cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Near BPS Skyrmions and Restricted Harmonic Maps
Creators: name: Speight, J. M.
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Motivated by a class of near BPS Skyrme models introduced by Adam, Sánchez-Guillén and Wereszczyński, the following variant of the harmonic map problem is introduced: a map $ϕ:(M,g)\rightarrow (N,h)$ between Riemannian manifolds is restricted harmonic (RH) if it locally extremizes $E_2$ on its $SDiff(M)$ orbit, where $SDiff(M)$ denotes the group of volume preserving diffeomorphisms of $(M,g)$, and $E_2$ denotes the Dirichlet energy. It is conjectured that near BPS skyrmions tend to RH maps in the BPS limit. It is shown that $ϕ$ is RH if and only if $ϕ^*h$ has exact divergence, and a linear stability theory of RH maps is developed, whence it follows that all weakly conformal maps, for example, are stable RH. Examples of RH maps in every degree class $R^3\to SU(2)$ and $R^2\to S^2$ are constructed. It is shown that the axially symmetric BPS skyrmions on which all previous analytic studies of near BPS Skyrme models have been based, are not RH, so each such field can be deformed along $SDiff(R^3)$ to yield BPS skyrmions with lower $E_2$, casting doubt on the predictions of such studies. The problem of minimizing $E_2$ for $ϕ:R^k\to N$ over all linear volume preserving diffeomorphisms is solved explicitly, and a deformed axially symmetric family of Skyrme fields constructed which are candidates for approximate near BPS skyrmions at low baryon number. The notion of restricted harmonicity is generalized to restricted $F$-criticality where $F$ is any functional on maps $(M,g)\to (N,h)$ which is, in a precise sense, geometrically natural. The case where $F$ is a linear combination of $E_2$ and $E_4$, the usual Skyrme term, is studied in detail, and it is shown that inverse stereographic projection $R^3\to S^3\equiv SU(2)$ is stable restricted $F$-critical for every such $F$.
description: 26 pages, 0 figures, updated bibliography, published version
Unification of Inflation and Dark Energy from Spontaneous Breaking of Scale Invariance
Creators: name: Guendelman, Eduardo
name: Nissimov, Emil
name: Pacheva, Svetlana
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We propose a new class of gravity-matter models defined in terms of two independent non-Riemannian volume forms (alternative generally covariant integration measure densities) on the spacetime manifold. For the matter we choose appropriate scalar field potentials of exponential form so that the full gravity-matter system is invariant under global Weyl-scale symmetry. Solution of the pertinent equations of motion produce two dimensionful integration constants which spontaneously break global Weyl-scale invariance. In the resulting effective Einstein-frame gravity-matter system we obtain an effective potential for the scalar matter field which has an interesting cosmological application, namely, it allows for a unified description of both an early universe inflation and present day dark energy.
description: v.1 LaTeX, 6 pages; v.2 reference added, typo corrected; v.3 significant upgrade - 11 pages, new section about canonical Hamiltonian treatment added, extended discussion and conclusions, additional citations; v.4 minor improvement in Sect.3, to appear in Proc. of VIII-th Math. Physics Meeting, B. Dragovich et.al. (eds), Belgrade Inst. Phys. Press (2015)
On Fourier-based inequality indices
Creators: name: Toscani, Giuseppe
Publisher: name: arXiv
Year: 2022
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Mathematical Physics (math-ph)
subject: Probability (math.PR)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: Originally developed for measuring the heterogeneity of wealth measures, inequality indices are quantitative scores that take values in the unit interval, with the zero score characterizing perfect equality. In this paper, we draw attention to a new inequality index, based on the Fourier transform, which exhibits a number of interesting properties that make it very promising in applications. As a by-product, it is shown that other inequality measures, including Gini and Pietra indices can be fruitfully expressed in terms of the Fourier transform, which allows to enlighten properties in a new and simple way.
Infinitely many singular interactions on noncompact manifolds
Creators: name: Kaynak, Burak Tevfik
name: Turgut, O. Teoman
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mathematical Physics (math-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We show that the ground state energy is bounded from below when there are infinitely many attractive delta function potentials placed in arbitrary locations, while all being separated at least by a minimum distance, on two dimensional non-compact manifold. To facilitate the reading of the paper, we first present the arguments in the setting of Cartan-Hadamard manifolds and then subsequently discuss the general case. For this purpose, we employ the heat kernel techniques as well as some comparison theorems of Riemannian geometry, thus generalizing the arguments in the flat case following the approach presented in Albeverio et. al. (2004).
