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arXiv 2020年

作者： Aad, G. Abbott, B. Abbott, D.C. Abed Abud, A. Abeling, K. Abhayasinghe, D.K. Abidi, S.H. AbouZeid, O.S. Abraham, N.L. Abramowicz, H. Abreu, H. Abulaiti, Y. Acharya, B.S. Achkar, B. Adam, L. Adam Bourdarios, C. Adamczyk, L. Adamek, L. Adelman, J. Adersberger, M. Adiguzel, A. Adorni, S. Adye, T. Affolder, A.A. Afik, Y. Agapopoulou, C. Agaras, M.N. Aggarwal, A. agheorghiesei, C. Aguilar-Saavedra, J.A. Ahmad, A. Ahmadov, F. Ahmed, W.S. Ai, X. Aielli, G. Akatsuka, S. Akbiyik, M. Åkesson, T.P.A. Akilli, E. Akimov, A.V. Al Khoury, K. Alberghi, G.L. Albert, J. Alconada Verzini, M.J. Alderweireldt, S. Aleksa, M. Aleksandrov, I.N. Alexa, C. CPPM Aix-Marseille Université CNRS/IN2P3 Marseille France Homer L. Dodge Department of Physics and Astronomy University of Oklahoma NormanOK United States Department of Physics University of Massachusetts AmherstMA United States CERN Geneva Switzerland II. Physikalisches Institut Georg-August-Universität Göttingen Göttingen Germany Department of Physics Royal Holloway University of London Egham United Kingdom Department of Physics University of Toronto TorontoON Canada Niels Bohr Institute University of Copenhagen Copenhagen Denmark 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 ArgonneIL United States INFN Gruppo Collegato di Udine Sezione di Trieste Udine Italy ICTP Trieste Italy Department of Physics King's College London London United Kingdom Institut für Physik Universität Mainz Mainz Germany LAPP Univ. Savoie Mont Blanc CNRS/IN2P3 Annecy France AGH University of Science and Technology Faculty of Physics and Applied Computer Science Krakow Poland Department of Physics Northern Illinois University DeKalbIL United States Fakultät für Physik Ludwig-Maximilians-Universität München München Germany Department of Physics Bogazici University Istanbul Turkey Istanbul University Dept. of Physics Istanbul Turkey Département de Physique Nucléaire et Corpusculaire Université de Genève Genève Switzerland Particle Physics Department Rutherford Appleton Laboratory Didcot United Kingdom Santa Cruz Institute for Particle Physics University of California Santa Cruz Santa CruzCA United States IJCLab Université Paris-Saclay CNRS/IN2P3 Orsay91405 France LPC Université Clermont Auvergne CNRS/IN2P3 Clermont-Ferrand France Institute for Mathematics Astrophysics and Particle Physics R

Exclusive dimuon production in ultraperipheral collisions (UPC), resulting from photon-photon interactions in the strong electromagnetic fields of colliding high-energy lead nuclei, PbPb(γγ) → μ+μ-(Pb(∗)Pb(∗)), is studied using Lint= 0.48 nb-of √SNN= 5.02 TeV lead-lead collision data at the LHC with the ATLAS detector. Dimuon pairs are measured in the fiducial region pT,μ→ > 4 GeV, |ημ| . 2.4, invariant mass mμμ→ 10 GeV, and pT,μμμμ, absolute pair rapidity (|γμμ|), scattering angle in the dimuon rest frame (|cos ∂μμ∗|) and the colliding photon energies. The total cross section of the UPC γγ → μ +μ-process in the fiducial volume is measured to be σfidμμ= 34.1±0.3(stat.)±0.7(syst.)μb. Generally good agreement is found with calculations from STARlight, which incorporate the leading-order Breit-Wheeler process with no final-state effects, albeit differences between the measurements and theoretical expectations are observed. In particular, the measured cross sections at larger |γμμ| are found to be about 10-20% larger in data than in the calculations, suggesting the presence of larger fluxes of photons in the initial state. Modification of the dimuon cross sections in the presence of forward and/or backward neutron production is also studied and is found to be associated with a harder incoming photon spectrum, consistent with expectations. © 2020, CC BY.

关键词： Binary alloys

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First-year ion-acoustic wave observations in the solar wind by the RPW/TDS instrument on board Solar Orbiter

