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June 2005 arXiv papers

Showing 1–100 of 4,007 papers

  1. Bassem Ben Hamed, Lubomir Gavrilov

    We classify all functions satisfying non-trivial families of PVI equations. It turns out that, up to an Okamoto equivalence, there are exactly four families parameterized by affine planes or lines. Each affine space is generated by points of "geometric origin", associated either to deformations of elliptic surfaces with four singular fibers, or to de

  2. Sergei M. Kopeikin

    Experimental discovery of the gravitomagnetic fields generated by translational and/or rotational currents of matter is one of primary goals of modern gravitational physics. The rotational (intrinsic) gravitomagnetic field of the Earth is currently measured by the Gravity Probe B. The present paper makes use of a parametrized post-Newtonian (PN) expansion of

  3. Luciano da Fontoura Costa, Fernando Rocha, Silene Araujo de Lima

    Several systems involve spatial arrangements of elements such as molecules or cells, the characterization of which bears important implications to biological and physical investigations. Traditional approaches to quantify spatial order and regularity have relied on nearest neighbor distances or the number of sides of cells. The current work shows that superi

  4. Anatoly Konechny, Andrei Parnachev, David A. Sahakyan

    We study the $\NN=2$ string theory or the $\NN=4$ topological string on the deformed CHS background. That is, we consider the $\NN=2$ minimal model coupled to the $\NN=2$ Liouville theory. This model describes holographically the topological sector of Little String Theory. We use degenerate vectors of the respective $\NN=2$ Verma modules to find the set of B

  5. BaBar Collaboration

    We present preliminary results from a lepton-tagged fully-inclusive measurement of $B \to X_{s}γ$ decays, where $X_{s}$ is any strange hadronic state. Results are based on a BaBar data set of 88.5 million $B\bar{B}$ pairs at the $Υ(4S)$ resonance. We present a reconstructed photon energy spectrum in the $Υ(4S)$ frame, and partial branching fractions above mi

  6. A. B. Clark, A. Karch

    We propose and study a supersymmetric version of the Janus domain wall solution of type IIB supergravity. Janus is dual to N=4 super Yang Mills theory with a coupling constant that jumps across an interface. While the interface in the Janus field theory completely breaks all supersymmetries, it was found earlier that some supersymmetry can be restored in the

  7. S. P. de Alwis

    We examine the procedure for integrating out heavy fields in supersymmetric (both global and local) theories. We find that the usual conditions need to be modified in general and we discuss the restrictions under which they are valid. These issues are relevant for recent work in string compactification with fluxes.

  8. S. P. de Alwis

    We examine recent work on compactifications of string theory with fluxes, where effective potentials for light moduli have been derived after integrating out moduli that are assumed to be heavy at the classical level, and then adding non-perturbative (NP) corrections to the superpotential. We find that this two stage procedure is not valid and that the corre

  9. Yves Elskens, Michael K. -H. Kiessling, Valeria Ricci

    In two recent publications [Commun. PDE, vol.22, p.307--335 (1997), Commun. Math. Phys., vol.203, p.1--19 (1999)], A. Komech, M. Kunze and H. Spohn studied the joint dynamics of a classical point particle and a wave type generalization of the Newtonian gravity potential, coupled in a regularized way. In the present paper the many-body dynamics of this model

  10. Hector Blandin, Rafael Diaz

    Replacing the usual notion of quotient sets by the notion of orbiquotient sets we obtain a generalization of Pólya theory. The key ingredient of our extended theory is the definition of the orbicycle index polynomial which we compute in several examples. We apply our theory to the study of orbicycles on orbiquotient sets. Keywords: Orbifolds, Pólya Theory, P

  11. Hassan Firouzjahi, S. -H. Henry Tye

    This paper has been withdrawn. The interpretation of tension spectrum of cosmic superstrings in terms of KK momentum is invalid as presented in section 2. A new paper based on calculations of the KK spectrum presented here will be submitted.

