Searching for doubly charged leptons at present and future colliders

Abstract

The production at the LHC of exotic excited leptons of charge Q=_s162e is considered. Such states are predicted in composite models with extended isospin multiplets (IW=1 and IW=3/2). The coupling among these doubly charged leptons and Standard Model fermions may occurs either via gauge or contact interactions. In the former case the decay channels are more constrained. We study the production cross section at the LHC of L_s16_s16 (pp_s13_s178594_s19L_s16_s16_s13_s178467_s19_s13_s178722_s19) and focus on the leptonic signature deriving from the subsequent decays L_s16_s16_s13_s178594_s19W_s16_s13_s178467_s19_s16_s13_s178594_s19_s13_s178467_s19_s16 _s13_s178467_s19_s16_s13_s17957_s19l. The invariant mass distribution of the like-sign dilepton exhibits a sharp end-point corresponding to excited doubly charged lepton mass m_s13_s178727_s19. A preliminary study for the production of doubly charged leptons at the future linear colliders, by considering the process e_s13_s178722_s19e_s13_s178722_s19_s13_s178594_s19L_s13_s178722_s19_s13_s178722_s19e_s13_s17957_s19e, is carried out. Both the contact and gauge interaction mechanisms are investigated and compared.