arXiv

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arXiv 2021年

作者： Píša, David Souček, J. Santolík, O. Hanzelka, M. Nicolaou, G. Maksimovic, M. Bale, S.D. Chust, T. Khotyaintsev, Y. Krasnoselskikh, V. Kretzschmar, M. Lorfèvre, E. Plettemeier, D. Steller, M. Štverák, Š. Trávníček, P. Vaivads, A. Vecchio, A. Horbury, T. O'Brien, H. Evans, V. Angelini, V. Owen, C.J. Louarn, P. Institute of Atmospheric Physics Czech Academy of Sciences Bocni II 1401 Prague141 00 Czech Republic Faculty of Mathematics and Physics Charles University V Holesovickach 2 Prague 818000 Czech Republic Southwest Research Institute San AntonioTX78238 United States Mullard Space Science Laboratory University College London Holmbury St. Mary Surrey DorkingRH5 6NT United Kingdom LESIA Observatoire de Paris Université PSL CNRS Sorbonne Université Univ. Paris Diderot Sorbonne Paris Cité 5 place Jules Janssen Meudon92195 France Space Sciences Laboratory University of California BerkeleyCA United States Physics Department University of California BerkeleyCA United States LPP CNRS Ecole Polytechnique Sorbonne Université Observatoire de Paris Université Paris-Saclay Palaiseau Paris France Uppsala Sweden LPC2E CNRS 3A avenue de la Recherche Scientifique Orléans France Université d'Orléans Orléans France CNES 18 Avenue Edouard Belin Toulouse31400 France Technische Universität Dresden Würzburger Str. 35 DresdenD-01187 Germany Space Research Institute Austrian Academy of Sciences Graz Austria Astronomical Institute The Czech Academy of Sciences Prague Czech Republic Department of Space and Plasma Physics School of Electrical Engineering and Computer Science Royal Institute of Technology Stockholm Sweden Radboud Radio Lab Department of Astrophysics Radboud University Nijmegen Netherlands Department of Physics Imperial College LondonSW7 2AZ United Kingdom Institut de Recherche en Astrophysique et Planétologie 9 Avenue du Colonel ROCHE BP 4346 Toulouse Cedex 431028 France

Context. Electric field measurements of the Time Domain Sampler (TDS) receiver, part of the Radio and Plasma Waves (RPW) instrument on board Solar Orbiter, often exhibit very intense broadband wave emissions at frequencies below 20 kHz in the spacecraft frame. During the first year of the mission, the RPW/TDS instrument was operating from the first perihelion in mid-June 2020 and through the first flyby of Venus in late December 2020. Aims. In this paper, we present a year-long study of electrostatic fluctuations observed in the solar wind at an interval of heliocentric distances from 0.5 to 1 AU. The RPW/TDS observations provide a nearly continuous data set for a statistical study of intense waves below the local plasma frequency. Methods. The on-board and continuously collected and processed properties of waveform snapshots allow for the mapping plasma waves at frequencies between 200 Hz and 20 kHz. We used the triggered waveform snapshots and a Doppler-shifted solution of the dispersion relation for wave mode identification in order to carry out a detailed spectral and polarization analysis. Results. Electrostatic ion-acoustic waves are the most common wave emissions observed between the local electron and proton plasma frequency by the TDS receiver during the first year of the mission. The occurrence rate of ion-acoustic waves peaks around perihelion at distances of 0.5 AU and decreases with increasing distances, with only a few waves detected per day at 0.9 AU. Waves are more likely to be observed when the local proton moments and magnetic field are highly variable. A more detailed analysis of more than 10000 triggered waveform snapshots shows the mean wave frequency at about 3 kHz and wave amplitude about 2.5 mV/m. The wave amplitude varies as R-1.38 with the heliocentric distance. The relative phase distribution between two components of the E-field projected in the Y-Z Spacecraft Reference Frame (SRF) plane shows a mostly linear wave polarization. Electric f

关键词： Polarization

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Constraints on the χc1 versus χc2 Polarizations in Proton-Proton Collisions at s=8 TeV

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Physical Review Letters 2020年第16期124卷 162002-162002页