description: Published version; 13 pages, no figures; both title and abstract changed, a new section and references added
Amplitude / Higgs Modes in Condensed Matter Physics
Creators: name: Pekker, David
name: Varma, C. M.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: The order parameter and its variations in space and time in many different states in condensed matter physics at low temperatures are described by the complex function $Ψ({\bf r}, t)$. These states include superfluids, superconductors, and a subclass of antiferromagnets and charge-density waves. The collective fluctuations in the ordered state may then be categorized as oscillations of phase and amplitude of $Ψ({\bf r}, t)$. The phase oscillations are the {\it Goldstone} modes of the broken continuous symmetry. The amplitude modes, even at long wavelengths, are well defined and decoupled from the phase oscillations only near particle-hole symmetry, where the equations of motion have an effective Lorentz symmetry as in particle physics, and if there are no significant avenues for decay into other excitations. They bear close correspondence with the so-called {\it Higgs} modes in particle physics, whose prediction and discovery is very important for the standard model of particle physics. In this review, we discuss the theory and the possible observation of the amplitude or Higgs modes in condensed matter physics -- in superconductors, cold-atoms in periodic lattices, and in uniaxial antiferromagnets. We discuss the necessity for at least approximate particle-hole symmetry as well as the special conditions required to couple to such modes because, being scalars, they do not couple linearly to the usual condensed matter probes.
description: 39 pages, 12 figures. Replaced with published version; Annual Reviews of Condensed Matter Physics Volume 6 (2015)
Guía de observación y análisis de la experiencia musical
Creators: name: Reyes-López, María Luisa
name: Ocaña-Fernández, Almudena
name: Montes-Rodríguez, Ramón
Publisher: name: Zenodo
Year: 2023
Subjects: Experiencia musical
Investigación cualitativa
Investigación en educación
Apropiación participativa

description: Presentamos una guía de observación y análisis de la experiencia musical desde la revisión de la literatura y la reflexión sobre la práctica que, con una mirada amplia y reflexiva, tiene un doble propósito: De una parte, permite analizar experiencias educativas y aportar evidencias acerca de qué se aprende, cómo se aprende y qué repercusión tiene lo que se aprende cuando desarrollamos una actividad musical. Y de otra, nos sirve como instrumento para que el docente que investiga pueda mejorar su propia práctica a partir de la observación sistematizada y la reflexión. La guía está estructurada en torno a los tres planos de la actividad sociocultural propuestos por Rogoff (1997, 2003): aprendizajes posibles; participación guiada y apropiación participativa. La revisión de la literatura y la observación sistemática de experiencias musicales nos han permitido identificar las dimensiones de análisis en cada plano y definir sus elementos. Ha sido construida y validada de manera colaborativa entre investigadores y docentes procedentes de diversos espacios educativos relacionados con la educación musical. Su utilidad no solo reside en la posibilidad de comprensión de la experiencia musical por parte del investigador, sino también por parte de los docentes que la pueden incorporar en su labor diaria como herramienta para el análisis y mejora de su actividad profesional y para la formación del profesorado.
description: {"references": ["Rogoff, B. (1997). Los tres planos de la actividad sociocultural: apropiaci\u00f3n participativa, participaci\u00f3n guiada y aprendizaje. En J. Wertsch, P. del R\u00edo, y A. \u00c1lvarez (Eds.), La mente sociocultural. Aproximaciones te\u00f3ricas y aplicadas (pp. 111-128). Fundaci\u00f3n Infancia y Aprendizaje.", "Rogoff, B. (2003). The cultural nature of human development. Oxford University Press."]}
Could kilomasers pinpoint supermassive stars?
Creators: name: Nowak, Katarzyna
name: Krause, Martin. G. H.
name: Schaerer, Daniel
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: A strong nuclear kilomaser, W1, has been found in the nearby galaxy NGC 253, associated with a forming super star cluster. Kilomasers could arise from the accretion disc around supermassive stars (>10^3 Msun), hypothetical objects that have been proposed as polluters responsible for the chemical peculiarities in globular clusters. The supermassive stars would form via runaway collisions, simultaneously with the cluster. Their discs are perturbed by stellar flybys, inspiralling and colliding stars. This raises the question if an accretion disc would at all be able to survive in such a dynamic environment and mase water lines. We investigated what the predicted maser spectrum of such a disc would look like using 2D hydrodynamic simulations and compared this to the W1 kilomaser. We derived model maser spectra from the simulations by using a general maser model for appropriate disc temperatures. All our model discs survived. The model maser spectra for the most destructive case for the simulations of M = 1000 Msun are a reasonable match with the W1 kilomaser spectrum in terms of scaling, flux values and some of the signal trends. Details in the spectrum suggest that a star of a few 1000 Msun might fit even better, with 10,000 Msun clearly giving too large velocities. Our investigations thus support the hypothesis that kilomasers could pinpoint supermassive stars.
description: 14 pages, 7 figures
Observational constraints on spinning, relativistic Bose-Einstein condensate stars
Creators: name: Mukherjee, Arunava
name: Shah, Shreya
name: Bose, Sukanta
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: Bose-Einstein condensates (BECs) have been proposed as candidate states of matter for the interior of neutron stars. Specifically, Chavanis and Harko obtained the mass-radius relation for a BEC star and proposed that the recently discovered neutron stars with masses around 2$M_\odot$ are BEC stars. They employed a barotropic equation of state (EOS), with one free parameter, that was first found by Colpi, Wasserman, and Shapiro (CSW), to describe them and derive stable equilibrium configurations of spinning BEC stars in General Relativity. In this work we show that while it is true that BECs allow for compact object masses as heavy as the heaviest observed ones, such stars cannot simultaneously have radii that are small enough to be consistent with the latest observations, in spite of the flexibility available in the EOS in the form of the free parameter. In fact, our conclusion applies to any spinning relativistic boson star that obeys the CSW EOS.
