cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Engineering of many-body Majorana states in a topological insulator/s-wave superconductor heterostructure
Creators: name: Hung, Hsiang-Hsuan
name: Wu, Jiansheng
name: Sun, Kuei
name: Chiu, Ching-Kai
Publisher: name: arXiv
Year: 2016
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We study a vortex chain in a thin film of a topological insulator with proximity-induced superconductivity---a promising platform to realize Majorana zero modes (MZMs)---by modeling it as a two-leg Majorana ladder. While each pair of MZMs hybridizes through vortex tunneling, we hereby show that MZMs can be stabilized on the ends of the ladder with the presence of tilted external magnetic field and four-Majorana interaction. Furthermore, a fruitful phase diagram is obtained by controlling the direction of magnetic field and the thickness of the sample. We reveal many-body Majorana states and interaction-induced topological phase transitions and also identify trivial-superconducting and commensurate/incommensurate charge-density-wave states in the phase diagram.
description: 10 pages, 4 figures
Normal amenable subgroups of the automorphism group of the full shift
Creators: name: Frisch, Joshua
name: Schlank, Tomer
name: Tamuz, Omer
Publisher: name: arXiv
Year: 2015
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: We show that every normal amenable subgroup of the automorphism group of the full shift is contained in its center. This follows from the analysis of this group's Furstenberg topological boundary, through the construction of a minimal and strongly proximal action. We extend this result to higher dimensional full shifts. This also provides a new proof of Ryan's Theorem and of the fact that these groups contain free groups.
Inequality, education and the social sciences
Creators: name: Kinville, Michael Robert
Publisher: name: Humboldt-Universität zu Berlin, Kultur-, Sozial- und Bildungswissenschaftliche Fakultät
Year: 2017
Subjects: subject: Deutschland
subject: Indien
subject: Ungleichheit
subject: Bildung
subject: kritische Theorie
subject: Education
subject: India
subject: German
subject: Inequality
subject: Critical Theory
subject: 950 Geschichte Asiens
subject: 64 Sozialgeschichte
subject: DU 2000
subject: DF 3000
subject: DV 2320

description: Die konzeptionelle Verbindung zwischen Bildung und Gesellschaft, die im 19. Jahrhundert deutlich gemacht und wissenschaftlich begründet wurde, wird oft als selbstverständlich betrachtet. Diese veraltete Verbindung bildete aber die Basis für Bildungsreformen im Sekundärbereich in Deutschland und Indien in der zweiten Hälfte des 20. Jahrhunderts. Diese Arbeit unternimmt den Versuch, zum Verständnis dieser Verzögerung zwischen den Ideen und den Reformen, die sie einrahmten, beizutragen, indem sie eine geeignete Theorie der Verbindung zwischen Bildung und einer komplexen Gesellschaft aufstellt. Grundsätzliche Annäherungen an Gesellschaft und Bildung treten in Dialog mit post-kolonialen und kritischen Theorien. Universalistische Annahmen werden problematisiert, und eine offene Lösung für die Vorstellung zukünftiger Reformen wird präsentiert. Nationale Bildungsreformen in Indien und Deutschland nach ihren „Critical Junctures“ von 1947/1945 werden eingehend und chronologisch verglichen, um einen spezifischen Charakter historisch- und bildungs-bedingter Reproduktion beider Länder herauszuarbeiten sowie einen gemeinsamen Lernprozess zu ermöglichen. Abschließend wird eine Lösung des Problems in der Form offener Bildung präsentiert. Bildung als öffentliches Gut muss nicht zwangsläufig nur auf soziale Probleme reagieren, stattdessen kann sie verändert werden, um sozialen Wandel voran zu treiben.
description: The conceptual link between education and society, forged in the 19th Century, is often taken for granted. This seemingly outdated connection, however, has guided reforms in secondary education in India and Germany throughout the second half of the 20th Century. This study attempts to understand this lag between underlying ideas and the reforms they framed by synthesizing a viable theory for imagining the connection between education and a complex society. Foundational approaches to society and education are brought into dialogue with post-colonial and critical theories. Universalistic assumptions are problematized, and an open-ended solution for theorizing new connections is presented. National educational reforms in India and Germany subsequent to their critical junctures of 1947/1945 are exhaustively and chronologically compared in order to conceptualize a generic character of historical-educational reproduction for each country and to facilitate a process of mutual learning. Finally, a solution to the problems associated with educational reproduction is presented. Education as a public good does not need to simply be reactive to social problems. Instead, it can be reconfigured so as to drive social change.
Single-ion quantum Otto engine with always-on bath interaction
Creators: name: Chand, Suman
name: Biswas, Asoka
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We demonstrate how a quantum Otto engine (QOE) can be implemented using a single ion and an always-on thermal environment. The internal degree of freedom of the ion is chosen as the working fluid, while the motional degree of freedom can be used as the cold bath. We show, that by adiabatically changing the local magnetic field, the work efficiency can be asymptotically made unity. We propose a projective measurement of the internal state of the ion that mimics the release of heat into the cold bath during the engine cycle. In our proposal, the coupling to the hot and the cold baths need not be switched off and on in an alternative fashion during the engine cycle, unlike other existing proposals of QOE. This renders the proposal experimentally feasible using the available tapped-ion engineering technology.
description: 8 pages, 5 figures
Patterns in Calabi-Yau Distributions
Creators: name: He, Yang-Hui
name: Jejjala, Vishnu
name: Pontiggia, Luca
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Algebraic Geometry (math.AG)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We explore the distribution of topological numbers in Calabi-Yau manifolds, using the Kreuzer-Skarke dataset of hypersurfaces in toric varieties as a testing ground. While the Hodge numbers are well-known to exhibit mirror symmetry, patterns in frequencies of combination thereof exhibit striking new patterns. We find pseudo-Voigt and Planckian distributions with high confidence and exact fit for many substructures. The patterns indicate typicality within the landscape of Calabi-Yau manifolds of various dimension.
description: 62 pages, 22 figures in main text, LaTeX, v.3: section 2.5 added; minor edits; matches version in CMP
title: Machine Learning, Emulation and Bayesian Dimension Reduction for Climate Change Projection
Creators: name: Mansfield, Laura
Publisher: name: University of Reading
Year: 2021

