November 2007 arXiv papers — page 16

Boris Buchmann, Ngai Hang Chan

This paper considers the effect of least squares procedures for nearly unstable linear time series with strongly dependent innovations. Under a general framework and appropriate scaling, it is shown that ordinary least squares procedures converge to functionals of fractional Ornstein--Uhlenbeck processes. We use fractional integrated noise as an example to i

Jonathan Plumridge

We propose two metamaterial waveguides, operating in the mid-IR, which would display negative refraction. The first waveguide is a metallic strip incorporating quantum wells, whereas the second is a dielectric waveguide which incorporates quantum wells. The negative refraction of both waveguides occurs around the intersubband transition (ISBT) of the quantum

Jean-Marc Bouclet

For certain non compact Riemannian manifolds with ends, we obtain Littlewood-Paley type estimates on (weighted) Lp spaces, using the usual square function defined by a dyadic partition.

Fabiola M. A. Ribeiro, Marcos P. Diaz

Both continuum and emission line flickering are phenomena directly associated with the mass accretion process. In this work we simulate accretion disk Doppler maps including the effects of winds and flickering flares. Synthetic flickering Doppler maps are calculated and the effect of the flickering parameters on the maps is explored. Jets and winds occur in

Jean-Marc Bouclet

For a class of non compact Riemannian manifolds with ends, we give pseudo-differential expansions of bounded functions of the semi-classical Laplacian and study related Lp boundedness properties.

Faycal Ben Adda

We have built a new kind of manifolds which leads to an alternative new geometrical space. The study of the nowhere differentiable functions via a family of mean functions leads to a new characterization of this category of functions. A fluctuant manifold has been built with an appearance of a new structure on it at every scale, and we embedded into it an in

Carl Chiarella, Giulia Iori, Josep Perello

In this paper we develop a model of an order-driven market where traders set bids and asks and post market or limit orders according to exogenously fixed rules. Agents are assumed to have three components to the expectation of future asset returns, namely-fundamentalist, chartist and noise trader. Furthermore agents differ in the characteristics describing t

Giovanni Feverati, Fabio Musso

The development of a large non-coding fraction in eukaryotic DNA and the phenomenon of the code-bloat in the field of evolutionary computations show a striking similarity. This seems to suggest that (in the presence of mechanisms of code growth) the evolution of a complex code can't be attained without maintaining a large inactive fraction. To test this

Valentin Poenaru

We show that a certain geometric property, the QSF introduced by S. Brick and M. Mihalik, is universally true for {\ibf all} finitely presented groups $Γ$. One way of defining this property is the existence of a smooth compact manifold $M$ with $π_1 M = Γ$, such that $\tilde M$ is geometrically simply-connected ({\it i.e.} without handles of index $λ= 1$). T

Maurice Courbage, Seyed Majid Saberi Fathi

In this paper, we study the one-level Friedrichs model with using the quantum time super-operator that predicts the excited state decay inside the continuum. Its survival probability in long time limit is an algebraically decreasing function and an exponentially decreasing multiplied by the oscillating functions.

T. Merkouris

An estimation method is proposed for a wide variety of discrete time stochastic processes that have an intractable likelihood function but are otherwise conveniently specified by an integral transform such as the characteristic function, the Laplace transform or the probability generating function. This method involves the construction of classes of transfor

Tamás Kálmán

Each ruling of a Legendrian link can be naturally treated as a surface. For knots, the ruling is 2-graded if and only if the surface is orientable. For 2-graded rulings of homogeneous (in particular, alternating) knots, we prove that the genus of this surface is at most the genus of the knot. While this is not true in general, we do prove that the canonical

M. Hehn, Daniel Lacour, F. Montaigne, J. Briones

High spatial resolution X-ray photo-emission electron microscopy technique has been used to study the influence of the dipolar coupling taking place between the NiFe and the Co ferromagnetic electrodes of micron sized, elliptical shaped magnetic tunnel junctions. The chemical selectivity of this technique allows to observe independently the magnetic domain s

Ezio Vasselli

An overview about C*-algebra bundles with a Z-grading is presented, with particular emphasis on classification questions. In particular, we discuss the role of the representable KK(X ; -, -)-bifunctor introduced by Kasparov. As an application, we consider Cuntz-Pimsner algebras associated with vector bundles, and give a classification in terms of K-theoretic

