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Evidence for four-top quark production in proton-proton collisions at s=13TeV

Physics Letters, Section b: Nuclear, Elementary Particle and High-Energy Physics 2023年 844卷

作者： Tumasyan, A. Adam, W. Andrejkovic, J.W. bergauer, T. Chatterjee, S. Damanakis, K. Dragicevic, M. Escalante Del Valle, A. Hussain, P.S. Jeitler, M. Krammer, N. Lechner, L. Liko, D. Mikulec, I. Paulitsch, P. Schieck, J. Schöfbeck, R. Schwarz, D. Sonawane, M. Templ, S. Waltenberger, W. Wulz, C.-E. Darwish, M.R. Janssen, T. Kello, T. Rejeb Sfar, H. Van Mechelen, P. bols, E.S. De Moor, A. Delcourt, M. El Faham, H. Lowette, S. Morton, A. Müller, D. Sahasransu, A.R. Tavernier, S. Van Doninck, W. Van Putte, S. Vannerom, D. Clerbaux, b. Dansana, S. De Lentdecker, G. Favart, L. Hohov, D. Jaramillo, J. Lee, K. Mahdavikhorrami, M. Makarenko, I. Malara, A. Paredes, S. Pétré, L. Postiau, N. Thomas, L. Vanden bemden, M. Vander Velde, C. Vanlaer, P. Dobur, D. Knolle, J. Lambrecht, L. Mestdach, G. Rendón, C. Samalan, A. Skovpen, K. Tytgat, M. Van Den bossche, N. Vermassen, b. Wezenbeek, L. benecke, A. bruno, G. bury, F. Caputo, C. David, P. Delaere, C. Donertas, I.S. Giammanco, A. Jaffel, K. Jain, Sa. Lemaitre, V. Mondal, K. Taliercio, A. Tran, T.T. Vischia, P. Wertz, S. Alves, G.A. Coelho, E. Hensel, C. Moraes, A. Rebello Teles, P. Aldá Júnior, W.L. Alves Gallo Pereira, M. barroso Ferreira Filho, M. brandao Malbouisson, H. Carvalho, W. Chinellato, J. Da Costa, E.M. Da Silveira, G.G. De Jesus Damiao, D. Dos Santos Sousa, V. Fonseca De Souza, S. Martins, J. Mora Herrera, C. Mota Amarilo, K. Mundim, L. Nogima, H. Santoro, A. Silva Do Amaral, S.M. Sznajder, A. Thiel, M. Vilela Pereira, A. bernardes, C.A. Calligaris, L. Fernandez Perez Tomei, T.R. Gregores, E.M. Mercadante, P.G. Novaes, S.F. Padula, Sandra S. Aleksandrov, A. Antchev, G. Hadjiiska, R. Iaydjiev, P. Misheva, M. Rodozov, M. Shopova, M. Sultanov, G. Dimitrov, A. Ivanov, T. Litov, L. Pavlov, b. Petkov, P. Petrov, A. Shumka, E. Thakur, S. Cheng, T. Guo, Q. Javaid, T. Mittal, M. Yuan, L. Ahmad, M. bauer, G. Hu, Z. Lezki, S. Yi, K. Chen, G.M. Chen, H.S. Chen, M. Iemmi, F. Jiang, C.H. Kapoor, A. Liao, H. Liu, Z.-A. Milosevic, V. Monti, F. Sharma, R. Tao, J. Thomas-Wilsker, J. Yerevan Physics Institute Yerevan Armenia Institut für Hochenergiephysik Vienna Austria 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 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 Instituto De Alta Investigación Universidad de Tarapacá Casilla 7 D Arica Chile Beihang University Beijing China Department of Physics Tsinghua University Beijing China Institute of High Energy Physics Beijing China State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China Sun Yat-Sen University Guangzhou China University of Science and Technology of China Hefei China Institute of Modern Physics Key Laboratory of Nuclear Physics Ion-beam Application (MOE) Fudan University Shanghai China Zhejiang University Zhejiang 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 Center for High Energy Physics (CHEP-FU) Fayoum University El-Fayoum Egypt National Institute of Chemical Physics and Biophysics Tallinn Estonia Department of Physics Univer

The production of four top quarks (tt¯tt¯) is studied with LHC proton-proton collision data samples collected by the CMS experiment at a center-of-mass energy of 13 TeV, and corresponding to integrated luminosities of up to 138fb⁻¹. Events that have no leptons (all-hadronic), one lepton, or two opposite-sign leptons (where lepton refers only to prompt electrons or prompt muons) are considered. This is the first tt¯tt¯ measurement that includes the all-hadronic final state. The observed significance of the tt¯tt¯ signal in these final states of 3.9 standard deviations (1.5 expected) provides evidence for tt¯tt¯ production, with a measured cross section of 36b>−11b>⁺¹²fb. Combined with earlier CMS results in other final states, the signal significance is 4.0 standard deviations (3.2 expected). The combination returns an observed cross section of 17±4(stat)±3(syst)fb, which is consistent with the standard model prediction. © 2023 The Author(s)

关键词： CMS Top quark

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Search for new physics using effective field theory in 13 TeV pp collision events that contain a top quark pair and a boosted Z or Higgs boson

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Physical Review D 2023年第3期108卷 032008-032008页

