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Arxiv.org
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Convenient Cutkosky-like diagrammatic rules for computing the spectral densities of arbitrary two-point correlation functions in finite temperature field theory are derived. The approach is based on an explicit analytic continuation of imaginary-time Feynman diagrams and avoids the complications of real-time finite temperature perturbation theory. The application of this method to the perturbative evaluation of transport coefficients is briefly discussed.
Source: http://arxiv.org/abs/hep-ph/9210227v1
Arxiv.org
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We discuss the consequences of recent experimental results from CDF, SLC, LEP and elsewhere for the Standard Model and for new physics. A global fit to all indirect precision data yields $m_t = 175 \pm 11^{+17}_{-19}$~GeV, $\sin^2\theta_{MS} = 0.2317(3)(2)$, and $\alpha_s = 0.127(5)(2)$, where the central values are for $M_H = 300$ GeV and the second uncertainties are for $M_H \rightarrow 1000$ GeV (+) and 60 GeV (-). The $m_t$ value is in remarkable agreement with the value $m_t=174 \pm 16$...
Source: http://arxiv.org/abs/hep-ph/9411203v1
Arxiv.org
by Dan Kiselman
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The formation of the resonance lines of neutral boron in solar-type stellar atmospheres is investigated taking into account effects of departures from local thermodynamic equilibrium (NLTE effects). The latter are due to a combination of overionisation and optical pumping in resonance lines, both caused by the hot, non-local, ultraviolet radiation fields in the line-forming regions. They lead to an underestimation of the boron abundance when analysis methods assuming local thermodynamic...
Source: http://arxiv.org/abs/astro-ph/9401018v1
Arxiv.org
by M. Joyce; T. Prokopec; N. Turok
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In unconstrained thermal equilibrium a local potential for total or fermionic hypercharge does not bias electroweak anomalous processes. We consider two proposed mechanisms for electroweak baryogenesis in this light. In `spontaneous' baryogenesis, which was argued to apply in the `adiabatic' limit of thick, slow walls, a non-zero result was obtained by setting globally conserved charges to be zero {\it locally}. We show that this is a poor approximation unless the walls are very thick. For more...
Source: http://arxiv.org/abs/hep-ph/9401351v3
Arxiv.org
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We study the nonequilibrium dynamics of line liquids as realized in the nonlinear motion of flux lines of a superconductor driven by an applied electric current. Our analysis suggests a transition in the dynamics of the lines from a smooth, laminar phase at small driving forces, to a rough, turbulent phase when the drive is increased. We explore the nature of these phases and describe interesting analogies to driven diffusion and growing interfaces.
Source: http://arxiv.org/abs/cond-mat/9206008v1
Arxiv.org
by G. Mannarini; R. Zimmermann
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Memory and correlation effects in the interband absorption from quantum wells due to exciton-phonon dynamics are investigated. They are traced back to the frequency dependence and matrix character of the self energy arising in a 2nd Born theory. It is found that interpeak absorption increases with respect to the case in which this memory and correlation effects are neglected.
Source: http://arxiv.org/abs/cond-mat/0604136v1
Arxiv.org
by Jonathan PL Hatchett; Yoshiyuki Kabashima
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We investigate how insights from statistical physics, namely survey propagation, can improve decoding of a particular class of sparse error correcting codes. We show that a recently proposed algorithm, time averaged belief propagation, is in fact intimately linked to a specific survey propagation for which Parisi's replica symmetry breaking parameter is set to zero, and that the latter is always superior to belief propagation in the high connectivity limit. We briefly look at further...
Source: http://arxiv.org/abs/cond-mat/0604267v1
Arxiv.org
by Yeekin Tsui; S. A. Vitkalov; M. P. Sarachik; T. M. Klapwijk
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A detailed comparison is presented of the temperature dependence of the conductivity of dilute, strongly interacting electrons in two-dimensional silicon inversion layers in the metallic regime in the presence and in the absence of a magnetic field. We show explicitly and quantitatively that a magnetic field applied parallel to the plane of the electrons reduces the slope of the conductivity versus temperature curves to near zero over a broad range of electron densities extending from $n_c$ to...
Source: http://arxiv.org/abs/cond-mat/0406566v1
Arxiv.org
by Gregory Eyink; Nigel Goldenfeld
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We discuss two distinct analogies between turbulence and field theory. In one analogue, the field theory has an infrared attractive renormalization-group fixed point and corresponds to critical phenomena. In the other analogue, the field theory has an ultraviolet attractive fixed point, as in quantum chromodynamics.
Source: http://arxiv.org/abs/cond-mat/9407021v1
Arxiv.org
by Ulrike von Luxburg; Mikhail Belkin; Olivier Bousquet
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Consistency is a key property of all statistical procedures analyzing randomly sampled data. Surprisingly, despite decades of work, little is known about consistency of most clustering algorithms. In this paper we investigate consistency of the popular family of spectral clustering algorithms, which clusters the data with the help of eigenvectors of graph Laplacian matrices. We develop new methods to establish that, for increasing sample size, those eigenvectors converge to the eigenvectors of...
Source: http://arxiv.org/abs/0804.0678v1
Arxiv.org
by Mu-Tao Wang; Shing-Tung Yau
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There have been many attempts to define the notion of quasilocal mass for a spacelike 2-surface in spacetime by the Hamilton-Jacobi analysis. The essential difficulty in this approach is to identify the right choice of the background configuration to be subtracted from the physical Hamiltonian. Quasilocal mass should be nonnegative for surfaces in general spacetime and zero for surfaces in flat spacetime. In this letter, we propose a new definition of gauge-independent quasilocal mass and prove...
Source: http://arxiv.org/abs/0804.1174v3
Arxiv.org
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We consider the Langevin equation describing a stochastically perturbed by uniform noise non-viscous Burgers fluid and introduce a deterministic function that corresponds to the mean of the velocity when we keep the value of position fixed. We study interrelations between this function and the solution of the non-perturbed Burgers equation. Especially we are interested in the property of the solution of the latter equation to develop unbounded gradients within a finite time. We study the...
Source: http://arxiv.org/abs/0804.1553v3
Arxiv.org
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A new approximation scheme to the centrifugal term is proposed to obtain the $l\neq 0$ solutions of the Schr\"{o}dinger equation with the Manning-Rosen potential. We also find the corresponding normalized wave functions in terms of the Jacobi polynomials. To show the accuracy of the new approximation scheme, we calculate the energy eigenvalues numerically for arbitrary quantum numbers $n$ and $l$ with two different values of the potential parameter $\alpha .$ The bound state energies of...
