March 2008 arXiv papers — page 4

Carl H. Gibson

Hubble Space telescope (HST) images of merging galaxy system VV29 reveal the 0.3 Mpc baryonic-dark-matter (BDM) halo composed of primordial protoglobularstarcluster (PGC) clumps of planets. Star-cluster-wakes trace the merger by formation of stars from the planets. Aligned young globular star clusters (YGCs), star-wakes and dust-trails show the frictional, s

Tomasz Blachowicz

This paper describes the so-called 1/f noise generated within the depleted region below a free semiconducting surface. It was shown that there is a link between the 1/f noise, which can be controlled by the band-bending, and the very narrow energy states (E<<kT) located on the top surface and vanishing into the bulk region. Also, it was shown that the noise

P. -A. Gourdain, S. C. Cowley, J. -N. Leboeuf

A new approach to high pressure magnetically-confined plasmas is necessary to design efficient fusion devices. This paper presents an equilibrium combining two solutions of the Grad-Shafranov equation, which describes the magnetohydrodynamic equilibrium in toroidal geometry. The outer equilibrium is paramagnetic and confines the inner equilibrium, whose stro

M. Cencelj, D. Repovš, M. Skopenkov

This paper is devoted to the classification of embeddings of higher dimensional manifolds. We study the case of embeddings $S^p\times S^q\to S^m$, which we call knotted tori. The set of knotted tori in the the space of sufficiently high dimension, namely in the metastable range $m\ge p+3q/2+2$, $p\le q$, which is a natural limit for the classical methods of

Robert L. Kosut

Maximizing the precision in estimating parameters in a quantum system subject to instrumentation constraints is cast as a convex optimization problem. We account for prior knowledge about the parameter range by developing a worst-case and average case objective for optimizing the precision. Focusing on the single parameter case, we show that the optimization

Zhi-An Ren, Jie Yang, Wei Lu, Wei Yi

Since the discovery of copper oxide superconductor in 1986 [1], extensive efforts have been devoted to the search of new high-Tc superconducting materials, especially high-Tc systems other than cuprates. The recently discovered quaternary superconductor La[O1-xFx]FeAs with the superconducting critical transition Tc of 26 K [2], which has a much simple layere

Edward W. Piotrowski, Malgorzata Schroeder, Anna Szczypinska

In this paper we compare two classical one-factor diffusion models which are used to model the term structure of interest rates. One of them is based on the Wiener-Bachelier process while the second one is based on the Ornstein-Uhlenbeck process. We show essential differences between the prices of European call options on a zero-coupon bond in these models.

Kamlesh Parwani

Let S be a connected orientable surface with finitely many punctures, finitely many boundary components, and genus at least 6. Then any C^1 action of the mapping class group of S on the circle is trivial. The techniques used in the proof of this result permit us to show that products of Kazhdan groups and certain lattices cannot have C^1 faithful actions on

B. Catinella, D. Schiminovich, G. Kauffmann

The GALEX Arecibo SDSS Survey (GASS) is a large targeted survey that started at Arecibo in March 2008. GASS is designed to measure the neutral hydrogen content of ~1000 massive galaxies (with stellar mass Mstar > 10^10 Msun) at redshift 0.025<z<0.05, uniformly selected from the SDSS spectroscopic and GALEX imaging surveys. Our selected mass range straddles t

Simon Catterall, Toby Wiseman

We report on lattice simulations of 16 supercharge SU(N) Yang-Mills quantum mechanics in the &#39;t Hooft limit. Maldacena duality conjectures that in this limit the theory is dual to IIA string theory, and in particular that the behavior of the thermal theory at low temperature is equivalent to that of certain black holes in IIA supergravity. Our simulation

A. Yamaguchi, K. Motoi, H. Miyajima

The rectifying effect of radio-frequency (RF) current is highly sensitive in terms of the spatial spin distribution and dynamics. It emerged that an additional spin wave mode was stimulated by the direct-current (DC) current and that this spin wave was detectable via rectification of the RF current. A phenomenological model to describe the time-dependent ani

D. A. Lidar, P. Zanardi, K. Khodjasteh

We derive rigorous upper bounds on the distance between quantum states in an open system setting, in terms of the operator norm between the Hamiltonians describing their evolution. We illustrate our results with an example taken from protection against decoherence using dynamical decoupling.

