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arXiv 2019年

作者： Nielsen, Eric L. de Rosa, Robert J. Macintosh, Bruce Wang, Jason J. Ruffio, Jean-Baptiste Chiang, Eugene Marley, Mark S. Saumon, Didier Savransky, Dmitry Mark Ammons, S. Bailey, Vanessa P. Barman, Travis Blain, Célia Bulger, Joanna Chilcote, Jeffrey Cotten, Tara Czekala, Ian Doyon, Rene Duchêne, Gaspard Esposito, Thomas M. Fabrycky, Daniel Fitzgerald, Michael P. Follette, Katherine B. Fortney, Jonathan J. Gerard, Benjamin L. Goodsell, Stephen J. Graham, James R. Greenbaum, Alexandra Z. Hibon, Pascale Hinkley, Sasha Hirsch, Lea A. Hom, Justin Hung, Li-Wei Dawson, Rebekah Ilene Ingraham, Patrick Kalas, Paul Konopacky, Quinn Larkin, James E. Lee, Eve J. Lin, Jonathan W. Maire, Jérôme Marchis, Franck Marois, Christian Metchev, Stanimir Millar-Blanchaer, Maxwell A. Morzinski, Katie M. Oppenheimer, Rebecca Palmer, David Patience, Jennifer Perrin, Marshall Poyneer, Lisa Pueyo, Laurent Rafikov, Roman R. Rajan, Abhijith Rameau, Julien Rantakyrö, Fredrik T. Ren, Bin Schneider, Adam C. Sivaramakrishnan, Anand Song, Inseok Soummer, Remi Tallis, Melisa Thomas, Sandrine Ward-Duong, Kimberly Wolff, Schuyler Kavli Institute for Particle Astrophysics and Cosmology Stanford University StanfordCA94305 United States Department of Astronomy California Institute of Technology PasadenaCA91125 United States Department of Astronomy University of California BerkeleyCA94720 United States NASA Ames Research Center Mountain ViewCA94035 United States Los Alamos National Laboratory P.O. Box 1663 Los AlamosNM87545 United States Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States Lawrence Livermore National Laboratory LivermoreCA94551 United States Jet Propulsion Laboratory California Institute of Technology PasadenaCA91109 United States Lunar and Planetary Laboratory University of Arizona TucsonAZ85721 United States National Research Council of Canada Herzberg 5071 West Saanich Rd VictoriaBCV9E 2E7 Canada Subaru Telescope NAOJ 650 North A’ohoku Place HiloHI96720 United States Department of Physics University of Notre Dame 225 Nieuwland Science Hall Notre DameIN46556 United States Department of Physics and Astronomy University of Georgia AthensGA30602 United States Institut de Recherche sur les Exoplanètes Département de Physique Université de Montréal MontréalQCH3C 3J7 Canada Univ. Grenoble Alpes/CNRS IPAG GrenobleF-38000 France Department of Astronomy & Astrophysics University of Chicago 5640 S. Ellis Ave. ChicagoIL60615 United States Department of Physics & Astronomy University of California Los AngelesCA90095 United States Physics and Astronomy Department Amherst College 21 Merrill Science Drive AmherstMA01002 United States Department of Astronomy UC Santa Cruz 1156 High St. Santa CruzCA95064 United States University of Victoria 3800 Finnerty Rd VictoriaBCV8P 5C2 Canada Gemini Observatory 670 N. A’ohoku Place HiloHI96720 United States Department of Astronomy University of Michigan Ann ArborMI48109 United States European Southern Observatory Alonso de Cordova 3107 Vitac

We present a statistical analysis of the first 300 stars observed by the Gemini Planet Imager Exoplanet Survey (GPIES). This subsample includes six detected planets and three brown dwarfs;from these detections and our contrast curves we infer the underlying distributions of substellar companions with respect to their mass, semi-major axis, and host stellar mass. We uncover a strong correlation between planet occurrence rate and host star mass, with stars M∗ > 1.5M☉ more likely to host planets with masses between 2–13MJup and semi-major axes of 3–100au at 99.92% confidence. We fit a double power-law model in planet mass (m) and semi-major axis (a) for planet populations around high-mass stars (M∗ > 1.5M☉) of the form d2N/(dm da)∝mα aβ, finding α = −2.4 ± 0.8 and β = −2.0 ± 0.5, and an integrated occurrence rate of 9+5−4% between 5–13MJup and 10–100au. A significantly lower occurrence rate is obtained for brown dwarfs around all stars, with 0.8+0−0..85% of stars hosting a brown dwarf companion between 13–80MJup and 10–100au. Brown dwarfs also appear to be distributed differently in mass and semi-major axis compared to giant planets;whereas giant planets follow a bottom-heavy mass distribution and favor smaller semi-major axes, brown dwarfs exhibit just the opposite behaviors. Comparing to studies of short-period giant planets from the RV method, our results are consistent with a peak in occurrence of giant planets between ∼1–10au. We discuss how these trends, including the preference of giant planets for high-mass host stars, point to formation of giant planets by core/pebble accretion, and formation of brown dwarfs by gravitational instability. Copyright © 2019, The Authors. All rights reserved.

