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作者： He, Shuangyu Wu, Qianhong Qin, Bo Liu, Jianwei Li, Yan School of Electronics and Information Engineering Beihang University Beijing100191 China State Key Laboratory of Integrated Services Networks Xidian University Xi'an710071 China State Key Laboratory of Information Security Institute of Information Engineering Chinese Academy of Sciences Beijing100193 China Key Laboratory of Cryptographic Technology and Information Security Ministry of Education Shandong University Shandong250100 China Ministry of Education School of Information Renmin University of China Beijing China School of Mathematics and Computing Science Guangxi Key Laboratory of Cryptography and Information Security Guilin University of Electronic Technology Guilin Guangxi541004 China State Key Laboratory of Cryptology P.O. Box 5159 Beijing100878 China Aerospace Hengxing Science and Technology Co. LTD Beijing China

It is challenging to secure group communications among large-scale networks due to their network scale. We observe that in many large-scale networks, the scale of actual group communication is nevertheless predicable and not very large. For instance, although the entire social network (e.g., Facebook) may have billions of users, the members in a concrete group are usually about tens to hundreds. We manage to secure group communication in such scenarios with efficient group management protocols. Technically, we achieve this goal by using a novel dual-ring approach in which two rings of nodes are established, one active and one dummy. When some nodes leave, the remaining nodes can replace these nodes with dummy nodes, minimizing the required communications and computations after the protocol is set up and thus providing significant advantage over existing group key management protocols. Formal security arguments show that our protocols are secure under standard computational assumptions. Thorough analysis confirms that our protocols are efficient in computation and communication. Copyright © 2015 John Wiley & Sons, Ltd.

关键词： Big data

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Initial Atomic Motion Immediately Following Femtosecond-Laser Excitation in Phase-Change Materials

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Physical Review Letters 2016年第13期117卷 135501-135501页

作者： E. Matsubara S. Okada T. Ichitsubo T. Kawaguchi A. Hirata P. F. Guan K. Tokuda K. Tanimura T. Matsunaga M. W. Chen N. Yamada Department of Materials Science and Engineering Kyoto University Kyoto 606-8501 Japan Office of Society-Academia Collaboration for Innovation Kyoto University Kyoto 611-0011 Japan WPI Advanced Institute for Materials Research Tohoku University Sendai 980-8577 Japan Mathematics for Advanced Materials-OIL AIST-Tohoku University Sendai 980-8577 Japan Beijing Computational Science Research Center Beijing 100084 People’s Republic of China The Institute of Scientific and Industrial Research Osaka University Osaka 567-0047 Japan State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200030 People’s Republic of China

Despite the fact that phase-change materials are widely used for data storage, no consensus exists on the unique mechanism of their ultrafast phase change and its accompanied large and rapid optical change. By using the pump-probe observation method combining a femtosecond optical laser and an x-ray free-electron laser, we substantiate experimentally that, in both GeTe and Ge2Sb2Te5 crystals, rattling motion of mainly Ge atoms takes place with keeping the off-center position just after femtosecond-optical-laser irradiation, which eventually leads to a higher symmetry or disordered state. This very initial rattling motion in the undistorted lattice can be related to instantaneous optical change due to the loss of resonant bonding that characterizes GeTe-based phase change materials. Based on the amorphous structure derived by first-principles molecular dynamics simulation, we infer a plausible ultrafast amorphization mechanism via nonmelting.

关键词： Crystal structure Crystal symmetry Glass transition Optical pumping Peierls transition

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The GALAH survey: Accurate radial velocities and library of observed stellar template spectra

