms of Shimura curves by Atkin-Lehner involutions. A particular example is the quotient of the Shimura curve X attached to the indefinite rational quaternion algebra of discriminant 23*107 by the Atk

  43. R. P. Ojha, A. R. Abate, D. J. Durian

    The dynamics of a sphere fluidized in a nearly-levitating upflow of air were previously found to be identical to those of a Brownian particle in a two-dimensional harmonic trap, consistent with a Langevin equation [Ojha {\it et al.}, Nature {\bf 427}, 521 (2004)]. The random forcing, the drag, and the trapping potential represent different aspects of the int

  44. Dominik Janzing, Pawel Wocjan

    We propose a (theoretical ;-) model for quantum computation where the result can be read out from the time average of the Hamiltonian dynamics of a 2-dimensional crystal on a cylinder. The Hamiltonian is a spatially local interaction among Wigner-Seitz cells containing 6 qubits. The quantum circuit that is simulated is specified by the initialization of prog

  45. Giulio Chiribella, Giacomo Mauro D'Ariano

    We consider the convex set of positive operator valued measures (POVM) which are covariant under a finite dimensional unitary projective representation of a group. We derive a general characterization for the extremal points, and provide bounds for the ranks of the corresponding POVM densities, also relating extremality to uniqueness and stability of optimiz

  46. Mario Leandro Aolita, Ignacio Garcia-Mata, Marcos Saraceno

    We study many-qubit generalizations of quantum noise channels that can be written as an incoherent sum of translations in phase space. Physical description in terms of the spectral properties of the superoperator and the action in phase space are provided. A very natural description of decoherence leading to a preferred basis is achieved with diffusion along

  47. Geraldine Servant

    We address the problem of baryon number violation in Randall-Sundrum backgrounds and provide a solution leading to a stable light Kaluza--Klein fermion in warped GUT. This adds to the list of dark matter candidates which stability can follow from ensuring proton stability in weak scale extensions of the Standard Model

  48. Vadim E. Levit, Eugen Mandrescu

    If for any $k$ the $k$-th coefficient of a polynomial I(G;x) is equal to the number of stable sets of cardinality $k$ in the graph $G$, then it is called the independence polynomial of $G$ (Gutman and Harary, 1983). Let $a$ be the size of a maximum stable set. Alavi, Malde, Schwenk and Erdos (1987)conjectured that I(T,x) is unimodal for any tree T, while, in

  49. F. A. B. F. de Moura, M. L. Lyra, F. Dominguez-Adame, V. A. Malyshev

    We study the dynamics of an electron subjected to a static uniform electric field within a one-dimensional tight-binding model with a slowly varying aperiodic potential. The unbiased model is known to support phases of localized and extended one-electron states separated by two mobility edges. We show that the electric field promotes sustained Bloch oscillat

  50. Vasili Perebeinos, Marshall Newton

    We use first principles density functional theory to calculate the electronic structure of the phenylthiolate (S-C$_6$H$_5$) self-assembled monolayer (SAM) on Cu(111) and Au(111) substrates. We find significant lateral dispersion of the SAM molecular states and discuss its implications for transport properties of the molecular wire array. We calculate the tw

  51. A. Denner, S. Dittmaier, M. Roth, M. M. Weber

    Some of the most interesting Higgs-production processes at future e+ e- colliders are of the type e+ e- -> f anti-f H. We present a calculation of the complete O(alpha) corrections to these processes in the Standard Model for final-state neutrinos and top quarks. Initial-state radiation beyond O(alpha) at the leading-logarithmic level as well as QCD correcti

  52. Alan A. Coley, Sigbjorn Hervik

    We use a dynamical systems approach to study Bianchi type VI$_0$ cosmological models containing two tilted $\gamma$-law perfect fluids. The full state space is 11-dimensional, but the existence of a monotonic function simplifies the analysis considerably. We restrict attention to a particular, physically interesting, invariant subspace and find all equilibri

  53. W. B. Vasantha Kandasamy, Florentin Smarandache

    The introduction of Fuzzy Relational Equations (FREs) has made problems that were unsolvable using algebraic linear equations into solvable ones. FREs have been applied to problemsin medicine, industry, transportation and all types of social problems where the data is an unsupervised one. Yet, FREs lack the capacity to tackle problems where an element of ind

