Eur. Phys. J. C (2025) 85: 706
https://doi.org/10.1140/epjc/s10052-025-14012-4

Regular Article - Experimental Physics

Improved reconstruction of highly boosted $\tau$-lepton pairs in the $\tau \tau \to (\mu {\nu }_{\mu }{\nu }_{\tau })(\text{hadrons}+{\nu }_{\tau })$ decay channels with the ATLAS detector

¹ Department of Physics, University of Adelaide, Adelaide, Australia
² Department of Physics, University of Alberta, Edmonton, AB, Canada
³ Department of Physics, Ankara University, Ankara, Turkey
⁴ Division of Physics, TOBB University of Economics and Technology, Ankara, Turkey
⁵ LAPP, Université Savoie Mont Blanc, CNRS/IN2P3, Annecy, France
⁶ APC, Université Paris Cité, CNRS/IN2P3, Paris, France
⁷ High Energy Physics Division, Argonne National Laboratory, Argonne, IL, USA
⁸ Department of Physics, University of Arizona, Tucson, AZ, USA
⁹ Department of Physics, University of Texas at Arlington, Arlington, TX, USA
¹⁰ Physics Department, National and Kapodistrian University of Athens, Athens, Greece
¹¹ Physics Department, National Technical University of Athens, Zografou, Greece
¹² Department of Physics, University of Texas at Austin, Austin, TX, USA
¹³ Institute of Physics, Azerbaijan Academy of Sciences, Baku, Azerbaijan
¹⁴ Institut de Física d’Altes Energies (IFAE), Barcelona Institute of Science and Technology, Barcelona, Spain
¹⁵ Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
¹⁶ Physics Department, Tsinghua University, Beijing, China
¹⁷ Institute of Physics, University of Belgrade, Belgrade, Serbia
¹⁸ Department for Physics and Technology, University of Bergen, Bergen, Norway
¹⁹ Physics Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
²⁰ University of California, Berkeley, CA, USA
²¹ Institut für Physik, Humboldt Universität zu Berlin, Berlin, Germany
²² Albert Einstein Center for Fundamental Physics and Laboratory for High Energy Physics, University of Bern, Bern, Switzerland
²³ School of Physics and Astronomy, University of Birmingham, Birmingham, UK
²⁴ Department of Physics, Bogazici University, Istanbul, Turkey
²⁵ Department of Physics Engineering, Gaziantep University, Gaziantep, Turkey
²⁶ Department of Physics, Istanbul University, Istanbul, Turkey
²⁷ Facultad de Ciencias y Centro de Investigaciónes, Universidad Antonio Nariño, Bogotá, Colombia
²⁸ Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia
²⁹ Dipartimento di Fisica e Astronomia A. Righi, Université di Bologna, Bologna, Italy
³⁰ INFN Sezione di Bologna, Bologna, Italy
³¹ Physikalisches Institut, Universität Bonn, Bonn, Germany
³² Department of Physics, Boston University, Boston, MA, USA
³³ Department of Physics, Brandeis University, Waltham, MA, USA
³⁴ Transilvania University of Brasov, Brasov, Romania
³⁵ Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania
³⁶ Department of Physics, Alexandru Ioan Cuza University of Iasi, Iasi, Romania
³⁷ Physics Department, National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj-Napoca, Romania
³⁸ National University of Science and Technology Politechnica, Bucharest, Romania
³⁹ West University in Timisoara, Timisoara, Romania
⁴⁰ Faculty of Physics, University of Bucharest, Bucharest, Romania
⁴¹ Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia
⁴² Department of Subnuclear Physics, Institute of Experimental Physics of the Slovak Academy of Sciences, Kosice, Slovak Republic
⁴³ Physics Department, Brookhaven National Laboratory, Upton, NY, USA
⁴⁴ Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Física, y CONICET, Instituto de Fí??sica de Buenos Aires (IFIBA), Buenos Aires, Argentina
⁴⁵ California State University, Long Beach, CA, USA
⁴⁶ Cavendish Laboratory, University of Cambridge, Cambridge, UK