Amir Mahmood, Saifullah, Georgiana Bolat

The velocity field and the associated tangential stress corresponding to flow of a generalized second grade fluid between two infinite coaxial circular cylinders, are determined by means of the Laplace and Hankel transforms. At time $t=0$ the fluid is at rest and at $t=0^+$ cylinders suddenly begin to rotate about their common axis with a constant angular ac

CDF Collaboration, T. Aaltonen

We report on a search for the process $p\bar{p}\to γ+W/Z$ with $W/Z\to q\bar{q}$ in events containing two jets and a photon at the center-of-mass energy $\sqrt{s}=1.96$ TeV, using 184 pb$^{-1}$ of data collected by the CDF II detector. A neural network event selection has been developed to optimize the rejection of the large QCD production background; it is

Pathikrit Bhattacharya, Bikas K. Chakrabarti, Kamal

We analyzed several aftershock sequences around the globe and calculated the cumulative integral of magnitude over time. This quantity is found to have a linear relationship with time, having a slope characteristic of the causative fault zone.

M. A. Hendry, S. J. Smartt, E. D. Skillman, C. J. Evans

The blue supergiant Sher 25 is surrounded by an asymmetric, hourglass-shaped circumstellar nebula. Its structure and dynamics have been studied previously through high-resolution imaging and spectroscopy, and it appears dynamically similar to the ring structure around SN 1987A. Here we present long-slit spectroscopy of the circumstellar nebula around Sher 25

Marián Dvorský

In this paper we show that the following problem is NP-complete: Given an alphabet $Σ$ and two strings over $Σ$, the question is whether there exists a permutation of $Σ$ which is a subsequence of both of the given strings.

Xin Han, Kazuo Iwama, Guochuan Zhang

In this paper, we study the following knapsack problem: Given a list of squares with profits, we are requested to pack a sublist of them into a rectangular bin (not a unit square bin) to make profits in the bin as large as possible. We first observe there is a Polynomial Time Approximation Scheme (PTAS) for the problem of packing weighted squares into rectan

Christof Schaefer, Tommy Hofmann, Dirk Wallacher, Patrick Huber

Freezing and melting of Ar condensed in a granular packing of template-grown arrays of linear mesopores (SBA-15, mean pore diameter 8 nanometer) has been studied by specific heat measurements C as a function of fractional filling of the pores. While interfacial melting leads to a single melting peak in C, homogeneous and heterogeneous freezing along with a d

Dušan Repovš, Pavel V. Semenov

Let $A+B$ be the pointwise (Minkowski) sum of two convex subsets $A$ and $B$ of a Banach space. Is it true that every continuous mapping $h:X \to A+B$ splits into a sum $h=f+g$ of continuous mappings $f:X \to A$ and $g:X \to B$? We study this question within a wider framework of splitting techniques of continuous selections. Existence of splittings is guaran

Jean-Marie Chauvet

Su-Doku, a popular combinatorial puzzle, provides an excellent testbench for heuristic explorations. Several interesting questions arise from its deceptively simple set of rules. How many distinct Su-Doku grids are there? How to find a solution to a Su-Doku puzzle? Is there a unique solution to a given Su-Doku puzzle? What is a good estimation of a puzzle&#3

Lidia Bazylevych, Dušan Repovš, Michael Zarichnyi

We investigate certain geometric properties of the spaces of idempotent measures. In particular, we prove that the space of idempotent measures on an infinite compact metric space is homeomorphic to the Hilbert cube.

D. Repovš, W. Rosicki, A. Zastrow, M. Željko

The purpose of this paper is to present, for all $n\ge 3$, very simple examples of continuous maps $f:M^{n-1} \to M^{n}$ from closed $(n-1)$-manifolds $M^{n-1}$ into closed $n$-manifold $M^n$ such that even though the singular set $S(f)$ of $f$ is countable and dense, the map $f$ can nevertheless be approximated by an embedding, i.e. $f$ is a {\sl near-embed

Ling Tang, Shuai Wang

In this paper the first principle noncollinear transport calculation for Cu/Co(111) including interfacial spin-flipping was performed. We modeled spin-flipping at the interface by assuming a noncollinear magnetic structure with random magnetization orientation which satisfied Gaussian distribution along average magnetization direction. The relationship betwe

David Simoncini, Philippe Collard, Sébastien Verel, Manuel Clergue

This paper presents the Anisotropic selection scheme for cellular Genetic Algorithms (cGA). This new scheme allows to enhance diversity and to control the selective pressure which are two important issues in Genetic Algorithms, especially when trying to solve difficult optimization problems. Varying the anisotropic degree of selection allows swapping from a