description: 10 pages, 5 figures, significantly added materials; to be published in PRD; AM and SB dedicate this paper to our co-author, late Shreya Shah
Cotton gravity and 84 galaxy rotation curves
Creators: name: Harada, Junpei
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Recently, as a generalization of general relativity, a gravity theory has been proposed in which gravitational field equations are described by the Cotton tensor. That theory allows an additional contribution to the gravitational potential of a point mass that rises linearly with radius as $Φ= -GM/r + γr/2$, where $G$ is the Newton constant. The coefficients $M$ and $γ$ are the constants of integration and should be determined individually for each physical system. When applied to galaxies, the coefficient $γ$, which has the dimension of acceleration, should be determined for each galaxy. This is the same as having to determine the mass $M$ for each galaxy. If $γ$ is small enough, the linear potential term is negligible at short distances, but can become significant at large distances. In fact, it may contribute to the extragalactic systems. In this paper, we derive the effective field equation for Cotton gravity applicable to extragalactic systems. We then use the effective field equation to numerically compute the gravitational potential of a sample of 84 rotating galaxies. The 84 galaxies span a wide range, from stellar disk-dominated spirals to gas-dominated dwarf galaxies. We do not assume the radial density profile of the stellar disk, bulge, or gas; we use only the observed data. We find that the rotation curves of 84 galaxies can be explained by the observed distribution of baryons. This is due to the flexibility of Cotton gravity to allow the integration constant $γ$ for each galaxy. In the context of Cotton gravity, "dark matter" is in some sense automatically included as a curvature of spacetime. Consequently, even galaxies that have been assumed to be dominated by dark matter do not need dark matter.
description: 22 pages, 7 figures, 1 table, accepted for publication in Phys. Rev. D, v2: published version
title: Anforderungsermittlung, Implementierung und Evaluierung einer mobilen App zur Ballbegleitung
Creators: name: Lien, Jenny
Year: 2022

description: Der Einsatz von mobilen Applikationen (Apps) hat sich im digitalen Zeitalter bereits in unterschiedlichen Anwendungsbereichen etabliert. Kulturelle Einrichtungen und gesellschaftliche Veranstaltungen, wie Museen und Festivals, setzen auf Apps, um das Besuchserlebnis zu steigern. Ballveranstaltungen in Österreich sind ein wichtiges kulturelles Erbe, das bereits in das 17. Jahrhundert zurück reicht. Sie bieten als Veranstaltungen den idealen Rahmen für interaktive Szenarien, dennoch gibt es kaum digitale Lösungen, wie eine interaktive Tanzpartnerfindung durch eine mobile App. Die vorliegende Arbeit befasst sich mit der Fragestellung, ob der Bedarf einer mobilen App für den Einsatz für Ballveranstaltungen vorliegt und in weiterer Folge mit Design und Realisierung einer mobilen App, mit dem Ziel das Ballerlebnis zu bereichern. Die Funktionalitäten der entwickelten App basieren auf den Ergebnissen der durchgeführten empirischen Bedarfsanalyse, bei der Wünsche und Bedürfnisse von Ballbesuchern erfasst wurden.
Banana Split: Testing the Dark Energy Consistency with Geometry and Growth
Creators: name: Ruiz, Eduardo J.
name: Huterer, Dragan
Publisher: name: arXiv
Year: 2014
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We perform parametric tests of the consistency of the standard $w$CDM model in the framework of general relativity by carefully separating information between the geometry and growth of structure. We replace each late-universe parameter that describes the behavior of dark energy with two parameters: one describing geometrical information in cosmological probes, and the other controlling the growth of structure. We use data from all principal cosmological probes: of these, Type Ia supernovae, baryon acoustic oscillations, and the peak locations in the cosmic microwave background angular power spectrum constrain the geometry, while the redshift space distortions, weak gravitational lensing and the abundance of galaxy clusters constrain both geometry and growth. Both geometry and growth separately favor the $Λ$CDM cosmology with the matter density relative to critical $Ω_M\simeq 0.3$. When the equation of state is allowed to vary separately for probes of growth and geometry, we find again a good agreement with the $Λ$CDM value ($w\simeq -1$), with the major exception of redshift-space distortions which favor less growth than in $Λ$CDM at 3-$σ$ confidence, favoring the equation of state $w^{\rm grow}\simeq -0.8$. The anomalous growth favored by redshift space distortions has been noted earlier, and is common to all redshift space distortion data sets, but may well be caused by systematics, or be explained by the sum of the neutrino masses higher than that expected from the simplest mass hierarchies, $m_ν\simeq 0.45$ eV. On the whole, the constraints are tight even in the new, larger parameter space due to impressive complementarity of different cosmological probes.