作者： A. Tumasyan W. Adam J. W. Andrejkovic T. bergauer S. Chatterjee K. Damanakis M. Dragicevic A. Escalante Del Valle P. S. Hussain M. Jeitler N. Krammer L. Lechner D. Liko I. Mikulec P. Paulitsch F. M. Pitters J. Schieck R. Schöfbeck D. Schwarz S. Templ W. Waltenberger C.-E. Wulz M. R. Darwish T. Janssen T. Kello H. Rejeb Sfar P. Van Mechelen E. S. bols J. D’Hondt A. De Moor M. Delcourt H. El Faham S. Lowette S. Moortgat A. Morton D. Müller A. R. Sahasransu S. Tavernier W. Van Doninck D. Vannerom b. Clerbaux G. De Lentdecker L. Favart D. Hohov J. Jaramillo K. Lee M. Mahdavikhorrami I. Makarenko A. Malara S. Paredes L. Pétré N. Postiau E. Starling L. Thomas M. Vanden bemden C. Vander Velde P. Vanlaer D. Dobur J. Knolle L. Lambrecht G. Mestdach M. Niedziela C. Rendón C. Roskas A. Samalan K. Skovpen M. Tytgat N. Van Den bossche b. Vermassen L. Wezenbeek A. benecke G. bruno F. bury C. Caputo P. David C. Delaere I. S. Donertas A. Giammanco K. Jaffel Sa. Jain V. Lemaitre K. Mondal J. Prisciandaro A. Taliercio T. T. Tran P. Vischia S. Wertz G. A. Alves E. Coelho C. Hensel A. Moraes P. Rebello Teles W. L. Aldá Júnior M. Alves Gallo Pereira M. barroso Ferreira Filho H. brandao Malbouisson W. Carvalho J. Chinellato E. M. Da Costa G. G. Da Silveira D. De Jesus Damiao V. Dos Santos Sousa S. Fonseca De Souza J. Martins C. Mora Herrera K. Mota Amarilo L. Mundim H. Nogima A. Santoro S. M. Silva Do Amaral A. Sznajder M. Thiel F. Torres Da Silva De Araujo A. Vilela Pereira C. A. bernardes L. Calligaris T. R. Fernandez Perez Tomei E. M. Gregores 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 A. Dimitrov T. Ivanov L. Litov b. Pavlov P. Petkov A. Petrov E. Shumka S. Thakur T. Cheng T. Javaid M. Mittal L. Yuan M. Ahmad G. bauer Z. Hu S. Lezki K. Yi G. M. Chen H. S. Chen M. Chen F. Iemmi C. H. Jiang A. Kapoor H. Kou H. Liao Z.-A. Liu V. Milosevic F. Monti R. Sharma J. Tao J. Thomas-Wilsker J. Wang H. Zhang J. Zhao A. Agapitos Y. An Y. ban C. C Yerevan Physics Institute Yerevan Armenia Institut für Hochenergiephysik Vienna Austria Universiteit Antwerpen Antwerpen Belgium Vrije Universiteit Brussel Brussel Belgium Université Libre de Bruxelles Bruxelles Belgium Korea University Seoul Korea 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 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 Instituto De Alta Investigación Universidad de Tarapacá Casilla 7 D Arica Chile Beihang University Beijing China Department of Physics Tsinghua University Beijing China Institute of High Energy Physics Beijing China Massachusetts Institute of Technology Cambridge Massachusetts USA State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China Sun Yat-Sen University Guangzhou China Institute of Modern Physics and Key Laboratory of Nuclear Physics and Ion-beam Application (MOE)—Fudan University Shanghai China Rice University Houston Texas USA Zhejiang University Hangzhou Zhejiang 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 Center for High Energy Physics (CHEP-FU) Fayoum University El-Fayoum Egypt National Institute

A data sample containing top quark pairs (tt¯) produced in association with a Lorentz-boosted Z or Higgs boson is used to search for signs of new physics using effective field theory. The data correspond to an integrated luminosity of 138 fb−1 of proton-proton collisions produced at a center-of-mass energy of 13 TeV at the LHC and collected by the CMS experiment. Selected events contain a single lepton and hadronic jets, including two identified with the decay of bottom quarks, plus an additional large-radius jet with high transverse momentum identified as a Z or Higgs boson decaying to a bottom quark pair. Machine learning techniques are employed to discriminate between tt¯Z or tt¯H events and events from background processes, which are dominated by tt¯+jets production. No indications of new physics are observed. The signal strengths of boosted tt¯Z and tt¯H production are measured, and upper limits are placed on the tt¯Z and tt¯H differential cross sections as functions of the Z or Higgs boson transverse momentum. The effects of new physics are probed using a framework in which the standard model is considered to be the low-energy effective field theory of a higher energy scale theory. Eight possible dimension-six operators are added to the standard model Lagrangian, and their corresponding coefficients are constrained via fits to the data.

关键词： Top quark W & Z bosons Hadron colliders

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Search for direct pair production of supersymmetric partners of τ leptons in the final state with two hadronically decaying τ leptons and missing transverse momentum in proton-proton collisions at s=13 TeV

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Physical Review D 2023年第1期108卷 012011-012011页