  12. Dominik Janzing

    What is the simplest Hamiltonian which can implement quantum computation without requiring any control operations during the computation process? In a previous paper we have constructed a 10-local finite-range interaction among qubits on a 2D lattice having this property. Here we show that pair-interactions among qutrits on a 2D lattice are sufficient, too,

  13. Darren Funk-Neubauer

    Let V denote a finite dimensional vector space over an algebraically closed field. Let U_0, U_1,..., U_d denote a sequence of nonzero subspaces whose direct sum is V. Let R:V \to V and L:V \to V denote linear maps with the following properties: for 0 \leq i \leq d, R U_i \subseteq U_{i+1} and L U_i \subseteq U_{i-1} where U_{-1}=0, U_{d+1}=0; for 0 \leq i \l

  14. M. N. Barreto, D. Bazeia, R. Menezes

    We investigate models described by real scalar fields, searching for defect structures in the presence of interactions which explicitly violate Lorentz and CPT symmetries. We first deal with a single field, and we investigate a class of models which supports traveling waves that violate Lorentz invariance. This scenario is then generalized to the case of two

  15. BaBar Collaboration, B. Aubert

    We present an updated measurement of time-dependent \CP asymmetries and the \CP-odd fraction in the decay $B^0 \to D^{*+}D^{*-}$ using $232 \times 10^{6} \BB$ pairs collected by the \babar detector at the PEP-II $B$ factory. We determine the \CP-odd fraction to be $0.125 \pm 0.044\stat \pm 0.007\syst$. The time-dependent \CP asymmetry parameters $C_+$ and $S

  16. Anthony J. Kuhlman, Ulrich W. Heinz

    We present a full Monte Carlo simulation of the multiplicity and eccentricity distributions in U+U collisions at sqrt(s) = 200 A GeV. While unavoidable trigger inefficiencies in selecting full-overlap U+U collisions cause significant modifications of the multiplicity distribution shown in PRL94, 132301 (2005), a selection of source eccentricities by cutting

  17. Jakob Jonsson, Tomas Dahlen, Ariel Goobar, Christofer Gunnarsson

    Gravitational lensing of high-redshift supernovae is potentially an important source of uncertainty when deriving cosmological parameters from the measured brightness of Type Ia supernovae, especially in deep surveys with scarce statistics. Photometric and spectroscopic measurements of foreground galaxies along the lines-of-sight of 33 supernovae discovered

  18. Christofer Gunnarsson, Tomas Dahlen, Ariel Goobar, Jakob Jonsson

    We investigate the possibility of correcting for the magnification due to gravitational lensing of standard candle sources, such as Type Ia supernovae. Our method uses the observed properties of the foreground galaxies along the lines-of-sight to each source and the accuracy of the lensing correction depends on the quality and depth of these observations as

  19. The BABAR Collaboration, B. Aubert

    We study initial-state radiation events, $e^+e^- \to γ_{ISR}π^+π^-J/ψ$, with data collected with the BaBar detector. We observe an accumulation of events near 4.26 GeV/$c^2$ in the invariant-mass spectrum of $π^+π^-J/ψ$. Fits of the mass spectrum indicate that a broad resonance with a mass of about 4.26 GeV/$c^2$ is required to describe the observed structur

  20. B. Wiendlocha, J. Tobola, S. Kaprzyk, D. Fruchart

    We present results of electronic structure calculations for intermetallic perovskite Sc3InB with Full--Potential KKR-LDA method. Sc3InB is very promising candidate for a new superconductor (related to 8K MgCNi3) and can be regarded as a boron-inserted cubic Sc3In, which is a high--pressure allotropic form of the hexagonal weak ferromagnet Sc3In. We predict t

  21. Oleg Y. Gnedin, Andrew Gould, Jordi Miralda-Escude, Andrew R. Zentner

    Precise proper motion measurements (sigma_mu ~ 10 mkas/yr) of the recently discovered hyper-velocity star (HVS) SDSS J090745.0+024507 would yield significant constraints on the axis ratios and orientation of a triaxial model for the Galactic halo. Triaxiality of dark matter halos is predicted by Cold Dark Matter models of galaxy formation and may be used to

  22. D. Mohapatra

    We report the observation of the flavor-changing neutral current process b --> d gamma using a sample of 386*10^6 B meson pairs accumulated by the Belle detector at the KEKB e+ e- collider. We measure branching fractions for the exclusive modes B- --> rho- gamma, B0bar --> rho0 gammaand B0bar --> omega gamma. Assuming that these three modes are related by is

  23. K. Abe

    We report measurements of B meson decays to two kaons using 250/fb of data collected with the Belle detector at the KEKB asymmetric energy e+ e- collider. We find evidence of signals in B+ -> K0(bar) K+ and B0 -> K0 K0(bar) with significances of 3.0 sigma and 3.5 sigma, respectively. The corresponding branching fractions are measured to be BF(B+ -> K0(bar) K

  24. Ding-fang Zeng

    We derive the metric of an expanding universe with zero accelerations by pure kinematic method. By doing so we expatiate physics related with co-moving coordinate system in details. The most important discovery or our study is, in an expanding universe with zero accelerations, the red-shift of photons from distance galaxies is determined by the co-moving coo

