Heavy Majorana neutrinos in the effective Lagrangian description: Application to hadron colliders

We consider the effects of heavy Majorana neutrinos N with sub-TeV masses and argue that the mere observation of these particles Would be a signal of physics beyond the minimal seesaw mechanism. We describe the N interactions rising ail effective Lagrangian and exhibit the complete set of effective operators of dimension <= 6 involving the N and Standard Model fields. We argue that these interactions can be relatively easy to track at high-energy colliders. For example, we find that new physics (beyond the N) at the TeV-scale can yield thousands of characteristic same-sign lepton number violating l(+) l(+) jj events (j = light jet) at the LHC if m(N) less than or similar to 600 GeV, which can also have a distinctive forward-backward asymmetry signal; even the Tevatron has good prospects for this signature if m(N) less than or similar to 300 GeV. (c) 2008 Elsevier B.V. All rights reserved.