  54. P. Watson, W. Cassing, P. C. Tandy

    The effect of quark-gluon vertex dressing on the ground state masses of the u/d-quark pseudoscalar, vector and axialvector mesons is considered with the Dyson-Schwinger equations. This extends the ladder-rainbow Bethe-Salpeter kernel to 2-loops. To render the calculations feasible for this exploratory study, we employ a simple infrared dominant model for the

  55. I. Devetak

    Recently Horodecki et al. [Phys. Rev. Lett. 90, 100402 (2003)] introduced an important quantum information processing paradigm, in which two parties sharing many copies of the same bipartite quantum state distill local pure states, by means of local unitary operations assisted by a one-way (two-way) completely dephasing channel. Local pure states are a valua

  56. Georg Bison, Robert Wynands, Antoine Weis

    Cardiomagnetometry is a growing field of noninvasive medical diagnostics that has triggered a need for affordable high-sensitivity magnetometers. Optical pumping magnetometers are promising candidates satisfying that need since it was demonstrated that they can map the heart magnetic field. For the optimization of such devices theoretical limits on the perfo

  57. J. P. B. C. de Melo

    The pion electromagnetic form factor is calculated with a light-front quark model. The "plus" and "minus" component of the electromagnetic current are used to calculate the electromagnetic form factor in the Breit frame with two models for the q\bar{q} vertex. The light front constituent quark models describes very well hadronic wave function for pseudo-scal

  58. P. Winter, R. Czyzykiewicz, H. -H. Adam, A. Budzanowski

    We propose to extend the investigations of the eta meson production in nucleon-nucleon collisions by studying single and double polarization observables. Over the last years, the eta meson has been studied at several different experiments mainly by measurements of unpolarized total and differential cross sections. To reveal the production mechanism, polariza

  59. M. Angeles Serrano, Marian Boguna, Albert Diaz-Guilera

    We model the evolution of the Internet at the Autonomous System level as a process of competition for users and adaptation of bandwidth capability. We find the exponent of the degree distribution as a simple function of the growth rates of the number of autonomous systems and the total number of connections in the Internet, both empirically measurable quanti

  60. A. Freise

    The French-Italian interferometric gravitational wave detector VIRGO is currently being commissioned. Its principal instrument is a Michelson interferometer with 3 km long optical cavities in the arms and a power-recycling mirror. This paper gives an overview of the present status of the system. We report on the presently attained sensitivity and the system'

  61. Teemu Murtola, Emma Falck, Michael Patra, Mikko Karttunen

    We construct a coarse-grained (CG) model for dipalmitoylphosphatidylcholine (DPPC)/cholesterol bilayers and apply it to large-scale simulation studies of lipid membranes. Our CG model is a two-dimensional representation of the membrane, where the individual lipid and sterol molecules are described by point-like particles. The effective intermolecular interac

  62. Eric Bedford, Kyounghee Kim

    Let $f$ be a birational map of ${\bf C}^d$, and consider the degree complexity, or asymptotic degree growth rate $\delta(f)=\lim_{n\to\infty}({\rm deg}(f^n))^{1/n}$. We introduce a family of elementary maps, which have the form $f=L\circ J$, where $L$ is (invertible) linear, and $J(x_1,...,x_d)=(x_1^{-1},...,x_d^{-1})$. We develop a method of regularization

  63. Arjun Berera, Rudnei O. Ramos

    The effective equation of motion is derived for a scalar field interacting with other fields in a Friedman-Robertson-Walker background space-time. The dissipative behavior reflected in this effective evolution equation is studied both in simplified approximations as well as numerically. The relevance of our results to inflation are considered both in terms o

  64. German Rodrigo, Stefano Catani, Daniel de Florian, Werner Vogelsang

    We consider the collinear limit of QCD amplitudes at one-loop order, and their factorization properties directly in colour space. These results apply to the multiple collinear limit of an arbitrary number of QCD partons, and are a basic ingredient in many higher-order computations. In particular, we discuss the triple collinear limit and its relation to flav