Source: http://arxiv.org/abs/0807.2085v1
Arxiv.org
by Michal Deák; Hannes Jung; Krzysztof Kutak
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We study in the $k_T$ factorisation framework jet production at LHC energies. In particular we are interested in valence quark and gluon initiated jets. The calculation of the relevant hard matrix element is presented. A CCFM like evolutionequation for valence quark distribution is solved and the cross section for valence quark and gluon initiated process is calculated using Monte Carlo event generator CASCADE.
Source: http://arxiv.org/abs/0807.2403v1
Arxiv.org
by Edgar M. Blokhuis; Joris Kuipers; Richard Vink
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To describe the full spectrum of surface fluctuations of the interface between phase-separated colloid-polymer mixtures from low scattering vector q (classical capillary wave theory) to high q (bulk-like fluctuations), one must take account of the interface's bending rigidity. We find that the bending rigidity is negative and that on approach to the critical point it vanishes proportionally to the interfacial tension. Both features are in agreement with Monte Carlo simulations.
Source: http://arxiv.org/abs/0807.3456v1
Arxiv.org
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The relation between quantum phase transitions, entanglement, and geometric phases is investigated with a system of two qubits with XY type interaction. A seam of level crossings of the system is a circle in parameter space of the anisotropic coupling and the transverse magnetic field, which is identical to the disorder line of an one-dimensional XY model. The entanglement of the ground state changes abruptly as the parameters vary across the circle except specific points crossing to the...
Source: http://arxiv.org/abs/0807.4662v1
Arxiv.org
by A. L. Kuzemsky
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A brief survey of the author's works on the fundamental conceptual ideas of quantum statistical physics developed by N. N. Bogoliubov and his school was given. The development and applications of the method of quasiaverages to quantum statistical physics and condensed matter physics were analyzed. The relationship with the concepts of broken symmetry, quantum protectorate and emergence was examined, and the progress to date towards unified understanding of complex many-particle systems was...
Source: http://arxiv.org/abs/1005.0987v1
Arxiv.org
by A. Alkin; O. Kovalenko; E. Martynov
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The standard Regge poles are considered as inputs for two unitarization methods: eikonal and U-matrix. It is shown that only models with three input pomerons and two input odderons can describe the high energy data on $pp$ and $\bar pp$ elastic scattering including the new data from Tevatron and LHC. However, it seems that the both considered models (eikonal and U-matrix) require a further modification (e.g., to explore nonlinear reggeon trajectories and/or nonexponential vertex functions) for...
Source: http://arxiv.org/abs/1304.0850v2
Arxiv.org
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In this note we analyse the propagation of a small density perturbation in a one-dimensional compressible fluid by means of fractional calculus modelling, replacing thus the ordinary time derivative with the Caputo fractional derivative in the constitutive equations. By doing so, we embrace a vast phenomenology, including subdiffusive, superdiffusive and also memoryless processes like classical diffusions. From a mathematical point of view, we study systems of coupled fractional equations,...
Source: http://arxiv.org/abs/1304.1055v1
Arxiv.org
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We separate the $AF$-algebras (correspondingly action of the countable groups on Cantor sets) onto two classes ---- "completely smooth" for which the set of all indecomposable traces (correspondingly list of all invariant ergodic measures) has nice parametrization, and the second class --- "completely non-smooth" for which the set of all traces (correspondingly set of all invariant measures) is Poulsen simplex and therefore there is no suitable parametrization of...
Source: http://arxiv.org/abs/1304.2193v1
Arxiv.org
by Tran Doan Huan; Maximilian Amsler; Riccardo Sabatini; Vu Ngoc Tuoc; Nam Ba Le; Lilia M. Woods; Nicola Marzari; Stefan Goedecker
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We study the thermodynamic stability at low temperatures of a series of alkali metal/zinc double-cation borohydrides, including LiZn(BH$_4$)$_3$, LiZn$_2$(BH$_4$)$_5$, NaZn(BH$_4$)$_3$, NaZn$_2$(BH$_4$)$_5$, KZn(BH$_4$)$_3$, and KZn$_2$(BH$_4$)$_5$. While LiZn$_2$(BH$_4$)$_5$, NaZn(BH$_4$)$_3$, NaZn$_2$(BH$_4$)$_5$ and KZn(BH$_4$)$_3$ were recently synthesized, LiZn(BH$_4$)$_3$ and KZn$_2$(BH$_4$)$_5$ are hypothetical compounds. Using the minima-hopping method, we discover two new lowest-energy...
Source: http://arxiv.org/abs/1304.4088v2
Arxiv.org
by Said Jabbour; Lakhdar Sais; Yakoub Salhi
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In this paper, we propose a first application of data mining techniques to propositional satisfiability. Our proposed Mining4SAT approach aims to discover and to exploit hidden structural knowledge for reducing the size of propositional formulae in conjunctive normal form (CNF). Mining4SAT combines both frequent itemset mining techniques and Tseitin's encoding for a compact representation of CNF formulae. The experiments of our Mining4SAT approach show interesting reductions of the sizes of...
Source: http://arxiv.org/abs/1304.4415v1
Arxiv.org
by Wei Xiong; Jefferson Zhe Liu; Zhiliang Zhang; Quanshui Zheng
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Reversible control of surface wettability has wide applications in lab-on-chip systems, tunable optical lenses, and microfluidic tools. Using a graphene sheet as a sample material and molecular dynamic (MD) simulations, we demonstrate that strain engineering can serve as an effective way to control the surface wettability. The contact angles $\theta$ of water droplets on a graphene vary from 72.5$^\circ$ to 106$^\circ$ under biaxial strains ranging from -10% to 10% that are applied on the...
Source: http://arxiv.org/abs/1304.4770v1
Arxiv.org
by Rolf T. Horn; Piotr Kolenderski; Dongpeng Kang; Carmelo Scarcella; Adriano Della Frera; Alberto Tosi; Lukas G. Helt; Sergei V. Zhukovsky; John E. Sipe; Gregor Weihs; Amr S. Helmy; Thomas Jennewein
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Creating miniature chip scale implementations of optical quantum information protocols is a dream for many in the quantum optics community. This is largely because of the promise of stability and scalability. Here we present a monolithically integratable chip architecture upon which is built a photonic device primitive called a Bragg reflection waveguide (BRW). Implemented in gallium arsenide, we show that, via the process of spontaneous parametric down conversion, the BRW is capable of...
Source: http://arxiv.org/abs/1304.4944v1
Arxiv.org
by U. Bissbort; D. Cocks; A. Negretti; Z. Idziaszek; T. Calarco; F. Schmidt-Kaler; W. Hofstetter; R. Gerritsma
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We propose and theoretically investigate a hybrid system composed of a crystal of trapped ions coupled to a cloud of ultracold fermions. The ions form a periodic lattice and induce a band structure in the atoms. This system combines the advantages of scalability and tunability of ultracold atomic systems with the high fidelity operations and detection offered by trapped ion systems. It also features close analogies to natural solid-state systems, as the atomic degrees of freedom couple to...