作者： A. M. Sirunyan A. Tumasyan W. Adam F. Ambrogi T. Bergauer M. Dragicevic J. Erö A. Escalante Del Valle M. Flechl R. Frühwirth M. Jeitler N. Krammer I. Krätschmer D. Liko T. Madlener I. Mikulec N. Rad J. Schieck R. Schöfbeck M. Spanring W. Waltenberger C.-E. Wulz M. Zarucki V. Drugakov V. Mossolov J. Suarez Gonzalez M. R. Darwish E. A. De Wolf D. Di Croce X. Janssen T. Kello A. Lelek M. Pieters H. Rejeb Sfar H. Van Haevermaet P. Van Mechelen S. Van Putte N. Van Remortel F. Blekman E. S. Bols S. S. Chhibra J. D’Hondt J. De Clercq D. Lontkovskyi S. Lowette I. Marchesini S. Moortgat Q. Python S. Tavernier W. Van Doninck P. Van Mulders D. Beghin B. Bilin B. Clerbaux G. De Lentdecker H. Delannoy B. Dorney L. Favart A. Grebenyuk A. K. Kalsi L. Moureaux A. Popov N. Postiau E. Starling L. Thomas C. Vander Velde P. Vanlaer D. Vannerom T. Cornelis D. Dobur I. Khvastunov M. Niedziela C. Roskas K. Skovpen M. Tytgat W. Verbeke B. Vermassen M. Vit G. Bruno C. Caputo P. David C. Delaere M. Delcourt A. Giammanco V. Lemaitre J. Prisciandaro A. Saggio P. Vischia J. Zobec G. A. Alves G. Correia Silva C. Hensel A. Moraes E. Belchior Batista Das Chagas W. Carvalho J. Chinellato E. Coelho E. M. Da Costa G. G. Da Silveira D. De Jesus Damiao C. De Oliveira Martins S. Fonseca De Souza H. Malbouisson J. Martins D. Matos Figueiredo M. Medina Jaime M. Melo De Almeida C. Mora Herrera L. Mundim H. Nogima W. L. Prado Da Silva P. Rebello Teles L. J. Sanchez Rosas A. Santoro A. Sznajder M. Thiel E. J. Tonelli Manganote F. Torres Da Silva De Araujo A. Vilela Pereira C. A. Bernardes L. Calligaris T. R. Fernandez Perez Tomei E. M. Gregores D. S. Lemos P. G. Mercadante S. F. Novaes Sandra S. Padula A. Aleksandrov G. Antchev R. Hadjiiska P. Iaydjiev M. Misheva M. Rodozov M. Shopova G. Sultanov M. Bonchev A. Dimitrov T. Ivanov L. Litov B. Pavlov P. Petkov A. Petrov W. Fang X. Gao L. Yuan M. Ahmad Z. Hu Y. Wang G. M. Chen H. S. Chen M. Chen C. H. Jiang D. Leggat H. Liao Z. Liu A. Spiezia J. Tao E. Yazgan H. Zhang S. Zhang J. Zhao A. Agapitos Y. Ban G. Ch Yerevan Physics Institute Yerevan Armenia Institut für Hochenergiephysik Wien Austria Institute for Nuclear Problems Minsk Belarus Universiteit Antwerpen Antwerpen Belgium Vrije Universiteit Brussel Brussel Belgium Université Libre de Bruxelles Bruxelles Belgium Ghent University Ghent Belgium Université Catholique de Louvain Louvain-la-Neuve Belgium Centro Brasileiro de Pesquisas Fisicas Rio de Janeiro Brazil Universidade do Estado do Rio de Janeiro Rio de Janeiro Brazil Universidade Estadual Paulista São Paulo Brazil Universidade Federal do ABC São Paulo Brazil Institute for Nuclear Research and Nuclear Energy Bulgarian Academy of Sciences Sofia Bulgaria University of Sofia Sofia Bulgaria Beihang University Beijing China National Centre for Physics Quaid-I-Azam University Islamabad Pakistan Department of Physics Tsinghua University Beijing China University of Virginia Charlottesville Virginia USA Institute of High Energy Physics Beijing China State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China The University of Kansas Lawrence Kansas USA Zhejiang University Hangzhou China Universidad de Los Andes Bogota Colombia Universidad de Antioquia Medellin Colombia University of Split Faculty of Electrical Engineering Mechanical Engineering and Naval Architecture Split Croatia University of Split Faculty of Science Split Croatia Institute Rudjer Boskovic Zagreb Croatia University of Cyprus Nicosia Cyprus Charles University Prague Czech Republic Escuela Politecnica Nacional Quito Ecuador Universidad San Francisco de Quito Quito Ecuador Academy of Scientific Research and Technology of the Arab Republic of Egypt Egyptian Network of High Energy Physics Cairo Egypt National Institute of Chemical Physics and Biophysics Tallinn Estonia Department of Physics University of Helsinki Helsinki Finland Helsinki Institute of Physics Helsinki Finland Lappeenranta University of Technology Lappeenranta Finland IRFU CEA Un

The polarizations of promptly produced χc1 and χc2 mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at s=8 TeV. The χc states are reconstructed via their radiative decays χc→J/ψγ, with the photons being measured through conversions to e+e−, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χc2 to χc1 yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ→μ+μ− decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum.

关键词： Charm quark Polarization Hadron colliders

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The 2-Genus of Kuratowski minors

The 2-Genus of Kuratowski minors

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34th International Symposium on Computational Geometry, SoCG 2018

作者： Fulek, Radoslav Kynčl, Jan IST Austria Am Campus 1 Klosterneuburg3400 Austria Department of Applied Mathematics Institute for Theoretical Computer Science Charles University Faculty of Mathematics and Physics Malostranské nám. 25 Praha 1118 00 Czech Republic

ISBN: (纸本)9783959770668

A drawing of a graph on a surface is independently even if every pair of nonadjacent edges in the drawing crosses an even number of times. The 2-genus of a graph G is the minimum g such that G has an independently even drawing on the orientable surface of genus g. An unpublished result by Robertson and Seymour implies that for every t, every graph of sufficiently large genus contains as a minor a projective t × t grid or one of the following so-called t-Kuratowski graphs: K3, t, or t copies of K5 or K3,3 sharing at most 2 common vertices. We show that the 2-genus of graphs in these families is unbounded in t;in fact, equal to their genus. Together, this implies that the genus of a graph is bounded from above by a function of its 2-genus, solving a problem posed by Schaefer and Štefankovič, and giving an approximate version of the Hanani-Tutte theorem on orientable surfaces. © Radoslav Fulek and Jan Kynčl;licensed under Creative Commons License CC-BY 34th Symposium on Computational Geometry (SoCG 2018).

关键词： Graph theory

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Localizability, gauge symmetry and Newton-Wigner operator for massless particles

arXiv

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arXiv 2018年

作者： Kosiński, P. Maślanka, P. Department of Computer Science Faculty of Physics and Applied Informatics University of Lódź Pomorska 149/153 Lódź90-236 Poland

The notion of position operator for massless spinning particles is discussed in some detail. The noncommutativity of coordinates is related to the gauge symmetry following from the freedom in definition of standard state in Wigner's construction of induced representations of Poincare group. The counterpart of Newton-Wigner operator is discussed. It is explained why the Newton-Wigner construction works only for helicity | λ |≤ 1/2. Copyright © 2018, The Authors. All rights reserved.