  65. P. Faccioli, D. Guadagnoli, S. Simula

    We investigate the role played by the fermionic determinant in the evaluation of the CP-violating neutron electric dipole moment (EDM) adopting the Instanton Liquid Model. Significant differences between quenched and unquenched calculations are found. In the case of unquenched simulations the neutron EDM decreases linearly with the quark mass and is expected

  66. Herbert S. Wilf

    We apply the method of characteristics for the solution of pde's to two combinatorial problems. The first is finding an explicit form for a distribution that arises in bio-informatics. The second is a question raised by Graham, Knuth and Patashnik abiout a sequence of generalized binomial coefficients. We find an exact formula, which factors in an interestin

  67. Diego Chialva, Roberto Iengo

    Motivated also by recent revival of interest about metastable string states (as cosmic strings or in accelerator physics), we study the decay, in presence of dimensional compactification, of a particular superstring state, which was proven to be remarkably long-lived in the flat uncompactified scenario. We compute the decay rate by an exact numerical evaluat

  68. Bartolomé Coll, Joan Josep Ferrando

    The Stephani universes that can be interpreted as an ideal gas evolving in local thermal equilibrium are determined. Five classes of thermodynamic schemes are admissible, which give rise to five classes of regular models and three classes of singular models. No Stephani universes exist representing an exact solution to a classical ideal gas (one for which th

  69. Vittoria Colizza, Jayanth R. Banavar, Amos Maritan, Andrea Rinaldo

    We present an analysis of the topologies of a class of networks which are optimal in terms of the requirements of having as short a route as possible between any two nodes while yet keeping the congestion in the network as low as possible. Strikingly, we find a variety of distinct topologies and novel phase transitions between them on varying the number of l

  70. S. Holland, Ch. Heyn, D. Heitmann, E. Batke

    We find that the long-wavelength magnetoplasmon, resistively detected by photoconductivity spectroscopy in high-mobility two-dimensional electron systems, deviates from its well-known semiclassical nature as uncovered in conventional absorption experiments. A clear filling-factor dependent plateau-type dispersion is observed that reveals a so far unknown rel

  71. M. Aguado, E. Seiler

    Several years ago it was found that perturbation theory for two-dimensional O(N) models depends on boundary conditions even after the infinite volume limit has been taken termwise, provided $N>2$. There ensued a discussion whether the boundary conditions introduced to show this phenomenon were somehow anomalous and there was a class of `reasonable' boundary

  72. Norio Konno

    The present letter gives a rigorous way from quantum to classical random walks by introducing an independent random fluctuation and then taking expectations based on a path integral approach.

  73. A. Ferroglia, G. Ossola, A. Sirlin

    Recent experimental and theoretical progress in the M_H estimates from M_W and Sin^2_eff_lept is reviewed, with particular emphasis on the role played by M_t. Assuming that the SM is correct and taking into account the lower bound on M_H from direct searches, we derive restrictive bounds on M_W and M_t. We also discuss a representative ``benchmark'' scenario

  74. Peter Foldi

    In this thesis concrete quantum systems are investigated in the framework of the environment induced decoherence. The focus is on the dynamics of highly nonclassical quantum states, the Wigner function of which are negative over some regions of their domains. One of the chosen physical systems is a diatomic molecule, where the potential energy of the nuclei

  75. Hendrik Linz, Bringfried Stecklum, Thomas Henning, Peter Hofner

    (abridged) We present the results of an extensive infrared study of the massive star-forming region G9.62+0.19. The data cover information from broad- and narrow-band filters in the wavelength range from 1 to 19 micrometer and are obtained with ESO's infrared cameras ISAAC and TIMMI2 and with SpectroCam-10 (Mt. Palomar). The high sensitivity and resolution p

  76. R. G. Jafarov, V. E. Rochev

    Two variants of the Nambu--Jona-Lasinio model -- the model with 4-dimensional cutoff and the model with dimensionally-analytical regularization -- are systematically compared. It is shown that they are, in essence, two different models of light-quark interaction. In the mean-field approximation the distinction becomes apparent in a behavior of scalar amplitu

