Time : 2021/06/03 (Thu.) 12:30
Place : online 

Abstract: 
We study the prospects of displaced-vertex searches for
sterile neutrinos at the Large Hadron Collider in the framework of the
neutrino-extended Standard Model Effective Field Theory (N_R SMEFT). The
production and decay of sterile neutrinos can proceed via the standard
active-sterile neutrino mixing in the weak current, as well as through
higher-dimensional operators arising from decoupled new physics. If
sterile neutrinos are long-lived, their decay can lead to displaced
vertices which can be reconstructed. We perform Monte-Carlo simulations
to investigate the search sensitivities for the ATLAS/CMS detector, the
future far-detector experiments: AL3X, ANUBIS, CODEX-b, FASER, MATHUSLA,
and MoEDAL-MAPP, and at the proposed fixed-target experiment SHiP. We
consider two scenarios: 1) sterile neutrinos are predominantly produced
via rare charm and bottom mesons decays through minimal mixing and/or
dimension-six operators in the N_R SMEFT Lagrangian, and 2) sterile
neutrinos are produced primarily via EFT operators which contain two
sterile neutrinos and decay only via the minimal mixing. We find that
these experiments are very competitive with other searches, and that in
the second scenario the phenomenology can actually differ for masses
above roughly 100 GeV between Dirac and Majorana sterile neutrinos.