关键词： Gages

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Estimating relationship between the Time over Threshold and energy loss by photons in plastic scintillators used in the J-PET scanner

arXiv

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arXiv 2019年

作者： Sharma, S. Chhokar, J. Curceanu, C. Czerwinski, E. Dadgar, M. Dulski, K. Gajewski, J. Gajos, A. Gorgol, M. Gupta-Sharma, N. Del Grande, R. Hiesmayr, B.C. Jasinska, B. Kacprzak, K. Kaplon, L. Karimi, H. Kisielewska, D. Klimaszewski, K. Korcyl, G. Kowalski, P. Kozik, T. Krawczyk, N. Krzemien, W. Kubicz, E. Mohammed, M. Niedzwiecki, S.Z. Palka, M. Pawlik-Niedzwiecka, M. Raczynski, L. Raj, J. Rucinski, A. Shivani Shopa, R.Y. Silarski, M. Skurzok, M. Stepien, E.L. Wislicki, W. Zgardzinska, B. Moskal, P. Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University prof. StanisLawa Lojasiewicza 11 Cracow30-348 Poland INFN Laboratori Nazionali di Frascati Frascati00044 Italy Institute of Nuclear Physics PAN Cracow Poland Institute of Physics Maria Curie-SkLodowska University Lublin20-031 Poland Faculty of Physics University of Vienna Vienna1090 Austria Department of Complex Systems National Centre for Nuclear Research Otwock-Swierk05-400 Poland High Energy Physics Division National Centre for Nuclear Research Otwock-Swierk05-400 Poland Department of Physics College of Education for Pure Sciences University of Mosul Mosul Iraq

Purpose: Time-Over-Threshold (TOT) technique is being used widely due to its implications in developing the multi-channel readouts mainly when fast signal processing is required. Using TOT technique as a measure of energy loss instead of charge integration methods significantly reduces the signals readout cost by combining the time and energy information. Therefore, this approach can potentially be used in J-PET tomograph which is build from plastic scintillators characterized by fast light signals. The drawback in adopting this technique is lying in the non-linear correlation between input energy loss and TOT of the signal. The main motivation behind this work is to develop the relationship between TOT and energy loss and validate it with the J-PET tomograph. Methods: The experiment was performed using the 22Na beta emitter source placed in the center of the J-PET tomograph. One can obtain primary photons of two different energies: 511 keV photon from the annihilation of positron (direct annihilation or through the formation of para-Positronim atom or pick-off process of ortho-Positronium atoms), and 1275 keV prompt photon. This allows to study the correlation between TOT values and energy loss for energy range up to 1000 keV. As the photon interacts dominantly via Compton scattering inside the plastic scintillator, there is no direct information of primary photon's energy. However, using the J-PET geometry one can measure the scattering angle of the interacting photon. Since, 22Na source emits photons of two different energies, it is required to know unambiguously the energy of incident photons and its corresponding scattering angle for the estimation of energy deposition. In this work, dedicated algorithms were developed to tag the photons of different energies and studying their scattering angles to calculate the energy deposition by the interacting photons. Results: A new method was elaborated to measure the energy loss by interacting photons with plastic scint

关键词： Positron emission tomography

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Isospin Amplitudes in Λb0→J/ψΛ(Σ0) and Ξb0→J/ψΞ0(Λ) Decays

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Physical Review Letters 2020年第11期124卷 111802-111802页

