45 research outputs found
Embeddings Into Thompson's Group V And Cocf Groups
No full textIt is shown in Lehnert and Schweitzer ('The co-word problem for the Higman-Thompson group is context-free', Bull. London Math. Soc. 39 (2007) 235-241) that R. Thompson's group V is a co-context-free (coCF) group, thus implying that all of its finitely generated subgroups are also coCF groups. Also, Lehnert shows in his thesis that V embeds inside the coCF group QAut(T-2,T- c), which is a group of particular bijections on the vertices of an infinite binary 2-edge-coloured tree, and he conjectures that QAut(T-2,T- c) is a universal coCF group. We show that QAut(T-2,T- c) embeds into V, and thus obtain a new form for Lehnert's conjecture. Following up on these ideas, we begin work to build a representation theory into R. Thompson's group V. In particular, we classify precisely which Baumslag-Solitar groups embed into V.94583597Fondation Mathematique Jacques Hadamard [ANR-10-CAMP-0151-02 FMJH
Continual release of differentially private synthetic data
No full textFG-2022-18482 - Alfred P. Sloan Foundation; CNS-2046425 - National Science Foundationhttps://arxiv.org/abs/2306.07884First author draf
New results from the antarctic muon and neutrino detector array
No full textWe present recent results from the Antarctic Muon And Neutrino Detector Array (AMANDA) on searches for high-energy neutrinos of extraterrestrial origin. We have searched for a diffuse flux of neutrinos, neutrino point sources and neutrinos from GRBs and from WIMP annihilations in the Sun or the center of the Earth. We also present a preliminary result on the first energy spectrum above a few TeV for atmospheric neutrinos. © 2005 Published by Elsevier B.V.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Results from the AMANDA detector
No full textThe Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy neutrino telescope based at the geographic South Pole. It is a lattice of photo-multiplier tubes buried deep in the polar ice, which is used as interaction and detection medium. The primary goal of this detector is the observation of astronomical sources of high-energy neutrinos. This paper shows the latest results of the search for a diffuse flux of extraterrestrial νμs with energies between 1011 eV and 10 18 eV, νμs emitted from point sources and νμs from dark matter annihilation in the Earth and the Sun
Muon track reconstruction and data selection techniques in AMANDA
No full textThe Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy neutrino telescope operating at the geographic South Pole. It is a lattice of photo-multiplier tubes buried deep in the polar ice between 1500 and 2000 m. The primary goal of this detector is to discover astrophysical sources of high-energy neutrinos. A high-energy muon neutrino coming through the earth from the Northern Hemisphere can be identified by the secondary muon moving upward through the detector. The muon tracks are reconstructed with a maximum likelihood method. It models the arrival times and amplitudes of Cherenkov photons registered by the photo-multipliers. This paper describes the different methods of reconstruction, which have been successfully implemented within AMANDA. Strategies for optimizing the reconstruction performance and rejecting background are presented. For a typical analysis procedure the direction of tracks are reconstructed with about 2° accuracy. © 2004 Elsevier B.V. All rights reserved.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Limits on Diffuse Fluxes of High Energy Extraterrestrial Neutrinos with the AMANDA – B10 Detector
No full textA report on the limits, which could be placed on diffuse fluxes of high energy extraterrestrial neutrinos, was presented. The incorporation of neutrino oscillations was necessary for interpreting the limits in terms of the flux from a cosmological distributions of sources. The energetic accelerated environments were presented as the sources of high energy extraterrestrial neutrinos.0SCOPUS: ar.jSCOPUS: ar.jinfo:eu-repo/semantics/publishe
Flux limits on ultra high energy neutrinos with AMANDA-B10
No full textData taken during 1997 with the AMANDA-B10 detector are searched for a diffuse flux of neutrinos of all flavors with energies above 1016eV. At these energies the Earth is opaque to neutrinos, and thus neutrino induced events are concentrated at the horizon. The background are large muon bundles from down-going atmospheric air shower events. No excess events above the background expectation are observed and a neutrino flux following E-2, with an equal mix of all flavors, is limited to E2φ(1015eV < E < 3 × 1018eV) ≤ 0.99 × 10-6GeV cm-2 s-1 sr-1 at 90% confidence level. This is the most restrictive experimental bound placed by any neutrino detector at these energies. Bounds to specific extra-terrestrial eutrino flux predictions are also presented. © 2004 Elsevier B.V. All rights reserved.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Measurement of the cosmic ray composition at the knee with the SPASE-2/AMANDA-B10 detectors
No full textThe mass composition of high-energy cosmic rays at energies above 10 15 eV can provide crucial information for the understanding of their origin. Air showers were measured simultaneously with the SPASE-2 air shower array and the AMANDA-B10 Cherenkov telescope at the South Pole. This combination has the advantage to sample almost all high-energy shower muons and is thus a new approach to the determination of the cosmic ray composition. The change in the cosmic ray mass composition was measured versus existing data from direct measurements at low energies. Our data show an increase of the mean log atomic mass 〈ln A 〉 by about 0.8 between 500 TeV and 5 PeV. This trend of an increasing mass through the “knee” region is robust against a variety of systematic effects
