Search for heavy neutral leptons in decays of W bosons using leptonic and semi-leptonic displaced vertices in s = 13 TeV pp collisions with the ATLAS detector

Journal article

A search is performed for long-lived heavy neutral leptons (HNLs), produced through the decay of a W boson along with a muon or electron. Two channels are explored: a leptonic channel, in which the HNL decays into two leptons and a neutrino, and a semi-leptonic channel, in which the HNL decays into a lepton and a charged pion. The search is performed with 140 fb−1 of s = 13 TeV proton-proton collision data collected by ATLAS during Run 2 of the Large Hadron Collider. No excess of events is observed; Dirac-like and Majorana-like HNLs with masses below 14.5 GeV and mixing coefficients as small as 10−7 are excluded at the 95% confidence level. The results are interpreted under different assumptions on the flavour of the leptons from the HNL decays.

Authors: Aad, G; Aakvaag, E; Abbott, B; Abdelhameed, S; Abeling, K

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer
• Journal: Journal of High Energy Physics
• Volume: 2025
• Issue: 7
• Article number: 196
• Publication date: 2025-07-17
• Acceptance date: 2025-06-20
• DOI: 10.1007/jhep07(2025)196
• EISSN: 1029-8479
• ISSN: 1126-6708
• Language: English
• Keywords: Exotics; Hadron-Hadron Scattering; Beyond Standard Model