description: 24 pages, 12 Figures, v2: references added; v3: minor clarifications added, plus additional graphs with separated contours to clarify constraints
Distributed Block Coordinate Descent for Minimizing Partially Separable Functions
Creators: name: Marecek, Jakub
name: Richtarik, Peter
name: Takac, Martin
Publisher: name: arXiv
Year: 2014
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics

description: In this work we propose a distributed randomized block coordinate descent method for minimizing a convex function with a huge number of variables/coordinates. We analyze its complexity under the assumption that the smooth part of the objective function is partially block separable, and show that the degree of separability directly influences the complexity. This extends the results in [Richtarik, Takac: Parallel coordinate descent methods for big data optimization] to a distributed environment. We first show that partially block separable functions admit an expected separable overapproximation (ESO) with respect to a distributed sampling, compute the ESO parameters, and then specialize complexity results from recent literature that hold under the generic ESO assumption. We describe several approaches to distribution and synchronization of the computation across a cluster of multi-core computers and provide promising computational results.
description: in Recent Developments in Numerical Analysis and Optimization, 2015
The Evolution of First Person Vision Methods: A Survey
Creators: name: Betancourt, Alejandro
name: Morerio, Pietro
name: Regazzoni, Carlo S.
name: Rauterberg, Matthias
Publisher: name: arXiv
Year: 2014
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: The emergence of new wearable technologies such as action cameras and smart-glasses has increased the interest of computer vision scientists in the First Person perspective. Nowadays, this field is attracting attention and investments of companies aiming to develop commercial devices with First Person Vision recording capabilities. Due to this interest, an increasing demand of methods to process these videos, possibly in real-time, is expected. Current approaches present a particular combinations of different image features and quantitative methods to accomplish specific objectives like object detection, activity recognition, user machine interaction and so on. This paper summarizes the evolution of the state of the art in First Person Vision video analysis between 1997 and 2014, highlighting, among others, most commonly used features, methods, challenges and opportunities within the field.
description: First Person Vision, Egocentric Vision, Wearable Devices, Smart Glasses, Computer Vision, Video Analytics, Human-machine Interaction
Directed energy deposition powder stream modeling using a Gaussian beam ray representation
Creators: name: Martinez-Marchese, Alexander
name: Klumpp, Maximilian
name: Toyserkani, Ehsan
Publisher: name: arXiv
Year: 2022
Subjects: subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: The powder stream from a side feed nozzle, or part of the powder stream in some coaxial nozzles, in a directed energy deposition via powder feeding (DED-PF) machine, can be modeled using a particle velocity field that has a constant downward component and a linearly increasing outward component, in proportion to the powder stream's center line distance. However, when the powder stream is subject to a force field, it was found that the shape of the powder concentration function close to the center of the powder stream diverges considerably at high degrees of focusing. This discrepancy is reduced by modeling the powder stream based on the ray representation of a Gaussian beam. Experimental results from high-speed camera particle tracking and numerically extrapolating the trajectories to the nozzle exit suggests that the statistics of the powder stream correspond to this model. A novel method to compute the particle concentration along the stream using an optical system analog, with the focusing force field modeled as the transfer matrix of a graded refractive index (GRIN) lens, is also demonstrated. This method is orders of magnitude faster than the corresponding Lagrangian simulation.
Decay of dark and bright plasmonic modes in a metallic nanoparticle dimer
Creators: name: Brandstetter-Kunc, Adam
name: Weick, Guillaume
name: Weinmann, Dietmar
name: Jalabert, Rodolfo A.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We develop a general quantum theory of the coupled plasmonic modes resulting from the near-field interaction between localized surface plasmons in a heterogeneous metallic nanoparticle dimer. In particular, we provide analytical expressions for the frequencies and decay rates of the bright and dark plasmonic modes. We show that, for sufficiently small nanoparticles, the main decay channel for the dark plasmonic mode, which is weakly coupled to light and, hence, immune to radiation damping, is of nonradiative origin and corresponds to Landau damping, i.e., decay into electron-hole pairs.
description: 9 pages, 3 figures; published version
Emergent loop current order from pair density wave superconductivity
Creators: name: Agterberg, Daniel F.
name: Melchert, Drew S.
name: Kashyap, Manoj K.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: There is evidence that the pseudogap phase in the cuprates breaks time-reversal symmetry. Here we show that pair density wave (PDW) states give rise to a translational invariant nonsuperconducting order parameter that breaks time-reversal and parity symmetries, but preserves their product. This secondary order parameter has a different origin, but shares the same symmetry properties as a magnetoelectric loop current order that has been proposed earlier in the context of the cuprates to explain the appearance of intracell magnetic order. We further show that, due to fluctuations, this secondary loop current order, which breaks only discrete symmetries, can preempt PDW order, which breaks both continuous and discrete symmetries. In such a phase, the emergent loop current order coexists with spatial short-range superconducting order and possibly short-range charge density wave (CDW) order. Finally, we propose a PDW phase that accounts for intracell magnetic order and the Kerr effect, has CDW order consistent with x-ray scattering and nuclear magnetic resonance observations, and quasi-particle properties consistent with angle-resolved photoemission scattering.
description: Typos corrected and References updated
Structural peculiarities of $\varepsilon$-Fe$_2$O$_3$ / GaN epitaxial layers unveiled by high-resolution transmission electron microscopy and neutron reflectometry
Creators: name: Suturin, Sergey M.