description: Climate change projection under different greenhouse gas and aerosol emission scenarios is crucial for informing societal adaptation and mitigation measures. This traditionally relies on computationally expensive global climate models (GCMs) run on decadal to centennial timescales. One of the goals of this thesis is in exploring machine learning models and emulators trained on the output of global climate models, that can assist in this endeavour by providing rapid estimations of the climate response. Two statistical models are developed, one of which emulates the global short-term climate response to an emissions perturbation and one which learns the mapping from the short-term climate response to the long-term climate response. Different perspectives are taken so that the short-term response is predicted with a probabilistic emulator which interpolates between known and unknown data points, while the global patterns of long-term response are predicted with machine learning methods. Both models are shown to accelerate climate change projections and also provide new insights into the main drivers of climate change through sensitivity analysis to different emission perturbations and by uncovering consistent early indicators of long-term climate response. Discovering structures in climate data that can explain patterns and behaviour is another focus of this thesis, addressed through a dimension reduction technique to simplify large datasets. This is approached from a Bayesian perspective which could allow a complete quantification of uncertainty when making predictions through an emulator trained on a reduced dataset. Reversible jump Markov chain Monte Carlo and Sequential Monte Carlo algorithms are developed for a latent factor model to infer the probability distribution on both the number of underlying dimensions and the structure of these. Sequential Monte Carlo is found to be significantly more effective at determining these and is demonstrated on weather observations to reveal underlying factors governing the weather behaviour.
Multivariate peaks over thresholds models
Creators: name: Rootzén, Holger
name: Segers, Johan
name: Wadsworth, Jennifer L.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Probability (math.PR)
subject: Methodology (stat.ME)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: 60G55, 60G70

description: Multivariate peaks over thresholds modeling based on generalized Pareto distributions has up to now only been used in few and mostly 2-dimensional situations. This paper contributes theoretical understanding, physically based models, inference tools, and simulation methods to support routine use, with an aim at higher dimensions. We derive a general point process model for extreme episodes in data, and show how conditioning the distribution of extreme episodes on threshold exceedance gives four basic representations of the family of generalized Pareto distributions. The first representation is constructed on the real scale of the observations. The second one starts with a model on a standard exponential scale which then is transformed to the real scale. The third and fourth are reformulations of a spectral representation proposed in A. Ferreira and L. de Haan [Bernoulli 20 (2014) 1717--1737]. Numerically tractable forms of densities and censored densities are found and give tools for flexible parametric likelihood inference. New simulation algorithms, explicit formulas for probabilities and conditional probabilities, and conditions which make the conditional distribution of weighted component sums generalized Pareto are derived.
description: 25 pages, 3 figure
La introducción de la energía eléctrica en México
Creators: name: Martínez Miranda, Elio Agustín
Publisher: name: Zenodo
Year: 2004
Subjects: energía eléctrica, electricidad, Frederick Stark Pearson, Arnoldo Vaquié, Necaxa

description: Este trabajo surgió con la idea de estudiar los inicios de la industria eléctrica en México, y en particular, analizar el papel que jugó la física en este proceso. Como los ingenieros eran los profesionistas, que en ese momento, contaban con la mejor formación de física en el país, nos interesó centrar esta investigación en el papel que tuvieron los ingenieros mexicanos en la puesta en marcha del proyecto hidroeléctrico más ambicioso e importante del país, el de la hidroeléctrica de Necaxa, que se convirtió en la principal fuente de energía eléctrica de la Ciudad de México y otras ciudades aledañas. Ésta se construyó a principios del siglo XX y, sin lugar a dudas, requirió de los más avanzados conocimientos de electricidad, mecánica, hidráulica, etc. Palabras clave: energía eléctrica, electricidad, México, Necaxa, Frederick Stark Pearson, Arnoldo Vaquié, Silvio Contri, Federico Trigueros Glennie, Gabriel M. Oropesa, The Mexican Light and Power Company, Limited.
New Bounds for Partial Spreads of $H(2d-1, q^2)$ and Partial Ovoids of the Ree-Tits Octagon
Creators: name: Ihringer, Ferdinand
name: Sin, Peter
name: Xiang, Qing
Publisher: name: arXiv
Year: 2016
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics

