Using displaced tracks to seek new physics in the ATLAS detector

The Standard Model of particle physics is a powerful theory of nature, yet it does not account for all physical observations. Notably, the nonzero masses of the three neutrino flavours and their transformations into one another suggest the need for an extension of the Standard Model. One such extension postulates the existence of Heavy Neutral Leptons (HNLs, N ) — right-handed neutrino states that do not interact with other particles except through mixing with Standard Model neutrinos. HNLs may generate light neutrino masses through the so-called “seesaw mechanism.”