name: Dvortsova, Polina A.
name: Snigirev, Leonid A.
name: Ukleev, Victor A.
name: Hanashima, Takayasu
name: Rosado, Marcos
name: Ballesteros, Belén
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The present paper is dedicated to the structural study of crystallographic peculiarities appearing in epitaxial films of metastable epsilon iron oxide ($\varepsilon$-Fe$_2$O$_3$) grown by pulsed laser deposition onto a semiconductor GaN (0001) substrate. The columnar structure of the nanoscale $\varepsilon$-Fe$_2$O$_3$ films has been for the first time investigated using high resolution electron microscopy (HRTEM) direct space technique complemented by reciprocal space methods of high-energy electron diffraction and color-enhanced HRTEM image Fourier filtering. The study of $\varepsilon$-Fe$_2$O$_3$ / GaN interface formation has been further expanded by carrying out a depth resolved analysis of density and chemical composition by neutron reflectometry and energy-dispersive X-ray spectroscopy. The obtained results shed light onto the properties and the origin of the enigmatic few-nanometer thick low density transition layer residing at the $\varepsilon$-Fe$_2$O$_3$ / GaN interface. A detailed knowledge of the properties of this layer is believed to be highly important for the development of $\varepsilon$-Fe$_2$O$_3$ / GaN heterostructures that can potentially become part of the iron-oxide based ferroic-on-semiconductor devices with room temperature magneto-electric coupling.
description: 14 pages, 9 figures
Small eigenvalues of the low temperature linear relaxation Boltzmann equation with a confining potential
Creators: name: Robbe, Virgile
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mathematical Physics (math-ph)
subject: Analysis of PDEs (math.AP)
subject: Spectral Theory (math.SP)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 35P20, 35Q20, 47A10, 47D06

description: We study the linear relaxation Boltzmann equation, a simple semiclassical kinetic model. We provide a resolvent estimate for an associated non-selfadjoint operator as well as an estimate on the return to equilibrium. This is done using a scaling argument and non-semiclassical hypocoercive estimate.
description: 17 pages
Bohr--Sommerfeld Lagrangians of moduli spaces of Higgs bundles
Creators: name: Biswas, Indranil
name: Gammelgaard, Niels Leth
name: Logares, Marina
Publisher: name: arXiv
Year: 2014
Subjects: subject: Algebraic Geometry (math.AG)
subject: Mathematical Physics (math-ph)
subject: Symplectic Geometry (math.SG)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 14H60, 14H70, 53D12

description: Let $X$ be a compact connected Riemann surface of genus at least two. Let $M_H(r,d)$ denote the moduli space of semistable Higgs bundles on $X$ of rank $r$ and degree $d$. We prove that the compact complex Bohr-Sommerfeld Lagrangians of $M_H(r,d)$ are precisely the irreducible components of the nilpotent cone in $M_H(r,d)$. This generalizes to Higgs $G$-bundles and also to the parabolic Higgs bundles.
description: Final version; Journal of Geometry and Physics (to appear)
Distinct Spin Liquids and their Transitions in Spin-1/2 XXZ Kagome Antiferromagnets
Creators: name: He, Yin-Chen
name: Chen, Yan
Publisher: name: arXiv
Year: 2014
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: By using the density matrix renormalization group, we study the spin-liquid phases of spin-$1/2$ XXZ kagome antiferromagnets. We find that the emergence of spin liquid phase does not depend on the anisotropy of the XXZ interaction. In particular, the two extreme limits---Ising (strong $S^z$ interaction) and XY (zero $S^z$ interaction)---host the same spin-liquid phases as the isotropic Heisenberg model. Both the time-reversal-invariant spin liquid and the chiral spin liquid with spontaneous time-reversal symmetry breaking are obtained. We show they evolve continuously into each other by tuning the second- and third-neighbor interactions. At last, we discuss the possible implication of our results on the nature of spin liquid in nearest neighbor XXZ kagome antiferromagnets, including the most studied nearest neighbor spin-$1/2$ kagome anti-ferromagnetic Heisenberg model.
