April 2006 arXiv papers — page 35

Erik Schnetter, Badri Krishnan, Florian Beyer

This paper presents a quasi-local method of studying the physics of dynamical black holes in numerical simulations. This is done within the dynamical horizon framework, which extends the earlier work on isolated horizons to time-dependent situations. In particular: (i) We locate various kinds of marginal surfaces and study their time evolution. An important

Aristide Baratin, Laurent Freidel

In this work we show that 3d Feynman amplitudes of standard QFT in flat and homogeneous space can be naturally expressed as expectation values of a specific topological spin foam model. The main interest of the paper is to set up a framework which gives a background independent perspective on usual field theories and can also be applied in higher dimensions.

Bruno G. Taketani, Eduardo S. Fraga

We consider an approximation procedure to evaluate the finite-temperature one-loop fermionic density in the presence of a chiral background field which systematically incorporates effects from inhomogeneities in the chiral field through a derivative expansion. We apply the method to the case of a simple low-energy effective chiral model which is commonly use

R. W. Crane, N. P. Armitage, A. Johansson, G. Sambandamurthy

The complex ac conductivity of thin highly disordered InOx films was studied as a function of magnetic field through the nominal two-dimensional superconductor-insulator transition. We have resolved a significant finite-frequency superfluid stiffness well into the insulating regime, giving direct evidence for quantum superconducting fluctuations around an in

R. J. White, T. P. Greene, G. W. Doppmann, K. R. Covey

(Abridged) High dispersion spectrographs on large aperture telescopes have recently allowed observers to study the stellar and accretion properties of deeply embedded young stars, commonly referred to as Class I stars. We summarize these newly determined properties and compare them with observations of more optically revealed Class II (T Tauri) stars. Class

Johan Nilsson, A. H. Castro Neto, F. Guinea, N. M. R. Peres

We study the effects of disorder in the electronic properties of graphene multilayers, with special focus on the bilayer and the infinite stack. At low energies and long wavelengths, the electronic self-energies and density of states exhibit behavior with divergences near half-filling. As a consequence, the spectral functions and conductivities do not follow

Desika Narayanan, Thomas J. Cox, Brant Robertson, Romeel Dave

We study the effects of feedback from active galactic nuclei (AGN) on emission from molecular gas in galaxy mergers by combining hydrodynamic simulations which include black holes with a three-dimensional, non-local thermodynamic equilibrium (LTE) radiative transfer code. We find that molecular clouds entrained in AGN winds produce an extended CO morphology

James Hirschorn

It is proved that there exists an (omega-1,omega-1) Souslin gap in the Boolean algebra (L(nu)/Fin,subseteq^*_ae) for every nonseparable measure nu. Thus a Souslin, also known as destructible, (omega-1,omega-1) gap in P(N)/Fin can always be constructed from uncountably many random reals. We explain how to obtain the corresponding conclusion from the hypothesi

Daniel S Silver, Susan G Williams

The group of a nontrivial knot admits a finite permutation representation such that the corresponding twisted Alexander polynomial is not a unit.

A. F. Ferrari, M. Gomes, J. R. S. Nascimento, A. Yu. Petrov

Within the superfield approach, we consider the duality between the supersymmetric Maxwell-Chern-Simons and self-dual theories in three spacetime dimensions. Using a gauge embedding method, we construct the dual theory to the self-dual model interacting with a matter superfield, which turns out to be not the Maxwell-Chern-Simons theory coupled to matter, but

Hans F. Stabenau, Bhuvnesh Jain

Theories in which gravity is weaker on cosmological scales have been proposed to explain the observed acceleration of the universe. The nonlinear regime in such theories is not well studied, though it is likely that observational tests of structure formation will lie in this regime. A class of alternate gravity theories may be approximated by modifying Poiss

Horacio E. Camblong, Luis N. Epele, Huner Fanchiotti, Carlos A. Garcia Canal

A unified S-matrix framework of quantum singular interactions is presented for the comparison of self-adjoint extensions and physical renormalization. For the long-range conformal interaction the two methods are not equivalent, with renormalization acting as selector of a preferred extension and regulator of the unbounded Hamiltonian.