arXiv

引用

arXiv 2018年

作者： Zwitter, Tomaz Kos, Janez Chiavassa, Andrea Buder, Sven Traven, Gregor Cotar, Klemen Lin, Jane Asplund, Martin Bland-Hawthorn, Joss Casey, Andrew R. De Silva, Gayandhi Duong, Ly Freeman, Kenneth C. Lind, Karin Martell, Sarah D'Orazi, Valentina Schlesinger, Katharine J. Simpson, Jeffrey D. Sharma, Sanjib Zucker, Daniel B. Anguiano, Borja Casagrande, Luca Collet, Remo Horner, Jonathan Ireland, Michael J. Kafle, Prajwal R. Lewis, Geraint Munari, Ulisse Nataf, David M. Ness, Melissa Nordlander, Thomas Stello, Dennis Ting, Yuan-Sen Tinney, Chris G. Watson, Fred Wittenmyer, Rob A. Žerjal, Maruša Faculty of Mathematics and Physics University of Ljubljana Jadranska 19 Ljubljana1000 Slovenia Sydney Institute for Astronomy School of Physics University of Sydney NSW2006 Australia Université Côte d'Azur Observatoire de la Côte d'Azur CNRS Lagrange CS 34229 Nice France Koenigstuhl 17 Heidelberg69117 Germany Research School of Astronomy & Astrophysics Australian National University ACT2611 Australia Australia School of Physics and Astronomy Monash University Clayton3800 Australia Faculty of Information Technology Monash University ClaytonVIC3800 Australia Australian Astronomical Observatory North RydeNSW2133 Australia Department of Physics and Astronomy Uppsala University Box 516 UppsalaSE-75120 Sweden School of Physics UNSW SydneyNSW2052 Australia I-36012 Italy Department of Physics and Astronomy Macquarie University SydneyNSW2109 Australia Department of Astronomy University of Virginia CharlottesvilleVA22904-4325 United States Stellar Astrophysics Centre Department of Physics and Astronomy Aarhus University Aarhus CDK-8000 Denmark University of Southern Queensland Computational Engineering and Science Research Centre ToowoombaQLD4350 Australia ICRAR University of Western Australia 35 Stirling Highway CrawleyWA6009 Australia Center for Astrophysical Sciences Department of Physics and Astronomy Johns Hopkins University BaltimoreMD21218 United States Institute for Advanced Study PrincetonNJ08540 United States Observatories of the Carnegie Institution of Washington 813 Santa Barbara Street PasadenaCA91101 United States Department of Astrophysical Sciences Princeton University PrincetonNJ08544 United States Western Sydney University Locked Bag 1797 PenrithNSW2751 Australia

GALAH is a large-scale magnitude-limited southern stellar spectroscopic survey. Its second data release (GALAH DR2) provides values of stellar parameters and abundances of 23 elements for 342,682 stars (Buder et al.). Here we add a description of the public release of radial velocities with a typical accuracy of 0.1 km s-1for 336,215 of these stars, achievable due to the large wavelength coverage, high resolving power and good signal to noise ratio of the observed spectra, but also because convective motions in stellar atmosphere and gravitational redshift from the star to the observer are taken into account. In the process we derive medians of observed spectra which are nearly noiseless, as they are obtained from between 100 and 1116 observed spectra belonging to the same bin with a width of 50 K in temperature, 0.2 dex in gravity, and 0.1 dex in metallicity. Publicly released 1181 median spectra have a resolving power of 28,000 and trace the well-populated stellar types with metallicities between-0.6 and +0.3. Note that radial velocities from GALAH are an excellent match to the accuracy of velocity components along the sky plane derived by Gaia for the same stars. The level of accuracy achieved here is adequate for studies of dynamics within stellar clusters, associations and streams in the Galaxy. So it may be relevant for studies of the distribution of dark matter. Copyright © 2018, The Authors. All rights reserved.

关键词： Surveys

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Search for Low-Mass Dijet Resonances Using Trigger-Level Jets with the ATLAS Detector in pp Collisions at s=13 TeV

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Physical Review Letters 2018年第8期121卷 081801-081801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 A. Adiguzel T. Adye A. A. Affolder Y. Afik C. Agheorghiesei J. A. Aguilar-Saavedra 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. Alderweireldt M. Aleksa I. N. Aleksandrov C. Alexa G. Alexander T. Alexopoulos M. Alhroob B. Ali 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. S. Amrouche 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. T. Anthony M. Antonelli D. J. A. 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 E. M. Asimakopoulou 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 A. J. Bailey 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 S. Banerjee A. A. E. Bannoura L. Barak W. M. Barbe E. L. Barberio D. Barberis M. Barbero T. Barillari M-S. Barisits J. Barkeloo T. Barklow N. Barlow R. Barnea S. L. Barnes B. M. Barnett R. M. Barnett Z. Barnovska-Blenessy A. Baroncelli G. Barone A. J. Barr L. Barranco Navarro F. Barreiro Faculté des Sciences Université Mohamed Premier and LPTPM Oujda Morocco CPPM Aix-Marseille Université 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 Université 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 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 Department of Physics Bogazici University Istanbul Turkey Particle Physics Department Rutherford Appleton Laboratory Didcot United Kingdom Department of Physics Alexandru Ioan Cuza University of Iasi Iasi Romania Departamento de Física Teorica y del Cosmos Universidad de Granada Granada (Spain) Spain Laboratório de Instrumentação e Física Experimental de Partículas - LIP Portugal Joint Institute for Nuclear Research 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 Sweden Département de Phys