description: Two results are obtained that give upper bounds on partial spreads and partial ovoids respectively. The first result is that the size of a partial spread of the Hermitian polar space $\mathsf{H}(3, q^2)$ is at most $\left(\frac{2p^3+p}{3} \right)^t+1$, where $q=p^t$, $p$ is a prime. For fixed $p$ this bound is in $o(q^3)$, which is asymptotically better than the previous best known bound of $(q^3+q+2)/2$. Similar bounds for partial spreads of $\mathsf{H}(2d-1, q^2)$, $d$ even, are given. The second result is that the size of a partial ovoid of the Ree-Tits octagon $\mathsf{O}(2^t)$ is at most $26^t+1$. This bound, in particular, shows that the Ree-Tits octagon $\mathsf{O}(2^t)$ does not have an ovoid.
description: 8 pages, corrected a false claim on collineations in the Ree-Tits octagon, see arXiv:2002.07977v1 [math.GR], Remark 2.3
Generation of cubic graphs and snarks with large girth
Creators: name: Brinkmann, Gunnar
name: Goedgebeur, Jan
Publisher: name: arXiv
Year: 2015
Subjects: subject: Combinatorics (math.CO)
subject: Discrete Mathematics (cs.DM)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences

description: We describe two new algorithms for the generation of all non-isomorphic cubic graphs with girth at least $k\ge 5$ which are very efficient for $5\le k \le 7$ and show how these algorithms can be efficiently restricted to generate snarks with girth at least $k$. Our implementation of these algorithms is more than 30, respectively 40 times faster than the previously fastest generator for cubic graphs with girth at least 6 and 7, respectively. Using these generators we have also generated all non-isomorphic snarks with girth at least 6 up to 38 vertices and show that there are no snarks with girth at least 7 up to 42 vertices. We present and analyse the new list of snarks with girth 6.
description: 27 pages (including appendix)
The weak neutral Fe fluorescence line and long-term X-ray evolution of the Compton-thick AGN in NGC 7674
Creators: name: Gandhi, P.
name: Annuar, A.
name: Lansbury, G. B.
name: Stern, D.
name: Alexander, D. M.
name: Bauer, F. E.
name: Bianchi, S.
name: Boggs, S. E.
name: Boorman, P. G.
name: Brandt, W. N.
name: Brightman, M.
name: Christensen, F. E.
name: Comastri, A.
name: Craig, W. W.
name: Del Moro, A.
name: Elvis, M.
name: Guainazzi, M.
name: Hailey, C. J.
name: Harrison, F. A.
name: Koss, M.
name: Lamperti, I.
name: Malaguti, G.
name: Masini, A.
name: Matt, G.
name: Puccetti, S.
name: Ricci, C.
name: Rivers, E.
name: Walton, D. J.
name: Zhang, W. W.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We present $NuSTAR$ X-ray observations of the active galactic nucleus (AGN) in NGC 7674. The source shows a flat X-ray spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested the alternate possibility that the source is a recently switched-off AGN with the observed X-rays being the lagged echo from the torus. Our high-quality data show the source to be reflection-dominated in hard X-rays, but with a relatively weak neutral Fe K$α$ emission line (equivalent width [EW] of $\approx$ 0.4 keV) and a strong Fe XXVI ionised line (EW $\approx$ 0.2 keV). We construct an updated long-term X-ray light curve of NGC 7674 and find that the observed 2-10 keV flux has remained constant for the past $\approx$ 20 years, following a high flux state probed by $Ginga$. Light travel time arguments constrain the minimum radius of the reflector to be $\sim$ 3.2 pc under the switched-off AGN scenario, $\approx$ 30 times larger than the expected dust sublimation radius, rendering this possibility unlikely. A patchy Compton-thick AGN (CTAGN) solution is plausible, requiring a minimum line-of-sight column density ($N_{\rm H}$) of 3 $\times$ 10$^{24}$ cm$^{-2}$ at present, and yields an intrinsic 2-10 keV luminosity of (3-5) $\times$ 10$^{43}$ erg s$^{-1}$. Realistic uncertainties span the range of $\approx$ (1-13) $\times$ 10$^{43}$ erg s$^{-1}$. The source has one of the weakest fluorescence lines amongst {\em bona fide} CTAGN, and is potentially a local analogue of bolometrically luminous systems showing complex neutral and ionised Fe emission. It exemplifies the difficulty of identification and proper characterisation of distant CTAGN based on the strength of the neutral Fe K$α$ line.
description: MNRAS accepted version
Grope metrics on the knot concordance set
Creators: name: Cochran, Tim D.
name: Harvey, Shelly
name: Powell, Mark
Publisher: name: arXiv
Year: 2015
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 57M25, 57M27, 57N13, 57N70