Preston Jones, Lucas F. Wanex

The gedanken experiment of the clock paradox is solved exactly using the general relativistic equations for a static homogeneous gravitational field. We demonstrate that the general and special relativistic clock paradox solutions are identical and in particular that they are identical for finite acceleration. Practical expressions are obtained for proper ti

Dmitry Panchenko, Michel Talagrand

In order to study certain questions concerning the distribution of the overlap in Sherrington--Kirkpatrick type models, such as the chaos and ultrametricity problems, it seems natural to study the free energy of multiple systems with constrained overlaps. One can write analogues of Guerra's replica symmetry breaking bound for such systems but it is not a

H. C. Rosu, V. Ibarra-Junquera

The dynamical systems observability properties of barotropic bosonic and fermionic FRW cosmological oscillators are investigated. Nonlinear techniques for dynamical analysis have been recently developed in many engineering areas but their application has not been extended beyond their standard field. This paper is a small contribution to an extension of this

Dmitry Panchenko

We develop a cavity method in the spherical Sherrington-Kirkpatrick model at high temperature and small external field. As one application we compute the limit of the covariance matrix for fluctuations of the overlap and magnetization.

X. Zhao, G. Yu, Y. Cho, G. Chabot-Couture

This paper is published in Advanced Materials (available at http://www3.interscience.wiley.com/cgi-bin/abstract/113511105/ABSTRACT). It has been withdrawn from the cond-mat preprint archive in order to avoid a violation of the Journal's policy.

Abhay Ashtekar, Tomasz Pawlowski, Parampreet Singh

Analytical and numerical methods are developed to analyze the quantum nature of the big bang in the setting of loop quantum cosmology. They enable one to explore the effects of quantum geometry both on the gravitational and matter sectors and significantly extend the known results on the resolution of the big bang singularity. Specifically, the following res

Carla Figueira de Morisson Faria, Andreas Fring

We provide time-evolution operators, gauge transformations and a perturbative treatment for non-Hermitian Hamiltonian systems, which are explicitly time-dependent. We determine various new equivalence pairs for Hermitian and non-Hermitian Hamiltonians, which are therefore pseudo-Hermitian and in addition in some cases also invariant under PT-symmetry. In par

Yun Wang, Pia Mukherjee

Type Ia supernova (SN Ia), galaxy clustering, and cosmic microwave background anisotropy (CMB) data provide complementary constraints on the nature of the dark energy in the universe. We find that the three-year Wilkinson Microwave Anisotropy Probe (WMAP) observations give a CMB shift parameter of R = (Ω_m H_0^2)^{1/2} \int_0^{z_{CMB}} dz'/H(z')= 1.7

M. Campanelli, C. O. Lousto, Y. Zlochower

We present the first fully-nonlinear numerical study of the dynamics of highly spinning black-hole binaries. We evolve binaries from quasicircular orbits (as inferred from Post-Newtonian theory), and find that the last stages of the orbital motion of black-hole binaries are profoundly affected by their individual spins. In order to cleanly display its effect

M. Chaichian, A. Tureanu

By applying properly the concept of twist symmetry to the gauge invariant theories, we arrive at the conclusion that previously proposed in the literature noncommutative gauge theories, with the use of $\star$-product, are the correct ones, which possess the twisted Poincaré symmetry. At the same time, a recent approach to twisted gauge transformations is in

Lamartine Liberato, Rogerio Rosenfeld

There is a plethora of dark energy parameterizations that can fit current supernovae Ia data. However, this data is only sensitive to redshifts up to order one. In fact, many of these parameterizations break down at higher redshifts. In this paper we study the effect of dark energy models on the formation of dark halos. We select a couple of dark energy para

Alexis Devulder

We consider a one-dimensional diffusion process $X$ in a $(-κ/2)$-drifted Brownian potential for $κ\neq 0$. We are interested in the maximum of its local time, and study its almost sure asymptotic behaviour, which is proved to be different from the behaviour of the maximum local time of the transient random walk in random environment. We also obtain the conv

Brian Geislinger, Ryoichi Kawai

We investigated three models of Brownian motors which convert rotational diffusion into directed translational motion by switching on and off a potential. In the first model a spatially asymmetric potential generates directed translational motion by rectifying rotational diffusion. It behaves much like a conventional flashing ratchet. The second model utiliz