  25. V. P. Goncalves, M. V. T. Machado

    The ultraperipheral heavy ion collisions (UPC's) are an important alternative to study the QCD dynamics until the next generation of $e^+e^-/ ep / eA $ colliders become reality. Due to the coherent action of all the protons in the nucleus, the electromagnetic field is very strong and the resulting flux of equivalent photons is large, which allows to stud

  26. T. Verechtchaguina, I. M. Sokolov, L. Schimansky-Geier

    Motivated by the dynamics of resonant neurons we consider a differentiable, non-Markovian random process $x(t)$ and particularly the time after which it will reach a certain level $x_b$. The probability density of this first passage time is expressed as infinite series of integrals over joint probability densities of $x$ and its velocity $\dot{x}$. Approxima

  27. Eleftherios Gkioulekas

    In this paper, we revisit the claim that the Eulerian and quasi-Lagrangian same time correlation tensors are equal. This statement allows us to transform the results of an MSR quasi-Lagrangian statistical theory of hydrodynamic turbulence back to the Eulerian representation. We define a hierarchy of homogeneity symmetries between incremental homogeneity and

  28. M. I. Vysotsky

    We determine the domains of the values of unitarity triangle angle alpha, allowed by the charmless strangeless B_d (\bar B_d) decays.

  29. Sam Payne

    We show that the dual of the cone of divisors on a complete Q-factorial toric variety X whose stable base loci have dimension less than k is generated by curves on small modifications that move in families sweeping out the birational transforms of k-dimensional subvarieties of X. We give an example showing that it does not suffice to consider curves on X its

  30. G. Chiribella, G. M. D'Ariano, M. F. Sacchi

    We derive the optimal input states and the optimal quantum measurements for estimating the unitary action of a given symmetry group, showing how the optimal performance is obtained with a suitable use of entanglement. Optimality is defined in a Bayesian sense, as minimization of the average value of a given cost function. We introduce a class of cost functio

  31. Minoru Eto, Youichi Isozumi, Muneto Nitta, Keisuke Ohashi

    We systematically classify 1/2, 1/4 and 1/8 BPS equations in SUSY gauge theories in d=6, 5, 4, 3 and 2 with eight supercharges, with gauge groups and matter contents being arbitrary. Instantons (strings) and vortices (3-branes) are only allowed 1/2 BPS solitons in d=6 with N=1 SUSY. We find two 1/4 BPS equations and the unique 1/8 BPS equation in d=6 by cons

  32. Caroline Rogers, Vlatko Vedral

    The Kolmogorov complexity of a physical state is the minimal physical resources required to reproduce that state. We define a second quantized quantum Turing machine and use it to define second quantized Kolmogorov complexity. There are two advantages to our approach - our measure of second quantized Kolmogorov complexity is closer to physical reality and un

  33. Frederic Magniez, Ashwin Nayak

    We consider the problem of testing the commutativity of a black-box group specified by its k generators. The complexity (in terms of k) of this problem was first considered by Pak, who gave a randomized algorithm involving O(k) group operations. We construct a quite optimal quantum algorithm for this problem whose complexity is in O (k^{2/3}). The algorithm

  34. Akihiko Inoue, Yumiharu Nakano

    We consider a financial market model driven by an R^n-valued Gaussian process with stationary increments which is different from Brownian motion. This driving noise process consists of $n$ independent components, and each component has memory described by two parameters. For this market model, we explicitly solve optimal investment problems. These include (i

  35. Michel Pleimling, I. A. Campbell

    The critical dynamics of Ising spin glasses with Bimodal, Gaussian, and Laplacian interaction distributions are studied numerically in dimensions 3 and 4. The data demonstrate that in both dimensions the critical dynamic exponent $z_{\rm c}$, the non-equilibrium autocorrelation decay exponent $λ_c/z_{\rm c}$, and the critical fluctuation-dissipation ratio $X

  36. W. Z. Zou, G. Hobbs, N. Wang, R. N. Manchester

    We have measured the positions of 74 pulsars from regular timing observations using the Nanshan radio telescope at Urumqi Observatory between 2000 January and 2004 August (MJD 51500 -- 53240). Proper motions were determined for these pulsars by comparing their current positions with positions given in pulsar catalogues. We compare our results to earlier meas