关键词： Extrasolar planets

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Proton temperature anisotropy variations in inner heliosphere estimated with first Parker Solar Probe observations

arXiv

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arXiv 2019年

作者： Huang, Jia Kasper, J.C. Vech, D. Klein, K.G. Stevens, M. Martinović, Mihailo M. Alterman, B.L. Ďurovcová, Tereza Paulson, Kristoff Maruca, Bennett A. Qudsi, Ramiz A. Case, A.W. Korreck, K.E. Jian, Lan K. Velli, Marco Lavraud, B. Hegedus, A. Bert, C.M. Holmes, J. Bale, Stuart D. Larson, Davin E. Livi, Roberto Whittlesey, P. Pulupa, Marc MacDowall, Robert J. Malaspina, David M. Bonnell, John W. Harvey, Peter Goetz, Keith de Wit, Thierry Dudok Climate and Space Sciences and Engineering University of Michigan Ann ArborMI48109 United States Smithsonian Astrophysical Observatory CambridgeMA02138 United States Laboratory for Atmospheric and Space Physics University of Colorado BoulderCO United States Lunar and Planetary Laboratory University of Arizona TucsonAZ85719 United States LESIA Observatoire de Paris Universite PSL CNRS Sorbonne Universite Universite de Paris 5 place Jules Janssen Meudon92195 France Department of Applied Physics University of Michigan 450 Church St. Ann ArborMI48109 United States Faculty of Mathematics and Physics Charles University Prague Czech Republic Department of Physics and Astronomy University of Delaware NewarkDE19716 United States Bartol Research Institute University of Delaware NewarkDE19716 United States Heliophysics Science Division NASA Goddard Space Flight Center Greenbelt United States Department of Earth Planetary and Space Sciences University of California Los AngelesCA90095 United States Institut de Recherche en Astrophysique et Plantologie CNRS UPS CNES Universit de Toulouse Toulouse France Physics Department University of California BerkeleyCA94720-7300 United States Space Sciences Laboratory University of California BerkeleyCA94720-7450 United States Blackett Laboratory Imperial College London LondonSW7 2AZ United Kingdom School of Physics and Astronomy Queen Mary University of London LondonE1 4NS United Kingdom University of California Berkeley BerkeleyCA United States NASA Goddard SFC GreenbeltMD United States Astrophysical and Planetary Sciences Department University of Colorado BoulderCO United States Laboratory for Atmospheric and Space Physics University of Colorado BoulderCO United States University of Colorado Boulder BoulderCO United States University of Minnesota MinneapolisMN United States LPC2E CNRS University of Orléans 3A avenue de la Recherche Scientifique Orléans France

We present a technique for deriving the temperature anisotropy of solar wind protons observed by the Parker Solar Probe mission in the near-Sun solar wind. The variation in the temperature of solar wind protons in the radial direction measured by the SWEAP Solar Probe Cup is compared with variation in the orientation of the local magnetic field measured by the FIELDS fluxgate magnetometer, and the components of the proton temperature parallel and perpendicular to the magnetic field are extracted. This procedure is applied to both moments of the proton velocity distribution function (VDF) and to the results of a non-linear fit of proton core and proton beam Maxwellian components of the VDF, and the results are compared and optimum timescales for data selection and trends in the uncertainty in the method are identified. We find that the moment-based proton temperature anisotropy is more physically consistent with the expected limits of the mirror and firehose instabilities, possibly because the fits do not capture a significant non-Maxwellian shape to the proton VDF near the Sun. Several radial trends in the temperature components and the variation of the anisotropy with parallel plasma beta are presented. We find that the proton parallel plasma beta seen by PSP in the first encounter is not significantly smaller than the values seen by Helios further from the Sun, possibly as a result of long term variation in the heliospheric density and magnetic field over the last half-century. The observed radial dependence of temperature variations in the fast solar wind implies stronger perpendicular heating and parallel cooling than previous results from Helios measurements made at larger radial distances, but a similar anti-correlation between proton temperature anisotropy and parallel plasma beta persists closer to the Sun. The temperature anisotropies of the slow solar wind are well constrained by the mirror and parallel firehose instabilities. The perpendicular heating of