S. Loth, M. Wenderoth, R. G. Ulbrich

The spatial distribution of the local density of states (LDOS) at Mn acceptors near the (110) surface of p-doped InAs is investigated by Scanning Tunneling Microscopy (STM). The shapes of the acceptor contrasts for different dopant depths under the surface are analyzed. Acceptors located within the first ten subsurface layers of the semiconductor show a lowe

D. Nutter, J. M. Kirk, D. Stamatellos, D. Ward-Thompson

We present continuum data from the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT), and the Mid-Infrared Photometer for Spitzer (MIPS) on the Spitzer Space Telescope, at submillimetre and infrared wavelengths respectively. We study the Taurus molecular cloud 1 (TMC1), and in particular the region of the Taurus Mo

A. Sokolov, T. Cawthorne

We report the results of a phase-referencing study aimed at uncovering precession of the VLBI jet of BL Lac. The observations were conducted at 8, 15, 22, and 43 GHz and consist of seven epochs spanning about two years. We investigated the change in the absolute position of BL Lac's radio core by means of phase-referencing with two nearby sources, 2151+4

J. van den Berg, B. N. B. de Lima

The self-destructive percolation model is defined as follows: Consider percolation with parameter $p > p_c$. Remove the infinite occupied cluster. Finally, give each vertex (or, for bond percolation, each edge) that at this stage is vacant, an extra chance $δ$ to become occupied. Let $δ_c(p)$ be the minimal value of $δ$, needed to obtain an infinite occupied

Andre Sopczak

Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for

M. Perucho, V. Bosch-Ramon

In high-mass microquasars (HMMQ), strong interactions between jets and stellar winds at binary system scales could occur. In order to explore this possibility, we have performed numerical 2-dimensional simulations of jets crossing the dense stellar material to study how the jet will be affected by these interactions. We find that the jet head generates stron

Jian Hu, Yu-Qing Lou

Presuming weak collisional interactions to exchange the kinetic energy between dark matter and baryonic matter in a galaxy cluster, we re-examine the effectiveness of this process in several `cooling flow' galaxy clusters using available X-ray observations and infer an upper limit on the heavy dark matter particle (DMP)$-$proton cross section $σ_{\rm xp}

M. Di Toro

Some considerations are reported, freely inspired from the presentations and discussions during the Beijing Normal University Workshop on the above Subject, held in July 2007. Of course this cannot be a complete summary but just a collection of personal thougths aroused during the meeting.

Massimo Pica Ciamarra

A Comment on the Letter by Raphael Blumenfeld and Sam F. Edwards, [Phys. Rev. Lett. 90, 114303 (2003)].

S. Flach, M. V. Ivanchenko, O. I. Kanakov, K. G. Mishagin

The Fermi-Pasta-Ulam problem was one of the first computational experiments. It has stirred the physics community since, and resisted a simple solution for half a century. The combination of straightforward simulations, efficient computational schemes for finding periodic orbits, and analytical estimates allows us to achieve significant progress. Recent resu

V. L. Katkov, V. A. Osipov

The field emission of crystalline AAA graphite is studied within a simple analytical approach with account of the exact dispersion relation near the Fermi level. The emission current is calculated for two crystal orientations with respect to the applied electric field. It is found that the exponent of the Fowler-Nordheim equation remains the same while the p

Atsushi Ito, Hiroaki Nakamura

New interlayer intermolecular potential model was proposed and it represented ``ABAB'' staking of graphite. Hydrogen atom sputtering on graphite surface was investigated using molecular dynamics simulation. In the initial short time period, maintaining the flat structure of graphenes, hydrogen atoms brought about the difference interaction process in

S. V. Maleyev

Comment on "Theory of helimagnons in itinerant quantum systems" by D.Belitz, T.K.Kirpatrick and A.Rosch and "Cubic magnets with Dzyaloshinskii-Moriya interaction at low temperatures" by S.V.Maleyev