作者： R. Aaij C. Abellán Beteta T. Ackernley B. Adeva M. Adinolfi H. Afsharnia C. A. Aidala S. Aiola Z. Ajaltouni S. Akar P. Albicocco J. Albrecht F. Alessio M. Alexander A. Alfonso Albero G. Alkhazov P. Alvarez Cartelle A. A. Alves, Jr. S. Amato Y. Amhis L. An L. Anderlini G. Andreassi M. Andreotti F. Archilli J. Arnau Romeu A. Artamonov M. Artuso K. Arzymatov E. Aslanides M. Atzeni B. Audurier S. Bachmann J. J. Back S. Baker V. Balagura W. Baldini A. Baranov R. J. Barlow S. Barsuk W. Barter M. Bartolini F. Baryshnikov G. Bassi V. Batozskaya B. Batsukh A. Battig A. Bay M. Becker F. Bedeschi I. Bediaga A. Beiter L. J. Bel V. Belavin S. Belin N. Beliy V. Bellee K. Belous I. Belyaev G. Bencivenni E. Ben-Haim S. Benson S. Beranek A. Berezhnoy R. Bernet D. Berninghoff H. C. Bernstein C. Bertella E. Bertholet A. Bertolin C. Betancourt F. Betti M. O. Bettler Ia. Bezshyiko S. Bhasin J. Bhom M. S. Bieker S. Bifani P. Billoir A. Bizzeti M. Bjørn M. P. Blago T. Blake F. Blanc S. Blusk D. Bobulska V. Bocci O. Boente Garcia T. Boettcher A. Boldyrev A. Bondar N. Bondar S. Borghi M. Borisyak M. Borsato J. T. Borsuk T. J. V. Bowcock C. Bozzi M. J. Bradley S. Braun A. Brea Rodriguez M. Brodski J. Brodzicka A. Brossa Gonzalo D. Brundu E. Buchanan A. Buonaura C. Burr A. Bursche J. S. Butter J. Buytaert W. Byczynski S. Cadeddu H. Cai R. Calabrese L. Calero Diaz S. Cali R. Calladine M. Calvi M. Calvo Gomez P. Camargo Magalhaes A. Camboni P. Campana D. H. Campora Perez L. Capriotti A. Carbone G. Carboni R. Cardinale A. Cardini P. Carniti K. Carvalho Akiba A. Casais Vidal G. Casse M. Cattaneo G. Cavallero S. Celani R. Cenci J. Cerasoli M. G. Chapman M. Charles Ph. Charpentier G. Chatzikonstantinidis M. Chefdeville V. Chekalina C. Chen S. Chen A. Chernov S.-G. Chitic V. Chobanova M. Chrzaszcz A. Chubykin P. Ciambrone M. F. Cicala X. Cid Vidal G. Ciezarek F. Cindolo P. E. L. Clarke M. Clemencic H. V. Cliff J. Closier J. L. Cobbledick V. Coco J. A. B. Coelho J. Cogan E. Cogneras L. Cojocariu P. Collins T. Colombo A. Comerma-Montells A. Contu N Nikhef National Institute for Subatomic Physics Amsterdam Netherlands Physik-Institut Universität Zürich Zürich Switzerland Oliver Lodge Laboratory University of Liverpool Liverpool United Kingdom Instituto Galego de Física de Altas Enerxías (IGFAE) Universidade de Santiago de Compostela Santiago de Compostela Spain H.H. Wills Physics Laboratory University of Bristol Bristol United Kingdom Université Clermont Auvergne CNRS/IN2P3 LPC Clermont-Ferrand France INFN Sezione di Milano Milano Italy Los Alamos National Laboratory (LANL) Los Alamos USA INFN Laboratori Nazionali di Frascati Frascati Italy Fakultät Physik Technische Universität Dortmund Dortmund Germany European Organization for Nuclear Research (CERN) Geneva Switzerland School of Physics and Astronomy University of Glasgow Glasgow United Kingdom ICCUB Universitat de Barcelona Barcelona Spain Petersburg Nuclear Physics Institute NRC Kurchatov Institute (PNPI NRC KI) Gatchina Russia Imperial College London London United Kingdom Universidade Federal do Rio de Janeiro (UFRJ) Rio de Janeiro Brazil LAL Univ. Paris-Sud CNRS/IN2P3 Université Paris-Saclay Orsay France INFN Sezione di Firenze Firenze Italy Institute of Physics Ecole Polytechnique Fédérale de Lausanne (EPFL) Lausanne Switzerland INFN Sezione di Ferrara Ferrara Italy Physikalisches Institut Ruprecht-Karls-Universität Heidelberg Heidelberg Germany Aix Marseille Univ CNRS/IN2P3 CPPM Marseille France Institute for High Energy Physics NRC Kurchatov Institute (IHEP NRC KI) Protvino Russia Protvino Russia Syracuse University Syracuse New York USA Yandex School of Data Analysis Moscow Russia INFN Sezione di Cagliari Monserrato Italy Department of Physics University of Warwick Coventry United Kingdom Department of Physics and Astronomy University of Manchester Manchester United Kingdom INFN Sezione di Genova Genova Italy INFN Sezione di Pisa Pisa Italy National Center for Nuclear Research (NCBJ) Warsaw Poland Centro Brasileiro

Ratios of isospin amplitudes in hadron decays are a useful probe of the interplay between weak and strong interactions and allow searches for physics beyond the standard model. We present the first results on isospin amplitudes in b-baryon decays, using data corresponding to an integrated luminosity of 8.5 fb−1, collected with the LHCb detector in pp collisions at center of mass energies of 7, 8, and 13 TeV. The isospin amplitude ratio |A1(Λb0→J/ψΣ0)/A0(Λb0→J/ψΛ)|, where the subscript on A indicates the final-state isospin, is measured to be less than 1/21.8 at 95% confidence level. The Cabibbo suppressed Ξb0→J/ψΛ decay is observed for the first time, allowing for the measurement |A0(Ξb0→J/ψΛ)/A1/2(Ξb0→J/ψΞ0)|=0.37±0.06±0.02, where the uncertainties are statistical and systematic, respectively.

关键词： Particle decays Quark model Strong interaction

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MODIFIED GRAVITY AND COSMOLOGY: An Update by the CANTATA Network