关键词： Mirrors

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Reproducible k-means clustering in galaxy feature data from the GAMA survey

arXiv

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arXiv 2018年

作者： Turner, Sebastian Kelvin, Lee S. Baldry, Ivan K. Lisboa, Paulo J. Longmore, Steven N. Collins, Chris A. Holwerda, Benne W. Hopkins, Andrew M. Liske, Jochen Astrophysics Research Institute Liverpool John Moores University 146 Brownlow Hill LiverpoolL3 5RF United Kingdom Department of Applied Mathematics Liverpool John Moores University Byrom Street LiverpoolL3 3AF United Kingdom Department of Physics and Astronomy 102 Natural Science Building University of Louisville LouisvilleKY40292 United States Australian Astronomical Observatory 105 Delhi Rd North RydeNSW2113 Australia Hamburger Sternwarte Universität Hamburg Gojenbergsweg 112 Hamburg21029 Germany

A fundamental bimodality of galaxies in the local Universe is apparent in many of the features used to describe them. Multiple sub-populations exist within this framework, each representing galaxies following distinct evolutionary pathways. Accurately identifying and characterising these sub-populations requires that a large number of galaxy features be analysed simultaneously. Future galaxy surveys such as LSST and Euclid will yield data volumes for which traditional approaches to galaxy classification will become unfeasible. To address this, we apply a robust k-means unsupervised clustering method to feature data derived from a sample of 7338 local-Universe galaxies selected from the Galaxy And Mass Assembly (GAMA) survey. This allows us to partition our sample into k clusters without the need for training on pre-labelled data, facilitating a full census of our high dimensionality feature space and guarding against stochastic effects. We find that the local galaxy population natively splits into 2, 3, 5 and a maximum of 6 sub-populations, with each corresponding to a distinct ongoing evolutionary mechanism. Notably, the impact of the local environment appears strongly linked with the evolution of low-mass (M∗ 10 M) galaxies, with more massive systems appearing to evolve more passively from the blue cloud onto the red sequence. With a typical run time of ∼ 3 minutes per value of k for our galaxy sample, we show how k-means unsupervised clustering is an ideal tool for future analysis of large extragalactic datasets, being scalable, adaptable, and providing crucial insight into the fundamental properties of the local galaxy population. Copyright © 2018, The Authors. All rights reserved.

关键词： Galaxies

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Role of the orbital moment in a series of isostructural weak ferromagnets

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Physical Review B 2018年第10期98卷 104424-104424页

作者： D. Pincini F. Fabrizi G. Beutier G. Nisbet H. Elnaggar V. E. Dmitrienko M. I. Katsnelson Y. O. Kvashnin A. I. Lichtenstein V. V. Mazurenko E. N. Ovchinnikova O. V. Dimitrova S. P. Collins London Centre for Nanotechnology and Department of Physics and Astronomy University College London Gower Street London WC1E6BT United Kingdom Diamond Light Source Ltd. Diamond House Harwell Science & Innovation Campus Didcot Oxfordshire OX11 0DE United Kingdom Université Grenoble Alpes CNRS Grenoble INP SIMaP F-38000 Grenoble France Utrecht University Debye Institute for Nanomaterials Science Universiteitsweg 99 3584 CG Utrecht The Netherlands A.V. Shubnikov Institute of Crystallography FSRC “Crystallography and Photonics” RAS Moscow 119333 Russia Radboud University Nijmegen Institute for Molecules and Materials Heyendaalseweg 135 NL-6525 AJ Nijmegen The Netherlands Department of Theoretical Physics and Applied Mathematics Ural Federal University Mira str. 19 620002 Ekaterinburg Russia Department of Physics and Astronomy Division of Materials Theory Uppsala University Box 516 SE-75120 Uppsala Sweden I. Institut für Theoretische Physik Universitt Hamburg Jungiusstrae 9 D-20355 Hamburg Germany Faculty of Physics M.V.Lomonosov Moscow State University Leninskie Gory Moscow 119991 Russia