M. Di Toro, M. Colonna, V. Greco, G. Ferini

Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. In this work we present a selection of reaction observables in dissipative collisions particularly sensitive to the isovector part of the interaction, i.e. to the symmetry term of the nuclear Equation of State (EoS). At low energies

Che Lin, Vasanthan Raghavan, Venu Veeravalli

Space-time codes leverage the availability of multiple antennas to enhance the reliability of communication over wireless channels. While space-time codes have initially been designed with a focus on open-loop systems, recent technological advances have enabled the possibility of low-rate feedback from the receiver to the transmitter. The focus of this paper

P. Esquinazi, N. García, J. Barzola-Quiquia, J. C. González

High resolution magnetoresistance data in highly oriented pyrolytic graphite thin samples manifest non-homogenous superconductivity with critical temperature $T_c \sim 25 $K. These data exhibit: i) hysteretic loops of resistance versus magnetic field similar to Josephson-coupled grains, ii) quantum Andreev's resonances and iii) absence of the Schubnikov-

Richard de Grijs

I review the long-term survival chances of young massive star clusters (YMCs), hallmarks of intense starburst episodes often associated with violent galaxy interactions. In particular, I address the key question as to whether at least some of these YMCs can be considered proto-globular clusters (GCs). In the absence of significant external perturbations, the

Hiroshi Toki, Carmen Garcia-Recio, Juan Nieves

We study the photon induced Lambda(1520) production in the effective Lagrangian method near threshold, E_γ^{LAB}<2 GeV, and in the quark-gluon string model at higher energies 3 GeV < E_γ^{LAB} < 5 GeV. In particular, we study the role of the K^* exchange for the production of Lambda(1520) within the SU(6) Weinberg-Tomozowa chiral unitary model proposed in Ph

M. Di Toro, M. Colonna, C. Rizzo, V. Baran

Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. In this work we present a selection of reaction observables in dissipative collisions particularly sensitive to the isovector part of the interaction, i.e. to the symmetry term of the nuclear Equation of State (EoS). At low energies

A. Calamida, G. Bono, P. B. Stetson, L. M. Freyhammer

We performed a new calibration of the Stroemgren metallicity index m1 based on the b-y color of cluster red giant stars. The current Metallicity-Index-Color relation is not linear in the color range 0.40 < b-y < 1.0, but provides iron abundances of cluster and field red giants with an accuracy of ~ 0.25 dex.

D. V. Fil, S. I. Shevchenko

The Bose-Einstein condensation of vacancies in a three-dimensional decorated lattice is considered. The model describes possible scenario of superfluidity of solid helium, caused by the presence of zero-point vacancies in a dislocation network. It is shown that the temperature of Bose-Einstein condensation decreases under increase of the length of the segmen

R. C. Andrew, H. G. Miller

The genesis of spurious solutions in finite basis approximations to operators which possess a continuum and a point spectrum is discussed and a simple solution for identifying these solutions is suggested.

Antonio Siber

I discuss the symmetry of fullerenes, viruses and geodesic domes within a unified framework of icosadeltahedral representation of these objects. The icosadeltahedral symmetry is explained in details by examination of all of these structures. Using Euler&#39;s theorem on polyhedra, it is shown how to calculate the number of vertices, edges, and faces in domes

Kiyoshi Tamaki

We propose an unconditionally secure quantum key distribution (QKD) protocol, which uses a relatively strong signal pulse. While our protocol shares similar security bases as the Bennett 1992 protocol with a strong reference pulse (B92), our scheme uses a smaller number of detectors and it is robust against Rayleigh scattering in an optical fibre. We derive

Debasish Chatterjee, Daniel Liberzon

We are concerned with input-to-state stability (ISS) of randomly switched systems. We provide preliminary results dealing with sufficient conditions for stochastic versions of ISS for randomly switched systems without control inputs, and with the aid of universal formulae we design controllers for ISS-disturbance attenuation when control inputs are present.