⁴⁷ Department of Physics, University of Cape Town, Cape Town, South Africa
⁴⁸ iThemba Labs, Cape Town, Western Cape, South Africa
⁴⁹ Department of Mechanical Engineering Science, University of Johannesburg, Johannesburg, South Africa
⁵⁰ National Institute of Physics, University of the Philippines Diliman (Philippines), Quezon City, Philippines
⁵¹ University of South Africa, Department of Physics, Pretoria, South Africa
⁵² University of Zululand, KwaDlangezwa, Ongoye, South Africa
⁵³ School of Physics, University of the Witwatersrand, Johannesburg, South Africa
⁵⁴ Department of Physics, Carleton University, Ottawa, ON, Canada
⁵⁵ Faculté des Sciences Ain Chock, Université Hassan II de Casablanca, Casablanca, Morocco
⁵⁶ Faculté des Sciences, Université Ibn-Tofail, Kenitra, Morocco
⁵⁷ Faculté des Sciences Semlalia, Université Cadi Ayyad, LPHEA-Marrakech, Marrakech, Morocco
⁵⁸ LPMR, Faculté des Sciences, Université Mohamed Premier, Oujda, Morocco
⁵⁹ Faculté des sciences, Université Mohammed V, Rabat, Morocco
⁶⁰ Institute of Applied Physics, Mohammed VI Polytechnic University, Ben Guerir, Morocco
⁶¹ CERN, Geneva, Switzerland
⁶² Affiliated with an Institute Formerly Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
⁶³ Affiliated with an Institute Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
⁶⁴ Affiliated with an International Laboratory Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
⁶⁵ Enrico Fermi Institute, University of Chicago, Chicago, IL, USA
⁶⁶ LPC, Université Clermont Auvergne, CNRS/IN2P3, Clermont-Ferrand, France
⁶⁷ Nevis Laboratory, Columbia University, Irvington, NY, USA
⁶⁸ Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
⁶⁹ Dipartimento di Fisica, Università della Calabria, Rende, Italy
⁷⁰ INFN Gruppo Collegato di Cosenza, Laboratori Nazionali di Frascati, Frascati, Italy
⁷¹ Physics Department, Southern Methodist University, Dallas, TX, USA
⁷² National Centre for Scientific Research “Demokritos”, Agia Paraskevi, Greece
⁷³ Department of Physics, Stockholm University, Stockholm, Sweden
⁷⁴ Oskar Klein Centre, Stockholm, Sweden
⁷⁵ Deutsches Elektronen-Synchrotron DESY, Hamburg and Zeuthen, Germany
⁷⁶ Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
⁷⁷ Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Dresden, Germany
⁷⁸ Department of Physics, Duke University, Durham, NC, USA
⁷⁹ SUPA-School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
⁸⁰ INFN e Laboratori Nazionali di Frascati, Frascati, Italy
⁸¹ Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
⁸² II. Physikalisches Institut, Georg-August-Universität Göttingen, Göttingen, Germany
⁸³ Département de Physique Nucléaire et Corpusculaire, Université de Genève, Geneva, Switzerland
⁸⁴ Dipartimento di Fisica, Università di Genova, Genoa, Italy
⁸⁵ INFN Sezione di Genova, Genoa, Italy
⁸⁶ II. Physikalisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany
⁸⁷ SUPA-School of Physics and Astronomy, University of Glasgow, Glasgow, UK
⁸⁸ LPSC, Université Grenoble Alpes, CNRS/IN2P3, Grenoble INP, Grenoble, France
⁸⁹ Laboratory for Particle Physics and Cosmology, Harvard University, Cambridge, MA, USA
⁹⁰ Department of Modern Physics and State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei, China
⁹¹ Institute of Frontier and Interdisciplinary Science and Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, Qingdao, China
⁹² School of Physics and Astronomy, Shanghai Jiao Tong University, Key Laboratory for Particle Astrophysics and Cosmology (MOE), SKLPPC, Shanghai, China
⁹³ Tsung-Dao Lee Institute, Shanghai, China
⁹⁴ School of Physics, Zhengzhou University, China
⁹⁵ Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
⁹⁶ Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