  37. Cong Tam Nguyen, Jozsef Zsigrai

    A non-destructive, gamma-spectrometric method for uranium age-dating is presented which is applicable to material of any physical form and geometrical shape. It relies on measuring the daughter/parent activity ratio 214Bi/234U by low-background, high-resolution gamma-spectrometry using intrinsic efficiency calibration. The method does not require the use of

  38. FINUDA Collaboration

    Lambda-hypernuclei are produced and studied, with the FINUDA spectrometer, for the first time at an e+e- collider: DAPHNE, the Frascati phi-factory. The slow negative kaons from phi(1020) decay are stopped in thin (0.2 g/cm^2) nuclear targets, and Lambda-hypernuclei formation is detected by measuring the momentum of the outgoing pi^-. A preliminary analysis

  39. I. T. Obukhovsky, D. Fedorov, Amand Faessler, Th. Gutsche

    The interference term between s- and t-pole contributions to the p(e,e' pi+)n cross section is evaluated on the basis of the constituent quark model. It is shown that the contribution of baryon s-poles can be modeled by a nonlocal extension of the Kroll-Rudermann contact term. This contribution is in a destructive interference with the pion t-pole that i

  40. Pierre Cladé, Saïda Guellati-Khélifa, Catherine Schwob, François Nez

    An obvious determination of the acceleration of gravity g can be deduced from the measurement of the velocity of falling atoms using a pi-pi pulses sequence of stimulated Raman transitions. By using a vertical standing wave to hold atoms against gravity, we expect to improve the relative accuracy by increasing the upholding time in the gravity field and to m

  41. Miao Li

    We discuss a class of matrix models describing cosmology with a light-like singularity, generalizing the model proposed by Craps et al. in hep-th/0506180.

  42. Stacy S. McGaugh

    I investigate the Baryonic Tully-Fisher relation for a sample of galaxies with extended 21 cm rotation curves spanning the range 20 < Vf < 300 km/s. A variety of scalings of the stellar mass-to-light ratio are considered. For each prescription for M/L, I give fits of the form Md = A Vf^x. Presumably, the prescription that comes closest to the correct value w

  43. Jin Zhu, Yue-Long Shen, Cai-Dian Lu

    $B_s \to ρ(ω) K^{\ast}$ are useful to determine the $B_s$ distribution amplitude, as well as constrain the CKM phase angle $α$. We study these decays within the Perturbative QCD (PQCD) picture. In this approach, we calculate factorizable, non-factorizable, as well as annihilation diagrams. We find the branching ratio for $B_s \to ρ^+ K^{*-}$ is big to order

  44. H. K. Jassal, J. S. Bagla, T. Padmanabhan

    The dark energy component of the universe is often interpreted either in terms of a cosmological constant or as a scalar field. A generic feature of the scalar field models is that the equation of state parameter w= P/rho for the dark energy need not satisfy w=-1 and, in general, it can be a function of time. Using the Markov chain Monte Carlo method we perf

  45. Hiroshi Koibuchi, Toshiya Kuwahata

    We show that the tethered surface model of Helfrich and Polyakov-Kleinert undergoes a first-order phase transition separating the smooth phase from the crumpled one. The model is investigated by the canonical Monte Carlo simulations on spherical and fixed connectivity surfaces of size up to N=15212. The first-order transition is observed when N>7000, which i

  46. N. K. Langford, T. J. Weinhold, R. Prevedel, K. J. Resch

    We demonstrate a new architecture for an optical entangling gate that is significantly simpler than previous realisations, using partially-polarising beamsplitters so that only a single optical mode-matching condition is required. We demonstrate operation of a controlled-Z gate in both continuous-wave and pulsed regimes of operation, fully characterising it

  47. R. Casana, G. Flores-Hidalgo, B. M. Pimentel

    The recent introduced \textit{dressed coordinates} are studied in the path-integral approach. These coordinates are defined in the context of a harmonic oscillator linearly coupled to massless scalar field and, it is shown that in this model the dressed coordinates appear as a coordinate transformation preserving the path-integral functional measure. The ana

  48. R. Casana, B. M. Pimentel, J. S. Valverde

    In this work we study the electromagnetic field at Finite Temperature via the massless DKP formalism. The constraint analysis is performed and the partition function for the theory is constructed and computed. When it is specialized to the spin 1 sector we obtain the well-known result for the thermodynamic equilibrium of the electromagnetic field.

  49. E. Guardo, B. Harbourne

    The graded Betti numbers of the minimal free resolution (and also therefore the Hilbert function) of the ideal of a fat point subscheme Z of P^2 are determined whenever Z is supported at any 6 or fewer distinct points. All results hold over an algebraically closed field k of arbitrary characteristic.