M. Sikora, R. Moderski, G. M. Madejski

Recent multi-wavelength observations of 3C454.3, in particular during its giant outburst in 2005, put severe constraints on the location of the &#39;blazar zone&#39;, its dissipative nature, and high energy radiation mechanisms. As the optical, X-ray, and millimeter light-curves indicate, significant fraction of the jet energy must be released in the vicinit

J. C. Morales, I. Ribas, C. Jordi

Recent analyses of low-mass eclipsing binary stars have unveiled a significant disagreement between the observations and the predictions of stellar structure models. Results show that theoretical models underestimate the radii and overestimate the effective temperatures of low-mass stars but yield luminosities that accord with observations. A hypothesis base

M. R. Pennington, D. J. Wilson

If a hadronic production process is dominated by two body final state interactions, the amplitude $A$ for the production process can be expanded as a sum of the scattering amplitudes $T$ for the relevant two body channels. Van Beveren and Rupp have claimed that the unitarity relation ${\rm {Im}} A= T^†A$ can be satisfied if the coefficients in this expansion

Pulak Ranjan Giri, S. K. Chakrabarti

The possible mismatch between the theoretical and experimental absorption of the edge peaks in semiconductors in a magnetic field background may arise due to the approximation scheme used to analytically calculate the absorption coefficient. As a possible remedy we suggest to consider nontrivial boundary conditions on x-y plane by in-equivalently quantizing

Eberhard Klempt

The evidence for the existence of mesons with exotic quantum numbers and of hybrid candidates with non-exotic quantum numbers is critically reviewed, including candidates with hidden charm. Aims and methods of future searches for hybrid mesons are briefly discussed.

Pablo Arrighi, Vincent Nesme, Reinhard Werner

One-dimensional quantum cellular automata (QCA) consist in a line of identical, finite dimensional quantum systems. These evolve in discrete time steps according to a local, shift-invariant unitary evolution. By local we mean that no instantaneous long-range communication can occur. In order to define these over a Hilbert space we must restrict to a base of

Kenji Bekki, Masashi Chiba, N. M. McClure-Griffiths

We show that collisions between the outer Galactic HI disk and the leading arms (LAs) of the Magellanic stream (MS) can create giant HI holes and chimney-like structures in the disk. Based on the results of our N-body simulations on the last 2.5 Gyr evolution of the Large and Small Magellanic Clouds (LMC and SMC, respectively) interacting with the Galaxy, we

Ryszard Szwarc

Let G be a group generated by $r$ elements $g_1,g_2,..., g_r.$ Among the reduced words in $g_1,g_2,..., g_r$ of length $n$ some, say $γ_n,$ represent the identity element of the group $G.$ It has been shown in a combinatorial way that the $2n$th root of $γ_{2n}$ has a limit, called the cogrowth exponent with respect to generators $g_1,g_2,..., g_r.$ We show

Julien Roques

In this paper we compute the difference Galois groups of the Lie-irreducible regular singular generalized q-hypergeometric equations of order 3 with q-real parameters by using a density theorem due to Sauloy. In contrast with the differential case, we show that these groups automatically contain the special linear group SL(3,C).

B. Ramakrishnan, Brundaban Sahu

We use Rankin-Cohen brackets for modular forms and quasimodular forms to give a different proof of the results obtained by D. Lanphier and D. Niebur on the van der Pol type identities for the Ramanujan&#39;s tau function. As consequences we obtain convolution sums and congruence relations involving the divisor functions.

Zhiqin Lu

In this paper, we proved the normal scalar curvature conjecture and the Bottcher-Wenzel conjecture.

N. Suresh, J. G. Storey, G. V. M. Williams, J. L. Tallon

We have carried out measurements of the pressure dependence to 1.2 GPa of the oxygen isotope effect on $T_c$ in the high-$T_c$ superconductor YBa$_2$Cu$_4$O$_8$ using a clamp cell in a SQUID magnetometer. This compound lies close to, but just above, the 1/8$^{th}$ doping point where in La$_{2-x}$Sr$_x$CuO$_4$ marked anomalies in isotope effects occur. Both i

Le Anh Vinh

We study the Erdos distance problem over finite Euclidean and non-Euclidean spaces. Our main tools are graphs associated to finite Euclidean and non-Euclidean spaces that are considered in Bannai-Shimabukuro-Tanaka (2004, 2007). These graphs are shown to be asymptotically Ramanujan graphs. The advantage of using these graphs is twofold. First, we can derive