Searches for dijet resonances with sub-TeV masses using the ATLAS detector at the Large Hadron Collider can be statistically limited by the bandwidth available to inclusive single-jet triggers, whose data-collection rates at low transverse momentum are much lower than the rate from standard model multijet production. This Letter describes a new search for dijet resonances where this limitation is overcome by recording only the event information calculated by the jet trigger algorithms, thereby allowing much higher event rates with reduced storage needs. The search targets low-mass dijet resonances in the range 450–1800 GeV. The analyzed data set has an integrated luminosity of up to 29.3 fb−1 and was recorded at a center-of-mass energy of 13 TeV. No excesses are found; limits are set on Gaussian-shaped contributions to the dijet mass distribution from new particles and on a model of dark-matter particles with axial-vector couplings to quarks.

关键词： Particle dark matter Quark & gluon jets Weakly interacting massive particles Hadron colliders

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A decade of Gamma-Ray Bursts observed by Fermi-LAT:

arXiv

引用

arXiv 2019年

作者： Ajello, M. Arimoto, M. Axelsson, M. Baldini, L. Barbiellini, G. Bastieri, D. Bellazzini, R. Bhat, P.N. Bissaldi, E. Blandford, R.D. Bonino, R. Bonnell, J. Bottacini, E. Bregeon, J. Bruel, P. Buehler, R. Cameron, R.A. Caputo, R. Caraveo, P.A. Cavazzuti, E. Chen, S. Cheung, C.C. Chiaro, G. Ciprini, S. Costantin, D. Crnogorcevic, M. Cutini, S. Dainotti, M. D’Ammando, F. de la Torre Luque, P. de Palma, F. Desai, A. Desiante, R. Di Lalla, N. Di Venere, L. Fana Dirirsa, F. Fegan, S.J. Franckowiak, A. Fukazawa, Y. Funk, S. Fusco, P. Gargano, F. Gasparrini, D. Giglietto, N. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Grove, J.E. Guiriec, S. Hays, E. Hewitt, J.W. Horan, D. Jóhannesson, G. Kocevski, D. Kuss, M. Latronico, L. Li, J. Longo, F. Loparco, F. Lovellette, M.N. Lubrano, P. Maldera, S. Manfreda, A. Martí-Devesa, G. Mazziotta, M.N. Mereu, I. Meyer, M. Michelson, P.F. Mirabal, N. Mitthumsiri, W. Mizuno, T. Monzani, M.E. Moretti, E. Morselli, A. Moskalenko, I.V. Negro, M. Nuss, E. Ohno, M. Omodei, N. Orienti, M. Orlando, E. Palatiello, M. Paliya, V.S. Paneque, D. Persic, M. Pesce-Rollins, M. Petrosian, V. Piron, F. Poolakkil, S. Poon, H. Porter, T.A. Principe, G. Racusin, J.L. Rainò, S. Rando, R. Razzano, M. Razzaque, S. Reimer, A. Reimer, O. Reposeur, T. Ryde, F. Serini, D. Sgrò, C. Siskind, E.J. Sonbas, E. Spandre, G. Spinelli, P. Suson, D.J. Tajima, H. Takahashi, M. Tak, D. Thayer, J.B. Torres, D.F. Troja, E. Valverde, J. Veres, P. Vianello, G. von Kienlin, A. Wood, K. Yassine, M. Zhu, S. Zimmer, S. Department of Physics and Astronomy Clemson University Kinard Lab of Physics ClemsonSC29634-0978 United States Faculty of Mathematics and Physics Institute of Science and Engineering Kanazawa University Kakuma Kanazawa Ishikawa920-1192 Department of Physics and Oskar Klein Center for Cosmoparticle Physics Stockholm University Stockholm106 91 Sweden Department of Physics KTH Royal Institute of Technology AlbaNova StockholmSE-106 91 Sweden Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Trieste TriesteI-34127 Italy Dipartimento di Fisica Università di Trieste TriesteI-34127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova PadovaI-35131 Italy Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy University of Alabama in Huntsville HuntsvilleAL35899 United States Dipartimento di Fisica "M. Merlin" dell’Università e del Politecnico di Bari BariI-70126 Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics SLAC National Accelerator Laboratory Stanford University StanfordCA94305 United States Istituto Nazionale di Fisica Nucleare Sezione di Torino TorinoI-10125 Italy Dipartimento di Fisica Università degli Studi di Torino TorinoI-10125 Italy NASA Goddard Space Flight Center GreenbeltMD20771 United States Department of Astronomy University of Maryland College ParkMD20742 United States Department of Physics and Astronomy University of Padova Vicolo Osservatorio 3 PadovaI-35122 Italy Laboratoire Univers et Particules de Montpellier Université Montpellier CNRS/IN2P3 MontpellierF-34095 France Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 PalaiseauF-91128 France