⁹⁷ Department of Physics, Chinese University of Hong Kong, Shatin, N.T., Hong Kong
⁹⁸ Department of Physics, University of Hong Kong, Pok Fu Lam, Hong Kong
⁹⁹ Department of Physics and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
¹⁰⁰ Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
¹⁰¹ IJCLab, Université Paris-Saclay, CNRS/IN2P3, 91405, Orsay, France
¹⁰² Centro Nacional de Microelectrónica (IMB-CNM-CSIC), Barcelona, Spain
¹⁰³ Department of Physics, Indiana University, Bloomington, IN, USA
¹⁰⁴ INFN Gruppo Collegato di Udine, Sezione di Trieste, Udine, Italy
¹⁰⁵ ICTP, Trieste, Italy
¹⁰⁶ Dipartimento Politecnico di Ingegneria e Architettura, Università di Udine, Udine, Italy
¹⁰⁷ INFN Sezione di Lecce, Lecce, Italy
¹⁰⁸ Dipartimento di Matematica e Fisica, Università del Salento, Lecce, Italy
¹⁰⁹ INFN Sezione di Milano, Milan, Italy
¹¹⁰ Dipartimento di Fisica, Università di Milano, Milan, Italy
¹¹¹ INFN Sezione di Napoli, Naples, Italy
¹¹² Dipartimento di Fisica, Università di Napoli, Naples, Italy
¹¹³ INFN Sezione di Pavia, Pavia, Italy
¹¹⁴ Dipartimento di Fisica, Università di Pavia, Pavia, Italy
¹¹⁵ INFN Sezione di Pisa, Pisa, Italy
¹¹⁶ Dipartimento di Fisica E. Fermi, Università di Pisa, Pisa, Italy
¹¹⁷ INFN Sezione di Roma, Rome, Italy
¹¹⁸ Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy
¹¹⁹ INFN Sezione di Roma Tor Vergata, Rome, Italy
¹²⁰ Dipartimento di Fisica, Università di Roma Tor Vergata, Rome, Italy
¹²¹ INFN Sezione di Roma Tre, Rome, Italy
¹²² Dipartimento di Matematica e Fisica, Università Roma Tre, Rome, Italy
¹²³ INFN-TIFPA, Povo, Italy
¹²⁴ Università degli Studi di Trento, Trento, Italy
¹²⁵ Universität Innsbruck, Department of Astro and Particle Physics, Innsbruck, Austria
¹²⁶ University of Iowa, Iowa City, IA, USA
¹²⁷ Department of Physics and Astronomy, Iowa State University, Ames, IA, USA
¹²⁸ Istinye University, Sariyer, Istanbul, Turkey
¹²⁹ Departamento de Engenharia Elétrica, Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, Brazil
¹³⁰ Universidade Federal do Rio De Janeiro COPPE/EE/IF, Rio de Janeiro, Brazil
¹³¹ Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
¹³² Rio de Janeiro State University, Rio de Janeiro, Brazil
¹³³ Federal University of Bahia, Bahia, Brazil
¹³⁴ KEK, High Energy Accelerator Research Organization, Tsukuba, Japan
¹³⁵ Graduate School of Science, Kobe University, Kobe, Japan
¹³⁶ Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland
¹³⁷ Marian Smoluchowski Institute of Physics, Jagiellonian University, Krakow, Poland
¹³⁸ Institute of Nuclear Physics Polish Academy of Sciences, Krakow, Poland
¹³⁹ Faculty of Science, Kyoto University, Kyoto, Japan
¹⁴⁰ Research Center for Advanced Particle Physics and Department of Physics, Kyushu University, Fukuoka, Japan
¹⁴¹ L2IT, Université de Toulouse, CNRS/IN2P3, UPS, Toulouse, France
¹⁴² Instituto de Física La Plata, Universidad Nacional de La Plata and CONICET, La Plata, Argentina
¹⁴³ Physics Department, Lancaster University, Lancaster, UK
¹⁴⁴ Oliver Lodge Laboratory, University of Liverpool, Liverpool, UK
¹⁴⁵ Department of Experimental Particle Physics, Jožef Stefan Institute and Department of Physics, University of Ljubljana, Ljubljana, Slovenia
¹⁴⁶ School of Physics and Astronomy, Queen Mary University of London, London, UK
¹⁴⁷ Department of Physics, Royal Holloway University of London, Egham, UK
¹⁴⁸ Department of Physics and Astronomy, University College London, London, UK
¹⁴⁹ Louisiana Tech University, Ruston, LA, USA
¹⁵⁰ Fysiska institutionen, Lunds universitet, Lund, Sweden
¹⁵¹ Departamento de Física Teorica C-15 and CIAFF, Universidad Autónoma de Madrid, Madrid, Spain
¹⁵² Institut für Physik, Universität Mainz, Mainz, Germany
