cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Effective field theories for two-component repulsive bosons on lattice and their phase diagrams
Creators: name: Kuno, Y.
name: Kataoka, K.
name: Ichinose, I.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: In this paper, we consider the bosonic t-J model, which describes two-component hard-core bosons with a nearest-neighbor (NN) pseudo-spin interaction and a NN hopping. To study phase diagram of this model, we derive effective field theories for low-energy excitations. In order to represent the hard-core nature of bosons, we employ a slave-particle representation. In the path-integral quantization, we first integrate our the radial degrees of freedom of each boson field and obtain the low-energy effective field theory of phase degrees of freedom of each boson field and an easy-plane pseudo-spin. Coherent condensates of the phases describe, e.g., a "magnetic order" of the pseudo-spin, superfluidity of hard-core bosons, etc. This effective field theory is a kind of extended quantum XY model, and its phase diagram can be investigated precisely by means of the Monte-Carlo simulations. We then apply a kind of Hubbard-Stratonovich transformation to the quantum XY model and obtain the second-version of the effective field theory, which is composed of fields describing the pseudo-spin degrees of freedom and boson fields of the original two-component hard-core bosons. As application of the effective-field theory approach, we consider the bosonic t-J model on the square lattice and also on the triangular lattice, and compare the obtained phase diagrams with the results of the numerical studies. We also study low-energy excitations rather in detail in the effective field theory. Finally we consider the bosonic t-J model on a stacked triangular lattice and obtain its phase diagram. We compare the obtained phase diagram with that of the effective field theory to find close resemblance.
description: 13 pages, 11 figures, Version to be published in Phys. Rev. B
Sharing research data and software - FAIR & FAIR4RS - Presentation 30/06/2022 Summer School Collaborative Scientific Software Development
Creators: name: Ostrop, Jenny
Publisher: name: Zenodo
Year: 2022
Subjects: FAIR
FAIR4RS
FAIR Data
Open Data
Research Software
Citable Code
Open Science

description: Presentation slides "Sharing research data and software - FAIR & FAIR4RS" for summer school Collaborative scientific software development hosted by University of Bergen Library Digital Lab. Open Science – a paradigm shift Sharing data: Open & FAIR research data Sharing software/code: FAIR for research software How to make your code citable
description: Contact: research-data@uib.no
O'ZBEKISTON QISHOQ XO'JALIGI SOHASINI MODERNIZATSIYA QILISH VA JADAL RIVOJLANTIRISH BO'YICHA OLIB BORILGAN ISLOHOTLAR
Creators: name: Axmedova, U.
Publisher: name: Zenodo
Year: 2024

description: Maqolada  qishloq xo’jaligi sohasi yurtimiz iqtisodiyotini  rivojlantirishda asosiy soha ekanligi va  hukumatimiz tomonidan qabul qilingan qonunlar,  qarorlar aholini oziq-ovqat mahsulotlariga bo’lgan ehtiyojini qondirishda muhim rol o’ynayotgani aytilgan.
A model for cross-cultural reciprocal interactions through mass media
Creators: name: González-Avella, J. C.
name: Cosenza, M. G.
name: Miguel, M. San
Publisher: name: arXiv
Year: 2012
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Social and Information Networks (cs.SI)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: We investigate the problem of cross-cultural interactions through mass media in a model where two populations of social agents, each with its own internal dynamics, get information about each other through reciprocal global interactions. As the agent dynamics, we employ Axelrod's model for social influence. The global interaction fields correspond to the statistical mode of the states of the agents and represent mass media messages on the cultural trend originating in each population. Several phases are found in the collective behavior of either population depending on parameter values: two homogeneous phases, one having the state of the global field acting on that population, and the other consisting of a state different from that reached by the applied global field; and a disordered phase. In addition, the system displays nontrivial effects: (i) the emergence of a largest minority group of appreciable size sharing a state different from that of the applied global field; (ii) the appearance of localized ordered states for some values of parameters when the entire system is observed, consisting of one population in a homogeneous state and the other in a disordered state. This last situation can be considered as a social analogue to a chimera state arising in globally coupled populations of oscillators.
description: 8 pages and 7 figures
Extended $f(R,L_m)$ gravity with generalized scalar field and kinetic term dependences
Creators: name: Harko, Tiberiu
name: Lobo, Francisco S. N.
name: Minazzoli, Olivier
Publisher: name: arXiv
Year: 2012
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We generalize previous work by considering a novel gravitational model with an action given by an arbitrary function of the Ricci scalar, the matter Lagrangian density, a scalar field and a kinetic term constructed from the gradients of the scalar field, respectively. The gravitational field equations in the metric formalism are obtained, as well as the equations of motion for test particles, which follow from the covariant divergence of the stress-energy tensor. Specific models with a nonminimal coupling between the scalar field and the matter Lagrangian are further explored. We emphasize that these models are extremely useful for describing an interaction between dark energy and dark matter, and for explaining the late-time cosmic acceleration.
description: 5 pages, no figures; the expression for the divergence of the energy-momentum tensor has been corrected; references added; minor modifications, accepted for publication in PRD
Baron Paul de Krüdener, ambassadeur de Russie. Impressions d'Allemagne pendant la révolution de 1848. Notice biographique et notes de F. Ley, 2001
Creators: name: Gretchanaia, Elena
Publisher: name: Francia
Year: 2019