  77. Giovanni Carraro, Fabio Bresolin, Sandro Villanova, Francesca Matteucci

    We report on high resolution spectroscopy of four giant stars in the Galactic old open clusters Berkeley~29 and Saurer~1 obtained with HIRES at the Keck telescope. These two clusters possess the largest galactocentric distances insofar known for open star clusters, and therefore are crucial objects to probe the chemical pattern and evolution of the outskirts

  78. B. B. Beard, M. Pepe, S. Riederer, U. J. Wiese

    D-theory provides an alternative lattice regularization of the (1+1)-d CP(N-1) quantum field theory. In this formulation the continuous classical CP(N-1) fields emerge from the dimensional reduction of discrete SU(N) quantum spins. In analogy to Haldane's conjecture, ladders consisting of an even number of transversely coupled spin chains lead to a CP(N-1) m

  79. Luca Angelani, Lapo Casetti, Marco Pettini, Giancarlo Ruocco

    The elsewhere surmised topological origin of phase transitions is given here new important evidence through the analytic study of an exactly solvable model for which both topology and thermodynamics are worked out. The model is a mean-field one with a k-body interaction. It undergoes a second order phase transition for k=2 and a first order one for k>2. This

  80. S. M. Arakelyan, A. V. Prokhorov, I. Vadeiko

    We consider $\Lambda$-type model of the Bose-Einstein condensate of sodium atoms interacting with the light. Coefficients of the Kerr-nonlinearity in the condensate can achieve large and negative values providing the possibility for effective control of group velocity and dispersion of the probe pulse. We find a regime when the observation of the "slow" and

  81. Gabriel Vasseur, Dietmar Weinmann

    We study the spectral statistics of interacting spinless fermions in a two-dimensional disordered lattice. Within a full quantum treatment for small few-particle-systems, we compute the low-energy many-body states numerically. While at weak disorder the interactions reduce spectral correlations and lead to localization, for the case of strong disorder we fin

  82. Ingo Kirsch

    We consider generalizations of the AdS/CFT correspondence in which probe branes are embedded in gravity backgrounds dual to either conformal or confining gauge theories. These correspond to defect conformal field theories (dCFT) or QCD-like theories with fundamental matter, respectively. Computing the quark condensate and the meson spectrum for a non-supersy

  83. T. R. Govindarajan, E. Harikumar

    We show that the non-commutative $CP^1$ model coupled with Hopf term in 3 dimensions is equivalent to an interacting spin-$s$ theory where the spin $s$ of the dual theory is related to the coefficient of the Hopf term. We use the Seiberg-Witten map in studying this non-commutative duality equivalence, keeping terms to order $\theta$ and show that the spin of

  84. D. Antonov, M. C. Diamantini

    In this review, we discuss the confining and finite-temperature properties of the 3D SU(N) Georgi-Glashow model, and of 4D compact QED. At zero temperature, we derive string representations of both theories, thus constructing the SU(N)-version of Polyakov's theory of confining strings. We discuss the geometric properties of confining strings, as well as the

  85. Jeppe C. Dyre

    It is shown that the elastic energy far from a point defect in an isotropic solid is mainly shear elastic energy. The calculation, which is based on a standard dipole expansion, shows that no matter how large or small the bulk modulus is compared to the shear modulus, less than 10% of the distant point defect energy is associated with volume changes.

  86. Francois Dahmani

    We introduce a class of thin combings and prove that it has a nice behaviour in free constructions. Among corollaries, we deduce the relative metabolicity, in the sense of Gersten, of Sela's limit groups.

  87. Andrzej Staruszkiewicz

    Let S(x) be a massless scalar quantum field which lives on the three-dimensional hyperboloid $xx= (x^0)^2-(x^1)^2-(x^2)^2-(x^3)^2=-1.$ The classical action is assumed to be $(\hbar=1=c)(8\pi e^2)^{-1}\int dx g^{ik}\partial_i S\partial_k S$, where $e^2$ is the coupling constant, $dx$ is the invariant measure on the de Sitter hyperboloid $xx=-1$ and $g_{ik}, i