作者： A. Tumasyan W. Adam J. W. Andrejkovic T. bergauer S. Chatterjee K. Damanakis M. Dragicevic A. Escalante Del Valle R. Frühwirth M. Jeitler N. Krammer L. Lechner D. Liko I. Mikulec P. Paulitsch F. M. Pitters J. Schieck R. Schöfbeck D. Schwarz S. Templ W. Waltenberger C.-E. Wulz M. R. Darwish E. A. De Wolf T. Janssen T. Kello A. Lelek H. Rejeb Sfar P. Van Mechelen S. Van Putte N. Van Remortel E. S. bols J. D’Hondt M. Delcourt H. El Faham S. Lowette S. Moortgat A. Morton D. Müller A. R. Sahasransu S. Tavernier W. Van Doninck D. Vannerom D. beghin b. bilin b. Clerbaux G. De Lentdecker L. Favart A. K. Kalsi K. Lee M. Mahdavikhorrami I. Makarenko L. Moureaux S. Paredes L. Pétré A. Popov N. Postiau E. Starling L. Thomas M. Vanden bemden C. Vander Velde P. Vanlaer T. Cornelis D. Dobur J. Knolle L. Lambrecht G. Mestdach M. Niedziela C. Rendón C. Roskas A. Samalan K. Skovpen M. Tytgat b. Vermassen L. Wezenbeek A. benecke A. bethani G. bruno F. bury C. Caputo P. David C. Delaere I. S. Donertas A. Giammanco K. Jaffel Sa. Jain V. Lemaitre K. Mondal J. Prisciandaro A. Taliercio M. Teklishyn T. T. Tran P. Vischia S. Wertz G. A. Alves C. Hensel A. Moraes P. Rebello Teles W. L. Aldá Júnior M. Alves Gallo Pereira M. barroso Ferreira Filho H. brandao Malbouisson W. Carvalho J. Chinellato E. M. Da Costa G. G. Da Silveira D. De Jesus Damiao V. Dos Santos Sousa S. Fonseca De Souza C. Mora Herrera K. Mota Amarilo L. Mundim H. Nogima A. Santoro S. M. Silva Do Amaral A. Sznajder M. Thiel 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 A. Dimitrov T. Ivanov L. Litov b. Pavlov P. Petkov A. Petrov T. Cheng T. Javaid M. Mittal L. Yuan M. Ahmad G. bauer C. Dozen Z. Hu J. Martins Y. Wang K. Yi E. Chapon G. M. Chen H. S. Chen M. Chen F. Iemmi A. Kapoor D. Leggat H. Liao Z.-A. Liu V. Milosevic F. Monti R. Sharma J. Tao J. T Yerevan Physics Institute Yerevan Armenia Institut für Hochenergiephysik Vienna Austria Universiteit Antwerpen Antwerpen Belgium Vrije Universiteit Brussel Brussel Belgium Université Libre de Bruxelles Bruxelles Belgium Korea University Seoul Korea 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 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 Department of Physics Tsinghua University Beijing China Institute of High Energy Physics Beijing China Massachusetts Institute of Technology Cambridge Massachusetts USA State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China Sun Yat-Sen University Guangzhou China Institute of Modern Physics and Key Laboratory of Nuclear Physics and Ion-beam Application (MOE)—Fudan University Shanghai China Rice University Houston Texas USA Zhejiang University Hangzhou Zhejiang 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 Center for High Energy Physics (CHEP-FU) Fayoum University El-Fayoum Egypt National Institute of Chemical Physics and Biophysics Tallinn Estonia Department of Physics Universi

A search for the direct production of a pair of τ sleptons, the supersymmetric partners of τ leptons, is presented. Each τ slepton is assumed to decay to a τ lepton and the lightest supersymmetric particle (LSP), which is assumed to be stable and to not interact in the detector, leading to an imbalance in the total reconstructed transverse momentum. The search is carried out in events identified as containing two τ leptons, each decaying to one or more hadrons and a neutrino, and significant transverse momentum imbalance. In addition to scenarios in which the τ sleptons decay promptly, the search also addresses scenarios in which the τ sleptons have sufficiently long lifetimes to give rise to nonprompt τ leptons. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC with the CMS detector in 2016–2018, and correspond to an integrated luminosity of 138 fb−1. No significant excess is seen with respect to standard model expectations. Upper limits on cross sections for the pair production of τ sleptons are obtained in the framework of simplified models. In a scenario in which the τ sleptons are superpartners of left-handed τ leptons, and each undergoes a prompt decay to a τ lepton and a nearly massless LSP, τ slepton masses between 115 and 340 GeV are excluded. In a scenario in which the lifetime of the τ sleptons corresponds to cτ0=0.1 mm, where τ0 represents the mean proper lifetime of the τ slepton, masses between 150 and 220 GeV are excluded.

关键词： Supersymmetric models Tau leptons Hadron colliders

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Search for narrow resonances in the b-tagged dijet mass spectrum in proton-proton collisions at s=13 TeV

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Physical Review D 2023年第1期108卷 012009-012009页

作者： A. Tumasyan W. Adam J. W. Andrejkovic T. bergauer S. Chatterjee K. Damanakis M. Dragicevic A. Escalante Del Valle R. Frühwirth M. Jeitler N. Krammer L. Lechner D. Liko I. Mikulec P. Paulitsch F. M. Pitters J. Schieck R. Schöfbeck D. Schwarz S. Templ W. Waltenberger C.-E. Wulz M. R. Darwish E. A. De Wolf T. Janssen T. Kello A. Lelek H. Rejeb Sfar P. Van Mechelen S. Van Putte N. Van Remortel F. blekman E. S. bols J. D’Hondt M. Delcourt H. El Faham S. Lowette S. Moortgat A. Morton D. Müller A. R. Sahasransu S. Tavernier W. Van Doninck D. beghin b. bilin b. Clerbaux G. De Lentdecker L. Favart A. Grebenyuk A. K. Kalsi K. Lee M. Mahdavikhorrami I. Makarenko L. Moureaux L. Pétré A. Popov N. Postiau E. Starling L. Thomas M. Vanden bemden C. Vander Velde P. Vanlaer T. Cornelis D. Dobur J. Knolle L. Lambrecht G. Mestdach M. Niedziela C. Roskas A. Samalan K. Skovpen M. Tytgat b. Vermassen L. Wezenbeek A. benecke A. bethani G. bruno F. bury C. Caputo P. David C. Delaere I. S. Donertas A. Giammanco K. Jaffel Sa. Jain V. Lemaitre K. Mondal J. Prisciandaro A. Taliercio M. Teklishyn T. T. Tran P. Vischia S. Wertz G. A. Alves C. Hensel A. Moraes W. L. Aldá Júnior M. Alves Gallo Pereira M. barroso Ferreira Filho H. brandao Malbouisson W. Carvalho J. Chinellato E. M. Da Costa G. G. Da Silveira D. De Jesus Damiao S. Fonseca De Souza C. Mora Herrera K. Mota Amarilo L. Mundim H. Nogima P. Rebello Teles A. Santoro S. M. Silva Do Amaral A. Sznajder M. Thiel 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 A. Dimitrov T. Ivanov L. Litov b. Pavlov P. Petkov A. Petrov T. Cheng T. Javaid M. Mittal L. Yuan M. Ahmad G. bauer C. Dozen Z. Hu J. Martins Y. Wang K. Yi E. Chapon G. M. Chen H. S. Chen M. Chen F. Iemmi A. Kapoor D. Leggat H. Liao Z.-A. Liu V. Milosevic F. Monti R. Sharma J. Tao J. Thomas-Wilsker J. Wang H. Zhan Yerevan Physics Institute Yerevan Armenia Institut für Hochenergiephysik Vienna Austria Universiteit Antwerpen Antwerpen Belgium Vrije Universiteit Brussel Brussel Belgium Université Libre de Bruxelles Bruxelles Belgium Korea University Seoul Korea 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 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 Department of Physics Tsinghua University Beijing China Institute of High Energy Physics Beijing China Massachusetts Institute of Technology Cambridge Massachusetts USA State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China The University of Kansas Lawrence Kansas USA Sun Yat-Sen University Guangzhou China Institute of Modern Physics and Key Laboratory of Nuclear Physics and Ion-beam Application (MOE)—Fudan University Shanghai China Rice University Houston Texas USA Zhejiang University Hangzhou Zhejiang 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 Center for High Energy Physics (CHEP-FU) Fayoum University El-Fayoum Egypt National Institute of Chemical Physics and Biophysics