description: Baron Paul de Krüdener, ambassadeur de Russie. Impressions d'Allemagne pendant la révolution de 1848. Notice biographique et notes de F. Ley, 2001 (E. Gretchanaia)
description: Francia, Bd. 30 Nr. 3 (2003)
52. Berlinale 2002 – Rückkehr des Politischen und Frauen verändern die Welt
Creators: name: Marchetta, Maria
Publisher: name: querelles-net
Year: 2002
Subjects: Medien; Film; Geschlecht; Gender

description: querelles-net, Nr. 6 (2002): Musik, Film, Bühne und Kunst
title: The properties and potential signal value of Atlantic puffin bill colouration
Creators: name: Kochvar, Katja Helgeson
Publisher: name: Memorial University of Newfoundland
Year: 2023

description: Conspicuous features in species with mutual ornamentation may be overlooked, especially concerning their potential adaptive function. Recent work has demonstrated that selection may act to produce and maintain features that are present in both sexes, but careful investigation is required to elucidate which selective force(s) are at play. The life history characteristics of the species, as well as the properties of the trait itself, are fundamental to generating informed hypotheses on what the adaptive function may be. In this thesis I explore the function of the colourful bill and rosette of Atlantic puffins (Fratercula arctica), a long-lived seabird with obligate bi-parental care. In Chapter 2, I assess whether bill colour aligns more closely with a signal of identity or quality based on three key properties: lability, condition-dependence, and degree of sexual dichromatism. My analysis had mixed results; bill colour was highly dynamic within individuals throughout the late breeding season, but no aspect of colour was condition-dependent and the sexes were monochromatic based on a model of avian visual perception. Although bill colour does not correspond to a traditional quality signal (i.e., correlation with body condition), it may signal a different aspect of individual quality, which I explore in Chapter 3. Specifically, I ask whether bill colour is related to parental quality, as reflected in offspring hatch date and growth patterns. Several aspects of maternal bill and rosette colouration predicted chick growth but not hatch date. Instead, timing of hatch itself was an important factor in determining patterns of offspring mass and wing growth. While these results provide a more nuanced picture of the colourful bill’s role in Atlantic puffins, there is ample room for further investigation, as discussed in Chapter 4.
Reconstructing the 125 GeV SM Higgs Boson Through $\ell\bar{\ell}γ$
Creators: name: Chen, Long-Bin
name: Qiao, Cong-Feng
name: Zhu, Rui-Lin
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: To ascertain the new boson with mass near 125 {GeV} observed recently by ATLAS and CMS Collaborations to be the Standard Model Higgs, and to determine its intrinsic properties, more measurements on its various decay channels are still necessary. In this work we reanalyze the processes of the Standard Model Higgs radiative decays to lepton pairs. We find that when photon and leptons are hard, that is possessing energies larger than 1 {GeV}, the branching fractions of $H\rightarrow \ell\bar{\ell}γ(\ell=e~or~μ)$ processes are about two-thirds of the $H\rightarrowμ^+μ^-$ process. Since the lepton-pair yields of the radiative processes mainly come from the Z-boson conversion, which will greatly suppress the backgrounds, we believe the signal should be observable in presently accumulated data or in the next run of the LHC experiment, provided the Standard Model Higgs is indeed light.
description: to appear in Phys. Lett. B
อัตลักษณ์ทางชาติพันธุ์และศาสนากับปัญหาความไม่สงบในจังหวัดชายแดนภาคใต้ (Ethno-religious Identities and the Unrest in the Southern Border Provinces)
Creators: name: อนุสรณ์ อุณโณ
Publisher: name: คณะสังคมศาสตร์ มหาวิทยาลัยนเรศวร
Year: 2566
Subjects: อัตลักษณ์ทางชาติพันธุ์
อัตลักษณ์ทางศาสนา
เหตุการณ์ความไม่สงบ
จังหวัดชายแดนใต้
Ethnic Identity
Religious Identity
Unrest
Southern Border Provinces

description: วารสารสังคมศาสตร์ มหาวิทยาลัยนเรศวร, 19, 1, 1-41
A. Mombauer, Helmuth von Moltke and the Origins of the First World War, 2001
Creators: name: Förster, Stig
Publisher: name: Francia
Year: 2019

