Roadmap of left-right models based on GUTs

Abstract

We perform a detailed study of the grand unified theories SO (10) and E(6) with left-right intermediate gauge symmetries of the form SU (N ) L ⊗ SU (N ) R ⊗ G. Proton decay lifetime constrains the unification scale to be 10 16 GeV and, as discussed in this paper, unwanted cosmological relics can be evaded if the intermediate symmetry scale is 10 12 GeV. With these conditions, we study the renormalisation group evolution of the gauge couplings and do a comparative analysis of all possible left-right models where unification can occur. Both the D-parity conserved and broken scenarios as well as the supersymmetric (SUSY) and Non-supersymmetric (Non-SUSY) versions are considered. In addition to the fermion and scalar representations at each stage of the symmetry breaking, contributing to the β-functions, we list the intermediate left-right groups which successfully meet these requirements. We make use of the dimension-5 kinetic mixing effective operators for achieving unification and large intermediate scale. A significant result in the supersymmetric case is that to achieve successful unification for some breaking patterns, the scale of SUSY breaking needs to be at least a few TeV. In some of these cases, intermediate scale can be as low as ∼ 10 12GeV, for SUSY scale to be ∼ 30 TeV. This has important consequences in the collider searches for SUSY particles and phenomenology of the lightest neutralino as dark matter. *

Unification, proton decay, and topological defects in non-SUSY GUTs with thresholds

“…So their presence may affect the matching conditions as well in the form of threshold corrections. In the absence of these threshold corrections, the detailed matching conditions for different scenarios are discussed in [7]. These conditions get modified in the presence of threshold corrections [62,[89][90][91][92][93][94][95][96][97].…”

“…In this paper, we estimate the proton lifetime in a wide class of non-supersymmetric GUTs, broken via left-right subgroups with one or two intermediate scales For the one intermediate scale breaking, we suppose that the GUT groups break into their maximal subgroups of the form SU (N ) L ⊗ SU (N ) R ⊗ G, see [7]. This restricts our choice of GUT groups to be SO(10), E (6), with certain breaking patterns.…”

“…We then go on to consider a general analysis of the two intermediate scale cases. To understand the status of the one intermediate scale case, we have recalled our earlier work [7] and computed the same for those breaking chain as well. This gives us a clear notion to understand the present status of one and two intermediate GUT scenarios.…”

SO(10) inspired Z′ models at the LHC

“…In order to allow gauge coupling unification, we need SUSY, but we shall assume it is broken above the Z 0 BLR mass scale so that SUSY particles are not present in the decays of the Z 0 BLR . Note that such SUSY decays have been considered extensively in [12][13][14][15][16][17][18].…”

“…It was recently realized that SUSY SOð10Þ models which break down to this gauge group may allow for a new type of seesaw model, namely the linear seesaw model [10,11]. Subsequently, the phenomenology of the SUSY Uð1Þ R × Uð1Þ B−L model has been studied in a number of works [12][13][14][15][16][17][18]. Indeed, it has been demonstrated that the Abelian BLR gauge group Uð1Þ R × Uð1Þ B−L is equivalent to Uð1Þ Y × Uð1Þ χ [arising from the breaking chain in Eq.…”