R. S. Decca, E. Fischbach, B. Geyer, G. L. Klimchitskaya

The recently suggested modification of the transverse electric contribution to the Lifshitz formula (S. K. Lamoreaux, arXiv:0801.1283) is discussed. We show that this modification is inconsistent with the data of two precise experiments, and violates the Nernst heat theorem. The preprint&#39;s suggestion concerning the resolution of the &#34;apparent violati

Lidia Bazylevych, Dušan Repovš, Michael Zarichnyi

Our main result states that the hyperspace of convex compact subsets of a compact convex subset $X$ in a locally convex space is an absolute retract if and only if $X$ is an absolute retract of weight $\leω_1$. It is also proved that the hyperspace of convex compact subsets of the Tychonov cube $I^{ω_1}$ is homeomorphic to $I^{ω_1}$. An analogous result is a

Antoine Henrot, Gérard A. Philippin, Abdesselam Safoui

In this paper we establish isoperimetric inequalities for the product of some moments of inertia. As an application, we obtain an isoperimetric inequality for the product of the $N$ first nonzero eigenvalues of the Stekloff problem in $\mathbb{R}^N$.

Maroun Bercachi, Philippe Collard, Manuel Clergue, Sébastien Verel

The application of genetic algorithms (GAs) to many optimization problems in organizations often results in good performance and high quality solutions. For successful and efficient use of GAs, it is not enough to simply apply simple GAs (SGAs). In addition, it is necessary to find a proper representation for the problem and to develop appropriate search ope

Sébastien Verel, Philippe Collard, Marco Tomassini, Leonardo Vanneschi

We study in detail the fitness landscape of a difficult cellular automata computational task: the majority problem. Our results show why this problem landscape is so hard to search, and we quantify the large degree of neutrality found in various ways. We show that a particular subspace of the solution space, called the &#34;Olympus&#34;, is where good soluti

F. Aurzada, I. A. Ibragimov, M. A. Lifshits, J. H. van Zanten

We investigate the small deviation probabilities of a class of very smooth stationary Gaussian processes playing an important role in Bayesian statistical inference. Our calculations are based on the appropriate modification of the entropy method due to Kuelbs, Li, and Linde as well as on classical results about the entropy of classes of analytic functions.

Takashi Shibata, Hidemitsu Furukawa, Toshihiro Kawakatsu

We propose a coarse-grained model for polymer chains and polymer networks based on the meso-scale dynamics. The model takes the internal degrees of freedom of the constituent polymer chains into account using memory functions and colored noises. We apply our model to dilute polymer solutions and polymer networks. A numerical simulation on a dilute polymer so

Quan Zhou, Ke-Qing Xia

We investigate experimentally the statistical properties of active and passive scalar fields in turbulent Rayleigh-Bénard convection in water, at $Ra\sim10^{10}$. Both the local concentration of fluorescence dye and the local temperature are measured near the sidewall of a rectangular cell. It is found that, although they are advected by the same turbulent f

Mathieu Bouville

It is widely agreed that exams must be fair; yet what this exactly means is not made clear. One may mean fairness of treatment, but this merely propagates the fairness or unfairness of pre-existing rules. Fairness of opportunity on the other hand necessarily leads to identical grades for everyone, which clearly makes it inapplicable. Neither view is helpful

Svetlana Poznanovik

We give a bijection between partially directed paths in the symmetric wedge y= +/-x and matchings, which sends north steps to nestings. This gives a bijective proof of a result of Prellberg et al. that was first discovered through the corresponding generating functions: the number of partially directed paths starting at the origin confined to the symmetric w

Feng Luo

We give a brief introduction to some of the recent works on finding geometric structures on triangulated surfaces using variational principles.

M. K. M. Prescott, N. Kashikawa, A. Dey, Y. Matsuda

Large nebulae (>50 kpc) emitting strongly in Lya (also known as Lya ``blobs&#39;&#39;) are likely signposts of ongoing massive galaxy formation. The relative rarity of these sources and their discovery in well-studied galaxy overdensities suggest that they may be associated with regions of high galaxy density. One of the largest Lya nebulae, discovered at a

Edoardo Ballico, Elizabeth Gasparim, Thomas Köppe

We study moduli of holomorphic vector bundles on non-compact varieties. We discuss filtrability and algebraicity of bundles and calculate dimensions of local moduli. As particularly interesting examples, we describe numerical invariants of bundles on some local Calabi-Yau threefolds.