The orbital contribution to the magnetic moment of the transition-metal ion in the isostructural weak ferromagnets ACO3 (A= Mn,Co,Ni) and FeBO3 was investigated by a combination of first-principles calculations, nonresonant x-ray magnetic scattering, and x-ray magnetic circular dichroism. A nontrivial evolution of the orbital moment as a function of the 3d orbitals filling is revealed, with a particularly large value found in the Co member of the family. Here, the coupling between magnetic and lattice degrees of freedom produced by the spin-orbit interaction results in a large single-ion anisotropy and a peculiar magnetic-moment-induced electron cloud distortion, evidenced by the appearance of a subtle scattering amplitude at space-group-forbidden reflections and significant magnetostrictive effects. Our results, which complement a previous investigation on the sign of the Dzyaloshinskii-Moriya interaction across the series, highlight the importance of spin-orbit coupling in the physics of weak ferromagnets and prove the ability of modern first-principles calculations to predict the properties of materials where the Dzyaloshinskii-Moriya interaction is a fundamental ingredient of the magnetic Hamiltonian.

关键词： Antiferromagnetism Dzyaloshinskii-Moriya interaction Magnetic anisotropy Magnetic interactions Magnetoelastic effect Spin-orbit coupling Spintronics Antiferromagnets Crystalline systems Density functional calculations Magnetization measurements X-ray diffraction X-ray magnetic circular dichroism X-ray scattering

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Particle identification studies with a full-size 4-GEM prototype for the ALICE TPC upgrade

arXiv

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arXiv 2018年

作者： Aggarwal, M.M. Ahammed, Z. Aiola, S. Alme, J. Alt, T. Amend, W. Andronic, A. Anguelov, V. Appelshäuser, H. Arslandok, M. Averbeck, R. Ball, M. Barnaföldi, G.G. Bartsch, E. Bellwied, R. Bencedi, G. Berger, M. Bialas, N. Bialas, P. Bianchi, L. Biswas, S. Boldizsár, L. Bratrud, L. Braun-Munzinger, P. Bregant, M. Britton, C.L. Brucken, E.J. Caines, H. Castro, A.J. Chattopadhyay, S. Christiansen, P. Clonts, L.G. Cormier, T.M. Das, S. Dash, S. Deisting, A. Dittrich, S. Dubey, A.K. Ehlers, R. Engel, M. Erhardt, F. Ezell, N.B. Fabbietti, L. Frankenfeld, U. Gaardhøje, J.J. Garabatos, C. Gasik, P. Gera, Á. Ghosh, P. Ghosh, S.K. Glässel, P. Grachov, O. Grein, A. Gunji, T. Hamagaki, H. Hamar, G. Harris, J.W. Hauer, P. Hehner, J. Hellbär, E. Helstrup, H. Hilden, T.E. Hohlweger, B. Ivanov, M. Jung, M. Just, D. Kangasaho, E. Keidel, R. Ketzer, B. Khan, S.A. Kirsch, S. Klemenz, T. Klewin, S. Knospe, A.G. Kowalski, M. Kumar, L. Lang, R. Langoy, R. Lautner, L. Liebske, F. Lien, J. Lippmann, C. Ljunggren, H.M. Llope, W.J. Mahmood, S. Mahmoud, T. Majka, R. Malzacher, P. Marín, A. Markert, C. Masciocchi, S. Mathis, A. Matyja, A. Meres, M. Mihaylov, D.L. Miskowiec, D. Mitra, J. Mittelstaedt, T. Morhardt, T. Mulligan, J. Munzer, R.H. Münning, K. Munhoz, M.G. Muhuri, S. Murakami, H. Nandi, B.K. Natal da Luz, H. Nattrass, C. Nayak, T.K. Negrao DeOliveira, R.A. Nicassio, M. Nielsen, B.S. Oláh, L. Oskarsson, A. Otwinowski, J. Oyama, K. Paić, G. Patra, R.N. Peskov, V. Pikna, M. Pinsky, L. Planinic, M. Poghosyan, M.G. Poljak, N. Pompei, F. Prasad, S.K. Pruneau, C.A. Putschke, J. Raha, S. Rak, J. Rasson, J. Ratza, V. Read, K.F. Rehman, A. Renfordt, R. Richert, T. Røed, K. Röhrich, D. Rudzki, T. Sahoo, R. Sahoo, S. Sahu, P.K. Saini, J. Schaefer, B. Schambach, J. Scheid, S. Schmidt, C. Schmidt, H.R. Schmidt, N.V. Schulte, H. Schweda, K. Selyuzhenkov, I. Sharma, N. Silvermyr, D. Singaraju, R.N. Sitar, B. Smirnov, N. Kolkata India Comenius University Bratislava Faculty of Mathematics Physics and Informatics Bratislava Slovakia Department of Physics University of Oslo Oslo Norway Department of Physics and Technology University of Bergen Bergen Norway Faculty of Engineering and Science Western Norway University of Applied Sciences Bergen Norway Worms Germany Helmholtz-Institut für Strahlen- und Kernphysik Rheinische Friedrich-Wilhelms-Universität Bonn Bonn Germany Helsinki Finland Mumbai India Indian Institute of Technology Indore Indore India Institute of Physics Bhubaneswar India Institut für Kernphysik Johann Wolfgang Goethe-Universität Frankfurt Frankfurt Germany Instituto de Ciencias Nucleares Universidad Nacional Autónoma de México Mexico City Mexico Lund University Department of Physics Division of Particle Physics Lund Sweden Nagasaki Institute of Applied Science Nagasaki Japan Niels Bohr Institute University of Copenhagen Copenhagen Denmark Oak Ridge National Laboratory Oak RidgeTN United States Physics department Faculty of science University of Zagreb Zagreb Croatia Physics Department Panjab University Chandigarh India Physikalisches Institut Eberhard-Karls-Universität Tübingen Tübingen Germany Physikalisches Institut Ruprecht-Karls-Universität Heidelberg Heidelberg Germany Physik Department Technische Universität München Munich Germany Research Division ExtreMe Matter Institute EMMI GSI Helmholtzzentrum für Schwerionenforschung GmbH Darmstadt Germany Technische Universität München Excellence Cluster'Universe' Munich Germany Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences Cracow Poland University of Texas at Austin AustinTX United States University College of Southeast Norway Tonsberg Norway São Paulo Brazil University of Houston HoustonTX United States University of Tennessee KnoxvilleTN United States University of Tokyo Tokyo Japan Variable Energy Cyclotron Centre Kolkata India Wayne State Un