description: To a special type of grope embedded in 4-space, that we call an admissible grope, we associate a length function for each real number q at least 1. This gives rise to a family of pseudo-metrics d^q, refining the slice genus metric, on the set of concordance classes of knots, as the infimum of the length function taken over all possible grope concordances between two knots. We investigate the properties of these metrics. The main theorem is that the topology induced by this metric on the knot concordance set is not discrete for all q>1. The analogous statement for links also holds for q=1. In addition we translate much previous work on knot concordance into distance statements. In particular, we show that winding number zero satellite operators are contractions in many cases, and we give lower bounds on our metrics arising from knot signatures and higher order order signatures. This gives further evidence in favor of the conjecture that the knot concordance group has a fractal structure.
description: 33 pages, 5 figures
Critical local moment fluctuations and enhanced pairing correlations in a cluster Anderson model
Creators: name: Cai, Ang
name: Pixley, J. H.
name: Ingersent, Kevin
name: Si, Qimiao
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The appearance of unconventional superconductivity near heavy-fermion quantum critical points (QCPs) motivates investigation of pairing correlations close to a ``beyond Landau'' Kondo-destruction QCP. We focus on a two-Anderson-impurity cluster in which Kondo destruction is induced by a pseudogap in the conduction-electron density of states. Analysis via continuous-time quantum Monte-Carlo and the numerical renormalization group reveals a previously unstudied QCP that both displays the critical-local moment fluctuations characteristic of Kondo destruction and leads to a strongly enhanced singlet-pairing susceptibility. Our results provide new insights into the mechanism for superconductivity in quantum critical metals.
description: 9 pages, 11 figures, published version
Classifying bicrossed products of two Taft algebras
Creators: name: Agore, A. L.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Rings and Algebras (math.RA)
subject: Quantum Algebra (math.QA)
subject: FOS: Mathematics

description: We classify all Hopf algebras which factorize through two Taft algebras $\mathbb{T}_{n^{2}}(\bar{q})$ and respectively $T_{m^{2}}(q)$. To start with, all possible matched pairs between the two Taft algebras are described: if $\bar{q} \neq q^{n-1}$ then the matched pairs are in bijection with the group of $d$-th roots of unity in $k$, where $d = (m,\,n)$ while if $\bar{q} = q^{n-1}$ then besides the matched pairs above we obtain an additional family of matched pairs indexed by $k^{*}$. The corresponding bicrossed products (double cross product in Majid's terminology) are explicitly described by generators and relations and classified. As a consequence of our approach, we are able to compute the number of isomorphism types of these bicrossed products as well as to describe their automorphism groups.
description: Continues arXiv:1205.6110, arXiv:1205.6564; restates preliminaries and definitions for sake of clarity. Final version, to appear in J. Pure Appl. Algebra
Quantum phase space measurement and entanglement validation made easy
Creators: name: Rundle, R. P.
name: Mills, P. W.
name: Tilma, Todd
name: Samson, J. H.
name: Everitt, M. J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: It has recently been shown that it is possible to represent the complete quantum state of any system as a phase-space quasi-probability distribution (Wigner function) [Phys Rev Lett 117, 180401]. Such functions take the form of expectation values of an observable that has a direct analogy to displaced parity operators. In this work we give a procedure for the measurement of the Wigner function that should be applicable to any quantum system. We have applied our procedure to IBM's Quantum Experience five-qubit quantum processor to demonstrate that we can measure and generate the Wigner functions of two different Bell states as well as the five-qubit Greenberger-Horne-Zeilinger (GHZ) state. As Wigner functions for spin systems are not unique, we define, compare, and contrast two distinct examples. We show how using these Wigner functions leads to an optimal method for quantum state analysis especially in the situation where specific characteristic features are of particular interest (such as for spin Schrödinger cat states). Furthermore we show that this analysis leads to straightforward, and potentially very efficient, entanglement test and state characterisation methods.
description: 12 pages, 7 figures, animations included. Accepted for publication in Phys Rev A
Optimal exponents for Hardy--Littlewood inequalities for $m$-linear operators
Creators: name: Aron, R. M.
name: Núñez-Alarcón, D.
name: Pellegrino, D.
name: Serrano-Rodríguez, D. M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 47B37, 47B10