A search is performed for narrow resonances decaying to final states of two jets, with at least one jet originating from a b quark, in proton-proton collisions at s=13 TeV. The data set corresponds to an integrated luminosity of 138 fb−1 collected with the CMS detector at the LHC. Jets originating from energetic b hadrons are identified through a b-tagging algorithm that utilizes a deep neural network or the presence of a muon inside a jet. The invariant mass spectrum of jet pairs is well described by a smooth parametrization and no evidence for the production of new particles is observed. Upper limits on the production cross section are set for excited b quarks and other resonances decaying to dijet final states containing b quarks. These limits exclude at 95% confidence level models of Z′ bosons with masses from 1.8 TeV to 2.4 TeV and of excited b quarks with masses from 1.8 TeV to 4.0 TeV. This is the most stringent exclusion of excited b quarks to date.

关键词： Quark & gluon jets bottom quark Hypothetical gauge bosons Hadron colliders

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Reconstruction of decays to merged photons using end-to-end deep learning with domain continuation in the CMS detector

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Physical Review D 2023年第5期108卷 052002-052002页

作者： A. Tumasyan W. Adam J. W. Andrejkovic T. bergauer S. Chatterjee K. Damanakis M. Dragicevic A. Escalante Del Valle R. Frühwirth M. Jeitler N. Krammer L. Lechner D. Liko I. Mikulec P. Paulitsch F. M. Pitters J. Schieck R. Schöfbeck D. Schwarz S. Templ W. Waltenberger C.-E. Wulz M. R. Darwish E. A. De Wolf T. Janssen T. Kello A. Lelek H. Rejeb Sfar P. Van Mechelen S. Van Putte N. Van Remortel E. S. bols J. D’Hondt A. De Moor M. Delcourt H. El Faham S. Lowette S. Moortgat A. Morton D. Müller A. R. Sahasransu S. Tavernier W. Van Doninck D. Vannerom D. beghin b. Clerbaux G. De Lentdecker L. Favart K. Lee M. Mahdavikhorrami I. Makarenko S. Paredes L. Pétré A. Popov N. Postiau E. Starling L. Thomas M. Vanden bemden C. Vander Velde P. Vanlaer D. Dobur J. Knolle L. Lambrecht G. Mestdach M. Niedziela C. Rendón C. Roskas A. Samalan K. Skovpen M. Tytgat N. Van Den bossche b. Vermassen L. Wezenbeek A. benecke A. bethani G. bruno F. bury C. Caputo P. David C. Delaere I. S. Donertas A. Giammanco K. Jaffel Sa. Jain V. Lemaitre K. Mondal J. Prisciandaro A. Taliercio T. T. Tran P. Vischia S. Wertz G. A. Alves C. Hensel A. Moraes P. Rebello Teles W. L. Aldá Júnior M. Alves Gallo Pereira M. barroso Ferreira Filho H. brandao Malbouisson W. Carvalho J. Chinellato E. M. Da Costa G. G. Da Silveira D. De Jesus Damiao V. Dos Santos Sousa S. Fonseca De Souza J. Martins C. Mora Herrera K. Mota Amarilo L. Mundim H. Nogima A. Santoro S. M. Silva Do Amaral A. Sznajder M. Thiel 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 A. Dimitrov T. Ivanov L. Litov b. Pavlov P. Petkov A. Petrov T. Cheng T. Javaid M. Mittal L. Yuan M. Ahmad G. bauer C. Dozen Z. Hu Y. Wang K. Yi E. Chapon G. M. Chen H. S. Chen M. Chen F. Iemmi A. Kapoor H. Liao Z.-A. Liu V. Milosevic F. Monti R. Sharma J. Tao J. Thomas-Wilsker J. Wang H. Zhang J. Zha Yerevan Physics Institute Yerevan Armenia Institut für Hochenergiephysik Vienna Austria Universiteit Antwerpen Antwerpen Belgium Vrije Universiteit Brussel Brussel Belgium Université Libre de Bruxelles Bruxelles Belgium Korea University Seoul Korea 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 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 Department of Physics Tsinghua University Beijing China Institute of High Energy Physics Beijing China Massachusetts Institute of Technology Cambridge Massachusetts USA State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China Sun Yat-Sen University Guangzhou China Institute of Modern Physics and Key Laboratory of Nuclear Physics and Ion-beam Application (MOE)—Fudan University Shanghai China Rice University Houston Texas USA Zhejiang University Hangzhou Zhejiang 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 Center for High Energy Physics (CHEP-FU) Fayoum University El-Fayoum Egypt National Institute of Chemical Physics and Biophysics Tallinn Estonia Department of Physics Universi

A novel technique based on machine learning is introduced to reconstruct the decays of highly Lorentz-boosted particles. Using an end-to-end deep learning strategy, the technique bypasses existing rule-based particle reconstruction methods typically used in high energy physics analyses. It uses minimally processed detector data as input and directly outputs particle properties of interest. The new technique is demonstrated for the reconstruction of the invariant mass of particles decaying in the CMS detector. The decay of a hypothetical scalar particle A into two photons, A→γγ, is chosen as a benchmark decay. Lorentz boosts γL=60–600 are considered, ranging from regimes where both photons are resolved to those where the photons are closely merged as one object. A training method using domain continuation is introduced, enabling the invariant mass reconstruction of unresolved photon pairs in a novel way. The new technique is validated using π0→γγ decays in LHC collision data.