Jesus Gomez-Gardenes, Yamir Moreno

We analyze a model that interpolates between scale-free and Erdos-Renyi networks. The model introduced generates a one-parameter family of networks and allows to analyze the role of structural heterogeneity. Analytical calculations are compared with extensive numerical simulations in order to describe the transition between these two important classes of net

Yan Levin

A model of a finite cylindrical ion channel through a phospholipid membrane of width $L$ separating two electrolyte reservoirs is studied. Analytical solution of the Poisson equation is obtained for an arbitrary distribution of ions inside the trans-membrane pore. The solution is asymptotically exact in the limit of large ionic strength of electrolyte on the

Robert L. Jack, Juan P. Garrahan, David Chandler

In a recent article [M. Merolle et al., Proc. Natl. Acad. Sci. USA 102, 10837 (2005)] it was argued that dynamic heterogeneity in $d$-dimensional glass formers is a manifestation of an order-disorder phenomenon in the $d+1$ dimensions of spacetime. By considering a dynamical analogue of the free energy, evidence was found for phase coexistence between active

G. W. Gibbons, P. K. Townsend

The (2k+2)-dimensional Einstein-Yang-Mills equations for gauge group SO(2k) (or SU(2) for k=2 and SU(3) for k=3) are shown to admit a family of spherically-symmetric magnetic monopole solutions, for both zero and non-zero cosmological constant Lambda, characterized by a mass m and a magnetic-type charge. The k=1 case is the Reissner-Nordstrom black hole. The

R. Lortz, F. Lin, N. Musolino, Y. Wang

The range of critical thermal fluctuations in classical bulk superconductors is extremely small and especially in low fields hardly experimentally inaccessible. With a new type of calorimeter we have been able to resolve a small lambda anomaly within a narrow temperature range around the Hc2 line. We show that the evolution of the anomaly as a function of ma

A. Mönnich, J. Lange, M. Bauer, M. Aeschlimann

We have studied the relaxation dynamics of optically excited electrons in molybdenum and rhodium by means of time resolved two-photon photoemission spectroscopy (TR-2PPE) and ab initio electron self-energy calculations performed within the GW and GW+T approximations. Both theoretical approaches reproduce qualitatively the experimentally observed trends and d

Paul Fendley, Matthew P. A. Fisher, Chetan Nayak

We analyze tunneling of non-Abelian quasiparticles between the edges of a quantum Hall droplet at Landau level filling fraction nu=5/2, assuming that the electrons in the first excited Landau level organize themselves in the non-Abelian Moore-Read Pfaffian state. We formulate a bosonized theory of the modes at the two edges of a Hall bar; an effective spin-1

M. Weides, M. Kemmler, H. Kohlstedt, A. Buzdin

We fabricated high quality $\Nb/\Al_2Ø_3/\Ni_{0.6}\Cu_{0.4}/\Nb$ superconductor-insulator-ferromagnet-superconductor Josephson tunnel junctions. Depending on the thickness of the ferromagnetic $\Ni_{0.6}\Cu_{0.4}$ layer and on the ambient temperature, the junctions were in the 0 or $π$ ground state. All junctions have homogeneous interfaces showing almost pe

Gunnar Moller, R. Moessner

We study a frustrated dipolar array recently manufactured lithographically by Wang {\em et al.} [Nature {\bf 439}, 303 (2006)] in order to realize the square ice model in an artificial structure. We discuss models for thermodynamics and dynamics of this system. We show that an ice regime can be stabilized by small changes in the array geometry; a different m

Micha Berkooz, Dori Reichmann, Joan Simon

We identify a large family of 1/16 BPS operators in N=4 SYM that qualitatively reproduce the relations between charge, angular momentum and entropy in regular supersymmetric AdS_5 black holes when the main contribution to their masses is given by their angular momentum.

B. Pozsgay, G. Takacs

We develop methods to extract resonance widths from finite volume spectra of 1+1 dimensional quantum field theories. Our two methods are based on Luscher's description of finite size corrections, and are dubbed the Breit-Wigner and the improved "mini-Hamiltonian" method, respectively. We establish a consistent framework for the finite volume desc

D. H. Phong, Jian Song, Jacob Sturm, Ben Weinkove

We prove the conjecture of Tian on the strong form of the Moser-Trudinger inequality for Kahler-Einstein manifolds with positive first Chern class, when there are no holomorphic vector fields, and, more generally, when the setting is invariant under a maximal compact subgroup of the automorphism group.