Toshiki Maruyama, Satoshi Chiba, Hans-Josef Schulze, Toshitaka Tatsumi

We investigate the properties of the hadron-quark mixed phase in compact stars using a Brueckner-Hartree-Fock framework for hadronic matter and the MIT bag model for quark matter. We find that the equation of state of the mixed phase is similar to that given by the Maxwell construction. The composition of the mixed phase, however, is very different from that

Toshiki Maruyama, Satoshi Chiba, Toshitaka Tatsumi

We investigate the non-uniform structures and the equation of state (EOS) of nuclear matter in the context of the first-order phase transitions (FOPT) such as liquid-gas phase transition, kaon condensation, and hadron-quark phase transition. During FOPT the mixed phases appear, where matter exhibits non-uniform structures called ``Pasta&#39;&#39; structures

Toshiki Maruyama, Satoshi Chiba, Hans-Josef Schulze, Toshitaka Tatsumi

We investigate the properties of the hadron-quark mixed phase in compact stars using a Brueckner-Hartree-Fock framework for hadronic matter and the MIT bag model for quark matter. We find that the equation of state of the mixed phase is similar to that given by the Maxwell construction. The composition of the mixed phase, however, is very different from that

Shiguo Lian

In recent work, various fractal image coding methods are reported, which adopt the self-similarity of images to compress the size of images. However, till now, no solutions for the security of fractal encoded images have been provided. In this paper, a secure fractal image coding scheme is proposed and evaluated, which encrypts some of the fractal parameters

Luc Binette, Yair Krongold

Luminous quasars are known to display a sharp steepening of the continuum near 1100A. This spectral feature is not well fitted by current accretion disk models, unless comptonization of the disk emission is invoked. Absorption by carbon crystalline dust has been proposed to account for this feature. Ton 34 (z=1.928) exhibits the steepest far-UV decline (F_nu

Paul P. Cook

We investigate some of the motivations and consequences of the conjecture that the Kac-Moody algebra E11 is the symmetry algebra of M-theory, and we develop methods to aid the further investigation of this idea. The definitions required to work with abstract root systems of Lie algebras are given in review leading up to the definition of a Kac-Moody algebra.

J. Pollanen, K. Shirer, S. Blinstein, J. P. Davis

We discuss two methods by which high porosity silica aerogels can be engineered to exhibit global anisotropy. First, anisotropy can be introduced with axial strain. In addition, intrinsic anisotropy can result during growth and drying stages and, suitably controlled, it can be correlated with preferential radial shrinkage in cylindrical samples. We have perf

Vladimir Nikiforov

We show that if a graph G of order n contains many copies of a given subgraph H, then it contains a blow-up of H of order log n.

Vladimir Nikiforov

We prove that if the spectral radius of a graph G of order n is larger than the spectral radius of the r-partite Turan graph of the same order, then G contains various supergraphs of the complete graph of order r+1. In particular G contains a complete r-partite graph of size log n with one edge added to the first part. These results complete a project of Erd

Vladimir Nikiforov

We extend the classical stability theorem of Erdos and Simonovits in two directions: first, we allow the order of the forbidden graph to grow as log of order of the host graph, and second, our extremal condition is on the spectral radius of the host graph.

R. R. Caldwell, A. Stebbins

The blackbody nature of the cosmic microwave background (CMB) radiation spectrum is used in a modern test of the Copernican Principle. The reionized universe serves as a mirror to reflect CMB photons, thereby permitting a view of ourselves and the local gravitational potential. By comparing with measurements of the CMB spectrum, a limit is placed on the poss

Frederick A. Matsen

Phylogenetic invariants are not the only constraints on site-pattern frequency vectors for phylogenetic trees. A mutation matrix, by its definition, is the exponential of a matrix with non-negative off-diagonal entries; this positivity requirement implies non-trivial constraints on the site-pattern frequency vectors. We call these additional constraints ``ed

Kate Okikiolu

For a closed surface M with metric g, the Robin mass m(p) at the point p is the value of the Green function G(p,q) at p=q after the logarithmic singularity has been removed. The Laplacian-mass is the average value of the Robin mass, minus the value of the Robin mass for the round sphere of the same area. The Laplacian-mass is a spectral invariant which is a