关键词： Deep learning Electromagnetic calorimeters Hadron colliders

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AtlFast3: The Next Generation of Fast Simulation in ATLAS

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Computing and Software for big Science 2022年第1期6卷 1-54页

作者： Aad, G. Abbott, b. Abbott, D.C. Abud, A. Abed Abeling, K. Abhayasinghe, D.K. Abidi, S.H. Aboulhorma, A. Abramowicz, H. Abreu, H. Abulaiti, Y. Hoffman, A. C. Abusleme Acharya, b.S. Achkar, b. Adam, L. bourdarios, C. Adam Adamczyk, L. Adamek, L. Addepalli, S.V. Adelman, J. Adiguzel, A. Adorni, S. Adye, T. Affolder, A.A. Afik, Y. Agapopoulou, C. Agaras, M.N. Agarwala, J. Aggarwal, A. Agheorghiesei, C. Aguilar-Saavedra, J.A. Ahmad, A. Ahmadov, F. Ahmed, W.S. Ai, X. Aielli, G. Aizenberg, I. Akatsuka, S. Akbiyik, M. Åkesson, T.P.A. Akimov, A.V. Khoury, K. Al Alberghi, G.L. Albert, J. Albicocco, P. Verzini, M. J. Alconada Alderweireldt, S. Aleksa, M. Aleksandrov, I.N. Alexa, C. Alexopoulos, T. Alfonsi, A. Alfonsi, F. Alhroob, M. Ali, b. Ali, S. Aliev, M. Alimonti, G. Allaire, C. Allbrooke, b.M.M. Allport, P.P. Aloisio, A. Alonso, F. Alpigiani, C. Camelia, E. Alunno Estevez, M. Alvarez Alviggi, M.G. Coutinho, Y. Amaral Ambler, A. Ambroz, L. Amelung, C. Amidei, D. Santos, S. P. Amor Dos Amoroso, S. Amos, K.R. Amrouche, C.S. Ananiev, V. Anastopoulos, C. Andari, N. Andeen, T. Anders, J.K. Andrean, S.Y. Andreazza, A. Angelidakis, S. Angerami, A. Anisenkov, A.V. Annovi, A. Antel, C. Anthony, M.T. Antipov, E. Antonelli, M. Antrim, D.J.A. Anulli, F. Aoki, M. Pozo, J. A. Aparisi Aparo, M.A. bella, L. Aperio Aranzabal, N. Ferraz, V. Araujo Arcangeletti, C. Arce, A.T.H. Arena, E. Arguin, J.-F. Argyropoulos, S. Arling, J.-H. Armbruster, A.J. Armstrong, A. Arnaez, O. Arnold, H. Tame, Z. P. Arrubarrena Artoni, G. Asada, H. Asai, K. Asai, S. Asbah, N.A. Asimakopoulou, E.M. Asquith, L. Assahsah, J. Assamagan, K. Astalos, R. Atkin, R.J. Atkinson, M. Atlay, N.b. Atmani, H. Atmasiddha, P.A. Augsten, K. Auricchio, S. Austrup, V.A. Avner, G. Avolio, G. Ayoub, M.K. Azuelos, G. babal, D. bachacou, H. bachas, K. bachiu, A. backman, F. badea, A. bagnaia, P. bahrasemani, H. bailey, A.J. bailey, V.R. baines, J.T. bakalis, C. baker, O.K. bakker, P.J. bakos, E. Gupta, D. bakshi balaji, S. balasubramanian, R. baldin, E.M. balek, P. ballabene, E. bal Department of Physics University of Adelaide Adelaide Australia Department of Physics University of Alberta Edmonton AB Canada Department of Physics Ankara University Ankara Turkey Division of Physics TOBB University of Economics and Technology Ankara Turkey LAPP Univ. Savoie Mont Blanc CNRS/IN2P3 Annecy France High Energy Physics Division Argonne National Laboratory Argonne IL United States Department of Physics University of Arizona Tucson AZ United States Department of Physics University of Texas at Arlington Arlington TX United States Physics Department National and Kapodistrian University of Athens Athens Greece Physics Department National Technical University of Athens Zografou Greece Department of Physics University of Texas at Austin Austin TX United States Bahcesehir University Faculty of Engineering and Natural Sciences Istanbul Turkey Istanbul Bilgi University Faculty of Engineering and Natural Sciences Istanbul Turkey Department of Physics Bogazici University Istanbul Turkey Department of Physics Engineering Gaziantep University Gaziantep Turkey Institut de Física d’Altes Energies (IFAE) Barcelona Institute of Science and Technology Barcelona Spain Institute of High Energy Physics Chinese Academy of Sciences Beijing China Physics Department Tsinghua University Beijing China Department of Physics Nanjing University Nanjing China University of Chinese Academy of Science (UCAS) Beijing China Institute of Physics University of Belgrade Belgrade Serbia Department for Physics and Technology University of Bergen Bergen Norway Physics Division Lawrence Berkeley National Laboratory and University of California Berkeley CA United States Institut für Physik Humboldt Universität zu Berlin Berlin Germany Albert Einstein Center for Fundamental Physics and Laboratory for High Energy Physics University of Bern Bern Switzerland School of Physics and Astronomy University of Birmingham Birmingham United Kingdom Facultad de Ciencias y Cen