title: Die Herstellung interpersoneller Nähe im experimentellen Kontext
Creators: name: Bechter, Marie
Year: 2022

description: In der vorliegenden Arbeit kommt es zu einer partiellen Replikation der Studie von Aron et al. (1997). Durch die Beantwortung von 36 von Aron et al. (1997) erstellten Fragen wird in einem experimentellen Kontext versucht, interpersonelle Nähe herzustellen. Des Weiteren werden die Ergebnisse mit der Originalstudie verglichen und der Unterschied des Ausmaßes der interpersonellen Nähe in drei verschiedenen Gruppen (Beantwortung der Fragen mittels Videotelefonat, vor Ort ohne und vor Ort mit anschließendem vierminütigen Blickkontakt) analysiert. Die untersuchte Stichprobe setzt sich aus N = 64 Personen zusammen. Innerhalb der verschiedenen Gruppen werden die Teilnehmenden randomisiert einer fremden Person zugeteilt, mit der sie in einer Zeitspanne von 45 Minuten die 36 von Aron et al. (1997) erstellten Fragen beantworten. Die interpersonelle Nähe wird vor und nach dem Experiment mittels eines Selbstbeurteilungsfragebogen erhoben. Dieser setzt sich aus Items der Inclusion of Other in the Self (IOS) Skala von Aron et al. (1992) und des Subjective Closeness Index (SCI) von Berscheid et al. (1989) zusammen. Es konnte eine signifikante Erhöhung der interpersonellen Nähe nach der Beantwortung der Fragen im Vergleich zu davor gefunden werden. Das Ausmaß der interpersonellen Nähe ist ähnlich hoch wie in der Originalstudie von Aron et al. (1997). Die drei Gruppen unterschieden sich im Hinblick auf die interpersonelle Nähe nicht signifikant voneinander. Die vorliegenden Ergebnisse implizieren, dass interpersonelle Nähe durch die Beantwortung der 36 von Aron et al. (1997) erstellten Fragen künstlich hergestellt werden kann und weder die Beantwortung mittels eines Videotelefonates noch ein zusätzlicher vierminütiger Blickkontakt zu signifikant unterschiedlichen Ergebnissen führt.
The Most Luminous Galaxies Discovered by WISE
Creators: name: Tsai, Chao-Wei
name: Eisenhardt, Peter
name: Wu, Jingwen
name: Stern, Daniel
name: Assef, Roberto
name: Blain, Andrew
name: Bridge, Carrie
name: Benford, Dominic
name: Cutri, Roc
name: Griffith, Roger
name: Jarrett, Thomas
name: Lonsdale, Carol
name: Masci, Frank
name: Moustakas, Leonidas
name: Petty, Sara
name: Sayers, Jack
name: Stanford, S. Adam
name: Wright, Edward
name: Yan, Lin
name: Leisawitz, David
name: Liu, Fengchuan
name: Mainzer, Amy
name: McLean, Ian
name: Padgett, Deborah
name: Skrutskie, Michael
name: Gelino, Christopher
name: Beichman, Charles
name: Juneau, Stéphanie
Publisher: name: arXiv
Year: 2014
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present 20 WISE-selected galaxies with bolometric luminosities L_bol > 10^14 L_sun, including five with infrared luminosities L_IR = L(rest 8-1000 micron) > 10^14 L_sun. These "extremely luminous infrared galaxies," or ELIRGs, were discovered using the "W1W2-dropout" selection criteria which requires marginal or non-detections at 3.4 and 4.6 micron (W1 and W2, respectively) but strong detections at 12 and 22 micron in the WISE survey. Their spectral energy distributions are dominated by emission at rest-frame 4-10 micron, suggesting that hot dust with T_d ~ 450K is responsible for the high luminosities. These galaxies are likely powered by highly obscured AGNs, and there is no evidence suggesting these systems are beamed or lensed. We compare this WISE-selected sample with 116 optically selected quasars that reach the same L_bol level, corresponding to the most luminous unobscured quasars in the literature. We find that the rest-frame 5.8 and 7.8 micron luminosities of the WISE-selected ELIRGs can be 30-80% higher than that of the unobscured quasars. The existence of AGNs with L_bol > 10^14 L_sun at z > 3 suggests that these supermassive black holes are born with large mass, or have very rapid mass assembly. For black hole seed masses ~ 10^3 M_sun, either sustained super-Eddington accretion is needed, or the radiative efficiency must be <15%, implying a black hole with slow spin, possibly due to chaotic accretion.
description: 17 pages in emulateapj format, including 11 figures and 5 tables. ApJ in press
PL-kNN: A Parameterless Nearest Neighbors Classifier
Creators: name: Jodas, Danilo Samuel
name: Passos, Leandro Aparecido
name: Adeel, Ahsan
name: Papa, João Paulo
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Demands for minimum parameter setup in machine learning models are desirable to avoid time-consuming optimization processes. The $k$-Nearest Neighbors is one of the most effective and straightforward models employed in numerous problems. Despite its well-known performance, it requires the value of $k$ for specific data distribution, thus demanding expensive computational efforts. This paper proposes a $k$-Nearest Neighbors classifier that bypasses the need to define the value of $k$. The model computes the $k$ value adaptively considering the data distribution of the training set. We compared the proposed model against the standard $k$-Nearest Neighbors classifier and two parameterless versions from the literature. Experiments over 11 public datasets confirm the robustness of the proposed approach, for the obtained results were similar or even better than its counterpart versions.