Donald Lynden-Bell, Shoko Jin

A useful crude approximation for Abelian functions is developed and applied to orbits. The bound orbits in the power-law potentials A*r^{-alpha} take the simple form (l/r)^k = 1 + e cos(m*phi), where k = 2 - alpha > 0 and &#39;l&#39; and &#39;e&#39; are generalisations of the semi-latus-rectum and the eccentricity. &#39;m&#39; is given as a function of &#39;

Shoko Jin, Donald Lynden-Bell

We present a geometrodynamical method for determining distances to orbital streams of HI gas in the Galaxy. The method makes use of our offset from the Galactic centre and assumes that the gas comprising the stream nearly follows a planar orbit about the Galactic centre. We apply this technique to the Magellanic Stream and determine the distances to all poin

Gouranga C. Nayak, Jian-Wei Qiu, George Sterman

We study the transfer of color between a heavy quark pair and an unpaired heavy quark or antiquark moving at a nonrelativistic velocity with respect to the pair. We find that the open heavy quark or antiquark can catalyze the transformation of the pair from octet representation at short distances to singlet at long distances. This process is infrared sensiti

Alice Devillers, Ralf Köhl, Bernhard Muhlherr

We prove that the complex of proper non-trivial non-degenerate subspaces of a finite-dimensional vector space endowed with a non-degenerate sesquilinear form is homotopy equivalent to a wedge of spheres. Additionally, we show that the same is true for a slight generalization, the so-called generalized Phan geometries of type A_n. These generalized Phan geome

E. Pascale, P. A. R. Ade, J. J. Bock, E. L. Chapin

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a sub-orbital surveying experiment designed to study the evolutionary history and processes of star formation in local galaxies (including the Milky Way) and galaxies at cosmological distances. The BLAST continuum camera, which consists of 270 detectors distributed between 3 arrays, observes

Justin Elser, Viktor A. Podolskiy

We develop an approach to utilize anisotropic metamaterials to solve one of the fundamental problems of modern plasmonics -- parasitic scattering of surface waves into free-space modes, opening the road to truly two-dimensional plasmonic optics. We illustrate the developed formalism on examples of plasmonic refractor and plasmonic crystal, and discuss limita

Anders M. N. Niklasson

A Lagrangian generalization of time-reversible Born-Oppenheimer molecular dynamics [Niklasson et al., Phys. Rev. Lett. vol. 97, 123001 (2006)] is proposed. The Lagrangian includes extended electronic degrees of freedom as auxiliary dynamical variables in addition to the nuclear coordinates and momenta. While the nuclear degrees of freedom propagate on the Bo

Cenke Xu, Subir Sachdev

We propose a critical spin liquid ground state for S=1/2 antiferromagnets on the square lattice. In a renormalization group analysis of the `staggered flux&#39; algebraic spin liquid, we examine perturbations, present in the antiferromagnet, which break its global SU(4) symmetry to SO(5). At physical parameter values, we find an instability towards a fixed p

Joel A. Shapiro

These are my personal impressions of the environment in which string theory was born, and what the important developments affecting my work were during the hadronic string era, 1968-1974. I discuss my motivations and concerns at the time, particularly in my work on loop amplitudes and on closed strings.

Veronique Bernard, Emilie Passemar

We perform a matching of the two loop-chiral perturbation theory representation of the scalar Kpi form factor to a dispersive one. Knowing the value of F_K/F_pi and f_+(0) in the Standard Model (SM) allows to determine two O(p^6) LECs, the slope of the scalar form factor and the deviation of the Callan-Treiman theorem. Going beyond the SM and assuming the kn

Yuki Watanabe, Eiichiro Komatsu

We study implications of the large-N species solution to the hierarchy problem, proposed by G. Dvali, for reheating of the universe after inflation. Dvali&#39;s proposal contains additional N~10^{32} Z_2-conserved quantum fields beyond the Standard Model particles with mass ~1 TeV, which weaken gravity by a factor of 1/N, and thus explain the hierarchy betwe

Benjamin K. Stephens

(NOTE: per referee comments, this article has been split; it is now superseded by &#34;Existence of thread-wire minimizers&#34; and &#34;Near-wire thread-wire minimizers&#34;; please see http://www.bkstephens.net.) Alt&#39;s thread problem asks for least-area surfaces bounding a fixed &#34;wire&#34; curve and a movable &#34;thread&#34; curve of length L. We