Ghasem Exirifard

The linear alpha-prime corrections and the field redefinition ambiguities are studied for half-BPS singular backgrounds representing a wrapped fundamental string. It is showed that there exist schemes in which the inclusion of all the linear alpha-prime corrections converts these singular solutions to black holes with a regular horizon for which the modified

C. E. Creffield, T. S. Monteiro

We study the time-dependent dynamics of a Bose-Einstein condensate trapped in an optical lattice. Modeling the system as a Bose-Hubbard model, we show how applying a periodic driving field can induce coherent destruction of tunneling. In the low-frequency regime, we obtain the novel result that the destruction of tunneling displays extremely sharp peaks when

Ali Ahanj, Pramod Joag

This paper has been withdrawn due to a fatal error in the argument of the simulation scheme.

Arnaud Gay

Understanding the mechanism of electroweak symmetry breaking and the origin of boson and fermion masses is among the most pressing questions raised in contemporary particle physics. If these issues involve one (several) Higgs boson(s), a precise measurement of all its (their) properties will be of prime importance. Among those, the Higgs coupling to matter f

Fabio D. A. Aarao Reis, J. P. Badiali, Thierry Pauporte, Daniel Lincot

We present models of electrodeposition of ZnO films with organic additives, with focus on the growth of hybrid films with eosin Y. First we propose a rate equation model which assumes that the additives form branches with an exposed part above the ZnO deposit, growing with larger rate than the pure film, and that the rate of production of ZnO near those bran

H. Chamati, E. Korutcheva

We study the critical dynamics of hyper-cubic finite size system in the presence of quenched short-range correlated disorder. By using the random $T_c$ model A for the critical dynamics and the renormalization group method in the vicinity of the upper critical dimension $d=4$, we derive in first order of $ε$ the expression for the relaxation time. Its finite

A. Mateus, Laerte Sodre, Roberto Cid Fernandes, Grazyna Stasinska

We investigate the environmental dependence of stellar population properties of galaxies in the local universe. Physical quantities related to the stellar content of galaxies are derived from a spectral synthesis method applied to a volume-limited sample containing more than 60 thousand galaxies extracted from the DR4 of the SDSS. Mean stellar ages, mean ste

Francisco Marcellan, Juan Jose Moreno-Balcazar

In this paper we present a survey about analytic properties of polynomials orthogonal with respect to a weighted Sobolev inner product such that the vector of measures has an unbounded support. In particular, we are focused in the study of the asymptotic behaviour of such polynomials as well as in the distribution of their zeros. Some open problems as well a

Adnene Ben Abdesselem, Brahim Dridi

This paper generalizes the first author's preceding works concerning admissible functions on certain Fano manifolds. Here, we study a larger class of functions which can be less symmetric than the ones studied before. When the sup of these functions is null, we prove that they admit a lower bound, giving precisely Tian invariant on these manifolds.

Nicholas James Rattenbury

Four planets have recently been discovered by gravitational microlensing. The most recent of these discoveries is the lowest-mass planet known to exist around a normal star. The detection of planets in gravitational microlensing events was predicted over a decade ago. Microlensing is now a mature field of astrophysical research and the recent planet detectio

Stoil Donev, Maria Tashkova

This paper aims to show that making use of Newton's view on equations of motion of a physical system and of the Maxwell stress tensor we come to a natural nonlinearization of Maxwell equations in vacuum making use only of nonrelativistic terms. The new equations include all Maxwell solutions plus new ones, among which one may find time-stable and spatial

Hendrick L. Bethlem, M. R. Tarbutt, Jochen Küpper, David Carty

Beams of polar molecules can be focused using an array of electrostatic lenses in alternating gradient (AG) configuration. They can also be accelerated or decelerated by applying an appropriate high voltage switching sequence to the lenses. AG focusing is applicable to molecules in both low-field and high-field-seeking states and is particularly well suited

G. Gaeta

The Yakushevich model of DNA torsion dynamics supports soliton solutions, which are supposed to be of special interest for DNA transcription. In the discussion of the model, one usually adopts the approximation $\ell_0 \to 0$, where $\ell_0$ is a parameter related to the equilibrium distance between bases in a Watson-Crick pair. Here we analyze the Yakushevi