¹⁵³ School of Physics and Astronomy, University of Manchester, Manchester, UK
¹⁵⁴ CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille, France
¹⁵⁵ Department of Physics, University of Massachusetts, Amherst, MA, USA
¹⁵⁶ Department of Physics, McGill University, Montreal, QC, Canada
¹⁵⁷ School of Physics, University of Melbourne, Melbourne, VIC, Australia
¹⁵⁸ Department of Physics, University of Michigan, Ann Arbor, MI, USA
¹⁵⁹ Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA
¹⁶⁰ Group of Particle Physics, University of Montreal, Montreal, QC, Canada
¹⁶¹ Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany
¹⁶² Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Munich, Germany
¹⁶³ Graduate School of Science and Kobayashi-Maskawa Institute, Nagoya University, Nagoya, Japan
¹⁶⁴ Department of Physics, Nanjing University, Nanjing, China
¹⁶⁵ School of Science, Shenzhen Campus of Sun Yat-sen University, Shenzhen, China
¹⁶⁶ University of Chinese Academy of Science (UCAS), Beijing, China
¹⁶⁷ Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM, USA
¹⁶⁸ Institute for Mathematics, Astrophysics and Particle Physics, Radboud University/Nikhef, Nijmegen, The Netherlands
¹⁶⁹ Nikhef National Institute for Subatomic Physics and University of Amsterdam, Amsterdam, The Netherlands
¹⁷⁰ Department of Physics, Northern Illinois University, DeKalb, IL, USA
¹⁷¹ New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
¹⁷² United Arab Emirates University, Al Ain, United Arab Emirates
¹⁷³ Department of Physics, New York University, New York, NY, USA
¹⁷⁴ Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo, Japan
¹⁷⁵ Ohio State University, Columbus, OH, USA
¹⁷⁶ Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK, USA
¹⁷⁷ Department of Physics, Oklahoma State University, Stillwater, OK, USA
¹⁷⁸ Palacký University, Joint Laboratory of Optics, Olomouc, Czech Republic
¹⁷⁹ Institute for Fundamental Science, University of Oregon, Eugene, OR, USA
¹⁸⁰ Graduate School of Science, Osaka University, Osaka, Japan
¹⁸¹ Department of Physics, University of Oslo, Oslo, Norway
¹⁸² Department of Physics, Oxford University, Oxford, UK
¹⁸³ LPNHE, Sorbonne Université, Université Paris Cité, CNRS/IN2P3, Paris, France
¹⁸⁴ Department of Physics, University of Pennsylvania, Philadelphia, PA, USA
¹⁸⁵ Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, USA
¹⁸⁶ Laboratório de Instrumentação e Física Experimental de Partículas - LIP, Lisbon, Portugal
¹⁸⁷ Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
¹⁸⁸ Departamento de Física, Universidade de Coimbra, Coimbra, Portugal
¹⁸⁹ Centro de Física Nuclear da Universidade de Lisboa, Lisbon, Portugal
¹⁹⁰ Departamento de Física, Escola de Ciências, Universidade do Minho, Braga, Portugal
¹⁹¹ Departamento de Física Teórica y del Cosmos, Universidad de Granada, Granada, Spain
¹⁹² Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
¹⁹³ Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic
¹⁹⁴ Czech Technical University in Prague, Prague, Czech Republic
¹⁹⁵ Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
¹⁹⁶ Particle Physics Department, Rutherford Appleton Laboratory, Didcot, UK
¹⁹⁷ IRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, France
¹⁹⁸ Santa Cruz Institute for Particle Physics, University of California Santa Cruz, Santa Cruz, CA, USA
¹⁹⁹ Departamento de Física, Pontificia Universidad Católica de Chile, Santiago, Chile
²⁰⁰ Millennium Institute for Subatomic physics at high energy frontier (SAPHIR), Santiago, Chile
²⁰¹ Instituto de Investigación Multidisciplinario en Ciencia y Tecnología, y Departamento de Física, Universidad de La Serena, La Serena, Chile
²⁰² Department of Physics, Universidad Andres Bello, Santiago, Chile