description: The Hardy--Littlewood inequalities on $\ell _{p}$ spaces provide optimal exponents for some classes of inequalities for bilinear forms on $\ell _{p}$ spaces. In this paper we investigate in detail the exponents involved in Hardy--Littlewood type inequalities and provide several optimal results that were not achieved by the previous approaches. Our first main result asserts that for $q_{1},...,q_{m}>0$ and an infinite-dimensional Banach space $Y$ attaining its cotype $\cot Y$, if \begin{equation*} \frac{1}{p_{1}}+...+\frac{1}{p_{m}}
description: 20 pages
Symmetry breaking patterns of the 3-3-1 model at finite temperature
Creators: name: Borges, J. Sá
name: Ramos, Rudnei O.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We consider the minimal version of an extension of the standard electroweak model based on the $SU(3)_c \times SU(3)_L \times U(1)_X$ gauge symmetry (the 3-3-1 model). We analyze the most general potential constructed from three scalars in the triplet representation of $SU(3)_L$, whose neutral components develop nonzero vacuum expectation values, giving mass for all the model's massive particles. {}For different choices of parameters, we obtain the particle spectrum for the two symmetry breaking scales: one where the $SU(3)_L \times U(1)_X$ group is broken down to $SU(2)_L\times U(1)_Y$ and a lower scale similar to the standard model one. Within the considerations used, we show that the model encodes two first-order phase transitions, respecting the pattern of symmetry restoration. The last transition, corresponding to the standard electroweak one, is found to be very weak first-order, most likely turning second-order or a crossover in practice. However, the first transition in this model can be strongly first-order, which might happen at a temperature not too high above the second one. We determine the respective critical temperatures for symmetry restoration for the model.
description: 13 pages, 8 figures. Minor changes to match published version
Superfluidity and spin superfluidity in spinor Bose gases
Creators: name: Armaitis, J.
name: Duine, R. A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We show that spinor Bose gases subject to a quadratic Zeeman effect exhibit coexisting superfluidity and spin superfluidity, and study the interplay between these two distinct types of superfluidity. To illustrate that the basic principles governing these two types of superfluidity are the same, we describe the magnetization and particle-density dynamics in a single hydrodynamic framework. In this description spin and mass supercurrents are driven by their respective chemical potential gradients. As an application, we propose an experimentally accessible stationary state, where the two types of supercurrents counterflow and cancel each other, thus resulting in no mass transport. Furthermore, we propose a straightforward setup to probe spin superfluidity by measuring the in-plane magnetization angle of the whole cloud of atoms. We verify the robustness of these findings by evaluating the four-magnon collision time, and find that the time scale for coherent (superfluid) dynamics is separated from that of the slower incoherent dynamics by one order of magnitude. Comparing the atom and magnon kinetics reveals that while the former can be hydrodynamic, the latter is typically collisionless under most experimental conditions. This implies that, while our zero-temperature hydrodynamic equations are a valid description of spin transport in Bose gases, a hydrodynamic description that treats both mass and spin transport at finite temperatures may not be readily feasible.
Orbital Mott transition in two dimensional Pyrochlore lattice
Creators: name: Saket, Abhinav
name: Tiwari, Rajarshi
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We study orbital Mott transition in two dimensional pyrochlore lattice, using a two orbital Hubbard model with only inter-orbital electronic hopping. We use a real space Monte Carlo based approach to study the model at finite temperature, and establish temperature-interaction phase diagrams that highlight the Mott transition, orbital ordering, and spectral trends, and possible window of pseudo gap. Due to only inter-orbital hopping, the Mott insulator `generates' ferro exchange resulting in ferro-orbital ordering, with T$_{corr}/t$ peaked at $\approx$ 0.2 around $U/t \approx 6$. The optical conductivity shows unusual two peak feature due to two dimensional pyrochlore lattice.
description: 7 pages, 4 figures. This is final revised version
A Lattice Study of $(\bar{D}_1 D^{*})^\pm$ Near-threshold Scattering
Creators: name: Chen, Ting
name: Chen, Ying
name: Gong, Ming
name: Lei, Yu-Hong
name: Li, Ning
name: Liu, Chuan
name: Liu, Yu-Bin
name: Liu, Zhao-Feng
name: Ma, Jian-Ping
name: Wang, Zhan-Lin
name: Zhang, Jian-Bo
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: In this exploratory lattice study, low-energy near threshold scattering of the $(\bar{D}_1 D^{*})^\pm$ meson system is analyzed using lattice QCD with $N_f=2$ twisted mass fermion configurations. Both s-wave ($J^P=0^-$) and p-wave ($J^P=1^+$) channels are investigated. It is found that the interaction between the two charmed mesons is attractive near the threshold in both channels. This calculation provides some hints in the searching of resonances or bound states around the threshold of $(\bar{D}_1 D^{*})^\pm$ system.
description: 20 pages, 15 figures, matches the version on PRD
Colour-Kinematics duality and the Drinfeld double of the Lie algebra of diffeomorphisms
Creators: name: Fu, Chih-Hao
name: Krasnov, Kirill
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Quantum Algebra (math.QA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: Colour-kinematics duality suggests that Yang-Mills (YM) theory possesses some hidden Lie algebraic structure. So far this structure has resisted understanding, apart from some progress in the self-dual sector. We show that there is indeed a Lie algebra behind the YM Feynman rules. The Lie algebra we uncover is the Drinfeld double of the Lie algebra of vector fields. More specifically, we show that the kinematic numerators following from the YM Feynman rules satisfy a version of the Jacobi identity, in that the Jacobiator of the bracket defined by the YM cubic vertex is cancelled by the contribution of the YM quartic vertex. We then show that this Jacobi-like identity is in fact the Jacobi identity of the Drinfeld double. All our considerations are off-shell. Our construction explains why numerators computed using the Feynman rules satisfy the colour-kinematics at four but not at higher numbers of points. It also suggests a way of modifying the Feynman rules so that the duality can continue to hold for an arbitrary number of gluons. Our construction stops short of producing explicit higher point numerators because of an absence of a certain property at four points. We comment on possible ways of correcting this, but leave the next word in the story to future work.
description: v2: published version, appendix on numerator identities at 5 points added, 34 pages, many feynmf diagrams
Natural gas meter set design
Creators: name: Wilde, Olivia
Publisher: name: Unknown
Year: 2019