A. D. Martin, C. S. Adams, S. A. Gardiner

Collisions between bright solitary waves in the 1D Gross-Pitaevskii equation with a harmonic potential, which models a trapped atomic Bose-Einstein condensate, are investigated theoretically. A particle analogy for the solitary waves is formulated, which is shown to be integrable for a two-particle system. The extension to three particles is shown to support

Se-Heon Kim, Sun-Kyung Kim, Yong-Hee Lee

We report that $> 80%$ of the photons generated inside a photonic crystal slab resonator can be funneled within a small divergence angle of $\pm 30^\circ$. The far-field radiation properties of a photonic crystal slab resonant mode are modified by tuning the cavity geometry and by placing a reflector below the cavity. The former method directly shapes the ne

C. Kuelske, E. Orlandi

We prove a finite volume lower bound of the order of the squareroot of log N on the delocalization of a disordered continuous spin model (resp. effective interface model) in d = 2 in a box of size N . The interaction is assumed to be massless, possibly anharmonic and dominated from above by a Gaussian. Disorder is entering via a linear source term. For this

Ross G. Pinsky

Let the random variable $Z_{n,k}$ denote the number of increasing subsequences of length $k$ in a random permutation from $S_n$, the symmetric group of permutations of $\{1,...,n\}$. In a recent paper [Random Structures Algorithms 29 (2006) 277--295] we showed that the weak law of large numbers holds for $Z_{n,k_n}$ if $k_n=o(n^{2/5})$; that is, \[\lim_{n\to

Garry Bowen, Nilanjana Datta

The information spectrum approach gives general formulae for optimal rates of codes in many areas of information theory. In this paper the quantum spectral divergence rates are defined and properties of the rates are derived. The entropic rates, conditional entropic rates, and spectral mutual information rates are then defined in terms of the spectral diverg

Smadar Naoz, Shay Noter, Rennan Barkana

Large telescopes have allowed astronomers to observe galaxies that formed as early as 850 million years after the Big Bang. We predict when the first star that astronomers can observe formed in the universe, accounting for the first time for the size of the universe and for three essential ingredients: the light travel time from distant galaxies, Poisson and

Laurent Boyer, Victor Poupet, Guillaume Theyssier

We study the notion of limit sets of cellular automata associated with probability measures (mu-limit sets). This notion was introduced by P. Kurka and A. Maass. It is a refinement of the classical notion of omega-limit sets dealing with the typical long term behavior of cellular automata. It focuses on the words whose probability of appearance does not tend

Yasuhiro Utsumi

Motivated by recent real-time electron counting experiments, we evaluate the full counting statistics (FCS) for the probability distribution of the electron number inside a quantum dot which is weakly coupled to source and drain leads. A non-Gaussian exponential distribution appears when there is no dot state close to the lead chemical potentials. We propose

Michael Müger, Lars Tuset

We show that the left regular representation \pi_l of a discrete quantum group (A,\Delta) has the absorbing property and forms a monoid (\pi_l,\tilde{m},\tilde{\eta}) in the representation category Rep(A,\Delta). Next we show that an absorbing monoid in an abstract tensor *-category C gives rise to an embedding functor E:C->Vect_C, and we identify conditions

Hongsu Kim

The pure Brans-Dicke (BD) gravity with or without the cosmological constant $Λ$ has been taken as a model theory for the dark matter. Indeed, there has been a consensus that unless one modifies either the standard theory of gravity, namely, general relativity, or the standard model for particle physics, or both, one can never achieve a satisfying understandi

Charles Bouveyron, Stéphane Girard, Cordelia Schmid

Clustering in high-dimensional spaces is a difficult problem which is recurrent in many domains, for example in image analysis. The difficulty is due to the fact that high-dimensional data usually live in different low-dimensional subspaces hidden in the original space. This paper presents a family of Gaussian mixture models designed for high-dimensional dat

A. Sarkar, A. Chatterjee, P. Barat, P. Mukherjee

Tensile tests were carried out by deforming polycrystalline samples of an interstitial alloy, low carbon steel at room temperature in a wide range of strain rates where the Portevin-Le Chatelier (PLC) effect was observed. The observed stress time series data were analyzed using the nonlinear dynamical methods. From the analyses, we could establish the presen