  50. J. C. Lopez-Dominguez, O. Obregon, C. Ramirez

    The influence of higher dimensions in noncommutative field theories is considered. For this purpose, we analyze the bosonic sector of a recently proposed 6 dimensional SU(3) orbifold model for the electroweak interactions. The corresponding noncommutative theory is constructed by means of the Seiberg-Witten map in 6D. We find in the reduced bosonic interacti

  51. K. Saito, K. Tsushima, A. W. Thomas

    We review the effect of hadron structure changes in a nuclear medium using the quark-meson coupling (QMC) model, which is based on a mean field description of non-overlapping nucleon (or baryon) bags bound by the self-consistent exchange of scalar and vector mesons. This approach leads to simple scaling relations for the changes of hadron masses in a nuclear

  52. Keiichi Umetsu, Masayuki Tanaka, Tadayuki Kodama, Ichi Tanaka

    We report the discovery and spectroscopic confirmation of three gravitationally-lensed images of a galaxy at z=3.9 in the background of a distant, rich cluster of galaxies at z=0.83, on the basis of observations with Faint Object Camera And Spectrograph (FOCAS) on the Subaru telescope. We construct a simple lens model of the cluster mass distribution based o

  53. Sven Aerts

    A property of a system is called actual, if the observation of the test that pertains to that property, yields an affirmation with certainty. We formalize the act of observation by assuming that the outcome correlates with the state of the observed system and is codified as an actual property of the state of the observer at the end of the measurement interac

  54. Dan Solomon

    Diracs hole theory (HT) and quantum field theory (QFT) are generally considered to be equivalent to each other. However, it has been recently shown by several researchers that this is not necessarily the case. When the change in the vacuum energy was calculated for a time independent perturbation HT and QFT yielded different results. In this paper we extend

  55. Nikolai Kiesel, Christian Schmid, Ulrich Weber, Rupert Ursin

    Linear optics quantum logic gates are the best tool to generate multi-photon entanglement. Simplifying a recent approach [Phys. Rev. A 65, 062324; Phys. Rev. A 66, 024308] we were able to implement the conditional phase gate with only one second order interference at a polarization dependent beam splitter, thereby significantly increasing its stability. The

  56. Claudio Altafini

    In an N-level quantum mechanical system, the problem of unitary feedback stabilization of mixed density operators to periodic orbits admits a natural Lyapunov-based time-varying feedback design. A global description of the domain of attraction of the closed-loop system can be provided based on a ``root-space&#39;&#39;-like structure of the space of density o

  57. P. Lodahl

    We investigate frequency correlations in multiple scattered light that are present in the quantum fluctuations. The memory effect for quantum and classical noise is compared, and found to have markedly different frequency scaling, which was confirmed in a recent experiment. Furthermore, novel mesoscopic correlations are predicted that depend on the photon st

  58. Ryo Okamoto, Holger F. Hofmann, Shigeki Takeuchi, Keiji Sasaki

    We report the first experimental demonstration of an optical quantum controlled-NOT gate without any path interference, where the two interacting path interferometers of the original proposals (Phys. Rev. A {\bf 66}, 024308 (2001), Phys. Rev. A {\bf 65}, 012314 (2002)) have been replaced by three partially polarizing beam splitters with suitable polarization

  59. Allen Stairs, Jeffrey Bub

    This paper has been withdrawn.

  60. Kiran K. Manne, Carlton M. Caves

    Computing the entanglement of formation of a bipartite state is generally difficult, but special symmetries of a state can simplify the problem. For instance, this allows one to determine the entanglement of formation of Werner states and isotropic states. We consider a slightly more general class of states, rotationally symmetric states, also known as SU(2)

  61. Gatis Midrijanis

    We study randomized and quantum query (a.k.a. decision tree) complexity for all total Boolean functions, with emphasis to derandomization and dequantization (removing quantumness from algorithms). Firstly, we show that $D(f) = O(Q_1(f)^3)$ for any total function $f$, where $D(f)$ is the minimal number of queries made by a deterministic query algorithm and $Q

  62. Van M. Savage, Geoffrey B. West

    Sleep is one of the most noticeable and widespread phenomena occurring in multicellular animals. Nevertheless, no consensus for a theory of its origins has emerged. In particular, no explicit, quantitative theory exists that elucidates or distinguishes between the myriad hypotheses proposed for sleep. Here, we develop a general, quantitative theory for mamma