description: The purpose of this project was to design and model a large custom meter set for a new industrial
customer. This project was assigned from We Energies which is a company that provides natural
gas to customers in the state of Wisconsin. Natural gas delivery from producing well to
consumers runs based on the fundamental understanding that natural gas flows from high to low
pressure. This means that a customer has a lower delivery pressure than the upstream gas. In fact,
customer delivery pressures are often much smaller than the upstream pressures. This decrease in
pressure is one of the reasons there is a need for natural gas meter sets.
The three main functions of a natural gas meter set are to reduce pressure, regulate pressure, and
measure gas usage. The two main system components necessary to achieve those three functions
are regulators and meters. Regulators reduce and regulate pressure by controlling flow based on
a set point on the regulator. That set point is used to cut pressure to a specific outlet pressure.
Meters are critical for fiscal purposes as they record gas usage. Both regulators and meters along
with additional components including valves, heaters, and filters were analyzed for use in this
customer's meter set design.
The design process began with determining specific customer needs and desires. These
considerations along with gas safety, gas standards, fluid characteristics, and system information
all played a role in the design. The project scope included preliminary component selection and
sizing, preliminary drawing, preliminary modeling, specific component selection, manufacturer
verification, and final drawing and modeling. AutoCAD software was used in the design process
to draw and determine a layout that would fit customer and maintenance needs. A robust
modeling software, Synergi Gas 4.9, was used to model and simulate the meter set throughout its
design phases. At the conclusion of the project there was a meter set design ready for the next
step of high-pressure design specification and material acquisition. The overall cost estimate for
the meter set was $313,000.
Spectral sequences for Hochschild cohomology and graded centers of derived categories
Creators: name: Neumann, Frank
name: Szymik, Markus
Publisher: name: arXiv
Year: 2016
Subjects: subject: Representation Theory (math.RT)
subject: Commutative Algebra (math.AC)
subject: Algebraic Geometry (math.AG)
subject: Algebraic Topology (math.AT)
subject: FOS: Mathematics

description: The Hochschild cohomology of a differential graded algebra, or a differential graded category, admits a natural map to the graded center of its homology category: the characteristic homomorphism. We interpret it as an edge homomorphism in a spectral sequence. This gives a conceptual explanation of the failure of the characteristic homomorphism to be injective or surjective, in general. To illustrate this, we discuss modules over the dual numbers, coherent sheaves over algebraic curves, as well as examples related to free loop spaces and string topology.
description: 29 pages, 1 figure, to appear in Selecta Mathematica
Two Photon Decays of $η_c$ from Lattice QCD
Creators: name: Chen, Ting
name: Chen, Ying
name: Gong, Ming
name: Lei, Yu-Hong
name: Li, Ning
name: Liu, Chuan
name: Liu, Yu-Bin
name: Liu, Zhaofeng
name: Ma, Jian-Ping
name: Qiu, Wei-Feng
name: Wang, Zhan-Lin
name: Zhang, Jian-Bo
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We present an exploratory lattice study for the two-photon decay of $η_c$ using $N_f=2$ twisted mass lattice QCD gauge configurations generated by the European Twisted Mass Collaboration. Two different lattice spacings of $a=0.067$fm and $a=0.085$fm are used in the study, both of which are of physical size of 2$fm$. The decay widths are found to be $1.025(5)$KeV for the coarser lattice and $1.062(5)$KeV for the finer lattice respectively where the errors are purely statistical. A naive extrapolation towards the continuum limit yields $Γ\simeq 1.122(14)$KeV which is smaller than the previous quenched result and most of the current experimental results. Possible reasons are discussed.
description: 13 pages, 7 figures; matches the published version
Fourientation activities and the Tutte polynomial
Creators: name: Backman, Spencer
name: Hopkins, Sam
name: Traldi, Lorenzo
Publisher: name: arXiv
Year: 2015
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05C31, 05A19