arXiv

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arXiv 2021年

作者： Saridakis, Emmanuel N. Lazkoz, Ruth Salzano, Vincenzo Moniz, Paulo Vargas Capozziello, Salvatore Jiménez, Jose Beltrán De Laurentis, Mariafelicia Olmo, Gonzalo J. Akrami, Yashar Bahamonde, Sebastian Blázquez-Salcedo, Jose Luis Böhmer, Christian G. Bonvin, Camille Bouhmadi-López, Mariam Brax, Philippe Calcagni, Gianluca Casadio, Roberto Cembranos, Jose A.R. de la Cruz-Dombriz, Álvaro Davis, Anne-Christine Delhom, Adrià Valentino, Eleonora Di Dialektopoulos, Konstantinos F. Elder, Benjamin Ezquiaga, Jose María Frusciante, Noemi Garattini, Remo Gergely, László Á. Giusti, Andrea Heisenberg, Lavinia Hohmann, Manuel Iosifidis, Damianos Kazantzidis, Lavrentios Kleihaus, Burkhard Koivisto, Tomi S. Kunz, Jutta Lobo, Francisco S.N. Martinelli, Matteo Martín-Moruno, Prado Mimoso, José Pedro Mota, David F. Peirone, Simone Perivolaropoulos, Leandros Pettorino, Valeria Pfeifer, Christian Pizzuti, Lorenzo Rubiera-Garcia, Diego Said, Jackson Levi Sakellariadou, Mairi Saltas, Ippocratis D. Mancini, Alessio Spurio Voicu, Nicoleta Wojnar, Aneta National Observatory of Athens Lofos Nymfon Athens11852 Greece CAS Key Laboratory for Researches in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Anhui Hefei230026 China School of Astronomy School of Physical Sciences University of Science and Technology of China Hefei230026 China Department of Theoretical Physics University of the Basque Country UPV/EHU P.O. Box 644 Bilbao48080 Spain Institute of Physics University of Szczecin Wielkopolska 15 Szczecin70-451 Poland Universidade da Beira Interior Covilhã6200 Portugal DAMTP Centre for Mathematical Sciences University of Cambridge CB3 0WA United Kingdom Dipartimento di Fisica "E. Pancini" Universitá di Napoli "Federico II" Napoli80126 Italy INFN Sezione di Napoli Complesso Universitario di Monte S. Angelo Via Cintia Edificio 6 Napoli80126 Italy Tomsk634050 Russia Departamento de Física Fundamental IUFFyM Universidad de Salamanca SalamancaE-37008 Spain Sezione di Torino Via P. Giuria 1 TorinoI-10125 Italy Depto. de Física Teórica and IFIC Centro Mixto Universidad de Valencia-CSIC Burjassot- Valencia46100 Spain Departamento de Física Universidade Federal da Paraíba Paraíba João Pessoa58051-900 Brazil Laboratoire de Physique de l’École Normale Supérieure ENS Université PSL CNRS Sorbonne Université Université de Paris ParisF-75005 France Observatoire de Paris Université PSL Sorbonne Université LERMA Paris75014 France Laboratory of Theoretical Physics Institute of Physics University of Tartu W. Ostwaldi 1 Tartu50411 Estonia Department of Mathematics University College London Gower Street LondonWC1E 6BT United Kingdom Departamento de Física Teórica IPARCOS Universidad Complutense de Madrid MadridE-28040 Spain Départment de Physique Théorique Center for Astroparticle Physics Université de Genève 24 quai Ernest-Ansermet Genève 4CH-1211 Switzerland IKERBASQUE Basque Foundation for Science Bilbao48011 Spain Institut de Phy

General Relativity and the ΛCDM framework are currently the standard lore and constitute the concordance paradigm. Nevertheless, long-standing open theoretical issues, as well as possible new observational ones arising from the explosive development of cosmology the last two decades, offer the motivation and lead a large amount of research to be devoted in constructing various extensions and modifications. All extended theories and scenarios are first examined under the light of theoretical consistency, and then are applied to various geometrical backgrounds, such as the cosmological and the spherical symmetric ones. Their predictions at both the background and perturbation levels, and concerning cosmology at early, intermediate and late times, are then confronted with the huge amount of observational data that astrophysics and cosmology are able to offer recently. Theories, scenarios and models that successfully and efficiently pass the above steps are classified as viable and are candidates for the description of Nature. This work is a Review of the recent developments in the fields of gravity and cosmology, presenting the state of the art, high-lighting the open problems, and outlining the directions of future research. Its realization was performed in the framework of the COST European Action "Cosmology and Astrophysics Network for Theoretical Advances and Training Actions". Copyright © 2021, The Authors. All rights reserved.

关键词： Cosmology

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Search for Supersymmetry with a Compressed Mass Spectrum in Events with a Soft τ Lepton, a Highly Energetic Jet, and Large Missing Transverse Momentum in Proton-Proton Collisions at s=13 TeV

