2023 Articles

Search for heavy Majorana or Dirac neutrinos and right-handed 𝑊 gauge bosons in final states with charged leptons and jets in 𝑝𝑝 collisions at √𝑠 = 13 TeV with the ATLAS detector

Aad, G.; Abbott, B.; Abeling, K.; Abicht, N. J.; Abidi, S. H.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Hoffman, A. C. A.; Acharya, B. S.; Bourdarios, C. A.; Adamczyk, L.; Adamek, L.; Addepalli, S. V.; Addison, M. J.; Adelman, J.; Adiguzel, A.; Adye, T.; Affolder, A. A.; Afik, Y.; Agaras, M. N.; Agarwala, J.; Aggarwal, A.; Agheorghiesei, C.; Ahmad, A.; Ahmadov, F.; Ahmed, W. S.; Ahuja, S.; Ai, X.; Aielli, G.; Tamlihat, M. A.; Aitbenchikh, B.; Aizenberg, I.; Akbiyik, M.; Åkesson, T. P. A.; Akimov, A. V.; Akiyama, D.; Akolkar, N. N.; Khoury, K. A.

A search for heavy right-handed Majorana or Dirac neutrinos 𝑁_𝑅 and heavy right-handed gauge bosons 𝑊_𝑅 is performed in events with energetic electrons or muons, with the same or opposite electric charge, and energetic jets. The search is carried out separately for topologies of clearly separated final-state products (“resolved” channel) and topologies with boosted final states with hadronic and/or leptonic products partially overlapping and reconstructed as a large-radius jet (“boosted” channel). The events are selected from 𝑝𝑝 collision data at the LHC with an integrated luminosity of 139 fb⁻¹ collected by the ATLAS detector at √𝑠 = 13 TeV. No significant deviations from the Standard Model predictions are observed.

The results are interpreted within the theoretical framework of a left-right symmetric model, and lower limits are set on masses in the heavy right-handed 𝑊_𝑅 boson and 𝑁_𝑅 plane. The excluded region extends to about 𝑚(𝑊_𝑅) = 6.4 TeV for both Majorana and Dirac 𝑁_𝑅 neutrinos at 𝑚(𝑁_𝑅) < 1 TeV. 𝑁_𝑅 with masses of less than 3.5 (3.6) TeV are excluded in the electron (muon) channel at 𝑚(𝑊_𝑅) = 4.8 TeV for the Majorana neutrinos, and lim- its of 𝑚(𝑁_𝑅) up to 3.6 TeV for m(𝑊_𝑅) = 5.2 (5.0) TeV in the electron (muon) channel are set for the Dirac neutrinos. These constitute the most stringent exclusion limits to date for the model considered.