²⁰³ Instituto de Alta Investigación, Universidad de Tarapacá, Arica, Chile
²⁰⁴ Departamento de Física, Universidad Técnica Federico Santa María, Valparaiso, Chile
²⁰⁵ Department of Physics, Institute of Science, Tokyo, Japan
²⁰⁶ Department of Physics, University of Washington, Seattle, WA, USA
²⁰⁷ Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
²⁰⁸ Department of Physics, Shinshu University, Nagano, Japan
²⁰⁹ Department Physik, Universität Siegen, Siegen, Germany
²¹⁰ Department of Physics, Simon Fraser University, Burnaby, BC, Canada
²¹¹ SLAC National Accelerator Laboratory, Stanford, CA, USA
²¹² Department of Physics, Royal Institute of Technology, Stockholm, Sweden
²¹³ Departments of Physics and Astronomy, Stony Brook University, Stony Brook, NY, USA
²¹⁴ Department of Physics and Astronomy, University of Sussex, Brighton, UK
²¹⁵ School of Physics, University of Sydney, Sydney, Australia
²¹⁶ Institute of Physics, Academia Sinica, Taipei, Taiwan
²¹⁷ E. Andronikashvili Institute of Physics, Iv. Javakhishvili Tbilisi State University, Tbilisi, Georgia
²¹⁸ High Energy Physics Institute, Tbilisi State University, Tbilisi, Georgia
²¹⁹ University of Georgia, Tbilisi, Georgia
²²⁰ Department of Physics, Technion, Israel Institute of Technology, Haifa, Israel
²²¹ Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
²²² Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece
²²³ International Center for Elementary Particle Physics and Department of Physics, University of Tokyo, Tokyo, Japan
²²⁴ Department of Physics, University of Toronto, Toronto, ON, Canada
²²⁵ TRIUMF, Vancouver, BC, Canada
²²⁶ Department of Physics and Astronomy, York University, Toronto, ON, Canada
²²⁷ Division of Physics and Tomonaga Center for the History of the Universe, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Japan
²²⁸ Department of Physics and Astronomy, Tufts University, Medford, MA, USA
²²⁹ Department of Physics and Astronomy, University of California Irvine, Irvine, CA, USA
²³⁰ University of West Attica, Athens, Greece
²³¹ University of Sharjah, Sharjah, United Arab Emirates
²³² Department of Physics and Astronomy, University of Uppsala, Uppsala, Sweden
²³³ Department of Physics, University of Illinois, Urbana, IL, USA
²³⁴ Instituto de Física Corpuscular (IFIC), Centro Mixto Universidad de Valencia-CSIC, Valencia, Spain
²³⁵ Department of Physics, University of British Columbia, Vancouver, BC, Canada
²³⁶ Department of Physics and Astronomy, University of Victoria, Victoria, BC, Canada
²³⁷ Fakultät für Physik und Astronomie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
²³⁸ Department of Physics, University of Warwick, Coventry, UK
²³⁹ Waseda University, Tokyo, Japan
²⁴⁰ Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot, Israel
²⁴¹ Department of Physics, University of Wisconsin, Madison, WI, USA
²⁴² Fakultät für Mathematik und Naturwissenschaften, Fachgruppe Physik, Bergische Universität Wuppertal, Wuppertal, Germany
²⁴³ Department of Physics, Yale University, New Haven, CT, USA
²⁴⁴ Yerevan Physics Institute, Yerevan, Armenia
²⁴⁵ Also Affiliated with an Institute Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
²⁴⁶ An-Najah National University, Nablus, Palestine
²⁴⁷ Borough of Manhattan Community College, City University of New York, New York, NY, USA
²⁴⁸ Center for High Energy Physics, Peking University, China
²⁴⁹ Center for Interdisciplinary Research and Innovation (CIRI-AUTH), Thessaloniki, Greece
²⁵⁰ CERN, Geneva, Switzerland
²⁵¹ CMD-AC UNEC Research Center, Azerbaijan State University of Economics (UNEC), Baku, Azerbaijan
²⁵² Département de Physique Nucléaire et Corpusculaire, Université de Genève, Geneva, Switzerland
