Search for Majorana neutrinos in same-sign WW scattering events from pp collisions at √s=13 TeV

Summary, in English

A search for Majorana neutrinos in same-sign WW scattering events is presented. The analysis uses s=13 TeV proton–proton collision data with an integrated luminosity of 140 fb - 1 recorded during 2015–2018 by the ATLAS detector at the Large Hadron Collider. The analysis targets final states including exactly two same-sign muons and at least two hadronic jets well separated in rapidity. The modelling of the main backgrounds, from Standard Model same-sign WW scattering and WZ production, is constrained with data in dedicated signal-depleted control regions. The distribution of the transverse momentum of the second-hardest muon is used to search for signals originating from a heavy Majorana neutrino with a mass between 50 GeV and 20 TeV. No significant excess is observed over the background expectation. The results are interpreted in a benchmark scenario of the Phenomenological Type-I Seesaw model. In addition, the sensitivity to the Weinberg operator is investigated. Upper limits at the 95% confidence level are placed on the squared muon-neutrino–heavy-neutrino mass-mixing matrix element | VμN| 2 as a function of the heavy Majorana neutrino’s mass mN , and on the effective μμ Majorana neutrino mass | mμμ| . © 2023, CERN for the benefit of the ATLAS Collaboration.

• Author: G. Aad; T.P.A. Åkesson; C. Doglioni; P.A. Ekman; V. Hedberg; H. Herde; B. Konya; E. Lytken; R. Poettgen; N.D. Simpson; O. Smirnova; L. Zwalinski
• Department/s: Particle and nuclear physics; eSSENCE: The e-Science Collaboration
• Publishing year: 2023
• Language: English
• Publication/Series: European Physical Journal C
• Volume: 83
• Issue: 9
• Links: http://dx.doi.org/10.1140/epjc/s10052-023-11915-y
• Document type: Journal article
• Publisher: Springer
• Topic: Subatomic Physics
• Status: Published
• ISBN/ISSN/Other: ISSN: 1434-6044