  88. Rosemary A. Mardling, D. N. C. Lin

    The currently feasible method of detection of Earth-mass planets is transit photometry, with detection probability decreasing with a planet's distance from the star. The existence or otherwise of short-period terrestrial planets will tell us much about the planet formation process, and such planets are likely to be detected first if they exist. Tidal forces

  89. Dorje C. Brody, Lane P. Hughston

    A generalised equivalence principle is put forward according to which space-time symmetries and internal quantum symmetries are indistinguishable before symmetry breaking. Based on this principle, a higher-dimensional extension of Minkowski space is proposed and its properties examined. In this scheme the structure of space-time is intrinsically quantum mech

  90. A. N. Ivanov, M. Cargnelli, M. Faber, H. Fuhrmann

    Within the Nambu-Jona-Lasinio model of light nuclei (the NNJL model), describing strong low-energy nuclear interactions, we compute the width of the energy level of the ground state of pionic deuterium. The theoretical value fits well the experimental data. Using the cross sections for the reactions nu_e + d -> p + p + e^- and nu_e + d -> p + n + nu_e, compu

  91. G. Heinrich

    It is described how the method of sector decomposition can serve to disentangle overlapping infrared singularities, in particular those occurring in the calculation of the real emission part of e+e- to 2 jets and e+e- to 3 jets at NNLO.

  92. K. U. Schreiber, A. Velikoseltsev, M. Rothacher, T. Klugel

    We report the first direct measurements of the very small effect of forced diurnal polar motion, successfully observed on three of our large ring lasers, which now measure the instantaneous direction of Earth's rotation axis to a precision of 1 part in 10^8 when averaged over a time interval of several hours. Ring laser gyroscopes provide a new viable techni

  93. J. G. Groshaus, V. Umansky, H. Shtrikman, Y. Levinson

    We measure the absorption spectrum of a two-dimensional electron system (2DES) in a GaAs quantum well in the presence of a perpendicular magnetic field. We focus on the absorption spectrum into the lowest Landau Level around nu=1. We find that the spectrum consists of bound electron-hole complexes, trion and exciton like. We show that their oscillator streng

  94. M. Yu. Kalmykov

    Recent progress in analytical calculation of the multiple [inverse, binomial, harmonic] sums, related with epsilon-expansion of the hypergeometric function of one variable are discussed.

  95. Lieven Le Bruyn

    In this paper we associate to a qurve A (formerly known as a quasi-free or formally smooth algebra) the one-quiver Q(A) and dimension vector a(A). This pair contains enough information to reconstruct for all natural numbers n the GL(n)-etale local structure of the representation scheme rep(n,A). In an appendix we indicate how one might extend this to qurves

  96. Takeshi Suzuki, Monica Vazirani

    We introduce and study an affine analogue of skew Young diagrams and tableaux on them. It turns out that the double affine Hecke algebra of type $A$ acts on the space spanned by standard tableaux on each diagram. It is shown that the modules obtained this way are irreducible, and they exhaust all irreducible modules of a certain class over the double affine

  97. Pavel M. Bleher, Arno B. J. Kuijlaars

    We give integral representations for multiple Hermite and multiple Hermite polynomials of both type I and II. We also show how these are connected with double integral representations of certain kernels from random matrix theory.

  98. M. Bullejos, E. Faro, V. Blanco

    The notion of geometric nerve of a 2-category (Street, \cite{refstreet}) provides a full and faithful functor if regarded as defined on the category of 2-categories and lax 2-functors. Furthermore, lax 2-natural transformations between lax 2-functors give rise to homotopies between the corresponding simplicial maps. These facts allow us to prove a representa

  99. H. Cebeci, T. Dereli

    We study models of axi-dilaton gravity in space-time geometries with torsion. We discuss conformal re-scaling rules in both Riemannian and non-Riemannian formulations. We give static, spherically symmetric solutions and examine their singularity structure.

  100. P. Minnhagen, M. Rosvall, K. Sneppen, A. Trusina

    We discuss merging-and-creation as a self-organizing process for scale-free topologies in networks. Three power-law classes characterized by the power-law exponents 3/2, 2 and 5/2 are identified and the process is generalized to networks. In the network context the merging can be viewed as a consequence of optimization related to more efficient signaling.