  63. D. Wang, E. E. Eyler, P. L. Gould, W. C. Stwalley

    We report on the state-selective detection of near-dissociation ultracold KRb molecules in the ground $X^1Σ^+$ state and the metastable $a^3Σ^+$ state. The molecules are produced by photoassociation of ultracold atoms followed by radiative decay into high vibrational levels of the $X$ and $a$ states. Detection utilizes resonance-enhanced one-color two-photon

  64. Gianluca Geloni, Evgeni Saldin, Evgeni Schneidmiller, Mikhail Yurkov

    This paper describes a theory of transverse coherence properties of Undulator Radiation. Our study is of very practical relevance, because it yields specific predictions of Undulator Radiation cross-spectral density in various parts of the beamline. On the contrary, usual estimations of coherence properties assume that the undulator source is quasi-homogeneo

  65. Sherry Towers

    The author has recently examined the departmental web pages of the `top 50&#39; physics research universities, as ranked by the National Research Council (NRC). Most of the departmental web pages contained biographical data (ie; year and institute of PhD, etc) of their faculty members. Of the approximately 1750 faculty members at the `top 50&#39; universitie

  66. S. I. Maximov

    In this article, I present a new approach and a novel model to the study of the life cycle of wages. The key idea is that wage can be thought as remuneration paid for the competency. It is assumed with the approach that there are three mechanisms acting at micro level and resulting in the change of workers&#39; competencies during their lives. These are an e

  67. V. Chiochia, M. Swartz, Y. Allkofer, D. Bortoletto

    In this paper we discuss the measurement of charge collection in irradiated silicon pixel sensors and the comparison with a detailed simulation. The simulation implements a model of radiation damage by including two defect levels with opposite charge states and trapping of charge carriers. The modeling proves that a doubly peaked electric field generated by

  68. Krzysztof Pachucki, Andrzej Czarnecki, Ulrich D. Jentschura, Vladimir A. Yerokhin

    Within a systematic approach based on the dimensionally regularized nonrelativistic quantum electrodynamics, we derive the complete result for the two-loop correction to order $(α/π)^2 (Z α)^4$ for the $g$ factor of an electron bound in an $nS$ state of a hydrogenlike ion. The results obtained significantly improve the accuracy of the theoretical predictions

  69. Stephan I. Tzenov

    The generation and evolution of nonlinear waves in microwave amplifiers such as travelling wave tubes, free electron lasers and klystrons have been studied. The analysis is based on the hydrodynamic and field equations for the self-consistent evolution of the beam density distribution, the current velocity and the electromagnetic fields. A system of coupled

  70. Baosheng Yuan, Kan Chen

    While the investors&#39; responses to price changes and their price forecasts are well accepted major factors contributing to large price fluctuations in financial markets, our study shows that investors&#39; heterogeneous and dynamic risk aversion (DRA) preferences may play a more critical role in the dynamics of asset price fluctuations. We propose and stu

  71. Dmitri V. Kuznetsov, Igor Mandel

    Processes of mass communications in complicated social or sociobiological systems such as marketing, economics, politics, animal populations, etc. as a subject for the special scientific discipline - &#34;mediaphysics&#34; - are considered in its relation with sociophysics. A new statistical physics approach to analyze these phenomena is proposed. A keystone

  72. Sven Maerivoet, Steven Logghe, Ben Immers, Bart De Moor

    In this paper, we describe a relation between a microscopic traffic cellular automaton (TCA) model (i.e., the stochastic TCA model of Nagel and Schreckenberg) and the macroscopic first-order hydrodynamic model of Lighthill, Whitham, and Richards (LWR). The innovative aspect of our approach, is that we explicitly derive the LWR&#39;s fundamental diagram direc

  73. Ch. Hartnack, H. Oeschler, Joerg Aichelin

    The stiffness of the hadronic equation of state has been extracted from the production rate of $K^+$ mesons in heavy ion collisions around 1 $A$ GeV incident energy. The data are best described with a compressibility coefficient $κ$ around 200 MeV, a value which is usually called ``soft&#39;&#39;. This is concluded from a detailed comparison of the results o

  74. S. Kimura, A. Bonasera, S. Cavallaro

    We study the effect of screening by bound electrons in low energy nuclear reactions. We use molecular dynamics to simulate the reactions involving many electrons: D+$d$, D+D, $^3$He+$d$, $^3$He+D, $^6$Li+$d$, $^6$Li+D, $^7$Li+$p$, $^7$Li+H. Quantum effects corresponding to the Pauli and Heisenberg principles are enforced by constraints in terms of the phase

  75. Maria B. Barbaro, Maria R. Quaglia

    We address the problem of the bosonization of finite fermionic systems with two different approaches. First we work in the path integral formalism, showing how a truly bosonic effective action can be derived from a generic fermionic one with a quartic interaction. We then apply our scheme to the pairing hamiltonian in the degenerate case proving that, in thi

  76. Olivier Besida

    An hybrid iterative Tykhonov regularization approach with an accelerating algorithm is considered. This method is illustrated by two neutron spectrum unfoldings measured with a Bonner Sphere system.

