TeV-scale pseudo-Dirac seesaw mechanisms in anE6inspired model

Abstract

TeV-scale seesaw mechanisms are interesting due to their potential testability at existing collider experiments. Herein we propose an E6-inspired model allowing a TeV-scale pseudo-Dirac singlet neutrino seesaw mechanism with naturally sizeable Yukawa couplings of O(10 −2 ). The model also contains new U(1) gauge interactions (and associated Z bosons with which the singlet neutrinos can be produced at colliders), typically long-lived colour triplet fermions, SU(2) doublet fermions, and a complex scalar -potentially all at the TeV-scale. Additionally we identify three possible explanations for the 750 GeV di-photon excess.

Phenomenological analysis of an E6 -inspired seesaw model

“…In this paper, we have explored the phenomenology of the model presented in Ref. [12]. The primary motivation for this model-the realization of a seesaw mechanism at mass scales testable at the lhc-was achieved without recourse to exceptionally small Yukawa couplings.…”

“…In order to facilitate the decay of exotic quarks, the authors of Ref. [12] introduced another scalar which gains a vev. This can allow the exotic quarks to decay promptly if produced at the lhc in which case searches place a lower bound on their masses of 810 GeV.…”

“…In Ref. [12], an additional scalar Φ 3 was introduced in order to facilitate the decay of the exotic quarks in case the vevs of Φ 1 and Φ 2 were insufficient to satisfy the bbn constraints. The quantum numbers of Φ 3 are shown in table Ib, and it introduces the following additional d5 terms that facilitate the decay of the exotic quark: The first term introduces another contribution to the off-diagonal entry in the mass matrix in eq.…”

“…In this vein, Cai et al presented in Ref. [12] a seesaw model inspired by unification into E 6 [13][14][15][16] which is realized at scales testable at the Large Hadron Collider (lhc). The purpose of this paper is to explore the rich phenomenology of this model in detail.…”

Searching for signatures of E6

“…Other recent discussions of E 6 stimulated by the initial CERN digamma reports but with more general validity include those in [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56]. See also extensive earlier work on E 6 in Refs.…”