Non equilibrium dissipation-driven steady many-body entanglement
Creators: name: Bellomo, Bruno
name: Antezza, Mauro
Publisher: name: arXiv
Year: 2014
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study an ensemble of two-level quantum systems (qubits) interacting with a common electromagnetic field in proximity of a dielectric slab whose temperature is held different from that of some far surrounding walls. We show that the dissipative dynamics of the qubits driven by this stationary and out of thermal equilibrium (OTE) field, allows the production of steady many-body entangled states, differently from the case at thermal equilibrium where steady states are always non-entangled. By studying up to ten qubits, we point out the role of symmetry in the entanglement production, which is exalted in the case of permutationally invariant configurations. In the case of three qubits, we find a strong dependence of tripartite entanglement on the spatial disposition of the qubits, and in the case of six qubits, we find several highly entangled bipartitions where entanglement can, remarkably, survive for large qubit-qubit distances up to 100 $μ$m.
description: 10 pages, 5 figures, updated version accepted for publication in Phys. Rev. A
The Initial Value Formulation of Dynamical Chern-Simons Gravity
Creators: name: Delsate, Térence
name: Hilditch, David
name: Witek, Helvi
Publisher: name: arXiv
Year: 2014
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We derive an initial value formulation for dynamical Chern-Simons gravity, a modification of general relativity involving parity-violating higher derivative terms. We investigate the structure of the resulting system of partial differential equations thinking about linearization around arbitrary backgrounds. This type of consideration is necessary if we are to establish well-posedness of the Cauchy problem. Treating the field equations as an effective field theory we find that weak necessary conditions for hyperbolicity are satisfied. For the full field equations we find that there are states from which subsequent evolution is not determined. Generically the evolution system closes, but the full field equations are in no sense hyperbolic. In a cursory mode analysis we find that the equations of motion contain terms that may cause ill-posedness of the initial value problem.
description: 16 pages; matches published version
A countable definable set of reals containing no definable elements
Creators: name: Kanovei, Vladimir
name: Lyubetsky, Vassily
Publisher: name: arXiv
Year: 2014
Subjects: subject: Logic (math.LO)
subject: FOS: Mathematics
subject: 03E35, 03E45, 03E15

description: We make use of a finite support product of Jensen forcing to define a model in which there is a countable non-empty lightface $Π^1_2$ set of reals containing no ordinal-definable real.
description: Revised version. The revision includes an updated proof of Lemma 4.5 (the density-preservation lemma for the product)
Scalable Tight-Binding Model for Graphene
Creators: name: Liu, Ming-Hao
name: Rickhaus, Peter
name: Makk, Péter
name: Tóvári, Endre
name: Maurand, Romain
name: Tkatschenko, Fedor
name: Weiss, Markus
name: Schönenberger, Christian
name: Richter, Klaus
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Artificial graphene consisting of honeycomb lattices other than the atomic layer of carbon has been shown to exhibit electronic properties similar to real graphene. Here, we reverse the argument to show that transport properties of real graphene can be captured by simulations using "theoretical artificial graphene." To prove this, we first derive a simple condition, along with its restrictions, to achieve band structure invariance for a scalable graphene lattice. We then present transport measurements for an ultraclean suspended single-layer graphene pn junction device, where ballistic transport features from complex Fabry-Pérot interference (at zero magnetic field) to the quantum Hall effect (at unusually low field) are observed and are well reproduced by transport simulations based on properly scaled single-particle tight-binding models. Our findings indicate that transport simulations for graphene can be efficiently performed with a strongly reduced number of atomic sites, allowing for reliable predictions for electric properties of complex graphene devices. We demonstrate the capability of the model by applying it to predict so-far unexplored gate-defined conductance quantization in single-layer graphene.
description: published version, with supplemental material
Catalytic stereodivergent allylic alkylation of 2-acylimidazoles for natural product synthesis
Creators: name: Chang, Guo
Publisher: name: Zenodo
Year: 2023

description: NMR data in a mnova file format and HPLC traces for Catalytic stereodivergent allylic alkylation of 2-acylimidazoles for natural product synthesis.
Axion Landscape and Natural Inflation
Creators: name: Higaki, Tetsutaro
name: Takahashi, Fuminobu
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Multiple axions form a landscape in the presence of various shift symmetry breaking terms. Eternal inflation populates the axion landscape, continuously creating new universes by bubble nucleation. Slow-roll inflation takes place after the tunneling event, if a very flat direction with a super-Planckian decay constant arises due to the alignment mechanism. We study the vacuum structure as well as possible inflationary dynamics in the axion landscape scenario, and find that the inflaton dynamics is given by either natural or multi-natural inflation. In the limit of large decay constant, it is approximated by the quadratic chaotic inflation, which however is disfavored if there is a pressure toward shorter duration of inflation. Therefore, if the spectral index and the tensor-to-scalar ratio turn out to be different from the quadratic chaotic inflation, there might be observable traces of the bubble nucleation. Also, the existence of small modulations to the inflaton potential is a common feature in the axion landscape, which generates a sizable and almost constant running of the scalar spectral index over CMB scales. Non-Gaussianity of equilateral type can also be generated if some of the axions are coupled to massless gauge fields.