引用

Physical Review Letters 2020年第4期124卷 041803-041803页

作者： A. M. Sirunyan A. Tumasyan W. Adam F. Ambrogi T. Bergauer J. Brandstetter M. Dragicevic J. Erö A. Escalante Del Valle M. Flechl R. Frühwirth M. Jeitler N. Krammer I. Krätschmer D. Liko T. Madlener I. Mikulec N. Rad J. Schieck R. Schöfbeck M. Spanring D. Spitzbart W. Waltenberger C.-E. Wulz M. Zarucki V. Drugakov V. Mossolov J. Suarez Gonzalez M. R. Darwish E. A. De Wolf D. Di Croce X. Janssen A. Lelek M. Pieters H. Rejeb Sfar H. Van Haevermaet P. Van Mechelen S. Van Putte N. Van Remortel F. Blekman E. S. Bols S. S. Chhibra J. D’Hondt J. De Clercq D. Lontkovskyi S. Lowette I. Marchesini S. Moortgat Q. Python K. Skovpen S. Tavernier W. Van Doninck P. Van Mulders D. Beghin B. Bilin H. Brun B. Clerbaux G. De Lentdecker H. Delannoy B. Dorney L. Favart A. Grebenyuk A. K. Kalsi A. Popov N. Postiau E. Starling L. Thomas C. Vander Velde P. Vanlaer D. Vannerom T. Cornelis D. Dobur I. Khvastunov M. Niedziela C. Roskas M. Tytgat W. Verbeke B. Vermassen M. Vit O. Bondu G. Bruno C. Caputo P. David C. Delaere M. Delcourt A. Giammanco V. Lemaitre J. Prisciandaro A. Saggio M. Vidal Marono P. Vischia J. Zobec F. L. Alves G. A. Alves G. Correia Silva C. Hensel A. Moraes P. Rebello Teles E. Belchior Batista Das Chagas W. Carvalho J. Chinellato E. Coelho E. M. Da Costa G. G. Da Silveira D. De Jesus Damiao C. De Oliveira Martins S. Fonseca De Souza L. M. Huertas Guativa H. Malbouisson J. Martins D. Matos Figueiredo M. Medina Jaime M. Melo De Almeida C. Mora Herrera L. Mundim H. Nogima W. L. Prado Da Silva L. J. Sanchez Rosas A. Santoro A. Sznajder M. Thiel E. J. Tonelli Manganote F. Torres Da Silva De Araujo A. Vilela Pereira C. A. Bernardes L. Calligaris T. R. Fernandez Perez Tomei E. M. Gregores D. S. Lemos P. G. Mercadante S. F. Novaes Sandra S. Padula A. Aleksandrov G. Antchev R. Hadjiiska P. Iaydjiev M. Misheva M. Rodozov M. Shopova G. Sultanov M. Bonchev A. Dimitrov T. Ivanov L. Litov B. Pavlov P. Petkov W. Fang X. Gao L. Yuan G. M. Chen H. S. Chen M. Chen C. H. Jiang D. Leggat H. Liao Z. Liu A. Spiezia J. Tao E. Yazgan H. Zhang Yerevan Physics Institute Yerevan Armenia Institut für Hochenergiephysik Wien Austria Institute for Nuclear Problems Minsk Belarus Universiteit Antwerpen Antwerpen Belgium Vrije Universiteit Brussel Brussel Belgium Université Libre de Bruxelles Bruxelles Belgium Ghent University Ghent Belgium Université Catholique de Louvain Louvain-la-Neuve Belgium Centro Brasileiro de Pesquisas Fisicas Rio de Janeiro Brazil Universidade do Estado do Rio de Janeiro Rio de Janeiro Brazil Universidade Estadual Paulista São Paulo Brazil Universidade Federal do ABC São Paulo Brazil Institute for Nuclear Research and Nuclear Energy Bulgarian Academy of Sciences Sofia Bulgaria University of Sofia Sofia Bulgaria Beihang University Beijing China Institute of High Energy Physics Beijing China State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China The University of Kansas Lawrence Kansas USA National Centre for Physics Quaid-I-Azam University Islamabad Pakistan Tsinghua University Beijing China University of Virginia Charlottesville Virginia USA Zhejiang University Hangzhou China Universidad de Los Andes Bogota Colombia Universidad de Antioquia Medellin Colombia University of Split Faculty of Electrical Engineering Mechanical Engineering and Naval Architecture Split Croatia University of Split Faculty of Science Split Croatia Institute Rudjer Boskovic Zagreb Croatia University of Cyprus Nicosia Cyprus Charles University Prague Czech Republic Escuela Politecnica Nacional Quito Ecuador Universidad San Francisco de Quito Quito Ecuador Academy of Scientific Research and Technology of the Arab Republic of Egypt Egyptian Network of High Energy Physics Cairo Egypt National Institute of Chemical Physics and Biophysics Tallinn Estonia Department of Physics University of Helsinki Helsinki Finland Helsinki Institute of Physics Helsinki Finland Lappeenranta University of Technology Lappeenranta Finland IRFU CEA Université Paris-Saclay

The first search for supersymmetry in events with an experimental signature of one soft, hadronically decaying τ lepton, one energetic jet from initial-state radiation, and large transverse momentum imbalance is presented. These event signatures are consistent with direct or indirect production of scalar τ leptons (τ˜) in supersymmetric models that exhibit coannihilation between the τ˜ and the lightest neutralino (χ˜10), and that could generate the observed relic density of dark matter. The data correspond to an integrated luminosity of 77.2 fb−1 of proton-proton collisions at s=13 TeV collected with the CMS detector at the LHC in 2016 and 2017. The results are interpreted in a supersymmetric scenario with a small mass difference (Δm) between the chargino (χ˜1±) or next-to-lightest neutralino (χ˜20), and the χ˜10. The mass of the τ˜ is assumed to be the average of the χ˜1± and χ˜10 masses. The data are consistent with standard model background predictions. Upper limits at 95% confidence level are set on the sum of the χ˜1±, χ˜20, and τ˜ production cross sections for Δm(χ˜1±,χ˜10)=50 GeV, resulting in a lower limit of 290 GeV on the mass of the χ˜1±, which is the most stringent to date and surpasses the bounds from the LEP experiments.

关键词： Supersymmetric models Superpartners Tau leptons Hadron colliders

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GRID: A Student Project to Monitor the Transient Gamma-Ray Sky in the Multi-Messenger Astronomy Era