The Large Area Telescope (LAT) aboard the Fermi spacecraft routinely observes high-energy emission from gamma-ray bursts (GRBs). Here we present the second catalog of LAT-detected GRBs, covering the first 10 years of operations, from 2008 August 4 to 2018 August 4. A total of 186 GRBs are found;of these, 91 show emission in the range 30–100 MeV (17 of which are seen only in this band) and 169 are detected above 100 MeV. Most of these sources were discovered by other instruments (Fermi/GBM, Swift/BAT, AGILE, INTEGRAL) or reported by the Interplanetary Network (IPN);the LAT has independently triggered on 4 GRBs. This catalog presents the results for all 186 GRBs. We study onset, duration and temporal properties of each GRB, as well as spectral characteristics in the 100 MeV–100 GeV energy range. Particular attention is given to the photons with highest energy. Compared with the first LAT GRB catalog, our rate of detection is significantly improved. The results generally confirm the main findings of the first catalog: the LAT primarily detects the brightest GBM bursts, and the high-energy emission shows delayed onset as well as longer duration. However, in this work we find delays exceeding 1 ks, and several GRBs with durations over 10 ks. Furthermore, the larger number of LAT detections shows that these GRBs cover not only the high-fluence range of GBM-detected GRBs, but also samples lower fluences. In addition, the greater number of detected GRBs with redshift estimates allows us to study their properties in both the observer and rest frames. Comparison of the observational results with theoretical predictions reveals that no model is currently able to explain all results, highlighting the role of LAT observations in driving theoretical models. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

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Selecting ultra-faint dwarf candidate progenitors in cosmological n-body simulations at high redshifts

arXiv

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arXiv 2017年

作者： Safarzadeh, Mohammadtaher Ji, Alexander P. Dooley, Gregory A. Frebel, Anna Scannapieco, Evan Gómez, Facundo A. O’Shea, Brian W. School of Earth and Space Exploration Arizona State University TempeAZ85287-1404 United States Observatories of the Carnegie Institution of Washington 813 Santa Barbara St. PasadenaCA91101 United States Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States Instituto de Investigación Multidisciplinar en Ciencia y Tecnología Universidad de La Serena Raúl Bitrán 1305 La Serena Chile Departamento de Física y Astronomía Universidad de La Serena Av. Juan Cisternas 1200 N La Serena Chile Department of Computational Mathematics Science and Engineering Michigan State University MI48823 United States Department of Physics and Astronomy Michigan State University MI48823 United States National Superconducting Cyclotron Laboratory Michigan State University MI48823 United States Joint Institute for Nuclear Astrophysics - Center for the Evolution of the Elements United States

