PT Journal
AU Cottin, G
   Helo, JC
   Hirsch, M
   Titov, A
   Wang, ZS
TI Heavy neutral leptons in effective field theory and the high-luminosity LHC
SO Journal of High Energy Physics
JI J. High Energy Phys.
PY 2021
BP 039
EP 34pp
VL 09
IS 9
DI 10.1007/JHEP09(2021)039
LA English
DE Beyond Standard Model; Effective Field Theories; Neutrino Physics
AB Heavy neutral leptons (HNLs) with masses around the electroweak scale are expected to be rather long-lived particles, as a result of the observed smallness of the active neutrino masses. In this work, we study long-lived HNLs in NRSMEFT, a Standard Model (SM) extension with singlet fermions to which we add non-renormalizable operators up to dimension-6. Operators which contain two HNLs can lead to a sizable enhancement of the production cross sections, compared to the minimal case where HNLs are produced only via their mixing with the SM neutrinos. We calculate the expected sensitivities for the ATLAS detector and the future far-detector experiments: AL3X, ANUBIS, CODEX-b, FASER, MATHUSLA, and MoEDAL-MAPP in this setup. The sensitive ranges of the HNL mass and of the active-heavy mixing angle are much larger than those in the minimal case. We study both, Dirac and Majorana, HNLs and discuss how the two cases actually differ phenomenologically, for HNL masses above roughly 100 GeV.
ER