Shikui Tang, Q. Daniel Wang, Yu Lu, H. J. Mo

We demonstrate that the feedback from stellar bulges can play an essential role in shaping the halo gas of galaxies with substantial bulge components by conducting 1-D hydrodynamical simulations. The feedback model we consider consists of two distinct phases: 1) an early starburst during the bulge formation and 2) a subsequent long-lasting mass and energy in

Stephen D. H. Hsu, David Reeb

Under the premises that physics is unitary and black hole evaporation is complete (no remnants, no topology change), there must exist a one-to-one correspondence between states on future null and timelike infinity and on any earlier spacelike Cauchy surface (e.g., slices preceding the formation of the hole). We show that these requirements exclude a large se

Vitor M. Pereira, Valeri N. Kotov, A. H. Castro Neto

We study the problem of Coulomb field-induced charging of the ground state in a system of 2D massive Dirac particles (gapped graphene). As in its 3D QED counterpart, the critical Coulomb coupling is renormalized to higher values, compared to the massless case. We find that in gapped graphene a novel supercritical regime is possible, where the screening charg

Oliver Hahn, Cristiano Porciani, Avishai Dekel, C. Marcella Carollo

We explore a possible origin for the puzzling anti-correlation between the formation epoch of galactic dark-matter haloes and their environment density. This correlation has been revealed from cosmological N-body simulations and is in conflict with the Extended Press-Schechter model of halo clustering. Using similar simulations, we first quantify the straigh

Krishna Hanumanthu

The toroidalization conjecture of D. Abramovich, K. Karu, K. Matsuki, and J. Wlodarczyk asks whether any given morphism of nonsingular varieties over an algebraically closed field of characteristic zero can be modified into a toroidal morphism. Following a suggestion by Dale Cutkosky, we define the notion of \emph{locally toroidal} morphisms and ask whether

Troy Lee, Rajat Mittal

The tendency of semidefinite programs to compose perfectly under product has been exploited many times in complexity theory: for example, by Lovasz to determine the Shannon capacity of the pentagon; to show a direct sum theorem for non-deterministic communication complexity and direct product theorems for discrepancy; and in interactive proof systems to show

Sebastien Lepine

Completion of the SUPERBLINK proper motion survey in the southern celestial hemisphere has turned up 170 new stars with proper motion 0.45 arcsec/yr < pm < 2.0 arcsec/yr. This fourth and final installment completes the all-sky, data-mining of the Digitized Sky Surveys for stars with large proper motions. The areas investigated in this final installment compr

P. Rocha, A. Y. Miguelote, R. Chan, M. F. da Silva

Dynamical models of prototype gravastars were constructed in order to study their stability. The models are the Visser-Wiltshire three-layer gravastars, in which an infinitely thin spherical shell of stiff fluid divides the whole spacetime into two regions, where the internal region is de Sitter, and the external is Schwarzschild. It is found that in some ca

Yuk Tung Liu, Stuart L. Shapiro, Zachariah B. Etienne, Keisuke Taniguchi

Binary neutron stars (NSNS) are expected to be among the leading sources of gravitational waves observable by ground-based laser interferometers and may be the progenitors of short-hard gamma ray bursts. We present a series of general relativistic NSNS coalescence simulations both for unmagnetized and magnetized stars. We adopt quasiequilibrium initial data

Koji Hashimoto, Takayuki Hirayama, Feng-Li Lin, Ho-Ung Yee

We propose several quark mass deformations of the holographic model of massless QCD using the D4/D8/D8bar brane configuration proposed by Sakai and Sugimoto. The deformations are based on introducing additional D4 or D6 branes away from the QCD D4 branes. The idea is similar to extended technicolor theories, where the chiral symmetry breaking by additional D

Michael Chesterman

I present a toy model for the Berkovits pure spinor superparticle. It is a D=1, N=2 superparticle with no physical degrees of freedom. We study the cohomology in various ways, in particular finding an explicit expression for the `b&#39;-field. Finally, we construct the topological string B-model from a straightforward generalization of the system.

