Common origin of 3.55 keV x-ray line and gauge coupling unification with left-right dark matter

Abstract

We present a minimal left-right dark matter framework that can simultaneously explain the recently observed 3.55 keV X-ray line from several galaxy clusters and gauge coupling unification at high energy scale. Adopting a minimal dark matter strategy, we consider both left and right handed triplet fermionic dark matter candidates which are stable by virtue of a remnant Z 2 (−1) B−L symmetry arising after the spontaneous symmetry breaking of left-right gauge symmetry to that of the standard model. A scalar bitriplet field is incorporated whose first role is to allow radiative decay of right handed triplet dark matter into the left handed one and a photon with energy 3.55 keV. The other role this bitriplet field at TeV scale plays is to assist in achieving gauge coupling unification at a high energy scale within a non-supersymmetric SO(10) model while keeping the scale of left-right gauge symmetry around the TeV corner. Apart from solving the neutrino mass problem and giving verifiable new contributions to neutrinoless double beta decay and charged lepton flavour violation, the model with TeV scale gauge bosons can also give rise to interesting collider signatures like diboson excess, dilepton plus two jets excess reported recently in the large hadron collider data.

Naturally light Dirac neutrino in Left-Right Symmetric Model

“…Thus, to have purely Dirac type neutrinos, one usually has to introduce additional symmetries that can prevent a Majorana mass term of the heavy fields introduced for seesaw and also can explain the origin of tiny Dirac mass. There have been several proposals already that can generate tiny Dirac neutrino masses [16][17][18][19][20][21][22][23][24][25]. While most of these scenarios explain the origin of tiny Dirac mass at one or two loop level, there are some scenarios [19] which consider an additional scalar doublet apart from the SM one which acquire a tiny vacuum expectation value (vev) naturally due to the presence of a softly broken global symmetry.…”

“…A specific version of LRSM discussed in a much earlier work [17] generates Dirac neutrino mass at two loop level. Recently, there have been a few proposals to realise a tiny Dirac type neutrino mass at one loop level within different variants of LRSM [22,23,25] where all of them considered additional discrete symmetries apart from the gauge symmetry mentioned above 2 . Here we consider a similar scenario but without any discrete symmetries.…”

The $$B-L$$ B - L scotogenic models for Dirac neutrino masses

“…Note that in conventional left-right symmetric models [33][34][35][36][37]52], the gauge symmetry breaking pattern…”

“…Recently, several efforts were made at tree level [55,[58][59][60], and a specific one-loop realization was also proposed based on a left-right symmetry scheme [52]. In this brief article, we propose the U (1) B−L extensions of scotogenic Dirac neutrino mass models with intermediate Dirac fermion singlets.…”

“…Several scotogenic models for the Dirac neutrino masses were proposed in Refs. [46][47][48][49][50][51][52]. The generic one-loop topographies are discussed in Ref.…”