Source: http://arxiv.org/abs/1304.4972v1
Arxiv.org
by Francisco de la Hoz; Luis Vega
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In this paper, we study the evolution of the localized induction approximation (LIA), also known as vortex filament equation, $$ \mathbf X_t = \mathbf X_s \wedge \mathbf X_{ss}, $$ for $\mathbf X(s, 0)$ a regular planar polygon. Using algebraic techniques, supported by full numerical simulations, we give strong evidence that $\mathbf X(s, t)$ is also a polygon at any rational time; moreover, it can be fully characterized, up to a rigid movement, by a generalized quadratic Gau{\ss} sum. We also...
Source: http://arxiv.org/abs/1304.5521v1
Arxiv.org
by Yves Revaz; Daniel Pfenniger
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Two methods generating warped galaxies with N-body simulations are presented. One uses an external potential as a disturber while the other is based on material accretion. The results of both methods are compared. A particular attention is given on the shape of the line of node (LON).
Source: http://arxiv.org/abs/astro-ph/0009053v1
Arxiv.org
by I. Iwata; K. Ohta; K. Nakanishi; K. Kohno; R. G. McMahon
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We present a result of the quasar CO(J=6-5) observations of SDSSp J104433.04-012502.2 at z = 5.8. Ten-days observations with the Nobeyama Millimeter Array yielded an rms noise level of ~ 2.1 mJy/beam in a frequency range from 101.28 GHz to 101.99 GHz at a velocity resolution of 120 km/s. No significant clear emission line was detected in the observed field and frequency range. Three sigma upper limit on the CO(J=6-5) luminosity of the object is 2.8 x 10^10 K km/s pc^2, corresponding to a...
Source: http://arxiv.org/abs/astro-ph/0107369v1
Arxiv.org
by M. Ali-Akbari
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We consider a D2-brane in the pp-wave backgrounds obtained from AdS$_4\times$CP$^3$ when electric and magnetic fields have been turned on. Upon fixing the light-cone gauge, light-cone Hamiltonian and BPS configurations are obtained. In particular we study BPS configurations with electric dipole on the two sphere giant and a giant graviton rotating in transverse directions. Moreover we show that the gauge field living on the D2-brane is replaced by a scalar field in the light-cone Hamiltonian....
Source: http://arxiv.org/abs/1005.0126v1
Arxiv.org
by Lijing Shao; Bo-Qiang Ma
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The occurrence of the nonzero leftmost digit, i.e., 1, 2, ..., 9, of numbers from many real world sources is not uniformly distributed as one might naively expect, but instead, the nature favors smaller ones according to a logarithmic distribution, named Benford's law. We investigate three kinds of widely used physical statistics, i.e., the Boltzmann-Gibbs (BG) distribution, the Fermi-Dirac (FD) distribution, and the Bose-Einstein (BE) distribution, and find that the BG and FD distributions...
Source: http://arxiv.org/abs/1005.0660v1
Arxiv.org
by D. Volovik; S. Redner
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We investigate the first-passage properties of bursty random walks on a finite one-dimensional interval of length L, in which unit-length steps to the left occur with probability close to one, while steps of length b to the right -- "bursts" -- occur with small probability. This stochastic process provides a crude description of the early stages of virus spread in an organism after exposure. The interesting regime arises when b is of the order of but less than 1, where the conditional...
Source: http://arxiv.org/abs/1005.1579v2
Arxiv.org
by P. P. Van der Werf; K. G. Isaak; R. Meijerink; M. Spaans; A. Rykala; T. Fulton; A. F. Loenen; F. Walter; A. Weiss; L. Armus; J. Fischer; F. P. Israel; A. I. Harris; S. Veilleux; C. Henkel; G. Savini; S. Lord; H. A. Smith; E. Gonzalez-Alfonso; D. Naylor; S. Aalto; V. Charmandaris; K. M. Dasyra; A. Evans; Y. Gao; T. R. Greve; R. Guesten; C. Kramer; J. Martin-Pintado; J. Mazzarella; P. P. Papadopoulos; D. B. Sanders; L. Spinoglio; G. Stacey; C. Vlahakis; M. C. Wiedner; E. M. Xilouris
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We present a full high resolution SPIRE FTS spectrum of the nearby ultraluminous infrared galaxy Mrk231. In total 25 lines are detected, including CO J=5-4 through J=13-12, 7 rotational lines of H2O, 3 of OH+ and one line each of H2O+, CH+, and HF. We find that the excitation of the CO rotational levels up to J=8 can be accounted for by UV radiation from star formation. However, the approximately flat luminosity distribution of the CO lines over the rotational ladder above J=8 requires the...
Source: http://arxiv.org/abs/1005.2877v1
Arxiv.org
by G. Risaliti; M. Elvis; S. Bianchi; G. Matt
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We present a Chandra monitoring campaign of the highly variable Seyfert galaxy UGC 4203 (the "Phoenix Galaxy") which revealed variations in the X-ray absorbing column density on time scales of two weeks. This is the third, clear case, after NGC 1365 and NGC 7582, of dramatic N_H variability on short time scales observed in a "changing look" source, i.e. an AGN observed in the past in both a reflection-dominated and a Compton-thin state. The inferred limits on the distance of...
Source: http://arxiv.org/abs/1005.3052v2
Arxiv.org
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We investigate how to effectively preserve the entanglement between two noninteracting multilevel oscillators coupled to a common reservoir under non-ideal pulse control. A universal characterization using fidelity is developed for the behavior of the system based on Nakajima-Zwanzig projection operator technique. Our analysis includes the validity of the approximation method and the decoherence-suppression by the non-ideal pulse control. The power of our strategy for protecting entanglement is...
Source: http://arxiv.org/abs/1005.3171v1
Arxiv.org
by Peter Zeiler Skands
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We present 9 new tunes of the pT-ordered shower and underlying-event model in PYTHIA 6.4. These "Perugia" tunes update and supersede the older "S0" family. The data sets used to constrain the models include hadronic Z0 decays at LEP, Tevatron minimum-bias data at 630, 1800, and 1960 GeV, Tevatron Drell-Yan data at 1800 and 1960 GeV, and SPS min-bias data at 200, 546, and 900 GeV. In addition to the central parameter set, called "Perugia 0", we introduce a set of 8...