F. del Aguila, J. de Blas, M. Perez-Victoria

We obtain limits on generic vector-like leptons at the TeV scale from electroweak precision tests. These limits are complementary to the ones obtained from lepton flavour violating processes. In general, the quality of the global electroweak fit is comparable to the one for the Standard Model. In the case of an extra neutrino singlet mixing with the muon or

M. Merkl, F. E. Zimmer, G. Juzeliunas, P. Öhberg

Ultra-cold atoms which are subject to ultra-relativistic dynamics are investigated. By using optically induced gauge potentials we show that the dynamics of the atoms is governed by a Dirac type equation. To illustrate this we study the trembling motion of the centre of mass for an effective two level system, historically called Zitterbewegung. Its origin is

Ramses van Zon

An effective description for spherical nanoparticles in a fluid of point particles is presented. The points inside the nanoparticles and the point particles are assumed to interact via spherically symmetric additive pair potentials, while the distribution of points inside the nanoparticles is taken to be spherically symmetric and smooth. The resulting effect

Michele Cirafici, Annamaria Sinkovics, Richard J. Szabo

We study the relation between Donaldson-Thomas theory of Calabi-Yau threefolds and a six-dimensional topological Yang-Mills theory. Our main example is the topological U(N) gauge theory on flat space in its Coulomb branch. To evaluate its partition function we use equivariant localization techniques on its noncommutative deformation. As a result the gauge th

Bernhelm Booss-Bavnbek, Matthias Lesch, Chaofeng Zhu

We consider an arbitrary linear elliptic first--order differential operator A with smooth coefficients acting between sections of complex vector bundles E,F over a compact smooth manifold M with smooth boundary N. We describe the analytic and topological properties of A in a collar neighborhood U of N and analyze various ways of writing A|U in product form.

Gudrun Heinrich

Sector decomposition is a constructive method to isolate divergences from parameter integrals occurring in perturbative quantum field theory. We explain the general algorithm in detail and review its application to multi-loop Feynman parameter integrals as well as infrared divergent phase-space integrals over real radiation matrix elements.

Christian Krattenthaler, Thomas W. Müller

Let $q$ be an odd prime, $m$ a positive integer, and let $\Ga_m(q)$ be the group generated by two elements $x$ and $y$ subject to the relations $x^{2m}=y^{qm}=1$ and $x^2=y^q$; that is, $\Ga_m(q)$ is the free product of two cyclic groups of orders $2m$ respectively $qm$, amalgamated along their subgroups of order $m$. Our main result determines the parity be

Hugues Lapointe, Iosif Polterovich, Yuri Safarov

We study average growth of the spectral function of the Laplacian on a Riemannian manifold. Two types of averaging are considered: with respect to the spectral parameter and with respect to a point on a manifold. We obtain as well related estimates of the growth of the pointwise zeta-function along vertical lines in the complex plane. Some examples and open

A. Borowiec, J. Lukierski, V. N. Tolstoy

We show how some classical r-matrices for the D=4 Poincare algebra can be supersymmetrized by an addition of part depending on odd supercharges. These r-matrices for D=4 super-Poincare algebra can be presented as a sum of the so-called subordinated r-matrices of super-Abelian and super-Jordanian type. Corresponding twists describing quantum deformations are

Bernhelm Booss-Bavnbek, Matthias Lesch

First, we review the Dirac operator folklore about basic analytic and geometrical properties of operators of Dirac type on compact manifolds with smooth boundary and on closed partitioned manifolds and show how these properties depend on the construction of a canonical invertible double and are related to the concept of the Calderon projection. Then we summa

J. Skocek, J. Zeman, M. Sejnoha

An efficient approach to the evaluation of effective elastic properties of carbon-carbon plain weave textile composites using the Mori-Tanaka method is presented. The method proves its potential even if applied to real material systems with various types of imperfections including the non-uniform waviness of the fiber-tow paths, both along its longitudinal d

Nikolay Nikolov

These are the lecture notes for the LMS/EPSRC short course on strong approximation methods in linear groups organized by Dan Segal in Oxford in September 2007.