J. M. Montanero, A. Santos, V. Garzo

A method is devised to measure the first-order Chapman-Enskog velocity distribution function associated with the heat flux in a dilute granular gas. The method is based on the application of a homogeneous, anisotropic velocity-dependent external force which produces heat flux in the absence of gradients. The form of the force is found under the condition tha

V. Garzo, A. Santos, J. M. Montanero

Motivated by the disagreement found at high dissipation between simulation data for the heat flux transport coefficients and the expressions derived from the Boltzmann equation by the standard first Sonine approximation [Brey et al., Phys. Rev. E 70, 051301 (2004); J. Phys.: Condens. Matter 17, S2489 (2005)], we implement in this paper a modified version of

Simon Hands, Seyong Kim, Jon-Ivar Skullerud

We study SU(2) lattice gauge theory with two flavors of Wilson fermion at non-zero chemical potential mu and low temperature on a 8^3x16 system. We identify three regimes along the mu-axis. For mu<~m_pi/2 the system remains in the vacuum phase, and all physical observables considered remain essentially unchanged. The intermediate regime is characterised by a

Hiroaki Onishi, Takashi Hotta

In order to discuss the spin-gap formation in a multiorbital system, we analyze an e_g-orbital Hubbard model on a geometrically frustrated zigzag chain by using a density-matrix renormalization group method. Due to the appearance of a ferro-orbital arrangement, the system is regarded as a one-orbital system, while the degree of spin frustration is controlled

Amand Faessler, Thomas Gutsche, Sergey Kovalenko, Valery E. Lyubovitskij

We calculate the electric dipole moments (EDM) of the neutral Hg(199) atom, neutron and deuteron within a generic R-parity violating SUSY model (RPV SUSY) on the basis of a one-pion exchange model with CP-odd pion-nucleon interactions. We consider two types of the RPV SUSY contributions to the above hadronic EDMs: via the quark chromoelectric dipole moments

Barak Kol, Evgeny Sorkin

This paper continues the study of the Gregory-Laflamme instability of black strings, or more precisely of the order of the transition, being either first or second order, and the critical dimension which separates the two cases. First, we describe a novel method based on the Landau-Ginzburg perspective for the thermodynamics that somewhat improves the existi

Manabu Machida, Naomichi Hatano, Jun Goryo

We study a nonadiabatic effect on the conductances in the quantum Hall effect of two-dimensional electrons with a periodic potential. We found that the Hall and longitudinal conductances oscillate in time with a very large frequencies due to quantum fluctuation.

Xiao-Liang Qi, Yong-Shi Wu, Shou-Cheng Zhang

We prove a general theorem on the relation between the bulk topological quantum number and the edge states in two dimensional insulators. It is shown that whenever there is a topological order in bulk, characterized by a non-vanishing Chern number, even if it is defined for a non-conserved quantity such as spin in the case of the spin Hall effect, one can al

Eon Kyung Lee, Sang Jin Lee

It is known that Garside groups are strongly translation discrete. In this paper, we show that the translation numbers in a Garside group are rational with uniformly bounded denominators and can be computed in finite time. As an application, we give solutions to some group-theoretic problems.

Masashi Hayakawa, Hiroto So, Hiroshi Suzuki

We construct a lattice Dirac operator of overlap type that describes the propagation of a Dirac fermion in an external gravitational field. The local Lorentz symmetry is manifestly realized as a lattice gauge symmetry, while it is believed that the general coordinate invariance is restored only in the continuum limit. Our doubler-free Dirac operator satisfie

Li Ma

In this paper, we study the partial convexity of smooth solutions to the heat equation on a compact or complete non-compact Riemannian manifold M or Kahler-Ricci flow. We show that under a natural assumption, a new partial convexity property for smooth solutions to the heat equation is preserved.

Weiping Li, Qingxue Wang

In this paper, by using the regulator map of Beilinson-Deligne, we show that the quantization condition posed by Gukov is true for the SL_2(\mathbb{C}) character variety of the hyperbolic knot in S^3. Furthermore, we prove that the corresponding \mathbb{C}^{*}-valued 1-form is a secondary characteristic class (Chern-Simons) arising from the vanishing first C

Shintaro Sawayama

One of the unsolved issues in the quantum gravity comes from the Wheeler-DeWitt equation, which is second order functional derivative equation. In this paper, we introduce a new method to solve the Wheeler-DeWitt equation. Usually one treats the state functional of the space of 3-dimensional metrics, which do not contain timelike metrics. However we can expa

Philippe Caldero, Andrei Zelevinsky

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.