description: A. Mombauer, Helmuth von Moltke and the Origins of the First World War, 2001 (S. Förster)
description: Francia, Bd. 30 Nr. 3 (2003)
Microbiome research mapping in Horizon 2020: lessons learnt and ways forward for sustainable food systems
Creators: name: Muscat, Abigail
name: Meisner, Annelein
name: Bunthof, Christine
Publisher: name: Zenodo
Year: 2023
Subjects: microbiome
research mapping
factsheet
research and innovation
food systems

description: Microbiomes are a key component of achieving sustainable food systems. To fully unlock their potential, it is essential that microbiomes are studied across different stages of the food supply chain and in all ecosystems that form part of the food system. This brief lays out key findings of a mapping exercise of Horizon2020 projects around the topic of microbiomes (funded between 2014 and 2022) and provides recommendations on future funding and research needs.
S. Paletschek, Die permanente Erfindung einer Tradition. Die Universität Tübingen im Kaiserreich und in der Weimarer Republik, 2001
Creators: name: Lingelbach, Gabriele
Publisher: name: Francia
Year: 2019

description: S. Paletschek, Die permanente Erfindung einer Tradition. Die Universität Tübingen im Kaiserreich und in der Weimarer Republik, 2001 (G. Lingelbach)
description: Francia, Bd. 30 Nr. 3 (2003)
H. Mommsen, Le nation-socialisme et la société allemande. Dix essais d'histoire sociale et politique. Préface par H. Rousso, traduit de l'allemand par F. Laroche, 1997
Creators: name: Baruch, Marc Oliver
Publisher: name: Francia
Year: 2019

description: H. Mommsen, Le nation-socialisme et la société allemande. Dix essais d'histoire sociale et politique. Préface par H. Rousso, traduit de l'allemand par F. Laroche, 1997 (M. O. Baruch)
description: Francia, Bd. 30 Nr. 3 (2003)
World citation and collaboration networks: uncovering the role of geography in science
Creators: name: Pan, Raj Kumar
name: Kaski, Kimmo
name: Fortunato, Santo
Publisher: name: arXiv
Year: 2012
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Digital Libraries (cs.DL)
subject: Social and Information Networks (cs.SI)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Modern information and communication technologies, especially the Internet, have diminished the role of spatial distances and territorial boundaries on the access and transmissibility of information. This has enabled scientists for closer collaboration and internationalization. Nevertheless, geography remains an important factor affecting the dynamics of science. Here we present a systematic analysis of citation and collaboration networks between cities and countries, by assigning papers to the geographic locations of their authors' affiliations. The citation flows as well as the collaboration strengths between cities decrease with the distance between them and follow gravity laws. In addition, the total research impact of a country grows linearly with the amount of national funding for research & development. However, the average impact reveals a peculiar threshold effect: the scientific output of a country may reach an impact larger than the world average only if the country invests more than about 100,000 USD per researcher annually.
description: Published version. 9 pages, 5 figures + Appendix, The world citation and collaboration networks at both city and country level are available at http://becs.aalto.fi/~rajkp/datasets.html
Pervasive Linear Polarization Signals in the Quiet Sun
Creators: name: Rubio, L. R. Bellot
name: Suárez, D. Orozco
Publisher: name: arXiv
Year: 2012
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: This paper investigates the distribution of linear polarization signals in the quiet Sun internetwork using ultra-deep spectropolarimetric data. We reduce the noise of the observations as much as is feasible by adding single-slit measurements of the Zeeman-sensitive Fe I 630 nm lines taken by the Hinode spectropolarimeter. The integrated Stokes spectra are employed to determine the fraction of the field of view covered by linear polarization signals. We find that up to 69% of the quiet solar surface at disk center shows Stokes Q or U profiles with amplitudes larger than 0.032% (4.5 times the noise level of 7 x 10^{-5} reached by the longer integrations). The mere presence of linear polarization in most of the quiet Sun implies that the weak internetwork fields must be highly inclined, but we quantify this by inverting those pixels with Stokes Q or U signals well above the noise. This allows for a precise determination of the field inclination, field strength, and field azimuth because the information carried by all four Stokes spectra is used simultaneously. The inversion is performed for 53% of the observed field of view at a noise level of 1.3 x 10^{-4}. The derived magnetic distributions are thus representative of more than half of the quiet Sun internetwork. Our results confirm the conclusions drawn from previous analyses using mainly Stokes I and V: internetwork fields are very inclined, but except in azimuth they do not seem to be isotropically distributed.
Global $W^{2,p}$ estimates for solutions to the linearized Monge--Ampère equations
Creators: name: Le, Nam Q.
name: Nguyen, Truyen
Publisher: name: arXiv
Year: 2012
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: In this paper, we establish global $W^{2,p}$ estimates for solutions to the linearized Monge-Ampère equations under natural assumptions on the domain, Monge-Ampère measures and boundary data. Our estimates are affine invariant analogues of the global $W^{2,p}$ estimates of Winter for fully nonlinear, uniformly elliptic equations, and also linearized counterparts of Savin's global $W^{2,p}$ estimates for the Monge-Ampère equations.
description: v2: presentation improved
Chaotic properties of Coulomb-interacting circular billiards
Creators: name: Solanpaa, J.
name: Nokelainen, J.
name: Luukko, P. J. J.
name: Rasanen, E.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We apply a molecular dynamics scheme to analyze classically chaotic properties of a two-dimensional circular billiard system containing two Coulomb-interacting electrons. As such, the system resembles a prototype model for a semiconductor quantum dot. The interaction strength is varied from the noninteracting limit with zero potential energy up to the strongly interacting regime where the relative kinetic energy approaches zero. At weak interactions the bouncing maps show jumps between quasi-regular orbits. In the strong-interaction limit we find an analytic expression for the bouncing map. Its validity in the general case is assessed by comparison with our numerical data. To obtain a more quantitative view on the dynamics as the interaction strength is varied, we compute and analyze the escape rates of the system. Apart from very weak or strong interactions, the escape rates show consistently exponential behavior, thus suggesting strongly chaotic dynamics and a phase space without significant sticky regions within the considered time scales.
An operator-theoretical treatment of the Maskawa-Nakajima equation in the massless abelian gluon model
Creators: name: Watanabe, Shuji
Publisher: name: arXiv
Year: 2012
Subjects: subject: Functional Analysis (math.FA)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 45P05, 47H10, 81T13