L. G. Aldrovandi, D. Marques

We analyze several aspects of R-symmetry and supersymmetry breaking in generalized O&#39;Raifeartaigh models with non-canonical Kahler potential. Some conditions on the Kahler potential are derived in order for the non-supersymmetric vacua to be degenerate. We calculate the Coleman-Weinberg (CW) effective potential for general quiral non-linear sigma models

B. Aharmim, B. T. Cleveland, X. Dai, G. Doucas

The existing hydrous titanium oxide (HTiO) technique for the measurement of 224Ra and 226Ra in the water at the Sudbury Neutrino Observatory (SNO) has been changed to make it faster and less sensitive to trace impurities in the HTiO eluate. Using HTiO-loaded filters followed by cation exchange adsorption and HTiO co-precipitation, Ra isotopes from 200-450 to

A. del Campo, V. I. Man&#39;ko, G. Marmo

The phase space is the natural ground to smoothly extrapolate between local and non-local correlation functions. With this objective, we introduce the symplectic tomography of many-body quantum gases in tight-waveguides, and concentrate on the reduced single-particle symplectic tomogram (RSPST) whose marginals are the density profile and momentum distributio

Pavel Fileviez Perez, Hoernisa Iminniyaz, German Rodrigo

The unification of gauge interactions in the context of Adjoint SU(5) and its phenomenological consequences are investigated. We show the allowed mass spectrum of the theory which is compatible with proton decay, and discuss the possibility to have a cold dark matter candidate. Due to the upper bounds on the proton decay partial lifetimes, tau (p --> K^+ nub

A. Tonyushkin, S. Wu, M. Prentiss

We demonstrate perfect coherence preservation in an atom interferometer perturbed by kicks from off-resonant standing wave pulses. Under most conditions, the decoherence induced by the pulses reduces the signal; however, the coherence is perfectly preserved when the kicking period is equal to the rational fraction of the inverse atomic recoil frequency, inde

Chhanda Samanta

Recent microscopic calculation based on the density functional theory predicts long-lived superheavy elements in a variety of shapes, including spherical, axial and triaxial configurations. Only when N=184 is approached one expects superheavy nuclei that are spherical in their ground states. Magic islands of extra-stability have been predicted to be around Z

Eric Bertin, Maxime Clusel, Peter C. W. Holdsworth

We consider the statistics of volume fluctuations in a one-dimensional classical gas of non-interacting particles confined by a piston, and subjected to an arbitrary external potential. We show that despite the absence of interactions between particles, volume fluctuations of the gas are non-Gaussian, and are described by generalized extreme value distributi

T. Senthil

At certain quantum critical points in metals an entire Fermi surface may disappear. A crucial question is the nature of the electronic excitations at the critical point. Here we provide arguments showing that at such quantum critical points the Fermi surface remains sharply defined even though the Landau quasiparticle is absent. The presence of such a critic

Sebastien Bosca, Georges Gras, Jean-François Jaulent

We give the complete proof of a conjecture of Georges Gras which claims that, for any extension $K/k$ of number fields in which at least one infinite place is totally split, every ideal $I$ of $K$ principalizes in the compositum $Kk^{ab}$ of $K$ with the maximal abelian extension $k^{ab}$ of $k$

Robert G. Petry, Derek Harnett, Randy Lewis, R. M. Woloshyn

Numerical simulations with access to all possible meson quantum numbers, J^{PC}, are presented using two-flavor (up and down) quenched twisted mass lattice QCD with three different lattice spacings and four different quark masses. The connection between the quantum numbers (P and C) and the symmetries of the twisted mass action are discussed, as is the conne

Bei Jia, Xi-Guo Lee, Peng-Ming Zhang

In this paper we discuss the properties of the general covariant angular momentum of a five-dimensional brane-world model. Through calculating the total angular momentum of this model, we are able to analyze the properties of the total angular momentum in the inflationary RS model. We show that the space-like components of the total angular momentum of are a

Danny Calegari

Let G be a word-hyperbolic group, obtained as a graph of free groups amalgamated along cyclic subgroups. If H_2(G;Q) is nonzero, then G contains a closed hyperbolic surface subgroup. Moreover, the unit ball of the Gromov-Thurston norm on H_2(G;R) is a finite-sided rational polyhedron.

Andrei Malashevich, David Vanderbilt

We have carried out a first-principles theoretical study of the magnetically induced polarization in orthorhombic TbMnO3, a prototypical material in which a cycloidal spin structure generates an electric polarization via the spin-orbit interaction. We compute both the electronic and the lattice-mediated contributions to the polarization and find that the lat

B. P. Kersevan, I. Hinchliffe, L. Mijovic

This paper presents the method of combining parton shower formalism with perturbative calculations (matrix elements) in form of a Monte-Carlo algorithm for the process g g -> Z b anti-b,consistenlty including the heavy quark masses and overlap removal.