description: A fourientation of a graph $G$ is a choice for each edge of the graph whether to orient that edge in either direction, leave it unoriented, or biorient it. We may naturally view fourientations as a mixture of subgraphs and graph orientations where unoriented and bioriented edges play the role of absent and present subgraph edges, respectively. Building on work of Backman and Hopkins (2015), we show that given a linear order and a reference orientation of the edge set, one can define activities for fourientations of $G$ which allow for a new 12 variable expansion of the Tutte polynomial $T_G$. Our formula specializes to both the Las Vergnas (1984) orientation activites expansion of the Tutte polynomial and the generalized activities expansion of Gordon and Traldi (1990).
description: 46 pages, 3 figures
A Conservative Scheme for Vlasov Poisson Landau modeling collisional plasmas
Creators: name: Zhang, Chenglong
name: Gamba, Irene M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: We have developed a deterministic conservative solver for the inhomogeneous Fokker-Planck-Landau equation coupled with the Poisson equation, which is a {classical mean-field} primary model for collisional plasmas. Two subproblems, i.e. the Vlasov-Poisson problem and homogeneous Landau problem, are obtained through time-splitting methods, and treated separately by the Runge-Kutta Discontinuous Galerkin method and a conservative spectral method, respectively. To ensure conservation when projecting between the two different computing grids, a special conservation routine is designed to link the solutions of these two subproblems. This conservation routine accurately enforces conservation of moments in Fourier space. The entire numerical scheme is implemented with parallelization with hybrid MPI and OpenMP. Numerical experiments are provided to study linear and nonlinear Landau Damping problems and two-stream flow problem as well.
description: To appear in Jour. Comp. Physics
Generalized Delta Functions and Their Use in Quantum Optics
Creators: name: Brewster, R. A.
name: Franson, J. D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The Dirac delta function is widely used in many areas of physics and mathematics. Here we consider the generalization of a Dirac delta function to allow the use of complex arguments. We show that the properties of a generalized delta function are very different from those of a Dirac delta function and that they behave more like a pole in the complex plane. We use the generalized delta function to derive the Glauber-Sudarshan P-function for a Schrödinger cat state in a surprisingly simple form. Aside from their potential applications in classical electromagnetism and quantum optics, these results provide insight into the ability of the diagonal P-function to describe density operators with off-diagonal elements.
description: 11 pages, 5 figures
Black holes and gravitational waves in models of minicharged dark matter
Creators: name: Cardoso, Vitor
name: Macedo, Caio F. B.
name: Pani, Paolo
name: Ferrari, Valeria
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In viable models of minicharged dark matter, astrophysical black holes might be charged under a hidden $U(1)$ symmetry and are formally described by the same Kerr-Newman solution of Einstein-Maxwell theory. These objects are unique probes of minicharged dark matter and dark photons. We show that the recent gravitational-wave detection of a binary black-hole coalescence by aLIGO provides various observational bounds on the black hole's charge, regardless of its nature. The pre-merger inspiral phase can be used to constrain the dipolar emission of (ordinary and dark) photons, whereas the detection of the quasinormal modes set an upper limit on the final black hole's charge. By using a toy model of a point charge plunging into a Reissner-Nordstrom black hole, we also show that in dynamical processes the (hidden) electromagnetic quasinormal modes of the final object are excited to considerable amplitude in the gravitational-wave spectrum only when the black hole is nearly extremal. The coalescence produces a burst of low-frequency dark photons which might provide a possible electromagnetic counterpart to black-hole mergers in these scenarios.
description: 19+14 pages, 9 figures, 3 appendices. Supplemental Mathematica notebook available at http://centra.tecnico.ulisboa.pt/network/grit/files/. v4: Corrects some typos and errors in the published version. Results for the inspiral phase are not affected at qualitative level, the other results are unchanged
Dual nature of magnetic dopants and competing trends in topological insulators
Creators: name: Sessi, Paolo
name: Biswas, Rudro
name: Bathon, Thomas
name: Storz, Oliver
name: Wilfert, Stefan
name: Barla, Alessandro
name: Kokh, Konstantin
name: Tereshchenko, Oleg
name: Fauth, Kai
name: Bode, Matthias
name: Balatsky, Alexander
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Topological insulators interacting with magnetic impurities have been reported to host several unconventional effects. These phenomena are described within the framework of gapping Dirac quasiparticles due to broken time-reversal symmetry. However, the overwhelming majority of studies demonstrate the presence of a finite density of states near the Dirac point even once Topological insulators become magnetic. Here, we map the response of topological states to magnetic impurities at the atomic scale. We demonstrate that magnetic order and gapless states can coexist. We show how this is the result of the delicate balance between two opposite trends, i.e. gap opening and emergence of a Dirac node impurity band, both induced by the magnetic dopants. Our results evidence a more intricate and rich scenario with respect to the once generally assumed, showing how different electronic and magnetic states may be generated and controlled in this fascinating class of materials.
Fock-Goncharov coordinates for rank two Lie groups
Creators: name: Zickert, Christian K.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 32G15, 57M27 (Primary), 13F60, 57M50 (Secondary)