The smallest satellites of the Milky Way ceased forming stars during the epoch of reionization and thus provide archaeological access to galaxy formation at z > 6. Numerical studies of these ultra-faint dwarf galaxies (UFDs) require expensive cosmological simulations with high mass resolution that are carried out down to z = 0. However, if we are able to statistically identify UFD host progenitors at high redshifts with relatively high probabilities, we can avoid this high computational cost. To find such candidates, we analyze the merger trees of Milky Way type halos from the high-resolution Caterpillar suite of dark matter only simulations. Satellite UFD hosts at z = 0 are identified based on four different abundance matching (AM) techniques. All the halos at high redshifts are traced forward in time in order to compute the probability of surviving as satellite UFDs today. Our results show that selecting potential UFD progenitors based solely on their mass at z=12 (8) results in a 10% (20%) chance of obtaining a surviving UFD at z = 0 in three of the AM techniques we adopted. We find that the progenitors of surviving satellite UFDs have lower virial ratios (η), and are preferentially located at large distances from the main MW progenitor, while they show no correlation with concentration parameter. Halos with favorable locations and virial ratios are ≈ 3 times more likely to survive as satellite UFD candidates at z = 0. Copyright © 2017, The Authors. All rights reserved.

关键词： Galaxies

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B- and D-meson leptonic decay constants and quark masses from four-flavor lattice QCD

arXiv

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arXiv 2018年

作者： Bazavov, A. Bernard, C. Brambilla, N. Brown, N. DeTar, C. El Khadra, A.X. Gámiz, E. Gottlieb, Steven Heller, U.M. Komijani, J. Kronfeld, A.S. Laiho, J. Mackenzie, P.M. Neil, E.T. Simone, J.N. Sugar, R.L. Toussaint, D. van de Water, R.S. Vairo, A. Department of Computational Mathematics Science and Engineering Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Department of Physics Washington University St. LouisMO63130 United States Physik-Department Technische Universität München James-Franck-Straße 1 Garching85748 Germany Institute for Advanced Study Technische Universität München Lichtenbergstraße 2a Garching85748 Germany Department of Physics and Astronomy University of Utah Salt Lake CityUT84112 United States Department of Physics University of Illinois UrbanaIL61801 United States Fermi National Accelerator Laboratory BataviaIL60510 United States CAFPE Departamento de Física Teórica y del Cosmos Universidad de Granada GranadaE-18071 Spain Department of Physics Indiana University BloomingtonIN47405 United States American Physical Society One Research Road RidgeNY11961 United States School of Physics and Astronomy University of Glasgow GlasgowG12 8QQ United Kingdom Department of Physics Syracuse University SyracuseNY13244 United States Department of Physics University of Colorado BoulderCO80309 United States RIKEN-BNL Research Center Brookhaven National Laboratory UptonNY11973 United States Department of Physics University of California Santa BarbaraCA93106 United States Physics Department University of Arizona TucsonAZ85721 United States

We describe a recent lattice-QCD calculation of the leptonic decay constants of heavy-light pseudoscalar mesons containing charm and bottom quarks and of the masses of the up, down, strange, charm, and bottom quarks. Results for these quantities are of the highest precision to date. Calculations use 24 isospin-symmetric ensembles of gauge-field configurations with six different lattice spacings as small as approximately 0.03 fm and several values of the light quark masses down to physical values of the average up- and down-sea-quark masses. We use the highly-improved staggered quark (HISQ) formulation for valence and sea quarks, including the bottom quark. The analysis employs heavy-quark effective theory (HQET). A novel HQET method is used in the determination of the quark masses. Copyright © 2018, The Authors. All rights reserved.

关键词： Bosons

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Double Nyström method: An efficient and accurate Nyström scheme for large-scale data sets 32

Double Nyström method: An efficient and accurate Nyström s...

引用

32nd International Conference on Machine Learning, ICML 2015

作者： Lim, Woosang Kim, Minhwan Park, Haesun Jung, Kyomin School of Computing KAIST Daejeon Korea Republic of LG Electronics Seoul Korea Republic of School of Computational Science and Engineering Georgia Institute of Technology AtlantaGA30332 United States Department of Electrical and Computer Engineering Seoul National University Seoul Korea Republic of

ISBN: (纸本)9781510810587

The Nyström method has been one of the most effective techniques for kernel-based approach that scales well to large data sets. Since its introduction, there has been a large body of work that improves the approximation accuracy while maintaining computational efficiency. In this paper, we present a novel Nyström method that improves both accuracy and efficiency based on a new theoretical analysis. We first provide a generalized sampling scheme, CAPS, that minimizes a novel error bound based on the subspace distance. We then present our double Nyström method that reduces the size of the decomposition in two stages. We show that our method is highly efficient and accurate compared to other state-of-the-art Nyström methods by evaluating them on a number of real data sets. Copyright © 2015 by the author(s).