  77. T. Shizuma, H. Utsunomiya, P. Mohr, T. Hayakawa

    Cross sections of the $^{186}$W, $^{187}$Re, $^{188}$Os($γ,n$) reactions were measured using quasi-monochromatic photon beams from laser Compton scattering (LCS) with average energies from 7.3 to 10.9 MeV. The results are compared with the predictions of Hauser-Feshbach statistical calculations using four different sets of input parameters. In addition, the

  78. Karin Baur, Jeffrey M. Rabin, David A. Meyer

    We study a one-dimensional lattice gas &#34;dynamical geometry model&#34; in which local reversible interactions of counter-rotating groups of particles on a ring can create or destroy lattice sites. We exhibit many periodic orbits and and show that all other solutions have asymptotically growing lattice length in both directions of time. We explain why the

  79. R. Cianci, S. Vignolo, D. Bruno

    In the gauge natural bundle framework a new space is introduced and a first-order purely frame-formulation of General Relativity is obtained.

  80. M. van den Berg, P. Gilkey, K. Kirsten, V. A. Kozlov

    The existence of a full asymptotic expansion for the heat content asymptotics of an operator of Laplace type with classical Zaremba boundary conditions on a smooth manifold is established. The first three coefficients in this asymptotic expansion are determined in terms of geometric invariants; partial information is obtained about the fourth coefficient.

  81. Emmanuel Kowalski, Olivier Robert, Jie Wu

    We discuss questions related to the non-existence of gaps in the series defining modular forms and other arithmetic functions of various types, and improve results of Serre, Balog and Ono, and Alkan, using new results about exponential sums and the distribution of $B$-free numbers.

  82. Allan P. Donsig, David R. Pitts

    For a Banach D-bimodule M over an abelian unital C*-algebra D, we define E(M) as the collection of norm-one eigenvectors for the dual action of D on the Banach space dual of M. Equip E(M) with the weak-* topology. We develop general properties of E(M). It is properly viewed as a coordinate system for M when M is a subset of C, where C is a unital C*-algebra

  83. Jozsef Balogh, Robin Pemantle

    An infinite sequence of 0&#39;s and 1&#39;s evolves by flipping each~1 to a~0 exponentially at rate one. When a~1 flips, all bits to its right also flip. Starting from any configuration with finitely many 1&#39;s to the left of the origin, we show that the leftmost~1 moves right with linear speed. Upper and lower bounds are given on the speed.

  84. Oana Dragulete, Tudor S. Ratiu, Miguel Rodriguez-Olmos

    This paper studies singular contact reduction for cosphere bundles at the zero value of the momentum map. A stratification of the singular quotient, finer than the contact one and better adapted to the bundle structure of the problem, is obtained. The strata of this new stratification are a collection of cosphere bundles and coisotropic or Legendrian submani

  85. Kristian Seip, Johannes Skaar

    We solve an extremal problem that arises in the study of the refractive indices of passive metamaterials. The problem concerns Hermitian functions in $H^2$ of the upper half-plane, i.e., $H^2$ functions satisfying $f(-x)=\bar{f(x)}$. An additional requirement is that the imaginary part of $f$ be nonnegative for nonnegative arguments. We parameterize the clas

  86. Elemer E Rosinger

    It is shown that in the case of a single decision maker who optimizes several possibly conflicting objectives, the amount of information available in preference relations among pairs of possible decisions, when compared with all other possible information, is tending to zero exponentially with the number of those different objectives. Consequently, in the ca

  87. Basudeb Datta

    A polyhedral map is called $\{p, q\}$-equivelar if each face has $p$ edges and each vertex belongs to $q$ faces. In 1983, it was shown that there exist infinitely many geometrically realizable $\{p, q\}$-equivelar polyhedral maps if $q > p = 4$, $p > q = 4$ or $q - 3 > p = 3$. It was shown in 2001 that there exist infinitely many $\{4, 4\}$- and $\{3, 6\}$-e