Source: http://arxiv.org/abs/1005.3457v4
Arxiv.org
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We discuss semiclassical expansions around a class of classical string configurations lying in AdS_3 x S^1 using the Pohlmeyer-reduced from of the AdS_5 x S^5 superstring theory. The Pohlmeyer reduction of the AdS_5 x S^5 superstring theory is a gauged Wess-Zumino-Witten model with an integrable potential and two-dimensional fermionic fields. It was recently conjectured that the quantum string partition function is equal to the quantum reduced theory partition function. Continuing the previous...
Source: http://arxiv.org/abs/1005.4386v2
Arxiv.org
by K. Perraut; M. Benisty; D. Mourard; S. Rajabi; F. Bacciotti; Ph. Bério; D. Bonneau; O. Chesneau; J. M. Clausse; O. Delaa; A. Marcotto; A. Roussel; A. Spang; Ph. Stee; I. Tallon-Bosc; H. McAlister; T. ten Brummelaar; J. Sturmann; L. Sturmann; N. Turner; C. Farrington; P. J. Goldfinger
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A crucial issue in star formation is to understand the physical mechanism by which mass is accreted onto and ejected by a young star. The visible spectrometer VEGA on the CHARA array can be an efficient means of probing the structure and the kinematics of the hot circumstellar gas at sub-AU. For the first time, we observed the Herbig Ae star AB Aur in the H$\alpha$ emission line, using the VEGA low spectral resolution on two baselines of the array. We computed and calibrated the spectral...
Source: http://arxiv.org/abs/1005.5267v1
Arxiv.org
by H. S. Ruiz; A. Bad\'\ia-Majós
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Several aspects of the general theory for the critical states of a vortex lattice and the magnetic flux dynamics in type-II superconductors are examined by a direct variational optimisation method and widespread physical principles. Our method allows to unify a number of conventional models describing the complex vortex configurations in the critical state regime. Special attention is given to the discussion of the relation between the flux-line cutting mechanism and the depinning threshold...
Source: http://arxiv.org/abs/1005.5540v1
Arxiv.org
by Simone Gasparinetti; Fabio Deon; Giorgio Biasiol; Lucia Sorba; Fabio Beltram; Francesco Giazotto
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We demonstrate local detection of the electron temperature in a two-dimensionalmicrodomain using a quantum dot. Our method relies on the observation that a temperature bias across the dot changes the functional form of Coulomb-blockade peaks. We apply our results to the investigation of electron-energy relaxation at subkelvin temperatures, find that the energy flux from electrons into phonons is proportional to the fifth power of temperature, and give a measurement of the coupling constant.
Source: http://arxiv.org/abs/1007.0172v2
Arxiv.org
by J. Bouttier; E. Guitter
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We present an unexpected connection between two map enumeration problems. The first one consists in counting planar maps with a boundary of prescribed length. The second one consists in counting planar maps with two points at a prescribed distance. We show that, in the general class of maps with controlled face degrees, the solution for both problems is actually encoded into the same quantity, respectively via its power series expansion and its continued fraction expansion. We then use known...
Source: http://arxiv.org/abs/1007.0419v3
Arxiv.org
by João Gouveia; Rekha R. Thomas
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This article describes a method to compute successive convex approximations of the convex hull of a set of points in R^n that are the solutions to a system of polynomial equations over the reals. The method relies on sums of squares of polynomials and the dual theory of moment matrices. The main feature of the technique is that all computations are done modulo the ideal generated by the polynomials defining the set to the convexified. This work was motivated by questions raised by Lov\'asz...
Source: http://arxiv.org/abs/1007.1191v1
Arxiv.org
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Linux package managers have to deal with dependencies and conflicts of packages required to be installed by the user. As an NP-complete problem, this is a hard task to solve. In this context, several approaches have been pursued. Apt-pbo is a package manager based on the apt project that encodes the dependency solving problem as a pseudo-Boolean optimization (PBO) problem. This paper compares different PBO solvers and their effectiveness on solving the dependency solving problem.
Source: http://arxiv.org/abs/1007.1022v1
Arxiv.org
by B. Letarte; V. Hill; E. Tolstoy; P. Jablonka; M. Shetrone; K. A. Venn; M. Spite; M. J. Irwin; G. Battaglia; A. Helmi; F. Primas; P. Francois; A. Kaufer; T. Szeifert; N. Arimoto; K. Sadakane
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For the first time we show the detailed late-stage chemical evolution history of small nearby dwarf spheroidal galaxy in the Local Group. We present the results of a high resolution (R$\sim$20000) FLAMES/GIRAFFE abundance study at ESO/VLT of 81 photometrically selected red giant branch stars in the central 25$'$ of the Fornax dwarf spheroidal galaxy. We present abundances of \alfe\ (Mg, Si, Ca and Ti), iron-peak elements (Fe, Ni and Cr) and heavy elements (Y, Ba, La, Nd and Eu). Our sample was...
Source: http://arxiv.org/abs/1007.1007v1
Arxiv.org
by I. Krasovsky
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We outline an approach recently used to prove formulae for the multiplicative constants in the asymptotics for the sine-kernel and Airy-kernel determinants appearing in random matrix theory and related areas.
Source: http://arxiv.org/abs/1007.1135v1
Arxiv.org
by S. G. Chigarev; E. M. Epshtein; Yu. V. Gulyaev; P. E. Zilberman
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The stability is analyzed of the equilibrium configurations of a magnetic junction with a free layer that has cubic symmetry and two anisotropy axes in the layer plane. Different variants of the switching between various configurations are considered. A possibility is shown of the substantial lowering of the threshold current density needed for the switching. Numerical simulation is made of the switching dynamics for various configurations.
Source: http://arxiv.org/abs/1007.2097v1
Arxiv.org
by Gianluca Giovannetti; Sanjeev Kumar; Alessandro Stroppa; Jeroen van den Brink; Silvia Picozzi; Jose Lorenzana
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Cupric oxide is multiferroic at unusual high temperatures. From density functional calculations we find that the low-T magnetic phase is paraelectric and the higher-T one ferroelectric, with a size and direction of polarization in good agreement with experiment. By mapping of the ab initio results on an effective spin model we find with Monte Carlo that in the high-T magnetic state non-collinearity and inversion symmetry breaking stabilize each other via the Dzyaloshinskii Moriya interaction....
Source: http://arxiv.org/abs/1007.3220v2
Arxiv.org
by Aya Bamba; Takayasu Anada; Tadayasu Dotani; Koji Mori; Ryo Yamazaki; Ken Ebisawa; Jacco Vink
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During the search for counterparts of very-high-energy gamma-ray sources, we serendipitously discovered large, extended, low surface brightness emission from PWNe around pulsars with the ages up to ~100 kyrs, a discovery made possible by the low and stable background of the Suzaku X-ray satellite. A systematic study of a sample of 8 of these PWNe, together with Chandra datasets, has revealed us that the nebulae keep expanding up to for ~100 kyrs, although time scale of the synchrotron X-ray...