description: The Maskawa-Nakajima equation has attracted considerable interest in elementary particle physics. From the viewpoint of operator theory, we study the Maskawa-Nakajima equation in the massless abelian gluon model. We first show that there is a nonzero solution to the Maskawa-Nakajima equation when the parameter $λ$ satisfies $λ>2$. Moreover, we show that the solution is infinitely differentiable and strictly decreasing. We thus conclude that the massless abelian gluon model generates the nonzero quark mass spontaneously and exhibits the spontaneous chiral symmetry breaking when $λ>2$. We next show that there is a unique solution $0$ to the Maskawa-Nakajima equation when $0
description: 10 pages
Production of the H dibaryon via the (K^-,K^+) reaction on a $^{12}$C target
Creators: name: Shyam, R.
name: Scholten, O.
name: Thomas, A. W.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: We study the production of the stable six-quark $H$ dibaryon via the $(K^-,K^+)$ reaction on a $^{12}$C target within a covariant effective Lagrangian model. The calculations are performed within a factorization approximation, in which the full production amplitude is written as a product of the amplitudes for the $K^- + p \to K^+ + Ξ^-$ and $Ξ^- + p \to H$ processes. The $K^+Ξ^-$ production vertex is described by excitation, propagation and decay of $Λ$ and $Σ$ resonance states in the initial collision of a $K^-$ meson with a target proton in the incident channel. The parameters of the resonance vertices are taken to be the same as those determined previously by describing the available data on total and differential cross sections for the $p(K^-, K^+)Ξ^-$ reaction within a similar model. The $Ξ^- + p \to H$ fusion process is treated within a quark model where the $H$ dibaryon is considered as a stable particle. For the $K^+$ meson angle fixed at 0$^o$, the $H$ production cross-section is found to be about 2.9 $μb/sr$ for $H$ mass just below the $ΛΛ$ threshold at a $K^-$ beam momentum of 1.67 GeV/c. This is an order of magnitude larger than the value for this quantity reported earlier in calculations performed on a $^3$He target using a different model for the cascade hyperon production. We have also calculated the beam momentum dependence of the $H$ production cross section and the energy spectrum of the emitted $K^+$ meson.
description: 21 pages, 9 figures, version accepted for publication by Physical Review C
BPS Z(2) monopoles and N=2 SU(n) superconformal field theories on the Higgs branch
Creators: name: Kneipp, Marco A. C.
name: Liebgott, Paulo J.
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We obtain BPS Z(2) monopole solutions in Yang-Mills-Higgs theories with the gauge group SU(n) broken to Spin(n)/Z(2) by a scalar field in the nxn representation. We show that the magnetic weights of the so-called fundamental Z(2) monopoles correspond to the weights of the defining representation of the algebra dual to so(n), and the masses of the nonfundamental BPS Z(2) monopoles are equal to the sum of the masses of the constituent fundamental monopoles. We also show that the vacua responsible for the existence of these Z(2) monopoles are present in the Higgs branch of a class of N=2 SU(n) superconformal field theories. We analyze some dualities these monopoles may satisfy.
description: 24 pages. Minor improvements in the text and typo corrections
Monotonicity of the value function for a two-dimensional optimal stopping problem
Creators: name: Assing, Sigurd
name: Jacka, Saul
name: Ocejo, Adriana
Publisher: name: arXiv
Year: 2012
Subjects: subject: Probability (math.PR)
subject: Optimization and Control (math.OC)
subject: FOS: Mathematics