A large Time Projection Chamber is the main device for tracking and charged-particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2019/20, the LHC will deliver Pb beams colliding at an interaction rate of about 50 kHz, which is about a factor of 50 above the present readout rate of the TPC. This will result in a significant improvement on the sensitivity to rare probes that are considered key observables to characterize the QCD matter created in such collisions. In order to make full use of this luminosity, the currently used gated Multi-Wire Proportional Chambers will be replaced. The upgrade relies on continuously operated readout detectors employing Gas Electron Multiplier technology to retain the performance in terms of particle identification via the measurement of the specific energy loss by ionization dE/dx. A full-size readout chamber prototype was assembled in 2014 featuring a stack of four GEM foils as an amplification stage. The performance of the prototype was evaluated in a test beam campaign at the CERN PS. The dE/dx resolution complies with both the performance of the currently operated MWPC-based readout chambers and the challenging requirements of the ALICE TPC upgrade program. Detailed simulations of the readout system are able to reproduce the data. Copyright © 2018, The Authors. All rights reserved.

关键词： Energy dissipation

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The VVV Infrared Variability Catalog (VIVA-I)

arXiv

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arXiv 2020年

作者： Lopes, Carlos Eduardo Ferreira Cross, N.J.G. Catelan, M. Minniti, D. Hempel, M. Lucas, P.W. Angeloni, R. Jablonsky, F. Braga, V.F. Leão, I.C. Herpich, F.R. Alonso-García, J. Papageorgiou, A. Pichara, K. Saito, R.K. Bradley, A. Beamin, J.C. Cortés, C. de Medeiros, J.R. Russell, Christopher M.P. Av. dos Astronautas 1758 São José dos CamposSP12227-010 Brazil Wide-Field Astronomy Unit Institute for Astronomy School of Physics and Astronomy University of Edinburgh Royal Observatory Blackford Hill EdinburghEH9 3HJ United Kingdom Instituto de Astrofísica Pontificia Universidad Católica de Chile Av. Vicuña Mackenna 4860 Macul Santiago7820436 Chile Millennium Institute of Astrophysics Santiago Chile Departamento de Ciencias Fisicas Facultad de Ciencias Exactas Universidad Andres Bello Av. Fernandez Concha 700 Las Condes Santiago Chile Vatican Observatory Vatican City StateV00120 Italy Centre for Astrophysics Research School of Physics Astronomy and Mathematics University of Hertfordshire College Lane HatfieldAL10 9AB United Kingdom Instituto de Investigación Multidisciplinar en Ciencia y Tecnología Universidad de La Serena Av. R. Bitrán 1305 La Serena Chile Departamento de Astronomía Universidad de La Serena Av. J. Cisternas 1200 La Serena Chile Departamento de Física Te órica e Experimental Universidade Federal do Rio Grande do Norte NatalRN Brazil Universidad de Antofagasta Av. Angamos 601 Antofagasta Chile Computer Science Department Pontificia Universidad Católica de Chile Santiago Chile Institute for Applied Computational Science Harvard University CambridgeMA United States Departamento de Física Universidade Federal de Santa Catarina Trindade 88040-900 FlorianópolisSC Brazil Universidade de São Paulo IAG Rua do Matão 1226 Cidade Universitária São Paulo05508-900 Brazil Núcleo de Astroquímica y Astrofísica Instituto de Ciencias Químicas Aplicadas Facultad de Ingeniería Universidad Autónoma de Chile Av. Pedro de Valdivia 425 Santiago7500912 Chile Departamento de Física Facultad de Ciencias Básicas Universidad Metropolitana de la Educación Av. José Pedro Alessandri 774 Nuñoa Santiago7760197 Chile