The ATLAS experiment at the Large Hadron Collider has a broad physics programme ranging from precision measurements to direct searches for new particles and new interactions, requiring ever larger and ever more accurate datasets of simulated Monte Carlo events. Detector simulation with Geant4 is accurate but requires significant CPU resources. Over the past decade, ATLAS has developed and utilized tools that replace the most CPU-intensive component of the simulation—the calorimeter shower simulation—with faster simulation methods. Here, AtlFast3, the next generation of high-accuracy fast simulation in ATLAS, is introduced. AtlFast3 combines parameterized approaches with machine-learning techniques and is deployed to meet current and future computing challenges, and simulation needs of the ATLAS experiment. With highly accurate performance and significantly improved modelling of substructure within jets, AtlFast3 can simulate large numbers of events for a wide range of physics processes. © 2022, Springer Nature Switzerland AG.

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Inclusive nonresonant multilepton probes of new phenomena at s=13 TeV

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Physical Review D 2022年第11期105卷 112007-112007页

作者： A. Tumasyan W. Adam J. W. Andrejkovic T. bergauer S. Chatterjee K. Damanakis M. Dragicevic A. Escalante Del Valle R. Frühwirth M. Jeitler N. Krammer L. Lechner D. Liko I. Mikulec P. Paulitsch F. M. Pitters J. Schieck R. Schöfbeck D. Schwarz S. Templ W. Waltenberger C.-E. Wulz V. Chekhovsky A. Litomin V. Makarenko M. R. Darwish E. A. De Wolf T. Janssen T. Kello A. Lelek H. Rejeb Sfar P. Van Mechelen S. Van Putte N. Van Remortel F. blekman E. S. bols J. D’Hondt M. Delcourt H. El Faham S. Lowette S. Moortgat A. Morton D. Müller A. R. Sahasransu S. Tavernier W. Van Doninck D. Vannerom D. beghin b. bilin b. Clerbaux G. De Lentdecker L. Favart A. K. Kalsi K. Lee M. Mahdavikhorrami I. Makarenko L. Moureaux S. Paredes L. Pétré A. Popov N. Postiau E. Starling L. Thomas M. Vanden bemden C. Vander Velde P. Vanlaer T. Cornelis D. Dobur J. Knolle L. Lambrecht G. Mestdach M. Niedziela C. Rendón C. Roskas A. Samalan K. Skovpen M. Tytgat b. Vermassen L. Wezenbeek A. benecke A. bethani G. bruno F. bury C. Caputo P. David C. Delaere I. S. Donertas A. Giammanco K. Jaffel Sa. Jain V. Lemaitre K. Mondal J. Prisciandaro A. Taliercio M. Teklishyn T. T. Tran P. Vischia S. Wertz G. A. Alves C. Hensel A. Moraes P. Rebello Teles W. L. Aldá Júnior M. Alves Gallo Pereira M. barroso Ferreira Filho H. brandao Malbouisson W. Carvalho J. Chinellato E. M. Da Costa G. G. Da Silveira D. De Jesus Damiao V. Dos Santos Sousa S. Fonseca De Souza C. Mora Herrera K. Mota Amarilo L. Mundim H. Nogima A. Santoro S. M. Silva Do Amaral A. Sznajder M. Thiel 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 A. Dimitrov T. Ivanov L. Litov b. Pavlov P. Petkov A. Petrov T. Cheng T. Javaid M. Mittal L. Yuan M. Ahmad G. bauer C. Dozen Z. Hu J. Martins Y. Wang K. Yi E. Chapon G. M. Chen H. S. Chen M. Chen F. Iemmi A. Kapoor D. Leggat H. Liao Z.-A Yerevan Physics Institute Yerevan Armenia. Institut für Hochenergiephysik Vienna Austria. Institute for Nuclear Problems Minsk Belarus. Universiteit Antwerpen Antwerpen Belgium. Vrije Universiteit Brussel Brussel Belgium. Université Libre de Bruxelles Bruxelles Belgium. Korea University Seoul Korea. 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 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. Department of Physics Tsinghua University Beijing China. Institute of High Energy Physics Beijing China. Massachusetts Institute of Technology Cambridge Massachusetts USA. State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China. Sun Yat-Sen University Guangzhou China. Institute of Modern Physics and Key Laboratory of Nuclear Physics and Ion-beam Application (MOE)—Fudan University Shanghai China. Rice University Houston Texas USA. Zhejiang University Hangzhou China Zhejiang 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. Center for High Energy Physics (CHEP-FU) Fayoum University El-Fayoum Egypt. National Insti

An inclusive search for nonresonant signatures of beyond the standard model (SM) phenomena in events with three or more charged leptons, including hadronically decaying τ leptons, is presented. The analysis is based on a data sample corresponding to an integrated luminosity of 138 fb−1 of proton-proton collisions at s=13 TeV, collected by the CMS experiment at the LHC in 2016–2018. Events are categorized based on the lepton and b-tagged jet multiplicities and various kinematic variables. Three scenarios of physics beyond the SM are probed, and signal-specific boosted decision trees are used for enhancing sensitivity. No significant deviations from the background expectations are observed. Lower limits are set at 95% confidence level on the mass of type-III seesaw heavy fermions in the range 845–1065 GeV for various decay branching fraction combinations to SM leptons. Doublet and singlet vectorlike τ lepton extensions of the SM are excluded for masses below 1045 GeV and in the mass range 125–150 GeV, respectively. Scalar leptoquarks decaying exclusively to a top quark and a lepton are excluded below 1.12–1.42 TeV, depending on the lepton flavor. For the type-III seesaw as well as the vectorlike doublet model, these constraints are the most stringent to date. For the vectorlike singlet model, these are the first constraints from the LHC experiments. Detailed results are also presented to facilitate alternative theoretical interpretations.