description: We consider a pair $(X,Y)$ of stochastic processes satisfying the equation $dX=a(X)Y\,dB$ driven by a Brownian motion and study the monotonicity and continuity in $y$ of the value function $v(x,y)=\sup_τE_{x,y}[e^{-qτ}g(X_τ)]$, where the supremum is taken over stopping times with respect to the filtration generated by $(X,Y)$. Our results can successfully be applied to pricing American options where $X$ is the discounted price of an asset while $Y$ is given by a stochastic volatility model such as those proposed by Heston or Hull and White. The main method of proof is based on time-change and coupling.
description: Published in at http://dx.doi.org/10.1214/13-AAP956 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org)
The Radiative Efficiency of Hot Accretion Flows
Creators: name: Xie, Fu-Guo
name: Yuan, Feng
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Two significant progresses have been made in the past years on our understanding of hot accretion flows. One is that only a small fraction of accretion flow available at the outer boundary can finally falls onto the black hole while most of them is lost in outflow. Another one is that electrons may directly receive a large fraction of the viscously dissipated energy in the accretion flow, i.e, $δ\sim 0.1-0.5$. The radiative efficiency of hot accretion flow when these two progresses are taken into account has not been systematically studied and is the subject of the present paper. We consider two regimes of hot accretion model. One is the advection dominated accretion flows (ADAFs) which lie on low accretion rate regime, $\la 10α^2\ledd/c^2$; another being the luminous hot accretion flows (LHAFs) which lie above this accretion rate. For the latter, we assume that the accretion flow will has a two-phase structure above a certain accretion rate, and a simplification is adopted in our calculation of the dynamics. Our results indicate that the radiative efficiency of hot accretion flow increases with the accretion rate and is highly enhanced by the direct viscous heating to electrons compared to the previous case of $δ\ll 1$. When the accretion rate is high, the radiative efficiency of hot accretion flow is comparable to that of the standard thin disk. Fitting formulae of radiative efficiency as a function of accretion rate for various $δ$ values are presented.
description: 8 pages with 3 figures. Slightly revised. MNRAS accepted
Health-care providers’ perspectives on an HIV patient navigation training to improve uptake of PrEP among Black sexual minority men
Creators: name: Omondi, Angela A
name: Monger, Mauda
name: Ward, Lori
name: Burns, Paul A
name: Anyimukwu, Chizoba
name: Poteat, Tonia
Publisher: name: Oxford University Press (OUP)
Year: 2023

description:
This article examines implementational factors associated with an HIV patient navigation training intervention for health care professionals working with Black sexual minority men to improve access to and uptake of HIV prevention services among Black MSM. Utilizing qualitative analysis to better understand healthcare professionals' perceptions of the training program, we conducted a thematic content analysis based on constructs from Professional Network and Reach Model-Systems Model Approach (PNRSMA) framework. Data analysis revealed four major themes: 1) Knowledge and skill building, 2) Novel and Innovation, 3) Barriers to Implementation, and 4) Recommendations and Future Directions. Implementation factors such as appropriate facilitators, content, mode of delivery, learning strategies, and understanding structural barriers were important to training success. Participants highlighted innovation strategies such as the use of social media and interactive communication (e.g. role-playing and bi-directional communication) enhanced learning and skill-building. The expansion of training to include other affected groups such as women and bisexual individuals and increasing the duration of the training emerged as areas for improvement and effectiveness. Our analysis of an HIV patient navigation training revealed important findings to improve the implementation process to increase uptake of PrEP and other HIV prevention, care and treatment services.
Preimages for the Shimura map on Hilbert modular forms
Creators: name: Sirolli, Nicolás
Publisher: name: arXiv
Year: 2012
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 11F37

description: In this article we give a method to construct preimages for the Shimura correspondence on Hilbert modular forms of odd and square-free level. The method relies in the ideas presented for the rational case by Pacetti and Tornaría, and is such that the Fourier coefficients of the preimages constructed can be computed explicitly.
description: Minor revision
Two unfortunate properties of pure f-vectors
Creators: name: Pastine, Adrian
name: Zanello, Fabrizio
Publisher: name: arXiv
Year: 2012
Subjects: subject: Combinatorics (math.CO)
subject: Commutative Algebra (math.AC)
subject: FOS: Mathematics
subject: Primary: 05E40, Secondary: 13F55, 05E45, 05B07, 13H10