Farhan Saif

In order to probe nanostructures on a surface we present a microscope based on the quantum recurrence phenomena. A cloud of atoms bounces off an atomic mirror connected to a cantilever and exhibits quantum recurrences. The times at which the recurrences occur depend on the initial height of the bouncing atoms above the atomic mirror, and vary following the s

Cyril Petitjean, Philippe Jacquod

In Echo experiments, imperfect time-reversal operations are performed on a subset of the total number of degrees of freedom. To capture the physics of these experiments, we introduce a partial fidelity, the Boltzmann echo, where only part of the system&#39;s degrees of freedom can be time-reversed. We present a semiclassical calculation of the Boltzmann echo

Jan Perina, Marco Centini, Concita Sibilia, Mario Bertolotti

We have developed a rigorous quantum model of spontaneous parametric down-conversion in a nonlinear 1D photonic-band-gap structure based upon expansion of the field into monochromatic plane waves. The model provides a two-photon amplitude of a created photon pair. The spectra of the signal and idler fields, their intensity profiles in the time domain, as wel

J. P. Keating, F. Mezzadri, M. Novaes

Bipartite entanglement in the ground state of a chain of $N$ quantum spins can be quantified either by computing pairwise concurrence or by dividing the chain into two complementary subsystems. In the latter case the smaller subsystem is usually a single spin or a block of adjacent spins and the entanglement differentiates between critical and non-critical r

L. Stenflo, P. K. Shukla, M. Marklund

The existence of two new low-frequency electrostatic modes in quantum dusty plasmas is pointed out. These modes can be useful to diagnose charged dust impurities in micro-electro-mechanical systems.

Francesco Plastina, Giuseppe Liberti, Angelo Carollo

We discuss the thermodynamic and finite size scaling properties of the geometric phase in the adiabatic Dicke model, describing the super-radiant phase transition for an $N$ qubit register coupled to a slow oscillator mode. We show that, in the thermodynamic limit, a non zero Berry phase is obtained only if a path in parameter space is followed that encircle

Luiz Carlos Ryff

An Einstein-Podolsky-Rosen (EPR)-like argument using events separated by a time-like interval strongly suggestes that measuring the polarization state of a photon of an entangled pair changes the polarization state of the other distant photon. Trough a very simple demonstration, the Wigner-D&#39;Espagnat inequality is used to show that in order to prove Bell

H. T. Quan, P. Zhang, C. P. Sun

We study the physical implementation of the Photon Carnot engine (PCE) based on the cavity QED system [M. Scully et al, Science, \textbf{299}, 862 (2003)]. Here, we analyze two decoherence mechanisms for the more practical systems of PCE, the dissipation of photon field and the pure dephasing of the input atoms. As a result we find that (I) the PCE can work

Jeroen S. van Zon, Marco J. Morelli, Sorin Tanase-Nicola, Pieter Rein ten Wolde

We study by simulation the effect of the diffusive motion of repressor molecules on the noise in mRNA and protein levels in the case of a repressed gene. We find that spatial fluctuations due to diffusion can drastically enhance the noise in gene expression. For a fixed repressor strength, the noise due to diffusion can be minimized by increasing the number

G. Gaeta

The Yakushevich (Y) model provides a very simple pictures of DNA torsion dynamics, yet yields remarkably correct predictions on certain physical characteristics of the dynamics. In the standard Y model, the interaction between bases of a pair is modelled by a harmonic potential, which becomes anharmonic when described in terms of the rotation angles; here we

Mauro Mobilia, Ivan T. Georgiev, Uwe C. Tauber

Including spatial structure and stochastic noise invalidates the classical Lotka-Volterra picture of stable regular population cycles emerging in models for predator-prey interactions. Growth-limiting terms for the prey induce a continuous extinction threshold for the predator population whose critical properties are in the directed percolation universality