²⁵³ Departament de Fisica de la Universitat Autonoma de Barcelona, Barcelona, Spain
²⁵⁴ Department of Financial and Management Engineering, University of the Aegean, Chios, Greece
²⁵⁵ Department of Mathematical Sciences, University of South Africa, Johannesburg, South Africa
²⁵⁶ Department of Physics, Bolu Abant Izzet Baysal University, Bolu, Turkey
²⁵⁷ Department of Physics, California State University, Sacramento, USA
²⁵⁸ Department of Physics, King’s College London, London, UK
²⁵⁹ Department of Physics, Stanford University, Stanford, CA, USA
²⁶⁰ Department of Physics, Stellenbosch University, South Africa
²⁶¹ Department of Physics, University of Fribourg, Fribourg, Switzerland
²⁶² Department of Physics, University of Thessaly, Volos, Greece
²⁶³ Department of Physics, Westmont College, Santa Barbara, USA
²⁶⁴ Faculty of Physics, Sofia University, ’St. Kliment Ohridski’, Sofia, Bulgaria
²⁶⁵ Hellenic Open University, Patras, Greece
²⁶⁶ Henan University, Kaifeng, China
²⁶⁷ Imam Mohammad Ibn Saud Islamic University, Riyadh, Saudi Arabia
²⁶⁸ Institucio Catalana de Recerca i Estudis Avancats, ICREA, Barcelona, Spain
²⁶⁹ at Institut für Experimentalphysik, Universität Hamburg, Hamburg, Germany
²⁷⁰ Institute for Nuclear Research and Nuclear Energy (INRNE) of the Bulgarian Academy of Sciences, Sofia, Bulgaria
²⁷¹ Institute of Applied Physics, Mohammed VI Polytechnic University, Ben Guerir, Morocco
²⁷² Institute of Particle Physics (IPP), Toronto, Canada
²⁷³ Institute of Physics and Technology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
²⁷⁴ Institute of Physics, Azerbaijan Academy of Sciences, Baku, Azerbaijan
²⁷⁵ National Institute of Physics, University of the Philippines Diliman (Philippines), Quezon Cit, Philippines
²⁷⁶ Technical University of Munich, Munich, Germany
²⁷⁷ The Collaborative Innovation Center of Quantum Matter (CICQM), Beijing, China
²⁷⁸ TRIUMF, Vancouver, BC, Canada
²⁷⁹ Università di Napoli Parthenope, Naples, Italy
²⁸⁰ University of Colorado Boulder, Department of Physics, Colorado, USA
²⁸¹ University of the Western Cape, Cape Town, South Africa
²⁸² Washington College, Chestertown, MD, USA
²⁸³ Yeditepe University, Physics Department, Istanbul, Turkey
²⁸⁴ CERN, 1211, Geneva 23, Switzerland

^a atlas.publications@cern.ch

Received: 20 December 2024
Accepted: 26 February 2025
Published online: 27 June 2025

Abstract

This paper presents a new $\tau$-lepton reconstruction and identification procedure at the ATLAS detector at the Large Hadron Collider, which leads to significantly improved performance in the case of physics processes where a highly boosted pair of $\tau$-leptons is produced and one $\tau$-lepton decays into a muon and two neutrinos (${\tau }_{\mu }$), and the other decays into hadrons and one neutrino (${\tau }_{\text{had}}$). By removing the muon information from the signals used for reconstruction and identification of the ${\tau }_{\text{had}}$ candidate in the boosted pair, the efficiency is raised to the level expected for an isolated ${\tau }_{\text{had}}$. The new procedure is validated by selecting a sample of highly boosted $Z\to {\tau }_{\mu }{\tau }_{\text{had}}$ candidates from the data sample of 140 ${\text{fb}}^{-1}$ of proton–proton collisions at 13 TeV recorded with the ATLAS detector. Good agreement is found between data and simulation predictions in both the $Z\to {\tau }_{\mu }{\tau }_{\text{had}}$ signal region and in a background validation region. The results presented in this paper demonstrate the effectiveness of the ${\tau }_{\text{had}}$ reconstruction with muon removal in enhancing the signal sensitivity of the boosted ${\tau }_{\mu }{\tau }_{\text{had}}$ channel at the ATLAS detector.