description: The set of f-vectors of pure simplicial complexes is an important but little understood object in combinatorics and combinatorial commutative algebra. Unfortunately, its explicit characterization appears to be a virtually intractable problem, and its structure very irregular and complicated. The purpose of this note, where we combine a few different algebraic and combinatorial techniques, is to lend some further evidence to this fact. We first show that pure (in fact, Cohen-Macaulay) f-vectors can be nonunimodal with arbitrarily many peaks, thus improving the corresponding results known for level Hilbert functions and pure O-sequences. We provide both an algebraic and a combinatorial argument for this result. Then, answering negatively a question of the second author and collaborators posed in the recent AMS Memoir on pure O-sequences, we show that the Interval Property fails for the set of pure f-vectors, even in dimension 2.
description: A few minor changes. To appear in the Proc. of the AMS
CMB power spectra induced by primordial cross-bispectra between metric perturbations and vector fields
Creators: name: Shiraishi, Maresuke
name: Saga, Shohei
name: Yokoyama, Shuichiro
Publisher: name: arXiv
Year: 2012
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study temperature and polarization anisotropies of the cosmic microwave background (CMB) radiation sourced from primordial cross-bispectra between metric perturbations and vector fields, which are generated from the inflation model where an inflaton and a vector field are coupled. In case the vector field survives after the reheating, both the primordial scalar and tensor fluctuations can be enhanced by the anisotropic stress composed of the vector fields during radiation dominated era. We show that through this enhancement the primordial cross-bispectra generate not only CMB bispectra but also CMB power spectra. In general, we can expect such cross-bispectra produce the non-trivial mode-coupling signals between the scalar and tensor fluctuations. However, we explicitly show that such mode-coupling signals do not appear in CMB power spectra. Through the numerical analysis of the CMB scalar-mode power spectra, we find that although signals from these cross-bispectra are smaller than primary non-electromagnetic ones, these have some characteristic features such as negative auto-correlations of the temperature and polarization modes, respectively. On the other hand, signals from tensor modes are almost comparable to primary non-electromagnetic ones and hence the shape of observed $B$-mode spectrum may deviate from the prediction in the non-electromagnetic case. The above imprints may help us to judge the existence of the coupling between the scalar and vector fields in the early Universe.
description: 32 pages, 1 figure. Accepted for publication in JCAP
One-loop divergences in the Galileon model
Creators: name: Netto, Tiberio de Paula
name: Shapiro, Ilya L.
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences
subject: 81T15, 81T18, 83D05

description: The investigation of UV divergences is a relevant step in better understanding of a new theory. In this work the one-loop divergences in the free field sector are obtained for the popular Galileons model. The calculations are performed by the generalized Schwinger-DeWitt technique and also by means of Feynman diagrams. The first method can be directly generalized to curved space, but here we deal only with the flat-space limit. We show that the UV completion of the theory includes the $π\Box^4π$ term. According to our previous analysis in the case of quantum gravity, this means that the theory can be modified to become superrenormalizable, but then its physical spectrum includes two massive ghosts and one massive scalar with positive kinetic energy. The effective approach in this theory can be perfectly successful, exactly as in the higher derivative quantum gravity, and in this case the non-renormalization theorem for Galileons remains valid in the low-energy region.
description: One more section after Conclusions, including one extra reference, all concerning generalized second-derivative metric-scalar model. Version accepted in Physics Letters B. LaTeX, 19 pages, 5 figures
Coherent Cooper-pair pumping by magnetic flux control
Creators: name: Gasparinetti, S.
name: Kamleitner, I.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We introduce and discuss a scheme for Cooper-pair pumping. The scheme relies on the coherent transfer of a superposition of charge states across a superconducting island and is realized by adiabatic manipulation of magnetic fluxes. Differently from previous implementations, it does not require any modulation of electrostatic potentials. We find a peculiar dependence of the pumped charge on the superconducting phase bias across the pump and that an arbitrarily large amount of charge can be pumped in a single cycle when the phase bias is π. We explain these features and their relation to the adiabatic theorem.
description: 9 pages, 6 figures
Fitness Landscape-Based Characterisation of Nature-Inspired Algorithms
Creators: name: Crossley, Matthew
name: Nisbet, Andy
name: Amos, Martyn
Publisher: name: arXiv
Year: 2012
Subjects: subject: Neural and Evolutionary Computing (cs.NE)
subject: FOS: Computer and information sciences