arXiv

引用

arXiv 2019年

作者： Wen, Jiaxing Long, Xiangyun Zheng, Xutao An, Yu Cai, Zhengyang Cang, Jirong Che, Yuepeng Chen, Changyu Chen, Liangjun Chen, Qianjun Chen, Ziyun Cheng, Yingjie Deng, Litao Deng, Wei Ding, Wenqing Du, Hangci Duan, Lian Gan, Quan Gao, Tai Gao, Zhiying Han, Wenbin Han, Yiying He, Xinbo He, Xinhao Hou, Long Hu, Fan Hu, Junling Huang, Bo Huang, Dongyang Huang, Xuefeng Jia, Shihai Jiang, Yuchen Jin, Yifei Li, Ke Li, Siyao Li, Yurong Liang, Jianwei Liang, Yuanyuan Lin, Wei Liu, Chang Liu, Gang Liu, Mengyuan Liu, Rui Liu, Tianyu Liu, Wanqiang Lu, Di'an Lu, Peiyibin Lu, Zhiyong Luo, Xiyu Ma, Sizheng Ma, Yuanhang Mao, Xiaoqing Mo, Yanshan Nie, Qiyuan Qu, Shuiyin Shan, Xiaolong Shi, Gengyuan Song, Weiming Sun, Zhigang Tan, Xuelin Tang, Songsong Tao, Mingrui Wang, Boqin Wang, Yue Wang, Zhiang Wu, Qiaoya Wu, Xuanyi Xia, Yuehan Xiao, Hengyuan Xie, Wenjin Xu, Dacheng Xu, Rui Xu, Weili Yan, Longbiao Yan, Shengyu Yang, Dongxin Yang, Hang Yang, Haoguang Yang, Yi-Si Yang, Yifan Yao, Lei Yu, Huan Yu, Yangyi Zhang, Aiqiang Zhang, Bingtao Zhang, Lixuan Zhang, Maoxing Zhang, Shen Zhang, Tianliang Zhang, Yuchong Zhao, Qianru Zhao, Ruining Zheng, Shiyu Zhou, Xiaolong Zhu, Runyu Zou, Yu An, Peng Cai, Yifu Chen, Hongbing Dai, Zigao Fan, Yizhong Feng, Changqing Feng, Hua Gao, He Huang, Liang Kang, Mingming Li, Lixin Li, Zhuo Liang, Enwei Lin, Lin Lin, Qianqian Liu, Congzhan Liu, Hongbang Liu, Xuewen Liu, Yinong Lu, Xiang Mao, Shude Shen, Rongfeng Shu, Jing Su, Meng Sun, Hui Tam, Pak-Hin Tang, Chi-Pui Tian, Yang Wang, Fayin Wang, Jianjun Wang, Wei Wang, Zhonghai Wu, Jianfeng Wu, Xuefeng Xiong, Shaolin Xu, Can Yu, Jiandong Yu, Wenfei Yu, Yunwei Zeng, Ming Zeng, Zhi Zhang, Bin-Bin Zhang, Bing Zhao, Zongqing Zhou, Rong Zhu, Zonghong Department of Engineering Physics Center for Astrophysics Tsinghua University Beijing100084 China Science and Technology on Plasma Physics Laboratory Laser Fusion Research Center Chinese Academy of Engineering Physics Mianyang621900 China Department of Physics Center for Astrophysics Tsinghua University Beijing100084 China Guangxi Key Laboratory for Relativistic Astrophysics Department of Physics Guangxi University NanningGuangxi530004 China School of Electronic and Information Engineering Ningbo University of Technology NingboZhejiang315211 China Department of Instruments Science & Engineering Shanghai Jiaotong University Shanghai200240 · China School of Materials Science & Chemical Engineering Ningbo University Ningbo315211 China School of Astronomy and Space Science Nanjing University NanjingJiangsu210093 China School of Aerospace Engineering Tsinghua University Beijing100084 China College of Physical Science and Technology Sichuan University Chengdu610065 China School of Physics and Astronomy Sun Yat-Sen University Zhuhai519082 China Department of Astronomy Xiamen University XiamenFujian361005 China School of Mathematics and Physics University of Science and Technology Beijing Beijing100083 China Department of Foreign Languages and Literatures Tsinghua University Beijing100084 China Department of Electrical Engineering Tsinghua University Beijing100084 China School of Software Tsinghua University Beijing100084 China Faculty of Electrical Engineering and Computer Science Ningbo University Ningbo315211 China Department of Modern Physics School of Physical Sciences University of Science and Technology of China HefeiAnhui230026 China Department of Astronomy Beijing Normal University Beijing100875 China Department of Astronomy School of Physical Sciences University of Science and Technology of China HefeiAnhui230026 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing210008 China Department of Astrono

The Gamma-Ray Integrated Detectors (GRID) is a space mission concept dedicated to monitoring the transient gamma-ray sky in the energy range from 10 keV to 2 MeV using scintillation detectors onboard CubeSats in low Earth orbits. The primary targets of GRID are the gamma-ray bursts (GRBs) in the local universe. The scientific goal of GRID is, in synergy with ground-based gravitational wave (GW) detectors such as LIGO and VIRGO, to accumulate a sample of GRBs associated with the merger of two compact stars and study jets and related physics of those objects. It also involves observing and studying other gamma-ray transients such as long GRBs, soft gamma-ray repeaters, terrestrial gamma-ray flashes, and solar flares. With multiple CubeSats in various orbits, GRID is unaffected by the Earth occultation and serves as a full-time and all-sky monitor. Assuming a horizon of 200 Mpc for ground-based GW detectors, we expect to see a few associated GW-GRB events per year. With about 10 CubeSats in operation, GRID is capable of localizing a faint GRB like 170817A with a 90% error radius of about 10 degrees, through triangulation and flux modulation. GRID is proposed and developed by students, with considerable contribution from undergraduate students, and will remain operated as a student project in the future. The current GRID collaboration involves more than 20 institutes and keeps growing. On August 29th, the first GRID detector onboard a CubeSat was launched into a Sun-synchronous orbit and is currently under test. Copyright © 2019, The Authors. All rights reserved.

关键词： Gravity waves

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