Arijit Saha, Sourin Das

We consider quantum charge pumping of electrons across a superconducting double barrier structure in the adiabatic limit. The superconducting barriers are assumed to be reflection-less so that an incident electron on the barrier can either tunnel through it or Andreev reflect from it. In this structure, quantum charge pumping can be achieved (a) by modulatin

Aaron Wangberg

We present the subalgebra structure of sl(3,O), a particular real form of E6 chosen for its relevance to particle physics through the connection between its associated Lie group SL(3,O) and generalized Lorentz groups. Given the complications related to the non-associativity of the octonions O and the restriction to working with a real form of E6, we find tha

Hendrik van Hees, Ralf Rapp

A quantitative evaluation of dilepton sources in heavy-ion reactions is performed taking into account both thermal and non-thermal production mechanisms. The hadronic thermal emission rate is based on an electromagnetic current-correlation function with a low-mass region (LMR, M \lsim 1 GeV) dominated by vector mesons (ρ, ω, ϕ) and an intermediate-mass regio

J. C. McGeorge, J. D. Kellie, J. R. M. Annand, J. Ahrens

The Glasgow photon tagging spectrometer at Mainz has been upgraded so that it can be used with the 1500 MeV electron beam now available from the Mainz microtron MAMI-C. The changes made and the resulting properties of the spectrometer are discussed.

Martin Kassabov, Nikolay Nikolov

In this note we give an alternative proof of a theorem of Linnell and Warhurst that the number of generators d(G) of a polycyclic group G is at most d(\hat G), where d(\hat G) is the number of generators of the profinite completion of G. While not claiming anything new we believe that our argument is much simpler that the original one. Moreover our result gi

Karl-Hermann Neeb, Christoph Wockel

If q : P -> M is a principal K-bundle over the compact manifold M, then any invariant symmetric V-valued bilinear form on the Lie algebra k of K defines a Lie algebra extension of the gauge algebra by a space of bundle-valued 1-forms modulo exact forms. In the present paper we analyze the integrability of this extension to a Lie group extension for non-conne

M. Aparicio Alcalde, G. Menezes, N. F. Svaiter

Using the Euclidean path integral approach with functional methods, we discuss the $(g_{0} ϕ^{p})_{d}$ self-interacting scalar field theory, in the strong-coupling regime. We assume the presence of macroscopic boundaries confining the field in a hypercube of side $L$. We also consider that the system is in thermal equilibrium at temperature $β^{-1}$. For spa

Tibra Ali, Gerald B. Cleaver

It is argued that the ten dimensional solution that corresponds to the compactification of $E_8 \times E_8$ heterotic string theory on a half-flat manifold is the product space-time $R^{1,2} \times Z_7$ where $Z_7$ is a generalized cylinder with $G_2$ riemannian holonomy. Standard embedding on $Z_7$ then implies an embedding on the half-flat manifold which i

Cedric Lecouvey, Cristian Lenart

The paper is devoted to the generalization of Lusztig&#39;s q-analog of weight multiplicities to the Lie superalgebras gl(n,m) and spo(2n,M). We define such q-analogs K_{lambda,mu}(q) for the typical modules and for the irreducible covariant tensor gl(n,m)-modules of highest weight lambda. For gl(n,m), the defined polynomials have nonnegative integer coeffic

Maciej M. Duras

In the present article a family of quantum anharmonic oscillators is studied using Hermite&#39;s function basis (Fock&#39;s basis) in the Hilbert space. The numerical investigation of the eigenenergies of that family is presented. The statistical properties of the calculated eigenvalues are compared with the theoretical predictions derived from the Random Ma

Bogdan Damski, Wojciech H. Zurek

We discuss the dynamics of a quantum phase transition in a spin-1 Bose-Einstein condensate when it is driven from the magnetized broken-symmetry phase to the unmagnetized ``symmetric&#39;&#39; polar phase. We determine where the condensate goes out of equilibrium as it approaches the critical point, and compute the condensate magnetization at the critical po