description: A significant challenge in nature-inspired algorithmics is the identification of specific characteristics of problems that make them harder (or easier) to solve using specific methods. The hope is that, by identifying these characteristics, we may more easily predict which algorithms are best-suited to problems sharing certain features. Here, we approach this problem using fitness landscape analysis. Techniques already exist for measuring the "difficulty" of specific landscapes, but these are often designed solely with evolutionary algorithms in mind, and are generally specific to discrete optimisation. In this paper we develop an approach for comparing a wide range of continuous optimisation algorithms. Using a fitness landscape generation technique, we compare six different nature-inspired algorithms and identify which methods perform best on landscapes exhibiting specific features.
description: 10 pages, 1 figure, submitted to the 11th International Conference on Adaptive and Natural Computing Algorithms
Large-scale N-body simulations of the viscous overstability in Saturn's rings
Creators: name: Rein, Hanno
name: Latter, Henrik
Publisher: name: arXiv
Year: 2012
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We present results from large-scale particle simulations of the viscous overstability in Saturn's rings. The overstability generates a variety of structure on scales covering a few hundred metres to several kilometres, including axisymmetric wavetrains and larger-scale modulations. Such patterns have been observed in Saturn's rings by the Cassini spacecraft. Our simulations model the collisional evolution of particles in a co-rotating patch of the disk. These are the largest N-body simulations of the viscous overstability yet performed. The radial box size is five orders of magnitude larger than a typical particle radius, and so describes a 20-50 km radial portion of the rings. Its evolution is tracked for more than 10,000 orbits. In agreement with hydrodynamics, our N-body simulations reveal that the viscous overstability exhibits a rich set of dynamics characterised by nonlinear travelling waves with wavelengths of a few hundred meters. In addition, wave defects, such as sources and shocks, punctuate this bed of waves and break them up into large-scale divisions of radial width ~5 km. We find that the wavelength of the travelling waves is positively correlated with the mean optical depth. In order to assess the role of the numerical boundary conditions and also background ring structure, we include simulations of broad spreading rings and simulations with a gradient in the background surface density. Overall, our numerical results and approach provide a tool with which to interpret Cassini occultation observations of microstructure in Saturn's rings. We present an example of such a synthetic occultation observation and discuss what features to expect. We also make the entire source code freely available.
description: 15 pages, 12 figures, accepted for publication by MNRAS
The Sphaleron Rate through the Electroweak Cross-over
Creators: name: D'Onofrio, Michela
name: Rummukainen, Kari
name: Tranberg, Anders
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: Using lattice simulations, we measure the sphaleron rate in the Standard Model as a function of temperature through the electroweak cross-over, for the Higgs masses m_H=115 and m_H=160 GeV. We pay special attention to the shutting off of the baryon rate as the temperature is lowered. This quantity enters computations of Baryogenesis via Leptogenesis, where non-zero lepton number is converted into non-zero baryon number by equilibrium sphaleron transitions. Combining existing numerical methods applicable in the symmetric and broken electroweak phases, we find the temperature dependence of the sphaleron rate at very high temperature, through the electroweak cross-over transition, and deep into the broken phase.
description: 25 pages, 11 figures
Low-scale SUSY breaking and the (s)goldstino physics
Creators: name: Antoniadis, I.
name: Ghilencea, D. M.
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: For a 4D N=1 supersymmetric model with a low SUSY breaking scale (f) and general Kahler potential K(Phi^i,Phi_j^*) and superpotential W(Phi^i) we study, in an effective theory approach, the relation of the goldstino superfield to the (Ferrara-Zumino) superconformal symmetry breaking chiral superfield X. In the presence of more sources of supersymmetry breaking, we verify the conjecture that the goldstino superfield is the (infrared) limit of X for zero-momentum and Lambda->\infty. (Lambda is the effective cut-off scale). We then study the constraint X^2=0, which in the one-field case is known to decouple a massive sgoldstino and thus provide an effective superfield description of the Akulov-Volkov action for the goldstino. In the presence of additional fields that contribute to SUSY breaking we identify conditions for which X^2=0 remains valid, in the effective theory below a large but finite sgoldstino mass. The conditions ensure that the effective expansion (in 1/Lambda) of the initial Lagrangian is not in conflict with the decoupling limit of the sgoldstino (1/m_sgoldstino\sim Lambda/f, f
description: 16 pages; (small comment added in Conclusions)
Full density matrix numerical renormalization group calculation of impurity susceptibility and specific heat of the Anderson impurity model
Creators: name: Merker, L.
name: Weichselbaum, A.
name: Costi, T. A.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Recent developments in the numerical renormalization group (NRG) allow the construction of the full density matrix (FDM) of quantum impurity models (see A. Weichselbaum and J. von Delft) by using the completeness of the eliminated states introduced by F. B. Anders and A. Schiller (2005). While these developments prove particularly useful in the calculation of transient response and finite temperature Green's functions of quantum impurity models, they may also be used to calculate thermodynamic properties. In this paper, we assess the FDM approach to thermodynamic properties by applying it to the Anderson impurity model. We compare the results for the susceptibility and specific heat to both the conventional approach within NRG and to exact Bethe ansatz results. We also point out a subtlety in the calculation of the susceptibility (in a uniform field) within the FDM approach. Finally, we show numerically that for the Anderson model, the susceptibilities in response to a local and a uniform magnetic field coincide in the wide-band limit, in accordance with the Clogston-Anderson compensation theorem.