High extinction and crowding create a natural limitation for optical surveys towards the central regions of the Milky Way where the gas and dust are mainly confined. Large scale near-IR surveys of the Galactic Plane and Bulge are a good opportunity to explore open scientific questions as well as to test our capability to explore future datasets efficiently. Thanks to the VISTA Variables in the Vía Láctea (VVV) ESO Public Survey it is now possible to explore a large number of objects in those regions. This paper addresses the variability analysis of all VVV point sources having more than 10 observations in VVVDR4 using a novel approach. In total, the near-IR light curves of 288,378,769 sources were analysed using methods developed in the New Insight Into Time Series Analysis project. As a result, we present a complete sample having 44,998,752 variable star candidates (VVV-CVSC), which include accurate individual coordinates, near-IR magnitudes (ZYJHs), extinctions A(Ks), variability indices, periods, amplitudes, among other parameters to assess the science. Unfortunately, a side effect of having a highly complete sample, is also having a high level of contamination by non-variable (contamination ratio of non-variables to variables is slightly over 10:1). To deal with this, we also provide some flags and parameters that can be used by the community to decrease the number of variable candidates without heavily decreasing the completeness of the sample. In particular, we icross-dentified 339,601 of our sources with Simbad and AAVSO databases, which provide us with information for these objects at other wavelegths. This subsample constitutes a unique resource to study the corresponding near-IR variability of known sources as well as to assess the IR variability related with X-ray and Gamma-Ray sources. On the other hand, the other ∼ 99.5% sources in our sample constitutes a number of potentially new objects with variability information for the heavily crowded and reddene

关键词： Surveys

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Effect of long-range structural corrugations on magnetotransport properties of phosphorene in tilted magnetic field

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Physical Review B 2017年第8期96卷 085434-085434页

作者： A. Mogulkoc M. Modarresi A. N. Rudenko Department of Physics Faculty of Sciences Ankara University 06100 Tandogan Ankara Turkey Department of Physics Ferdowsi University of Mashhad Mashhad Iran Laboratory of Organic Electronics Department of Science and Technology Campus Norrköping Linköping University SE-60174 Norrköping Sweden Radboud University Institute for Molecules and Materials Heyendaalseweg 135 6525 AJ Nijmegen The Netherlands Theoretical Physics and Applied Mathematics Department Ural Federal University Mira Str. 19 620002 Ekaterinburg Russia

Rippling is an inherent quality of two-dimensional materials playing an important role in determining their properties. Here, we study the effect of structural corrugations on the electronic and transport properties of monolayer black phosphorus (phosphorene) in the presence of tilted magnetic field. We follow a perturbative approach to obtain analytical corrections to the spectrum of Landau levels induced by a long-wavelength corrugation potential. We show that surface corrugations have a non-negligible effect on the electronic spectrum of phosphorene in tilted magnetic field. Particularly, the Landau levels are shown to exhibit deviations from the linear field dependence. The observed effect become especially pronounced at large tilt angles and corrugation amplitudes. Magnetotransport properties are further examined in the low temperature regime taking into account impurity scattering. We calculate magnetic field dependence of the longitudinal and Hall resistivities and find that the nonlinear effects reflecting the corrugation might be observed even in moderate fields (B<10 T).