Fang-Yu Hong, Shi-Jie Xiong

So far, all experimental tests of Bell inequalities which must be satisfied by all local realistic hidden-variable theories and are violated by quantum mechanical predictions have left at least one loophole open. We propose a feasible setup allowing for a loophole-free test of the Bell inequalities. Two electron spin qubits of phosphorus donors in semiconduc

Sergei M. Ageev, Dušan Repovš

Problems of dense and closed extension of actions of compact transformation groups are solved. The method developed in the paper is applied to problems of extension of equivariant maps and of construction of equivariant compactifications.

Alexander Gorodnik, Theron Hitchman, Ralf Spatzier

Let α_0 be an affine action of a discrete group Γon a compact homogeneous space X and α_1 a smooth action of Γon X which is C^1-close to α_0. We show that under some conditions, every topological conjugacy between α_0 and α_1 is smooth. In particular, our results apply to Zariski dense subgroups of SL_d(Z) acting on the torus T^d and Zariski dense subgroups

Cecile Monthus, Thomas Garel

The motion of driven interfaces in random media at finite temperature $T$ and small external force $F$ is usually described by a linear displacement $h_G(t) \sim V(F,T) t$ at large times, where the velocity vanishes according to the creep formula as $V(F,T) \sim e^{-K(T)/F^μ}$ for $F \to 0$. In this paper, we question this picture on the specific example of

Chao-Shang Huang, Tianjun Li, Wei Liao, Shou-Hua Zhu

We study the possible origin of Friedberg-Lee symmetry. First, we propose the generalized Friedberg-Lee symmetry in the potential by including the scalar fields in the field transformations, which can be broken down to the FL symmetry spontaneously. We show that the generalized Friedberg-Lee symmetry allows a typical form of Yukawa couplings, and the realist

Mikhail Khovanov, Aaron D. Lauda

To each graph without loops and multiple edges we assign a family of rings. Categories of projective modules over these rings categorify $U^-_q(\mathfrak{g})$, where $\mathfrak{g}$ is the Kac-Moody Lie algebra associated with the graph.

Marco Baiesi, Roberto Livi

The denaturation dynamics of a long double-stranded DNA is studied by means of a model of the Poland-Scheraga type. We note that the linking of the two strands is a locally conserved quantity, hence we introduce local updates that respect this symmetry. Linking dissipation via untwist is allowed only at the two ends of the double strand. The result is a slow

Paul C. Clark, Ian A. Bonnell, Ralf S. Klessen

We investigate how the dynamical state of a turbulently supported, 1000 solar mass, molecular cloud affects the properties of the cluster it forms, focusing our discussion on the star formation efficiency (SFE) and the initial mass function (IMF). A variety of initial energy states are examined in this paper, ranging from clouds with PE = 0.1 KE to clouds wi

A. Deur, V. Burkert, J. P. Chen, W. Korsch

We present a new extraction of the effective strong coupling constant α_{s,g_1}(Q^2). The result agrees with a previous determination and extends the measurement of the low and high Q^2 behavior of α_{s,g_1}(Q^2) that was previously deduced from sum rules. In particular, it experimentally verifies the lack of Q^2-dependence of α_{s,g_1}(Q^2) in the low Q^2 l

E. Molinaro, S. T. Petcov

We analyse within the &#34;flavoured&#34; leptogenesis scenario of baryon asymmetry generation, the interplay of the &#34;low energy&#34; CP-violation, originating from the PMNS neutrino mixing matrix $U$, and the &#34;high energy&#34; CP-violation which can be present in the matrix of neutrino Yukawa couplings, $λ$, and can manifest itself only in &#34;high

Vadim Lensky, Vladimir Pascalutsa

We compute the Compton scattering off the nucleons in the framework of manifestly covariant baryon chiral perturbation theory (B$χ$PT). The results for observables differ substantially from the corresponding calculations in heavy-baryon chiral perturbation theory (HB$χ$PT), most appreciably in the forward kinematics. We verify that the covariant $p^3$ result

A. V. Geramita, B. Harbourne, J. Migliore

A recent paper by the first and third authors together with Sabourin raised the question of what the possible Hilbert functions are for fat point subschemes of the form $2p_1+...+2p_r$, for all possible choices of $r$ distinct points in the projective plane. We study this problem for $r$ points in the plane over an algebraically closed field $k$ of arbitrary

Tomotada Akutsu, Seiji Kawamura, Atsushi Nishizawa, Koji Arai

This letter reports the results of a search for a stochastic background of gravitational waves (GW) at 100 MHz by laser interferometry. We have developed a GW detector, which is a pair of 75-cm baseline synchronous recycling (resonant recycling) interferometers. Each interferometer has a strain sensitivity of ~ 10^{-16} Hz^{-1/2} at 100 MHz. By cross-correla