关键词： Hypothetical fermions Leptoquarks Tau leptons Hadron colliders

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Measurement of the Wγ Production Cross Section in Proton-Proton Collisions at s=13 TeV and Constraints on Effective Field Theory Coefficients

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Physical Review Letters 2021年第25期126卷 252002-252002页

作者： A. M. Sirunyan A. Tumasyan W. Adam J. W. Andrejkovic T. bergauer S. Chatterjee M. Dragicevic A. Escalante Del Valle R. Frühwirth M. Jeitler N. Krammer L. Lechner D. Liko I. Mikulec F. M. Pitters J. Schieck R. Schöfbeck M. Spanring S. Templ W. Waltenberger C.-E. Wulz V. Chekhovsky A. Litomin V. Makarenko M. R. Darwish E. A. De Wolf X. Janssen T. Kello A. Lelek H. Rejeb Sfar P. Van Mechelen S. Van Putte N. Van Remortel F. blekman E. S. bols J. D’Hondt J. De Clercq M. Delcourt S. Lowette S. Moortgat A. Morton D. Müller A. R. Sahasransu S. Tavernier W. Van Doninck P. Van Mulders D. beghin b. bilin b. Clerbaux G. De Lentdecker L. Favart A. Grebenyuk A. K. Kalsi K. Lee I. Makarenko L. Moureaux L. Pétré A. Popov N. Postiau E. Starling L. Thomas C. Vander Velde P. Vanlaer D. Vannerom L. Wezenbeek T. Cornelis D. Dobur M. Gruchala G. Mestdach M. Niedziela C. Roskas K. Skovpen M. Tytgat W. Verbeke b. Vermassen M. Vit A. bethani G. bruno F. bury C. Caputo P. David C. Delaere I. S. Donertas A. Giammanco V. Lemaitre K. Mondal J. Prisciandaro A. Taliercio M. Teklishyn P. Vischia S. Wertz S. Wuyckens G. A. Alves C. Hensel A. Moraes W. L. Aldá Júnior M. barroso Ferreira Filho H. brandao Malbouisson W. Carvalho J. Chinellato E. M. Da Costa G. G. Da Silveira D. De Jesus Damiao S. Fonseca De Souza D. Matos Figueiredo C. Mora Herrera K. Mota Amarilo L. Mundim H. Nogima P. Rebello Teles L. J. Sanchez Rosas A. Santoro S. M. Silva Do Amaral A. Sznajder M. Thiel 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 I. Atanasov R. Hadjiiska P. Iaydjiev M. Misheva M. Rodozov M. Shopova G. Sultanov A. Dimitrov T. Ivanov L. Litov b. Pavlov P. Petkov A. Petrov T. Cheng W. Fang Q. Guo T. Javaid M. Mittal H. Wang L. Yuan M. Ahmad G. bauer C. Dozen Z. Hu J. Martins Y. Wang K. Yi E. Chapon G. M. Chen H. S. Chen M. Chen A. Kapoor D. Leggat H. Liao Z.-A. LIU R. Sharma A. Spiezia J. Tao J. Thomas-wils 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 Korea University Seoul Korea 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 Rutgers The State University of New Jersey Piscataway New Jersey USA Department of Physics Tsinghua University Beijing China Institute of High Energy Physics Beijing China Massachusetts Institute of Technology Cambridge Massachusetts USA State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China The University of Kansas Lawrence Kansas USA Sun Yat-Sen University Guangzhou China Institute of Modern Physics and Key Laboratory of Nuclear Physics and Ion-beam Application (MOE)—Fudan University Shanghai China 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 Center for High Energy Physics (CHEP-FU) Fa

A fiducial cross section for Wγ production in proton-proton collisions is measured at a center-of-mass energy of 13 TeV in 137 fb−1 of data collected using the CMS detector at the LHC. The W→eν and μν decay modes are used in a maximum-likelihood fit to the lepton-photon invariant mass distribution to extract the combined cross section. The measured cross section is compared with theoretical expectations at next-to-leading order in quantum chromodynamics. In addition, 95% confidence level intervals are reported for anomalous triple-gauge couplings within the framework of effective field theory.

关键词： Effective field theory Perturbative QCD W & Z bosons Hadron colliders

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Search for Long-Lived Particles Decaying in the CMS End Cap Muon Detectors in Proton-Proton Collisions at s=13 TeV

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Physical Review Letters 2021年第26期127卷 261804-261804页