description: 20 pages, 5 figures. v3: Replaced with version that matches the one published in PLB
A Framework for Formal Verification of DRAM Controllers
Creators: name: Steiner, Lukas
name: Sudarshan, Chirag
name: Jung, Matthias
name: Stoffel, Dominik
name: Wehn, Norbert
Publisher: name: arXiv
Year: 2022
Subjects: subject: Formal Languages and Automata Theory (cs.FL)
subject: Hardware Architecture (cs.AR)
subject: FOS: Computer and information sciences

description: The large number of recent JEDEC DRAM standard releases and their increasing feature set makes it difficult for designers to rapidly upgrade the memory controller IPs to each new standard. Especially the hardware verification is challenging due to the higher protocol complexity of standards like DDR5, LPDDR5 or HBM3 in comparison with their predecessors. With traditional simulation-based verification it is laborious to guarantee the coverage of all possible states, especially for control flow rich memory controllers. This has a direct impact on the time-to-market. A promising alternative is formal verification because it allows to ensure protocol compliance based on mathematical proofs. However, with regard to memory controllers no fully-automated verification process has been presented in the state-of-the-art yet, which means there is still a potential risk of human error. In this paper we present a framework that automatically generates SystemVerilog Assertions for a DRAM protocol. In addition, we show how the framework can be used efficiently for different tasks of memory controller development.
description: ACM/IEEE International Symposium on Memory Systems (MEMSYS 2022)
Pairing effects in the normal phase of a two-dimensional Fermi gas
Creators: name: Marsiglio, F.
name: Pieri, P.
name: Perali, A.
name: Palestini, F.
name: Strinati, G. C.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: In a recent experiment [M. Feld et al., Nature 480, 75 (2011); B. Froehlich et al., Phys. Rev. Lett. 109,130403 (2012)], a pairing gap was detected in a two-dimensional (2D) Fermi gas with attractive interaction at temperatures where superfluidity does not occur. The question remains open as to whether this gap is a pseudogap phenomenon or is due to a molecular state. In this paper, by using a t-matrix approach, we reproduce quite well the experimental data for a 2D Fermi gas, and set the boundary between the pseudogap and molecular regimes. We also show that pseudogap phenomena occurring in 2D and 3D can be related through a variable spanning the BCS-BEC crossover in a universal way.
description: 10 pages, 9 figures; final version
Cox rings over nonclosed fields
Creators: name: Derenthal, Ulrich
name: Pieropan, Marta
Publisher: name: arXiv
Year: 2014
Subjects: subject: Algebraic Geometry (math.AG)
subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 14C20 (Primary), 11G35, 14L30 (Secondary)

description: We give a definition of Cox rings and Cox sheaves for varieties over nonclosed fields that is compatible with torsors under quasitori, including universal torsors. We study their existence and classification, we make the relation to torsors precise, and we present arithmetic applications.
description: 30 pages; reorganized, Section 5 shortened
A new mechanism for dark energy: the adaptive screening
Creators: name: Hektor, Andi
name: Marzola, Luca
name: Raidal, Martti
name: Veermäe, Hardi
Publisher: name: arXiv
Year: 2014
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We describe how known matter effects within a well-motivated particle physics framework can explain the dark energy component of the Universe. By considering a cold gas of particles which interact via a vector mediator, we show that there exists a regime where the gas reproduces the dynamics of dark energy. In this regime the screening mass of the mediator is proportional to the number density of the gas, hence we refer to this phenomenon as "the adaptive screening mechanism". As an example, we argue that such screening mass can result from strong localization of the vector mediators. The proposed dark energy mechanism could be experimentally verified through cosmological observations by the Euclid experiment, as well as by studying properties of dark photons and sterile neutrinos.
description: Accepted for publication in JHEP. 8 pages, 2 figures
Unveiling the Real Performance of LPDDR5 Memories
Creators: name: Steiner, Lukas
name: Jung, Matthias
name: Huonker, Michael
name: Wehn, Norbert
Publisher: name: arXiv
Year: 2022
Subjects: subject: Hardware Architecture (cs.AR)
subject: FOS: Computer and information sciences

description: LPDDR5 is the latest low-power DRAM standard and expected to be used in various application fields. The vendors have published promising peak bandwidths up to 50 % higher than those of the predecessor LPDDR4. In this paper we evaluate the best-case and worst-case real bandwidth utilization of different LPDDR5 configurations and compare the results to corresponding LPDDR4 configurations. We also show that an upgrade from LPDDR4 to LPDDR5 does not always bring a bandwidth advantage and that some LPDDR5 configurations should be avoided for specific workloads.
description: ACM/IEEE International Symposium on Memory Systems (MEMSYS 2022)
Any Orthonormal Basis in High Dimension is Uniformly Distributed over the Sphere
Creators: name: Goldstein, Sheldon
name: Lebowitz, Joel L.
name: Tumulka, Roderich
name: Zanghi, Nino
Publisher: name: arXiv
Year: 2014
Subjects: subject: Probability (math.PR)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: Let X be a real or complex Hilbert space of finite but large dimension d, let S(X) denote the unit sphere of X, and let u denote the normalized uniform measure on S(X). For a finite subset B of S(X), we may test whether it is approximately uniformly distributed over the sphere by choosing a partition A_1,...,A_m of S(X) and checking whether the fraction of points in B that lie in A_k is close to u(A_k) for each k=1,...,m. We show that if B is any orthonormal basis of X and m is not too large, then, if we randomize the test by applying a random rotation to the sets A_1,...,A_m, B will pass the random test with probability close to 1. This statement is related to, but not entailed by, the law of large numbers. An application of this fact in quantum statistical mechanics is briefly described.
description: 22 pages LaTeX, no figures; v2 minor improvements