Source: http://arxiv.org/abs/1007.3203v1
Arxiv.org
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In this report, firstly, we presents state of the art survey on Data Management and Data Dissemination techniques with Mobile Sink. Moreover we classify these techniques into two ample sub-categories. Under this classification, we identify, review, compare, and highlight these techniques and their pros and cons. We do a SWOT (Strength, Weaknesses, Opportunities, Threats) analysis of each scheme. We also discuss where each scheme is appropriate. Secondly, we presents a new distributed data...
Source: http://arxiv.org/abs/1007.4068v2
Arxiv.org
by Artur Siemaszko; Maciej P. Wojtkowski
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We call a Markov partition of a two dimensional hyperbolic toral automorphism a Berg partition if it contains just two rectangles. We describe all Berg partitions for a given hyperbolic toral automorphism. In particular there are exactly (k + n + l + m)/2 nonequivalent Berg partitions with the same connectivity matrix (k, l, m, n).
Source: http://arxiv.org/abs/1007.3984v1
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We review the interplay of frustration and strong electronic correlations in quasi-two-dimensional organic charge transfer salts, such as k-(BEDT-TTF)_2X and Et_nMe_{4-n}Pn[Pd(dmit)2]2. These two forces drive a range of exotic phases including spin liquids, valence bond crystals, pseudogapped metals, and unconventional superconductivity. Of particular interest is that in several materials there is a direct transition as a function of pressure from a spin liquid Mott insulating state to a...
Source: http://arxiv.org/abs/1007.5381v2
This paper concerns continuous dependence estimates for Hamilton-Jacobi-Bellman-Isaacs operators (briefly, HJBI). For the parabolic Cauchy problem, we establish such an estimate in the whole space $[0,+\infty)\times\Rn$. Moreover, under some periodicity and ellipticity assumptions, we obtain a similar estimate for the ergodic constant associated to the HJBI operator. An interesting byproduct of the latter result will be the local uniform convergence for some classes of singular perturbation...
Source: http://arxiv.org/abs/1007.5445v1
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by Sona Pochybova
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The separate study of quark and gluon jets is vital for the interpretation of multiple variables behaviour observed in both high-energy hadron and heavy-ion collisions in the present and future experiments. We propose a set of jet-energy dependent cuts to be used to distinguish between quark and gluon jets experimentally based on a Monte-Carlo study of their properties. Further, we introduce the possibility to calibrate these cuts via gamma-jet and multi-jet events, which represent clean...
Source: http://arxiv.org/abs/1107.0128v1
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The CKM angle $\gamma/\phi_{3}$ had been measured by two B-factories, the PEPII collider for the BaBar experiment and the KEKB collider for the Belle experiments. The present paper reports recent progress in $\gamma/\phi_{3}$.
Source: http://arxiv.org/abs/1107.0159v3
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by A. -M. Uimonen; E. Khosravi; A. Stan; G. Stefanucci; S. Kurth; R. van Leeuwen; E. K. U. Gross
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We study time-dependent electron transport through an Anderson model. The electronic interactions on the impurity site are included via the self-energy approximations at Hartree-Fock (HF), second Born (2B), GW, and T-Matrix level as well as within a time-dependent density functional (TDDFT) scheme based on the adiabatic Bethe-Ansatz local density approximation (ABALDA) for the exchange correlation potential. The Anderson model is driven out of equilibrium by applying a bias to the leads and its...
Source: http://arxiv.org/abs/1107.0162v2
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by Kiran Jain; S. C. Tripathy; F. Hill
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In this paper, we address the controversy regarding the recent extended solar minimum as seen in helioseismic low- and intermediate-degree mode frequencies: studies from different instruments identify different epochs of seismic minima. Here we use mode frequencies from a network of six identical instruments, Global Oscillation Network Group, continuously collecting data for more than 15 years, to investigate the epoch of minimum in solar oscillation frequencies prior to the beginning of solar...
Source: http://arxiv.org/abs/1107.0049v1
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by Linyuan Lü; Duan-Bing Chen; Tao Zhou
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Spreading dynamics of information and diseases are usually analyzed by using a unified framework and analogous models. In this paper, we propose a model to emphasize the essential difference between information spreading and epidemic spreading, where the memory effects, the social reinforcement and the non-redundancy of contacts are taken into account. Under certain conditions, the information spreads faster and broader in regular networks than in random networks, which to some extent supports...
Source: http://arxiv.org/abs/1107.0429v2
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by K. P. Khemchandani; A. Martínez Torres; H. Kaneko; H. Nagahiro; A. Hosaka
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A study of meson-baryon systems with total strangeness -1 is made within a framework based on the chiral and hidden local symmetries. These systems consist of octet baryons, pseudoscalar and vector mesons. The pseudoscalar meson-baryon (PB) dynamics has been earlier found determinant for the existence of some strangeness -1 resonances, for example, $\Lambda(1405)$, $\Lambda(1670)$, etc. The motivation of the present work is to study the effect of coupling the closed vector meson-baryon (VB)...
Source: http://arxiv.org/abs/1107.0574v2
We study, in the semi-classical approximation, the convergence of the quantum density and the quantum action, solutions to the Madelung equations, when the Planck constant h tends to 0. We find two different solutions which depend to the initial density . In the first case where the initial quantum density is a classical density rho_0(x), the quantum density and the quantum action converge to a classical action and a classical density which satisfy the statistical Hamilton-Jacobi equations....
Source: http://arxiv.org/abs/1107.0790v1
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Recent observations have revealed the emergence of an unusual normal phase when a magnetic flux threads an ultra-thin superconducting cylinder. Moreover, with increasing temperature, the resistance rises in a series of abrupt jumps. These phenomena are explained using a novel approach, which allows calculation of the resistance in the presence of amplitude and phase fluctuations of the superconducting order parameter, and at the same time introduces a local probe of the current and chemical...
Source: http://arxiv.org/abs/1107.1246v2
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General relativity under the assumption of noncommuting components of the tetrad field is considered in this paper. Since the algebraic properties of the tetrad field representing the gravitational field are assumed to correspond to the noncommutativity algebra of the coordinates in the canonical case of noncommutative geometry, this idea is closely related to noncommutative geometry as well as to canonical quantization of gravity. According to this presupposition generalized field equations...
Source: http://arxiv.org/abs/1107.1071v2
We give a theoretical framework to obtain a low-energy effective theory of quantum chromodynamics (QCD) towards a first-principle derivation of confinement/deconfinement and chiral-symmetry breaking/restoration crossover transitions. In fact, we demonstrate that an effective theory obtained using simple but non-trivial approximations within this framework enables us to treat both transitions simultaneously on equal footing. A resulting effective theory is regarded as a modified and improved...