关键词： Electrical conductivity Electronic structure Landau levels

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Choose your path wisely: Gradient descent in a bregman distance framework

arXiv

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arXiv 2017年

作者： Benning, Martin Betcke, Marta M. Ehrhardt, Matthias J. Schönlieb, Carola-Bibiane School of Mathematical Sciences Queen Mary University of London United Kingdom Department of Computer Science University College London United Kingdom Institute for Mathematical Innovation University of Bath United Kingdom Department of Applied Mathematics and Theoretical Physics University of Cambridge United Kingdom

We propose an extension of a special form of gradient descent - in the literature known as linearised Bregman iteration - to a larger class of non-convex functions. We replace the classical (squared) two norm metric in the gradient descent setting with a generalised Bregman distance, based on a proper, convex and lower semi-continuous function. The algorithm's global convergence is proven for functions that satisfy the Kurdyka-Lojasiewicz property. Examples illustrate that features of different scale are being introduced throughout the iteration, transitioning from coarse to fine. This coarse-to-fine approach with respect to scale allows to recover solutions of non-convex optimisation problems that are superior to those obtained with conventional gradient descent, or even projected and proximal gradient descent. The effectiveness of the linearised Bregman iteration in combination with early stopping is illustrated for the applications of parallel magnetic resonance imaging, blind deconvolution as well as image classification with neural *** Codes 49M37, 65K05, 65K10, 90C26, 90C30 Copyright © 2017, The Authors. All rights reserved.

关键词： Convolution

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Search for electroweak production of supersymmetric states in scenarios with compressed mass spectra at s=13 TeV with the ATLAS detector

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Physical Review D 2018年第5期97卷 052010-052010页

作者： M. Aaboud G. Aad B. Abbott O. Abdinov B. Abeloos S. H. Abidi O. S. AbouZeid N. L. Abraham H. Abramowicz H. Abreu Y. Abulaiti B. S. Acharya S. Adachi L. Adamczyk J. Adelman M. Adersberger T. Adye A. A. Affolder Y. Afik C. Agheorghiesei J. A. Aguilar-Saavedra S. P. Ahlen F. Ahmadov G. Aielli S. Akatsuka T. P. A. Åkesson E. Akilli A. V. Akimov G. L. Alberghi J. Albert P. Albicocco M. J. Alconada Verzini S. C. Alderweireldt M. Aleksa I. N. Aleksandrov C. Alexa G. Alexander T. Alexopoulos M. Alhroob B. Ali M. Aliev G. Alimonti J. Alison S. P. Alkire C. Allaire B. M. M. Allbrooke B. W. Allen P. P. Allport A. Aloisio A. Alonso F. Alonso C. Alpigiani A. A. Alshehri M. I. Alstaty B. Alvarez Gonzalez D. Álvarez Piqueras M. G. Alviggi B. T. Amadio Y. Amaral Coutinho L. Ambroz C. Amelung D. Amidei S. P. Amor Dos Santos S. Amoroso C. Anastopoulos L. S. Ancu N. Andari T. Andeen C. F. Anders J. K. Anders K. J. Anderson A. Andreazza V. Andrei S. Angelidakis I. Angelozzi A. Angerami A. V. Anisenkov A. Annovi C. Antel M. Antonelli A. Antonov D. J. Antrim F. Anulli M. Aoki L. Aperio Bella G. Arabidze Y. Arai J. P. Araque V. Araujo Ferraz R. Araujo Pereira A. T. H. Arce R. E. Ardell F. A. Arduh J-F. Arguin S. Argyropoulos A. J. Armbruster L. J. Armitage O. Arnaez H. Arnold M. Arratia O. Arslan A. Artamonov G. Artoni S. Artz S. Asai N. Asbah A. Ashkenazi L. Asquith K. Assamagan R. Astalos R. J. Atkin M. Atkinson N. B. Atlay K. Augsten G. Avolio R. Avramidou B. Axen M. K. Ayoub G. Azuelos A. E. Baas M. J. Baca H. Bachacou K. Bachas M. Backes P. Bagnaia M. Bahmani H. Bahrasemani J. T. Baines M. Bajic O. K. Baker P. J. Bakker D. Bakshi Gupta E. M. Baldin P. Balek F. Balli W. K. Balunas E. Banas A. Bandyopadhyay Sw. Banerjee A. A. E. Bannoura L. Barak E. L. Barberio D. Barberis M. Barbero T. Barillari M-S Barisits J. T. Barkeloo T. Barklow N. Barlow S. L. Barnes B. M. Barnett R. M. Barnett Z. Barnovska-Blenessy A. Baroncelli G. Barone A. J. Barr L. Barranco Navarro F. Barreiro J. Barreiro Guimarães da Costa R. Bartoldus A. E. Barton P. B Faculté des Sciences Université Mohamed Premier and LPTPM Oujda Morocco CPPM Aix-Marseille Université and CNRS/IN2P3 Marseille France Homer L. Dodge Department of Physics and Astronomy University of Oklahoma Norman Oklahoma USA Institute of Physics Azerbaijan Academy of Sciences Baku Azerbaijan LAL Univ. Paris-Sud CNRS/IN2P3 Université Paris-Saclay Orsay France Department of Physics University of Toronto Toronto Ontario Canada Santa Cruz Institute for Particle Physics University of California Santa Cruz Santa Cruz California USA Department of Physics and Astronomy University of Sussex Brighton United Kingdom Raymond and Beverly Sackler School of Physics and Astronomy Tel Aviv University Tel Aviv Israel Department of Physics Technion: Israel Institute of Technology Haifa Israel High Energy Physics Division Argonne National Laboratory Argonne Illinois USA INFN Gruppo Collegato di Udine Sezione di Trieste Udine Italy ICTP Trieste Italy International Center for Elementary Particle Physics and Department of Physics The University of Tokyo Tokyo Japan AGH University of Science and Technology Faculty of Physics and Applied Computer Science Krakow Poland Department of Physics Northern Illinois University DeKalb Illinois USA Fakultät für Physik Ludwig-Maximilians-Universität München München Germany Particle Physics Department Rutherford Appleton Laboratory Didcot United Kingdom Department of Physics Alexandru Ioan Cuza University of Iasi Iasi Romania Laboratório de Instrumentação e Física Experimental de Partículas - LIP Lisboa Portugal Departamento de Fisica Teorica y del Cosmos Universidad de Granada Granada Spain Department of Physics Boston University Boston Massachusetts USA Joint Institute for Nuclear Research JINR Dubna Dubna Russia INFN Sezione di Roma Tor Vergata Italy Dipartimento di Fisica Università di Roma Tor Vergata Roma Italy Faculty of Science Kyoto University Kyoto Japan Fysiska institutionen Lunds universitet Lund Swed