description: Let G be a simply connected, simple, complex Lie group of rank 2. We give explicit Fock-Goncharov coordinates for configurations of triples and quadruples of affine flags in G. We show that the action on triples by orientation preserving permutations corresponds to explicit quiver mutations, and that the same holds for the flip (changing the diagonal in a quadrilateral). This gives explicit coordinates on higher Teichmuller space, and also coordinates for boundary-unipotent representations of 3-manifold groups. As an application, we compute the (generic) boundary-unipotent representations in Sp(4,C) for the figure-eight knot complement.
description: 31 pages, 24 figures; Version 2 fixed several typos
Lorentz violations in multifractal spacetimes
Creators: name: Calcagni, Gianluca
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Using the recent observation of gravitational waves (GW) produced by a black-hole merger, we place a lower bound on the energy above which a multifractal spacetime would display an anomalous geometry and, in particular, violations of Lorentz invariance. In the so-called multifractional theory with $q$-derivatives, we show that the deformation of dispersion relations is much stronger than in generic quantum-gravity approaches (including loop quantum gravity) and, contrary to the latter, present observations on GWs can place very strong bounds on the characteristic scales at which spacetime deviates from standard Minkowski. The energy at which multifractal effects should become apparent is $E_*>10^{14}\,{\rm GeV}$ (thus improving previous bounds by 12 orders of magnitude) when the exponents in the measure are fixed to their central value $1/2$. We also estimate, for the first time, the effect of logarithmic oscillations in the measure (corresponding to a discrete spacetime structure) and find that they do not change much the bounds obtained in their absence, unless the amplitude of the oscillations is fine tuned. This feature, unavailable in known quantum-gravity scenarios, may help the theory to avoid being ruled out by gamma-ray burst (GRB) observations, for which $E_*> 10^{17}\,{\rm GeV}$ or greater.
description: 12 pages, 1 figure. v2: discussion expanded at several points, comparison with the Lorentz-violating Standard-Model extension added, references added
Anomalous Hall effect in Weyl semimetal half Heusler compounds RPtBi (R = Gd and Nd)
Creators: name: Shekhar, Chandra
name: Kumar, Nitesh
name: Grinenko, V.
name: Singh, Sanjay
name: Sarkar, R.
name: Luetkens, H.
name: Wu, Shu-Chun
name: Zhang, Yang
name: Komarek, Alexander C.
name: Kampert, Erik
name: Skourski, Yurii
name: Wosnitza, Jochen
name: Schnelle, Walter
name: McCollam, Alix
name: Zeitler, Uli
name: Kübler, Jürgen
name: Yan, Binghai
name: Klauss, H. -H.
name: Parkin, S. S. P.
name: Felser, C.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Topological materials ranging from topological insulators to Weyl and Dirac semimetals form one of the most exciting current fields in condensed-matter research. Many half-Heusler compounds, RPtBi (R= rare earth) have been theoretically predicted to be topological semimetals. Among various topological attributes envisaged in RPtBi, topological surface states, chiral anomaly and planar Hall effect have been observed experimentally. Here, we report on an unusual intrinsic anomalous Hall effect (AHE) in the antiferromagnetic Heusler Weyl semimetal compounds GdPtBi and NdPtBi that is observed over a wide temperature range. In particular, GdPtBi exhibits an anomalous Hall conductivity of up to 60 ohm-1cm-1 and an anomalous Hall angle as large as 23%. Muon spin resonance (mu-SR) studies of GdPtBi indicate a sharp antiferromagnetic transition (T_N) at 9 K without any noticeable magnetic correlations above T_N. Our studies indicate that Weyl points in these half-Heuslers are induced by a magnetic field via exchange-splitting of the electronic bands at or near to the Fermi energy which is the source of the chiral anomaly and the AHE.
description: 24 pages including supplementary information
A shared XR system with full body avatars and AI agent integration for enhanced inclusivity
Creators: name: Spanlang, Bernhard
Publisher: name: Zenodo
Year: 2023

description: Slides of the webinar "A shared XR system with full body avatars and AI agent integration for enhanced inclusivity", held in May 17th, 2023, and part of the GuestXR webinar series "Fostering inclusion and social interaction in XR".
SCIENCE AND ENGINEERING STUDENTS’ DYNAMIC TRANSFER OF THE FIRST LAW OF THERMODYNAMICS AND RELATED CONCEPTS
Creators: name: Parobek, Alexander P
Publisher: name: Purdue University Graduate School
Year: 2023
Subjects: Science, technology and engineering curriculum and pedagogy
Higher education
Learning sciences

description: Cultivating cross-disciplinary understanding across science and engineering instruction will be essential to preparing the next generation of scientists to prosper in an increasingly interdisciplinary STEM workforce. This study reports on the culmination of a project that has been aimed at addressing this challenge by investigating how science and engineering students use the first law of thermodynamics, a guiding principle of the crosscutting concept of energy and matter, to transfer across disciplinary boundaries. A qualitative interview study was undertaken in which chemistry-, engineering-, and physics-major students were recruited and tasked with addressing familiar and unfamiliar first law problems that incorporated the systems, language, and notation of each respective discipline. Guided by the dynamic transfer framework, data were analyzed via a general inductive approach to categorize the contextual resources, or target tools, students leveraged to address the provided problems. This analysis revealed three unique guiding epistemologies whose frequency and character of emergence signify field-specific approaches to transferring into an unfamiliar disciplinary context. Connections are drawn to highlight the capacity of the derived findings and developed methodology to support cross-disciplinary understanding in the classroom and in future transfer of learning research.