作者： A. Tumasyan W. Adam J. W. Andrejkovic T. bergauer S. Chatterjee M. Dragicevic A. Escalante Del Valle R. Frühwirth M. Jeitler N. Krammer L. Lechner D. Liko I. Mikulec P. Paulitsch F. M. Pitters J. Schieck R. Schöfbeck D. Schwarz S. Templ W. Waltenberger C.-E. Wulz V. Chekhovsky A. Litomin V. Makarenko M. R. Darwish E. A. De Wolf T. Janssen T. Kello A. Lelek H. Rejeb Sfar P. Van Mechelen S. Van Putte N. Van Remortel F. blekman E. S. bols J. D’Hondt M. Delcourt H. El Faham S. Lowette S. Moortgat A. Morton D. Müller A. R. Sahasransu S. Tavernier W. Van Doninck P. Van Mulders D. beghin b. bilin b. Clerbaux G. De Lentdecker L. Favart A. Grebenyuk A. K. Kalsi K. Lee M. Mahdavikhorrami I. Makarenko L. Moureaux L. Pétré A. Popov N. Postiau E. Starling L. Thomas M. Vanden bemden C. Vander Velde P. Vanlaer L. Wezenbeek T. Cornelis D. Dobur J. Knolle L. Lambrecht G. Mestdach M. Niedziela C. Roskas A. Samalan K. Skovpen M. Tytgat b. Vermassen M. Vit A. benecke A. bethani G. bruno F. bury C. Caputo P. David C. Delaere I. S. Donertas A. Giammanco K. Jaffel Sa. Jain V. Lemaitre K. Mondal J. Prisciandaro A. Taliercio M. Teklishyn T. T. Tran P. Vischia S. Wertz G. A. Alves C. Hensel A. Moraes W. L. Aldá Júnior M. Alves Gallo Pereira M. barroso Ferreira Filho H. brandao Malbouisson W. Carvalho J. Chinellato E. M. Da Costa G. G. Da Silveira D. De Jesus Damiao S. Fonseca De Souza D. Matos Figueiredo C. Mora Herrera K. Mota Amarilo L. Mundim H. Nogima P. Rebello Teles A. Santoro S. M. Silva Do Amaral A. Sznajder M. Thiel 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 A. Dimitrov T. Ivanov L. Litov b. Pavlov P. Petkov A. Petrov T. Cheng T. Javaid M. Mittal L. Yuan M. Ahmad G. bauer C. Dozen Z. Hu J. Martins Y. Wang K. Yi E. Chapon G. M. Chen H. S. Chen M. Chen F. Iemmi A. Kapoor D. Leggat H. Liao Z.-A. Liu V. Mi 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 Korea University Seoul Korea 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 Department of Physics Tsinghua University Beijing China Institute of High Energy Physics Beijing China Massachusetts Institute of Technology Cambridge Massachusetts USA State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China The University of Kansas Lawrence Kansas USA Sun Yat-Sen University Guangzhou China Institute of Modern Physics and Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) - Fudan University Shanghai China 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 Center for High Energy Physics (CHEP-FU) Fayoum University El-Fayoum Egypt National Institute of Chemical Physic

A search for long-lived particles (LLPs) produced in decays of standard model (SM) Higgs bosons is presented. The data sample consists of 137 fb−1 of proton-proton collisions at s=13 TeV, recorded at the LHC in 2016–2018. A novel technique is employed to reconstruct decays of LLPs in the end cap muon detectors. The search is sensitive to a broad range of LLP decay modes and to masses as low as a few GeV. No excess of events above the SM background is observed. The most stringent limits to date on the branching fraction of the Higgs boson to LLPs subsequently decaying to quarks and τ+τ− are found for proper decay lengths greater than 6, 20, and 40 m, for LLP masses of 7, 15, and 40 GeV, respectively.

关键词： Hypothetical particles Tau leptons Hadron colliders

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Constraints on the Initial State of Pb-Pb Collisions via Measurements of Z-boson Yields and Azimuthal Anisotropy at sNN=5.02 TeV

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Physical Review Letters 2021年第10期127卷 102002-102002页

作者： A. M. Sirunyan A. Tumasyan W. Adam F. Ambrogi T. bergauer M. Dragicevic J. Erö A. Escalante Del Valle R. Frühwirth M. Jeitler N. Krammer L. Lechner D. Liko T. Madlener I. Mikulec F. M. Pitters N. Rad J. Schieck R. Schöfbeck M. Spanring S. Templ W. Waltenberger C.-E. Wulz M. Zarucki V. Chekhovsky A. Litomin V. Makarenko 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 A. Morton Q. Python S. Tavernier W. Van Doninck P. Van Mulders D. beghin b. bilin b. Clerbaux G. De Lentdecker b. Dorney L. Favart A. Grebenyuk A. K. Kalsi I. Makarenko L. Moureaux L. Pétré A. Popov N. Postiau E. Starling L. Thomas C. Vander Velde P. Vanlaer D. Vannerom L. Wezenbeek T. Cornelis D. Dobur M. Gruchala I. Khvastunov M. Niedziela C. Roskas K. Skovpen M. Tytgat W. Verbeke b. Vermassen M. Vit G. bruno F. bury C. Caputo P. David C. Delaere M. Delcourt I. S. Donertas A. Giammanco V. Lemaitre K. Mondal J. Prisciandaro A. Taliercio M. Teklishyn P. Vischia S. Wuyckens J. Zobec G. A. Alves G. Correia Silva C. Hensel A. Moraes W. L. Aldá Júnior E. belchior batista Das Chagas H. brandao Malbouisson W. Carvalho J. Chinellato E. Coelho E. M. Da Costa G. G. Da Silveira D. De Jesus Damiao S. Fonseca De Souza J. Martins D. Matos Figueiredo M. Medina Jaime M. Melo De Almeida C. Mora Herrera L. Mundim H. Nogima P. Rebello Teles L. J. Sanchez Rosas A. Santoro S. M. Silva Do Amaral 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 I. Atanasov 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 Q. Guo H. Wang L. Yuan M. Ahmad Z. Hu 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 Rutgers The State University of New Jersey Piscataway New Jersey USA Department of Physics Tsinghua University Beijing China University of Virginia Charlottesville Virginia USA Institute of High Energy Physics Beijing China Massachusetts Institute of Technology Cambridge Massachusetts USA State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China The University of Kansas Lawrence Kansas USA Sun Yat-Sen University Guangzhou China Institute of Modern Physics and Key Laboratory of Nuclear Physics and Ion-beam Application (MOE)—Fudan University Shanghai China 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 Center for High Ener

The CMS experiment at the LHC has measured the differential cross sections of Z bosons decaying to pairs of leptons, as functions of transverse momentum and rapidity, in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The measured Z boson elliptic azimuthal anisotropy coefficient is compatible with zero, showing that Z bosons do not experience significant final-state interactions in the medium produced in the collision. Yields of Z bosons are compared to Glauber model predictions and are found to deviate from these expectations in peripheral collisions, indicating the presence of initial collision geometry and centrality selection effects. The precision of the measurement allows, for the first time, for a data-driven determination of the nucleon-nucleon integrated luminosity as a function of lead-lead centrality, thereby eliminating the need for its estimation based on a Glauber model.

关键词： Relativistic heavy-ion collisions W & Z bosons Hadron colliders

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