  88. Eric Mwambene

    This paper presents a solution of the polycirculant conjecture which states that every vertex-transitive graph G has an automorphism that permutes the vertices in cycles of the same length. This is done by identifying vertex-transitive graphs as coset graphs. For a coset graph H, an equivalence relation $\sim$ is defined on the vertices of cosets with classe

  89. Florent Balacheff

    To any weighted graph of first Betti number b is naturally associated a lattice of dimension b, definite in a similar way that the jacobian for a Riemann surface. This class of lattices generated by graphs is particularly interesting. We show here an upperbound of the Hermite invariant of such a lattice according to b whose order is ln b. This order is optim

  90. Riikka Kangaslampi, Alina Vdovina

    We construct triangular hyperbolic polyhedra whose links are generalized 4-gons. The universal cover of those polyhedra are hyperbolic buildings, which appartments are hyperbolic planes tesselated by regular triangles with angles $π/4$. Moreover, the fundamental groups of the polyhedra acts simply transitively on vertices of the buildings.

  91. D. -Q. Zhang

    In this note, we report some progress we made recently on the automorphisms groups of K3 surfaces. A short and straightforward proof of the impossibility of Z/(60) acting purely non-symplectically on a K3 surface, is also given, by using Lefschetz fixed point formula for vector bundles.

  92. D. -Q. Zhang

    In this note, we consider all possible extensions G of a non-trivial perfect group H acting faithfully on a K3 surface X. The pair (X, G) is proved to be uniquely determined by G if the transcendental value of G is maximum. In particular, we have G/H < Z/(2) + Z/(2), if H is the alternating group A_5 and normal in G.

  93. Art M. Duval

    A recursion due to Kook expresses the Laplacian eigenvalues of a matroid M in terms of the eigenvalues of its deletion M-e and contraction M/e by a fixed element e, and an error term. We show that this error term is given simply by the Laplacian eigenvalues of the pair (M-e, M/e). We further show that by suitably generalizing deletion and contraction to arbi

  94. David A. Lowe

    It has been proposed that a quantum group structure underlies de Sitter/Conformal field theory duality. These ideas are used to give a microscopic operator counting interpretation for the entropy of two-dimensional dilaton de Sitter space. This agrees with the Bekenstein-Hawking entropy up to a factor of order unity.

  95. Allan Adams, Jacques Distler, Morten Ernebjerg

    We prove the existence of topological rings in (0,2) theories containing non-anomalous left-moving U(1) currents by which they may be twisted. While the twisted models are not topological, their ground operators form a ring under non-singular OPE which reduces to the (a,c) or (c,c) ring at (2,2) points and to a classical sheaf cohomology ring at large radius

  96. Jens O. Andersen

    We consider the Gross-Neveu model with a continuous chiral symmetry in two and three spacetime dimensions at zero and finite temperature. In order to study long-range phase coherence, we construct an effective low-energy Lagrangian for the phase $θ$. This effective Lagrangian is used to show that the fermionic two-particle correlation function at finite temp

  97. Yasushi Tenjinbayashi, Hiroshi Igarashi, Takanori Fujiwara

    We study Dirac operator zero-modes on a torus for gauge background with uniform field strengths. Under the basic translations of the torus coordinates the wave functions are subject to twisted periodic conditions. In a suitable torus coordinates the zero-mode wave functions can be related to holomorphic functions of the complex torus coordinates. We construc

  98. Kimyeong Lee, Ho-Ung Yee

    We explore BPS soliton configurations in N=2 supersymmetric Yang-Mills theory with matter fields arising from parallel D3 branes on D7 branes. Especially we focus on two parameter family of 1/8 BPS equations, dyonic objects, and 1/8 BPS objects and raise a possibility of absence of BPS vortices when the number of D3 branes is larger than that of D7 branes.

  99. S. J. Gates, S. M. Kuzenko

    For the gauge massless higher spin 4D, N = 1 off-shell supermultiplets previously developed, we provide evidence of a twistor-like oscillator realization that is intrinsically related to the superfield structure of the dynamical variables and gauge transformations. Gauge invariant field strengths and linearized Bianchi identities for these multiplets are wor

  100. Horacio E. Camblong, Carlos R. Ordonez

    Improved semiclassical techniques are developed and applied to a treatment of a real scalar field in a $D$-dimensional gravitational background. This analysis, leading to a derivation of the thermodynamics of black holes, is based on the simultaneous use of: (i) a near-horizon description of the scalar field in terms of conformal quantum mechanics; (ii) a no