description: 9 pages, 8 figures, published version
3d superconformal indices and isomorphisms of M2-brane theories
Creators: name: Honda, Masazumi
name: Honma, Yoshinori
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We test several expected isomorphisms between the U(N)xU(N) ABJM theory and (SU(N)xSU(N))/Z_N theory including the BLG theory by comparing their superconformal indices. From moduli space analysis, it is expected that this equivalence can hold if and only if the rank N and Chern-Simons level k are coprime. We also calculate the index of the ABJ theory and investigate whether some theories with identical moduli spaces are isomorphic or not.
description: 28 pages, no figure; v2: references added; v3: few typos corrected
The Metal Aversion of LGRBs
Creators: name: Graham, J. F.
name: Fruchter, A. S.
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Recently, it has been suggested that the metallicity aversion of long-duration gamma-ray bursts (LGRBs) is not intrinsic to their formation, but rather a consequence of the anti-correlation between star-formation and metallicity seen in the general galaxy population. To investigate this proposal, we compare the metallicity of the hosts of LGRBs, broad-lined Type Ic (Ic-bl) supernovae (SNe), and Type II SNe to each other and to the metallicity distribution of star-forming galaxies using the SDSS to represent galaxies in the local universe and the TKRS for galaxies at intermediate redshifts. The differing metallicity distributions of the LGRB hosts and the star formation in local galaxies forces us to conclude that the low-metallicity preference of LGRBs is not primarily driven by the anti-correlation between star-formation and metallicity, but rather must be overwhelmingly due to the astrophysics of the LGRBs themselves. Three quarters of our LGRB sample are found at metallicities below 12+log(O/H) < 8.6, while less than a tenth of local star-formation is at similarly low metallicities. However, our SN samples are statistically consistent with the metallicity distribution of the general galaxy population. Using the TKRS population of galaxies, we are able to exclude the possibility that the LGRB host metallicity aversion is caused by the decrease in galaxy metallicity with redshift. The presence of the strong metallicity difference between LGRBs and Ic-bl SNe largely eliminates the possibility that the observed LGRB metallicity bias is a byproduct of a difference in the initial mass functions of the galaxy populations. Rather, metallicity below half-solar must be a fundamental component of the evolutionary process that separates LGRBs from the vast majority of Ic-bl SNe and from the bulk of local star-formation.
description: 27 pages, 11 figures. ApJ in press
Exploiting spatial sparsity for multi-wavelength imaging in optical interferometry
Creators: name: Thiébaut, Éric
name: Soulez, Ferréol
name: Denis, Loïc
Publisher: name: arXiv
Year: 2012
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Optimization and Control (math.OC)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: Optical interferometers provide multiple wavelength measurements. In order to fully exploit the spectral and spatial resolution of these instruments, new algorithms for image reconstruction have to be developed. Early attempts to deal with multi-chromatic interferometric data have consisted in recovering a gray image of the object or independent monochromatic images in some spectral bandwidths. The main challenge is now to recover the full 3-D (spatio-spectral) brightness distribution of the astronomical target given all the available data. We describe a new approach to implement multi-wavelength image reconstruction in the case where the observed scene is a collection of point-like sources. We show the gain in image quality (both spatially and spectrally) achieved by globally taking into account all the data instead of dealing with independent spectral slices. This is achieved thanks to a regularization which favors spatial sparsity and spectral grouping of the sources. Since the objective function is not differentiable, we had to develop a specialized optimization algorithm which also accounts for non-negativity of the brightness distribution.
description: This version has been accepted for publication in J. Opt. Soc. Am. A
Making cities through migration industries: Introduction to the special issue
Creators: name: Cohen, Nir
name: Fogelman, Tatiana
name: Lebuhn, Henrik
Publisher: name: Humboldt-Universität zu Berlin
Year: 2022
Subjects: subject: editorial
subject: migration industry
subject: transnationalism
subject: theory
subject: urban
subject: 550 Geowissenschaften

description: This publication is with permission of the rights owner (Sage) freely accessible.
description: Migration industry has recently emerged as a lens through which to theorise the intertwinement of non-state actors who aim to provide diverse migration-pertaining services. However, while much of their work is done in and through cities, consequently (re)forming variegated urban landscapes, scholarly literature has thus far neglected the nexus between cities and the migration industry. In this special issue, we begin filling this gap by exploring the significance of migration industries – as a resurgent concept and an area of research from migration studies – for understanding the urban. We start by reviewing the urbanisation of migration studies, highlighting its key limits. We then move on to introduce the migration industries debate, pointing out its existing implicit urban dimensions. We proceed by elaborating our main argument about why and how migration industries provide an especially productive lens for urbanists to consider. Specifically, we stress the three key analytical vantage points that the attention to migration industries enables us to see as central to contemporary city-making. These are its political-economic embeddedness, the urban-constitutive nature of trans-local connectivities, and how business-driven city-making dovetails with more serendipitous, bottom-up shaping of the arrival city. Each of these points also describes how individual papers speak to them. We conclude by briefly outlining a research agenda for migration industries that is thoughtfully embroiled in the (post-)pandemic urban.