关键词： computational efficiency

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Euclid preparation: IX. EuclidEmulator2 – Power spectrum emulation with massive neutrinos and self-consistent dark energy perturbations

arXiv

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arXiv 2020年

作者： Knabenhansz, M. Stadel, J. Potter, D. Dakin, J. Hannestad, S. Tram, T. Marelli, S. Schneider, A. Teyssier, R. Andreon, S. Auricchio, N. Baccigalupi, C. Balaguera-Antolínez, A. Baldi, M. Bardelli, S. Battaglia, P. Bender, R. Biviano, A. Bodendorf, C. Bozzo, E. Branchini, E. Brescia, M. Burigana, C. Cabanac, R. Camera, S. Capobianco, V. Cappi, A. Carbone, C. Carretero, J. Carvalho, C.S. Casas, R. Casas, S. Castellano, M. Castignani, G. Cavuoti, S. Cledassou, R. Colodro-Conde, C. Congedo, G. Conselice, C.J. Conversi, L. Copin, Y. Corcione, L. Coupon, J. Courtois, H.M. da Silva, A. de la Torre, S. Di Ferdinando, D. Duncan, C.A.J. Dupac, X. Fabbian, G. Farrens, S. Ferreira, P.G. Finelli, F. Frailis, M. Franceschi, E. Galeotta, S. Garilli, B. Giocoli, C. Gozaliasl, G. Graciá-Carpio, J. Grupp, F. Guzzo, L. Holmes, W. Hormuth, F. Israel, H. Jahnke, K. Keihanen, E. Kermiche, S. Kirkpatrick, C.C. Kubik, B. Kunz, M. Kurki-Suonio, H. Ligori, S. Lilje, P.B. Lloro, I. Maino, D. Marggraf, O. Markovic, K. Martinet, N. Marulli, F. Massey, R. Mauri, N. Maurogordato, S. Medinaceli, E. Meneghetti, M. Metcalf, B. Meylan, G. Moresco, M. Morin, B. Moscardini, L. Munari, E. Neissner, C. Niemi, S.M. Padilla, C. Paltani, S. Pasian, F. Patrizii, L. Pettorino, V. Pires, S. Polenta, G. Poncet, M. Raison, F. Renzi, A. Rhodes, J. Riccio, G. Romelli, E. Roncarelli, M. Saglia, R. Sánchez, A.G. Sapone, D. Schneider, P. Scottez, V. Secroun, A. Serrano, S. Sirignano, C. Sirri, G. Stanco, L. Sureau, F. Tallada Crespí, P. Taylor, A.N. Tenti, M. Tereno, I. Toledo-Moreo, R. Torradeflot, F. Valenziano, L. Valiviita, J. Vassallo, T. Viel, M. Wang, Y. Welikala, N. Whittaker, L. Zacchei, A. Zucca, E. Institute for Computational Science University of Zurich Winterthurerstrasse 190 Zurich8057 Switzerland Department of Physics and Astronomy University of Aarhus Ny Munkegade 120 Aarhus CDK-8000 Denmark Risk Safety and Uncertainty Quantification Dept. of Civil Engineering ETH Zurich Stefano-Franscini-Platz 5 Zurich8093 Switzerland Institute for Particle Physics and Astrophysics Dept. of Physics ETH Zurich Wolfgang-Pauli-Strasse 27 Zurich8093 Switzerland INAF-Osservatorio Astronomico di Brera via Brera 28 MilanoI-20122 Italy INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna via Piero Gobetti 93/3 BolognaI-40129 Italy SISSA International School for Advanced Studies via Bonomea 265 Trieste TSI-34136 Italy INFN Sezione di Trieste via Valerio 2 Trieste TSI-34127 Italy INAF-Osservatorio Astronomico di Trieste via G. B. Tiepolo 11 TriesteI-34131 Italy Universidad de la Laguna E-38206 San Cristóbal de La Laguna Tenerife Spain Instituto de Astrofísica de Canarias Calle vía Làctea s/n San Cristóbal de la Laguna Tenerife38204 Spain via Gobetti 93/3 BolognaI-40127 Italy Dipartimento di Fisica e Astronomia Universitá di Bologna via Gobetti 93/2 BolognaI-40129 Italy INFN-Sezione di Bologna viale Berti Pichat 6/2 BolognaI-40127 Italy INAF-IASF Bologna via Piero Gobetti 101 BolognaI-40129 Italy Universitäts-Sternwarte München Fakultät für Physik Ludwig-Maximilians-Universität München Scheinerstrasse 1 München81679 Germany Max Planck Institute for Extraterrestrial Physics Giessenbachstr. 1 GarchingD-85748 Germany IFPU Institute for Fundamental Physics of the Universe via Beirut 2 Trieste34151 Italy Department of Astronomy University of Geneva ch. d’Écogia 16 VersoixCH-1290 Switzerland INFN-Sezione di Roma Tre via della Vasca Navale 84 RomaI-00146 Italy Department of Mathematics and Physics Roma Tre University via della Vasca Navale 84 RomeI-00146 Italy INAF-Osservatorio Astronomico di Roma via Frascati 33 Montepo