Kenji Kajiwara, Atsushi Nobe, Teruhisa Tsuda

We consider the ultradiscretization of a solvable one-dimensional chaotic map which arises from the duplication formula of the elliptic functions. It is shown that ultradiscrete limit of the map and its solution yield the tent map and its solution simultaneously. A geometric interpretation of the dynamics of the tent map is given in terms of the tropical Jac

Anna Watts, Badri Krishnan, Lars Bildsten, Bernard Schutz

Detection of gravitational waves from accreting neutron stars (NSs) in our galaxy, due to ellipticity or internal oscillation, would be a breakthrough in our understanding of compact objects and explain the absence of NSs rotating near the break-up limit. Direct detection, however, poses a formidable challenge. Using the current data available on the propert

Pulak Ranjan Giri, P. Roy

Isotropic oscillator on a plane is discussed where both the coordinate and momentum space are considered to be noncommutative. We also discuss the symmetry properties of the oscillator for three separate cases when both the noncommutative parameters Θand \barΘ satisfy specific relations. We compare the Landau problem with the isotropic oscillator on noncommu

Sergio Cacciatori, Fabio Costa, Federico Piazza

Standard entropy calculations in quantum field theory, when applied to a subsystem of definite volume, exhibit area-dependent UV divergences that make a thermodynamic interpretation troublesome. In this paper we define a renormalized entropy which is related with the Newton-Wigner position operator. Accordingly, whenever we trace over a region of space, we t

Raoul Dillenschneider, Eric Lutz

We consider a photo--Carnot engine that consists of a single--mode radiation field in an optical cavity. One the heat reservoirs is made of a beam of thermally entangled pairs of two--level atoms that interact resonantly with the cavity. We express the thermodynamic efficiency of the engine in terms of the quantum discord of the atomic pair and find that it

Gereon Quick

We construct a model structure on simplicial profinite sets such that the homotopy groups carry a natural profinite structure. This yields a rigid profinite completion functor for spaces and pro-spaces. One motivation is the étale homotopy theory of schemes in which higher profinite étale homotopy groups fit well with the étale fundamental group which is alw

Andreas Ruegg, Sebastian Pilgram, Manfred Sigrist

We investigate the low-temperature electrical and thermal transport properties in atomically precise metallic heterostructures involving strongly-correlated electron systems. The model of the Mott-insulator/ band-insulator superlattice was discussed in the framework of the slave-boson mean-field approximation and transport quantities were derived by use of t

Manoj K. Yadav

Let $G$ be a finite $p$-group of nilpotency class 2. We find necessary and sufficient conditions on $G$ such that each central automorphism of $G$ fixes the center of $G$ element-wise.

Somnath Bhowmick, Vijay B. Shenoy

We study edge state magnetism in graphene nanostructures using a mean field theory of the Hubbard model. We investigate how the magnetism of the zigzag edges of graphene is affected by the presence of other types of terminating edges and defects. By a detailed study of both regular shapes, such as polygonal nanodots and nanoribbons, and irregular shapes, we

A. R. Mehta, G. R. Vijayakumar

B. D. Acharya has conjectured that if $\bigl(A_i: i=1, 2, ..., 2^{|X|}-1\bigr)$ is a permutation of all nonempty subsets of a set $X$ with at least two elements such that for each even positive integer $j<2^{|X|}-1$, $A_{j-1}\triangle A_j\triangle A_{j+1}=\emptyset$, then $|X|=2$. In this article, we show that if the cardinality of a set $X$ is more than fou

F. Ferlaino, S. Knoop, M. Mark, M. Berninger

We study inelastic collisions in a pure, trapped sample of Feshbach molecules made of bosonic cesium atoms in the quantum halo regime. We measure the relaxation rate coefficient for decay to lower-lying molecular states and study the dependence on scattering length and temperature. We identify a pronounced loss minimum with varying scattering length along wi

Sadanori Okamura

We describe the results and the current status of our program to search for intracluster planetary nebulae (ICPNe) in the Virgo and the Coma clusters of galaxies. For the Virgo cluster, ICPNe candidates were detected with narrow band imaging combined with broad band imaging. The use of two narrow band filters for H$α$ and [O III] lines tuned for the cluster