Search for heavy Majorana or Dirac neutrinos and right-handed W gauge bosons in final states with two charged leptons and two jets at $$ \sqrt{s}=13 $$ TeV with the ATLAS detector

Abstract

Search for heavy Majorana or Dirac neutrinos and right-handed W gauge bosons in final states with two charged leptons and two jets at √ s = 13 TeV with the ATLAS detector The ATLAS Collaboration 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 a pair of energetic electrons or muons, with the same or opposite electric charge, and two energetic jets. The events are selected from pp collision data with an integrated luminosity of 36.1 fb −1 collected by the ATLAS detector at √ s = 13 TeV. No significant deviations from the Standard Model 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 boson and neutrino mass plane. The excluded region extends to m W R = 4.7 TeV for both Majorana and Dirac N R neutrinos.

Heavy Neutral Leptons from low-scale seesaws at the DUNE Near Detector

“…Other bounds of this type can be found in refs. [62][63][64][65][66][67][68] as well as collider ones, from LHCb [69], ATLAS [70], CMS [71,72], BELLE [73] (see also ref. [74]).…”

On lepton number violation in heavy neutrino decays at colliders

“…Studying the ratio between LNV and LNC decay rates as well as the angular distribution of the decay products can give interesting insight into the underlying mechanism of neutrino mass generation. already fixed by solving (24), the size of the radiative corrections is completely determined by the mixing θ a2 , and the masses M 1 and M 2 ,…”

Relaxing LHC constraints on the WR mass

“…The branching fraction of W R → tb is quoted as (0.32 -0.33) in the first scenario and (0.24 -0.25) in the second scenario, for a W R mass range of 500 GeV to 5 TeV, where the 1% difference is due the phase space effects coming from the top quark mass (as compared to the vanishing light quark mass). The ATLAS analysis [25] also considered both scenarios. However, they searched for W R gauge bosons in final states with two charged leptons and two jets.…”