A search for electroweak production of supersymmetric particles in scenarios with compressed mass spectra in final states with two low-momentum leptons and missing transverse momentum is presented. This search uses proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2015–2016, corresponding to 36.1 fb−1 of integrated luminosity at s=13 TeV. Events with same-flavor pairs of electrons or muons with opposite electric charge are selected. The data are found to be consistent with the Standard Model prediction. Results are interpreted using simplified models of R-parity-conserving supersymmetry in which there is a small mass difference between the masses of the produced supersymmetric particles and the lightest neutralino. Exclusion limits at 95% confidence level are set on next-to-lightest neutralino masses of up to 145 GeV for Higgsino production and 175 GeV for wino production, and slepton masses of up to 190 GeV for pair production of sleptons. In the compressed mass regime, the exclusion limits extend down to mass splittings of 2.5 GeV for Higgsino production, 2 GeV for wino production, and 1 GeV for slepton production. The results are also interpreted in the context of a radiatively-driven natural supersymmetry model with nonuniversal Higgs boson masses.

关键词： Supersymmetric models Superpartners Supersymmetry

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Wada structures in a binary black hole system

arXiv

引用

arXiv 2018年

作者： Daza, Álvar Shipley, Jake O. Dolan, Sam R. Sanjuán, Miguel A.F. Nonlinear Dynamics Chaos and Complex Systems Group Departamento de Física Universidad Rey Juan Carlos Tulipán s/n Móstoles Madrid28933 Spain Consortium for Fundamental Physics School of Mathematics and Statistics University of Sheffield Hicks Building Hounsfield Road SheffieldS3 7RH United Kingdom Department of Applied Informatics Kaunas University of Technology Studentu 50-415 KaunasLT-51368 Lithuania Institute for Physical Science and Technology University of Maryland College ParkMD20742 United States

A key goal of the Event Horizon Telescope is to observe the shadow cast by a black hole. Recent simulations have shown that binary black holes, the progenitors of gravitational waves, present shadows with fractal structure. Here we study the binary shadow structure using techniques from nonlinear dynamics, recognising shadows as exit basins of open Hamiltonian dynamical systems. We apply a recently developed numerical algorithm to demonstrate that parts of the Majumdar-Papapetrou binary black hole shadow exhibit the Wada property: any point of the boundary of one basin is also on the boundary of at least two additional basins. We show that the algorithm successfully distinguishes between the fractal and regular (i.e., non-fractal) parts of the binary shadow. Copyright © 2018, The Authors. All rights reserved.

关键词： Fractals

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