Source: http://arxiv.org/abs/1005.0314v2
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Consider a process, stochastic or deterministic, obtained by using a numerical integration scheme, or from Monte-Carlo methods involving an approximation to an integral, or a Newton-Raphson iteration to approximate the root of an equation. We will assume that we can sample from the distribution of the process from time 0 to finite time n. We propose a scheme for unbiased estimation of the limiting value of the process, together with estimates of standard error and apply this to examples...
Source: http://arxiv.org/abs/1005.2228v2
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by Peter T. Winslow; Kris Sigurdson; John N. Ng
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We demonstrate a new model which uses an ADD type braneworld scenario to produce a multi-state theory of dark matter. Compactification of the extra dimensions onto a sphere leads to the association of a single complex scalar in the bulk with multiple Kaluza-Klein towers in an effective four-dimensional theory. A mutually interacting multi-state theory of dark matter arises naturally within which the dark matter states are identified with the lightest Kaluza-Klein particles of fixed magnetic...
Source: http://arxiv.org/abs/1005.3013v1
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by Asantha Cooray; A. Amblard; L. Wang; B. Altieri; V. Arumugam; R. Auld; H. Aussel; T. Babbedge; A. Blain; J. Bock; A. Boselli; V. Buat; D. Burgarella; N. Castro-Rodriguez; A. Cava; P. Chanial; D. L. Clements; A. Conley; L. Conversi; C. D. Dowell; E. Dwek; S. Eales; D. Elbaz; D. Farrah; M. Fox; A. Franceschini; W. Gear; J. Glenn; M. Griffin; M. Halpern; E. Hatziminaoglou; E. Ibar; K. Isaak; R. J. Ivison; A. A. Khostovan; G. Lagache; L. Levenson; N. Lu; S. Madden; B. Maffei; G. Mainetti; L....
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We measure the angular correlation function, w(theta), from 0.5 to 30 arcminutes of detected sources in two wide fields of the Herschel Multi-tiered Extragalactic Survey (HerMES). Our measurements are consistent with the expected clustering shape from a population of sources that trace the dark matter density field, including non-linear clustering at arcminute angular scales arising from multiple sources that occupy the same dark matter halos. By making use of the halo model to connect the...
Source: http://arxiv.org/abs/1005.3303v1
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Sub-threshold stimuli cannot initiate excitations in active media, but surprisingly as we show in this paper, they can alter the time-evolution of spatially heterogeneous activity by modifying the recovery dynamics. This results in significant reduction of waveback velocity which may lead to spatial coherence, terminating all activity in the medium including spatiotemporal chaos. We analytically derive model-independent conditions for which such behavior can be observed.
Source: http://arxiv.org/abs/1005.5032v1
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by PawełT. Jochym; Krzysztof Parlinski; Andrzej M. Oleś
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The magnetization distribution, its energetic characterization by the interlayer coupling constants and lattice dynamics of (001)-oriented Fe/Pt multilayers are investigated using density functional theory combined with the direct method to determine phonon frequencies. It is found that ferromagnetic order between consecutive Fe layers is favoured, with the enhanced magnetic moments at the interface. The bilinear and biquadratic coupling coefficients between Fe layers are shown to saturate fast...
Source: http://arxiv.org/abs/1005.5454v1
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by Curtis Menton
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We study the behavior of Range Voting and Normalized Range Voting with respect to electoral control. Electoral control encompasses attempts from an election chair to alter the structure of an election in order to change the outcome. We show that a voting system resists a case of control by proving that performing that case of control is computationally infeasible. Range Voting is a natural extension of approval voting, and Normalized Range Voting is a simple variant which alters each vote to...
Source: http://arxiv.org/abs/1005.5698v3
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by Steven W. Peters; Robert W. Heath Jr
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This paper presents a study on multiple-antenna interference channels, accounting for general overhead as a function of the number of users and antennas in the network. The model includes both perfect and imperfect channel state information based on channel estimation in the presence of noise. Three low complexity methods are proposed for reducing the impact of overhead in the sum network throughput by partitioning users into orthogonal groups. The first method allocates spectrum to the groups...
Source: http://arxiv.org/abs/1007.0512v2
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It is typically assumed, without justification, that a weak coupling between a system and a bath is a necessary condition for the equivalence of a canonical ensemble and a microcanonical ensemble. For instance, in a canonical ensemble, temperature emerges if the system and the bath are uncoupled or weakly coupled. We investigate the validity region of this weak coupling approximation, using a coupled composite-spin system. Our results show that the spin coupling strength can be as large as the...
Source: http://arxiv.org/abs/1007.3877v1
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by German Valencia
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In this talk I review how to search for CP violation in top-quark pair production and decay using T-odd correlations. I discuss two examples which illustrate many of the relevant features: CP violation in a heavy neutral Higgs boson; and CP violating anomalous top-quark couplings. I present some numerical results for the LHC and some for the Tevatron.
Source: http://arxiv.org/abs/1007.4765v1
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We investigate both the locus of ambiguity in the architecture of language and the origin of ambiguity in natural communication. We 1) locate ambiguity at the externalization branch of language, 2) provide a rigorous, general definition of ambiguity through the concept of logical irreversibility, quantifying the amount of ambiguity within the framework of Shannon's information theory, and 3) provide a proof of concept that the constraints acting over a natural code force ambiguity to emerge....
Source: http://arxiv.org/abs/1107.0193v2
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by Giacomo Ceccarelli; Andrea Pelissetto; Ettore Vicari
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We investigate the ferromagnetic-glassy transitions which separate the low-temperature ferromagnetic and spin-glass phases in the temperature-disorder phase diagram of three-dimensional Ising spin-glass models. For this purpose, we consider the cubic-lattice +-J (Edwards-Anderson) Ising model with bond distribution $P(J) = p \delta(J - 1) + (1-p) \delta(J + 1)$, and present a numerical Monte Carlo study of the critical behavior along the line that marks the onset of ferromagnetism. The...
Source: http://arxiv.org/abs/1107.3005v1
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by M. Ferrero; D. Salgado; J. L. Sanchez-Gomez
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It is argued that the traditional "realist" methodology of physics, according to which human concepts, laws and theories can grasp the essence of reality, is incompatible with the most fruitful interpretation of quantum formalism. The proof rests on the violation by quantum mechanics of the foundational principles of that methodology. An alternative methodology, in which the construction of sciences finishes at the level of human experience, as standard quantum theory strongly...
