Observation of a pseudoscalar excess at the top quark pair production threshold
A search for resonances in top quark pair (tt-) production in final states with two charged leptons and multiple jets is presented, based on proton-proton collision data collected by the CMS experiment at the CERN LHC ats=13TeV, corresponding to 138 fb<sup>-1</sup>. The analysis explores the invariant mass of thett-system and two angular observables that provide direct access to the correlation of top quark and antiquark spins. A significant excess of events is observed near the kinematictt-threshold compared to the non-resonant production predicted by fixed-order perturbative quantum chromodynamics (pQCD). The observed enhancement is consistent with the production of a color-singlet pseudoscalar (1S0[1]) quasi-bound toponium state, as predicted by non-relativistic quantum chromodynamics. Using a simplified model for1S0[1]toponium, the cross section of the excess above the pQCD prediction is measured to be8.8-1.4+1.2pb.
Institutions
- Deutsches Elektronen-Synchrotron DESY (DE)
- European Organization for Nuclear Research (CH)
- RWTH Aachen University (DE)
Publication Details
- Journal
- Reports on Progress in Physics
- Published
- 2025-08-01
- DOI
- https://doi.org/10.1088/1361-6633/adf7d3
- Citations
- 18
- Primary Topic
- Particle physics theoretical and experimental studies
- Type
- article
- Field-Weighted Citation Impact
- 33.66
Funders
- National Science Foundation
- U.S. Department of Energy
- Alfred P. Sloan Foundation
- Alexander von Humboldt-Stiftung
- Nvidia
- Weston Havens Foundation
- CERN
- Türkiye Enerji, Nükleer ve Maden Araştırma Kurumu
- European Commission
- Department of Science and Technology, Ministry of Science and Technology, India
- Science Foundation Ireland
- Deutsche Forschungsgemeinschaft
- Fundação de Amparo à Pesquisa do Estado de São Paulo
- National Natural Science Foundation of China
- Ministerstvo Školství, Mládeže a Tělovýchovy
- Fonds National de la Recherche Luxembourg
- National Science Council
- Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
- Bundesministerium für Bildung und Forschung
- Austrian Science Fund
- Fonds De La Recherche Scientifique - FNRS
- Fonds Wetenschappelijk Onderzoek
- Consejo Nacional de Ciencia y Tecnología
- Ministerio de Economía y Competitividad
- Bulgarian National Science Fund
- Conselho Nacional de Desenvolvimento Científico e Tecnológico
- Ministry of Science, ICT and Future Planning
- Magyar Tudományos Akadémia
- A.G. Leventis Foundation
- National Science and Technology Development Agency
- Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul
- Secretaría de Educación Superior, Ciencia, Tecnología e Innovación
- Türkiye Bilimsel ve Teknolojik Araştırma Kurumu
- Ministry of Education, India
- Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
- National Academy of Sciences of Ukraine
- Centre National de la Recherche Scientifique
- Shota Rustaveli National Science Foundation
- Universidad Autónoma de San Luis Potosí
- Latvijas Zinātnes Padome
- Benemérita Universidad Autónoma de Puebla
- Pakistan Atomic Energy Commission
- Ministry of Science,Technology and Research
- Nemzeti Kutatási Fejlesztési és Innovációs Hivatal
- Hellenic Foundation for Research and Innovation
- Ministry of Higher Education, Science, Research and Innovation, Thailand
- Qatar National Research Fund
- Science and Technology Facilities Council
- Fundação para a Ciência e a Tecnologia
- Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture
- European Regional Development Fund
- Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional
- Agencia Estatal de Investigación
- Fundamental Research Funds for the Central Universities
- Institut National de Physique Nucléaire et de Physique des Particules