Search for heavy neutral leptons in decays of W bosons produced in 13 TeV pp collisions using prompt signatures in the ATLAS detector



Aad, G, Aakvaag, E, Abbott, B, Abdelhameed, S, Abeling, K, Abicht, NJ, Abidi, SH, Aboelela, M, Aboulhorma, A, Abramowicz, H
et al (show 2872 more authors) (2026) Search for heavy neutral leptons in decays of W bosons produced in 13 TeV pp collisions using prompt signatures in the ATLAS detector EUROPEAN PHYSICAL JOURNAL C, 86 (2). 153-. ISSN 1434-6044, 1434-6052

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Abstract

The existence of right-handed neutrinos with Majorana masses below the electroweak scale could help address the origins of neutrino masses, the matter–antimatter asymmetry, and dark matter. In this paper, leptonic decays of W bosons from 140 fb-1 of 13 TeV proton–proton collisions at the LHC, reconstructed in the ATLAS experiment, are used to search for heavy neutral leptons produced through their mixing with muon or electron neutrinos in a scenario with lepton number violation. The search is conducted using prompt leptonic decay signatures. The considered final states require two same-charge leptons or three leptons, while vetoing three-lepton same-flavour topologies. No significant excess over the expected Standard Model backgrounds is found, leading to constraints on the heavy neutral lepton’s mixing with muon and electron neutrinos for heavy-neutral-lepton masses. The analysis excludes |Ue|2 values above 8×10-5 and |Uμ|2 values above 5.0×10-5 in the full mass range of 8–65 GeV. The strongest constraints are placed on heavy-neutral-lepton masses in the range 15–30 GeV of |Ue|2<1.1×10-5 and |Uμ|2<5×10-6.

Item Type: Article
Uncontrolled Keywords: 5106 Nuclear and Plasma Physics, 5107 Particle and High Energy Physics, 51 Physical Sciences
Divisions: Faculty of Science & Engineering
Faculty of Science & Engineering > School of Physical Sciences
Faculty of Science & Engineering > School of Physical Sciences > Physics
Depositing User: Symplectic Admin
Date Deposited: 03 Mar 2026 09:01
Last Modified: 22 May 2026 15:22
DOI: 10.1140/epjc/s10052-025-15191-w
Open Access URL: https://link.springer.com/article/10.1140/epjc/s10...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3197302
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