A. M. Gainutdinov, I. Yu. Tipunin

We introduce p-1 pseudocharacters in the space of (1,p) model vacuum torus amplitudes to complete the distinguished basis in the 2p-dimensional fusion algebra to a basis in the whole (3p-1)-dimensional space of torus amplitudes, and the structure constants in this basis are integer numbers. We obtain a generalized Verlinde-formula that gives these structure

Ishwaree P. Neupane

The modified Gauss-Bonnet gravity can be motivated by a number of physical reasons, including: the uniqueness of a gravitational Lagrangian in four and higher dimensions and the leading order $α^\prime$ corrections in superstring theory. Such an effective theory of scalar-tensor gravity has been modeled in the recent past to explain both the initial cosmolog

Zhao Wang, Matthäus Pietz, Arno Förster, Mihail I. Lepsa

Current pulses of up to 20 A and as short as 3 ps are generated by a low temperature grown GaAs (lt-GaAs) photoconductive switch and guided through a coplanar waveguide, resulting in a 0.6 Tesla terahertz (THz) magnetic field pulse. The pulse length is directly calibrated using photocurrent autocorrelation. Magnetic excitations in Fe microstructures are stud

Arnaud Koetsier, R. A. Duine, Immanuel Bloch, H. T. C. Stoof

We theoretically study the possibility of reaching the antiferromagnetic phase of the Hubbard model by starting from a normal gas of trapped fermionic atoms and adiabatically ramping up an optical lattice. Requirements on the initial temperature and the number of atoms are determined for a three dimensional square lattice by evaluating the Neel state entropy

R. Armillis, C. Coriano, M. Guzzi

We present a study of the trilinear gauge interactions in extensions of the Standard Model (SM) with several anomalous extra U(1)&#39;s, identified in various constructions, from special vacua of string theory to large extra dimensions. In these models an axion and generalized Chern-Simons interactions for anomalies cancelation are present. We derive general

Willy Fischler, Chethan Krishnan, Sonia Paban, Marija Zanic

We study the propagation of bubbles of new vacuum in a radially inhomogeneous Lemaitre-Tolman-Bondi background that includes a cosmological constant. This exemplifies the classical evolution of a tunneling bubble through a metastable state with curvature inhomogeneities, and will be relevant in the context of the Landscape. We demand that the matter profile

Peter Linnell, Thomas Schick

Let G be a group such that its finite subgroups have bounded order, let d denote the lowest common multiple of the orders of the finite subgroups of G, and let K be a subfield of C that is closed under complex conjugation. Let U(G) denote the algebra of unbounded operators affiliated to the group von Neumann algebra N(G), and let D(KG,U(G)) denote the divisi

Ram Band, Idan Oren, Uzy Smilansky

The purpose of the present manuscript is to collect known results and present some new ones relating to nodal domains on graphs, with special emphasize on nodal counts. Several methods for counting nodal domains will be presented, and their relevance as a tool in spectral analysis will be discussed.

Kyryl Kazymyrenko, Xavier Waintal

We propose a fast and versatile algorithm to calculate local and transport properties such as conductance, shot noise, local density of state or local currents in mesoscopic quantum systems. Within the non equilibrium Green function formalism, we generalize the recursive Green function technique to tackle multiterminal devices with arbitrary geometries. We a

Wendong Wang, Liqun Zhang

We obtain the $C^{\a}$ regularity for weak solutions of a class of non-homogeneous ultraparabolic equation, with measurable coefficients. The result generalizes our recent $C^{\a}$ regularity results of homogeneous ultraparabolic equation.

P. Valageas

We describe various expansion schemes that can be used to study gravitational clustering. Obtained from the equations of motion or their path-integral formulation, they provide several perturbative expansions that are organized in different fashion or involve different partial resummations. We focus on the two-point and three-point correlation functions, but

Cesar Gomez, Johan Gunnesson, Rafael Hernandez

The scattering-matrix for planar Yang-Mills with N=4 supersymmetry relies on the assumption that integrability holds to all orders in perturbation theory. In this note we define a map from the spectral variables x^{\pm}, parameterizing the long-range magnon momenta, to couplings in a two-dimensional Ising model. Under this map integrability of planar N=4 Yan