Andrzej Mercik, Szymon Mercik

We propose a new approach to the model of an origin of the universe built by Oscar Klein and Hannes Alfvén. Some modifications of assumptions underlying the model result in a possible scenario of the universe creation consistent with observations. We explain the large scale structre of the universe and we estimate the Hubble constant value as well as the num

Ute Ebert, Carolynne Montijn, T. M. P. Briels, Willem Hundsdorfer

Streamers are a generic mode of electric breakdown of large gas volumes. They play a role in the initial stages of sparks and lightning, in technical corona reactors and in high altitude sprite discharges above thunderclouds. Streamers are characterized by a self-generated field enhancement at the head of the growing discharge channel. We briefly review rece

Rajesh G. Kavasseri †~, Radhakrishnan Nagarajan

The complexity of the atmosphere endows it with the property of turbulence by virtue of which, wind speed variations in the atmospheric boundary layer (ABL) exhibit highly irregular fluctuations that persist over a wide range of temporal and spatial scales. Despite the large and significant body of work on microscale turbulence, understanding the statistics

A. Saichev, D. Sornette

We propose a simple theory for the ``universal&#39;&#39; scaling law previously reported for the distributions of waiting times between earthquakes. It is based on a largely used benchmark model of seismicity, which just assumes no difference in the physics of foreshocks, mainshocks and aftershocks. Our theoretical calculations provide good fits to the data

X. Q. Huang

We study the energy conversion laws of the macroscopic harmonic $LC $ oscillator, the electromagnetic wave (photon) and the hydrogen atom. As our analysis indicates that the energies of these apparently different systems obey exactly the same energy conversion law. Based on our results and the wave-particle duality of electron, we find that the atom in fact

L. Bonneau

A static microscopic study of potential-energy surfaces within the Skyrme-Hartree-Fock-plus-BCS model is carried out for the 256Fm and 258Fm isotopes with the goal of deducing some properties of spontaneous fission. The calculated fission modes are found to be in agreement with the experimentaly observed asymmetric-to-symmetric transition in the fragment-mas

A. S. Umar, V. E. Oberacker

We outline a formalism to carry out TDHF calculations of fusion cross sections for spherical + deformed nuclei. The procedure incorporates the dynamic alignment of the deformed nucleus into the calculation of the fusion cross section. The alignment results from multiple E2/E4 Coulomb excitation of the ground state rotational band. Implications for TDHF fusio

Kazuhiro Hikami

We give a transformation formula for the ``2nd order&#39;&#39; mock theta function which was recently proposed in connection with the quantum invariant for the Seifert manifold.

Mikhail Shubin, Toshikazu Sunada

We discuss, from a geometric standpoint, the specific heat of a solid. This is a classical subject in solid state physics which dates back to a pioneering work by Einstein (1907) and its refinement by Debye (1912). Using a special quantization of crystal lattices and calculating the asymptotic of the integrated density of states at the bottom of the spectrum

Palle E. T. Jorgensen, Steen Pedersen

This paper introduces Fourier duality for a class of affine iterated function systems (IFS) T_i. These systems are determined by a finite family of contractive affine maps in R^d. Our Fourier duality applies to the resulting probability measure mu which is fixed by (T_i). When the IFS is given, the support of the associated mu is a compact set X in R^d, typi

V. V. Bavula

Let $A$ be an algebra over a field $K$ of characteristic zero, let $\d_1, >..., \d_s\in \Der_K(A)$ be {\em commuting locally nilpotent} $K$-derivations such that $\d_i(x_j)=\d_{ij}$, the Kronecker delta, for some elements $x_1,..., x_s\in A$. A set of algebra generators for the algebra $A^\d:= \cap_{i=1}^s\ker (\d_i)$ is found {\em explicitly} and a set of {

Szu-yu Sophie Chen

We consider a nonlinear version of the Yamabe problem on locally conformally flat compact manifolds with boundary. The main technique we used is to derive boundary $C^2$ estimates directly from boundary $C^0$ estimates. In particular, the result is a generalization of the work by Escobar.

Peter Ozsvath, Zoltan Szabo

We give a Dehn surgery characterization of the trefoil and the figure eight knots. These results are gotten by combining surgery formulas in Heegaard Floer homology from an earlier paper with the characterization of these knots in terms of their knot Floer homology given in a recent paper of Ghiggini.