Probes of the Standard Model effective field theory extended with a right-handed neutrino

If neutrinos are Dirac particles and, as suggested by the so far null LHC results, any new physics lies at energies well above the electroweak scale, the Standard Model effective field theory has to be extended with operators involving the right-handed neutrinos. In this paper, we study this effective field theory and set constraints on the different dimension-six interactions. To that aim, we use LHC searches for associated production of light (and tau) leptons with missing energy, monojet searches, as well as pion and tau decays. Our bounds are generally above the TeV for order one couplings. One particular exception is given by operators involving top quarks. These provide new signals in top decays not yet studied at colliders. Thus, we also design an LHC analysis to explore these signatures in the tt¯ production. Our results are also valid if the right-handed neutrinos are Majorana and long-lived.JA is supported by the Spanish MINECO under grant FPA2014-54459-P. SB is supported by a Durham Junior Research Fellowship COFUNDed between Durham University and the European Union under grant agreement number 609412. MC is supported by the Spanish MINECO under the Juan de la Cierva programme and by the Royal Society under the Newton International Fellowship programme. AT acknowledges funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 674896 (ITN Elusives