Source: http://arxiv.org/abs/1107.3366v1
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by A. V. Kuznetsov; N. V. Mikheev; A. V. Serghienko
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The low-energy manifestations of a minimal extension of the electroweak standard model based on the quark-lepton symmetry $SU(4)_V \otimes SU(2)_L \otimes G_R$ of the Pati--Salam type are analyzed. Given this symmetry the third type of mixing in the interactions of the $SU(4)_V$ leptoquarks with quarks and leptons is shown to be required. An additional arbitrariness of the mixing parameters could allow, in principle, to decrease noticeably the lower bound on the vector leptoquark mass...
Source: http://arxiv.org/abs/1203.0196v2
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by Antoine Hakassou; Youssef Ouknine
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In this note, we introduce the notion of $\alpha$-IDT processes which is obtained from a slight and fundamental modification of the IDT property. Several examples of $\alpha$-IDT processes are given and Gaussian processes which are $\alpha$-IDT are characterized. A kind example of this Gaussian $\alpha$-IDT is the standard fractional Brownian motion. Also, we invest some links between the $\alpha$-IDT property, with selfdecomposability, temporal selfdecomposability, stability and self...
Source: http://arxiv.org/abs/1203.0874v3
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by Mircea Mustata; Karl Schwede
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We define and study a version of Seshadri constant for ample line bundles in positive characteristic. We prove that lower bounds for this constant imply the global generation or very ampleness of the corresponding adjoint line bundle. As a consequence, we deduce that the criterion for global generation and very ampleness of adjoint line bundles in terms of usual Seshadri constants holds also in positive characteristic.
Source: http://arxiv.org/abs/1203.1081v1
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by Miguel Abreu; Matthew Strom Borman; Dusa McDuff
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In this paper we introduce a new way of displacing Lagrangian fibers in toric symplectic manifolds, a generalization of McDuff's original method of probes. Extended probes are formed by deflecting one probe by another auxiliary probe. Using them, we are able to displace all fibers in Hirzebruch surfaces except those already known to be nondisplaceable, and can also displace an open dense set of fibers in the weighted projective space P(1,3,5) after resolving the singularities. We also...
Source: http://arxiv.org/abs/1203.1074v2
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by M. Kowal; J. Skalski
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We study the existence of third, hyperdeformed minima in a number of even-even Th, U and Pu nuclei using the Woods-Saxon microscopic-macroscopic model that very well reproduces first and second minima and fission barriers in actinides. Deep ($3 \div 4$ MeV) minima found previously by \'Cwiok et al. are found spurious after sufficiently general shapes are included. Shallow third wells may exist in $^{230,232}$Th, with IIIrd barriers $\le$ 200 and 330 keV (respectively). Thus, a problem of...
Source: http://arxiv.org/abs/1203.4449v1
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by Machiko Hatsuda; Tetsuji Kimura
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We present an extension of the Courant bracket to the ones for Dp-branes by analyzing Hamiltonians and local superalgebras. Contrast to the basis of the bracket for a fundamental string which consists of the momentum and the winding modes, the ones for Dp-branes contain higher rank R-R coupling tensors. We show that the R-R gauge transformation rules are obtained by these Courant brackets for Dp-branes where the Dirac-Born-Infeld gauge field and the "two-vierbein field" play an...
Source: http://arxiv.org/abs/1203.5499v4
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by Clément Charpentier; Eric Sopena
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An incidence of a graph $G$ is a pair $(v,e)$ where $v$ is a vertex of $G$ and $e$ an edge incident to $v$. Two incidences $(v,e)$ and $(w,f)$ are adjacent whenever $v = w$, or $e = f$, or $vw = e$ or $f$. The incidence coloring game [S.D. Andres, The incidence game chromatic number, Discrete Appl. Math. 157 (2009), 1980-1987] is a variation of the ordinary coloring game where the two players, Alice and Bob, alternately color the incidences of a graph, using a given number of colors, in such a...
Source: http://arxiv.org/abs/1304.0166v1
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Probability answer set programming is a declarative programming that has been shown effective for representing and reasoning about a variety of probability reasoning tasks. However, the lack of probability aggregates, e.g. {\em expected values}, in the language of disjunctive hybrid probability logic programs (DHPP) disallows the natural and concise representation of many interesting problems. In this paper, we extend DHPP to allow arbitrary probability aggregates. We introduce two types of...
Source: http://arxiv.org/abs/1304.1684v1
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The factors that influence genetic architecture shape the structure of the fitness landscape, and therefore play a large role in the evolutionary dynamics. Here the NK model is used to investigate how epistasis and pleiotropy -- key components of genetic architecture -- affect the structure of the fitness landscape, and how they affect the ability of evolving populations to adapt despite the difficulty of crossing valleys present in rugged landscapes. Populations are seen to make use of...
Source: http://arxiv.org/abs/1304.3738v1
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We define a weak notion of universality in symbolic dynamics and, by generalizing a proof of Mike Hochman, we prove that this yields necessary conditions on the forbidden patterns defining a universal subshift: These forbidden patterns are necessarily in a Medvedev degree greater or equal than the degree of the set of subshifts for which it is universal. We also show that this necessary condition is optimal by giving constructions of universal subshifts in the same Medvedev degree as the...
Source: http://arxiv.org/abs/1304.5418v2
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We augment LP with a strong conditional operator, to yield a logic we call "strong LP," or LP=>. The resulting logic can speak of consistency in more discriminating ways, but introduces new possibilities for trivializing paradoxes.
Source: http://arxiv.org/abs/1304.6467v1
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We study the vortex dynamics of a quantum degenerate Bose gas through the intensity fluctuations of the interference from particles extracted at two different positions. It is shown numerically with classical field simulations that an interacting Bose gas with proliferating vortices exhibits long correlation times for these intensity fluctuations. This behavior is contrasted with the case of a noninteracting gas, that we describe analytically, and with the case of a well condensed Bose gas...
Source: http://arxiv.org/abs/1304.6201v1
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In 1983, N. Herrndorf proved that for a $\phi$-mixing sequence satisfying the central limit theorem and $\phi(1)
Source: http://arxiv.org/abs/1304.7960v1
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Circumstances are described in which symmetry breaking during the formation of our three-dimensional brane within a higher-dimensional space in the early universe excites mesoscopic classical radion or brane-displacement degrees of freedom and produces a detectable stochastic background of gravitational radiation. The spectrum of the background is related to the unification energy scale and the the sizes and numbers of large extra dimensions. It is shown that properties of the background...