We present a new, updated version of the EuclidEmulator (called EuclidEmulator2), a fast and accurate predictor for the nonlinear correction of the matter power spectrum. Percent-level accurate emulation is now supported in the eight-dimensional parameter space of w0waCDM+ ∑ mv models between redshift z = 0 and z = 3 for spatial scales within the range 0.01 ℎ Mpc−1 ≤ k ≤ 10 ℎ Mpc−1. In order to achieve this level of accuracy, we have had to improve the quality of the underlying N-body simulations used as training data: (i) we use self-consistent linear evolution of non-dark matter species such as massive neutrinos, photons, dark energy and the metric field, (ii) we perform the simulations in the so-called N-body gauge, which allows one to interpret the results in the framework of general relativity, (iii) we run over 250 high-resolution simulations with 30003 particles in boxes of 1(ℎ−1 Gpc)3 volumes based on paired-and-fixed initial conditions and (iv) we provide a resolution correction that can be applied to emulated results as a post-processing step in order to drastically reduce systematic biases on small scales due to residual resolution effects in the simulations. We find that the inclusion of the dynamical dark energy parameter wa significantly increases the complexity and expense of creating the emulator. The high fidelity of EuclidEmulator2 is tested in various comparisons against N-body simulations as well as alternative fast predictors like HALOFIT, HMCode and CosmicEmu. A blind test is successfully performed against the Euclid Flagship v2.0 simulation. Nonlinear correction factors emulated with EuclidEmulator2 are accurate at the level of 1% or better for 0.01 ℎ Mpc−1 ≤ k ≤ 10 ℎ Mpc−1 and z ≤ 3 compared to high-resolution dark matter only simulations. EuclidEmulator2 is publicly available at https://***/miknab/EuclidEmulator2. © 2020, CC-BY-NC-SA.

关键词： Power spectrum

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Measurement of the Soft-Drop Jet Mass in pp Collisions at s=13 TeV with the ATLAS Detector

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Physical Review Letters 2018年第9期121卷 092001-092001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 R. 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 H. Akerstedt 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 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 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 N. Anjos 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 A. T. H. Arce R. E. Ardell F. A. Arduh J-F. Arguin S. Argyropoulos M. Arik 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 M. Atkinson N. B. Atlay K. Augsten G. Avolio 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 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. Bartos A. Basalaev A. Bassalat R. L. Bates 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 Center for High Energy Physics University of Oregon Eugene Oregon USA Department of Physics Stockholm University Sweden The Oskar Klein Centre Stockholm Sweden 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 Roma Italy Dipartimento di Fisica Università di Roma Tor Vergata Roma Italy Faculty of Sci

Jet substructure observables have significantly extended the search program for physics beyond the standard model at the Large Hadron Collider. The state-of-the-art tools have been motivated by theoretical calculations, but there has never been a direct comparison between data and calculations of jet substructure observables that are accurate beyond leading-logarithm approximation. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. This Letter documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next-to-leading-logarithm accuracy. The normalized, differential cross section is measured as a function of log10ρ2, where ρ is the ratio of the soft-drop mass to the ungroomed jet transverse momentum. This quantity is measured in dijet events from 32.9 fb−1 of s=13 TeV proton-proton collisions recorded by the ATLAS detector. The data are unfolded to correct for detector effects and compared to precise QCD calculations and leading-logarithm particle-level Monte Carlo simulations.

关键词： Perturbative QCD Quark & gluon jets

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