Source: http://arxiv.org/abs/astro-ph/0009136v1
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by Michael Blanton; Pasquale Blasi; Angela V. Olinto
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We calculate numerically the spectrum of ultra-high energy cosmic rays on Earth assuming that their sources are distributed in space like the observed galaxies. We use the CfA2 and the PSCz galaxy redshift surveys to model the local galaxy distribution, properly taking into account the galaxy selection functions for each survey. When the survey selection effects are included, we find that the local overdensity is only a factor of two, an order of magnitude less than used in some earlier...
Source: http://arxiv.org/abs/astro-ph/0009466v1
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by M. S. Wheatland
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The question of whether flares occur as a Poisson process has important consequences for flare physics. Recently Lepreti et al. presented evidence for local departure from Poisson statistics in the Geostationary Operational Environmental Satellite (GOES) X-ray flare catalog. Here it is argued that this effect arises from a selection effect inherent in the soft X-ray observations; namely that the slow decay of enhanced flux following a large flare makes detection of subsequent flares less...
Source: http://arxiv.org/abs/astro-ph/0107147v1
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by William H. Kinney
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I examine the status of inflationary cosmology in light of the first-year data from the WMAP satellite, focusing on the simplest models of inflation: those driven by a single scalar field. The WMAP observation of the Cosmic Microwave Background is the first unified, self-consistent data set capable of putting meaningful constraints on the inflationary parameter space. WMAP provides significant support for the inflationary paradigm in general, and single-field slow-roll inflation models provide...
Source: http://arxiv.org/abs/astro-ph/0406670v1
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by Susmita Bhowmik Duari; U. A. Yajnik
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If cosmic strings are present at the electroweak phase transition, they can act as seeds on which bubbles of true vacuum nucleate. We explore the nature of such a phase transition, in particular the wall velocity and thickness of the bubbles. {}From the viewpoint of electroweak baryogenesis, adiabatic conditions exist in the expanding bubble walls, and such models of baryogenesis can be successfully applied. In the present mechanism, the nature of the electroweak phase transition is insensitive...
Source: http://arxiv.org/abs/hep-ph/9401247v1
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by J. Bolz; R. Jakob; P. Kroll; M. Bergmann; N. G. Stefanis
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Two recently proposed concepts to improve the perturbative calculation of exclusive amplitudes, gluonic radiative corrections (Sudakov factor) and confinement size effects (intrinsic transverse momentum) are combined to study the neutron magnetic form factor in the space-like region. We find that nucleon distribution amplitudes modelled on the basis of current QCD sum rules indicate overlap with the existing data at the highest measured values of momentum transfer. However, sizeable...
Source: http://arxiv.org/abs/hep-ph/9407250v2
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by Glennys R. Farrar
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Gluinos in the mass range ~1 1/2 - 3 1/2 GeV are absolutely excluded. Lighter gluinos are allowed, except for certain ranges of lifetime. Only small parts of the mass-lifetime parameter space are excluded for larger masses unless the lifetime is shorter than ~ 2 10^{-11} (m_{gluino}/ GeV) sec. Refined mass and lifetime estimates for R-hadrons are given, present direct and indirect experimental constraints are reviewed, and experiments to find or definitively exclude these possibilities are...
Source: http://arxiv.org/abs/hep-ph/9407401v3
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by S. Ya. Jitomirskaya; I. V. Krasovsky
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We study discrete Schroedinger operators $(H_{\alpha,\theta}\psi)(n)= \psi(n-1)+\psi(n+1)+f(\alpha n+\theta)\psi(n)$ on $l^2(Z)$, where $f(x)$ is a real analytic periodic function of period 1. We prove a general theorem relating the measure of the spectrum of $H_{\alpha,\theta}$ to the measures of the spectra of its canonical rational approximants under the condition that the Lyapunov exponents of $H_{\alpha,\theta}$ are positive. For the almost Mathieu operator ($f(x)=2\lambda\cos 2\pi x$) it...
Source: http://arxiv.org/abs/math/0107061v2
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by Masashi Ishida; Claude LeBrun
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We show that there exist smooth, simply connected, four-dimensional spin manifolds which do not admit Einstein metrics, but nonetheless satisfy the strict Hitchin-Thorpe inequality. Our construction makes use of the Bauer/Furuta cohomotopy refinement of the Seiberg-Witten invariant, in conjunction with curvature estimates previously proved by the second author. These methods also easily allow one to construct examples of topological 4-manifolds which admit an Einstein metric for one smooth...
Source: http://arxiv.org/abs/math/0107111v2
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by Philippe Caldero; Andrei Zelevinsky
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We study Laurent expansions of cluster variables in a cluster algebra of rank 2 associated to a generalized Kronecker quiver. In the case of the ordinary Kronecker quiver, we obtain explicit expressions for Laurent expansions of the elements of the canonical basis for the corresponding cluster algebra.
Source: http://arxiv.org/abs/math/0604054v4
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by D. Huard; H. Kröger; G. Melkonyan; L. P. Nadeau; K. J. M. Moriarty
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We consider a mixed chaotic Hamiltonian system and compare classical with quantum chaos. As alternative to the methods of enegy level spacing statistics and trace formulas, we construct a quantum action and a quantum analogue phase space to analyse quantum chaos.
Source: http://arxiv.org/abs/quant-ph/0406131v1
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by R. Mohayaee
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We consider the anomalies of $W_\infty$ gravity in the context of path-integralquantization. We derive the ghost-loop anomalies to all orders in $\hbar$ directly from the path-integral measure by the Fujikawa method. We also show that in the matter sector the higher-loop anomalies can be obtained by implementation of the Wess-Zumino consistency condition using the one-loop anomaly. Cancellation of the anomalies between these two sectors then leaves the theory anomaly-free.
Source: http://arxiv.org/abs/hep-th/9407006v1
We consider the effect of the nearest neighbour copper-oxygen repulsion, V, when coupled to the charge transfer resonances Cu2+ to Cu3+ and Cu2+ to Cu+ in the high temperature cuprate superconductors. This is done by deriving effective low energy Hamiltonians correct to second order in the copper-oxygen hybridisation. Only hole doping is considered. When Cu2+ to Cu3+ fluctuations dominate we derive an effective one-band model of `Zhang-Rice' singlets with a nearest neighbour repulsion between...
Source: http://arxiv.org/abs/cond-mat/9407065v1
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by Johan Bijnens
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The class of phenomenological Lagrangians used for light constituent quarks is discussed. The Nambu-Jona-Lasinio model is then argued to be a good phenomenological choice and the quality of its prediction in the purely hadronic sector including several relations between parameters illustrated. Then we use these models to calculate nonleptonic matrix elements. The $\pi^+-\pi^0$ mass difference and the $B_K$ parameter, relevant in $K^0-\overline{K}^0$ mixing, are treated in more detail.
Source: http://arxiv.org/abs/hep-ph/9411420v1