Related papers: GUT Scale Threshold Corrections in a Complete Supe…
We calculate the proton lifetime and discuss topological defects in a wide class of non-supersymmetric (non-SUSY) $SO(10)$ and $E(6)$ Grand Unified Theories (GUTs), broken via left-right subgroups with one or two intermediate scales (a…
In the supersymmetric grand unified theories (SUSY GUTs), gauge bosons associated with the unified gauge group induce proton decay. We investigate the proton decay rate via the gauge bosons in the SUSY GUTs under the two situations; one is…
We study the proton lifetime in the $SO(10)$ Grand Unified Theory (GUT), which has the left-right (LR) symmetric gauge theory below the GUT scale. In particular, we focus on the minimal model without the bi-doublet Higgs field in the LR…
It is well known that in single step breaking of R-parity conserving SUSY SO(10) that needs the Higgs representations $126+\bar 126$ the GUT-gauge coupling violates the perturbative constraint at mass scales few times larger than the GUT…
We study the correlation between proton lifetime and leptonic CP violation in a class of renormalizable supersymmetric SO(10) grand unified theories (GUTs) with {\bf 10}, {\bf 126} and {\bf 120} Higgs fields, which provides a unified…
We present our best estimates of the uncertainties due to heavy particle threshold corrections on the unification scale $M_U$, intermediate scale $M_I$ and coupling constant Alpha_U in the minimal non-supersymmetric SO(10) models. Using…
An analytical formalism, including RG running at two loop order, is used to link the supersymmetric and GUT spectra in any GUT model in which the three gauge couplings unify. In each specific GUT model, one can then fully explore the…
We calculate the proton lifetime in an SO(10) supersymmetric grand unified theory [SUSY GUT] with U(2) family symmetry. This model fits the low energy data, including the recent data for neutrino oscillations. We discuss the predictions of…
We derive the threshold corrections in $\mathrm{SO}(10)$ grand unified models with the intermediate symmetry being flipped $\mathrm{SU}(5)\times\mathrm{U}(1)$ or $\mathrm{SU}(3)\times\mathrm{SU}(2)\times\mathrm{U}(1)\times\mathrm{U}(1)$,…
Despite the successes of the Standard Model of particle physics, it is known to suffer from a number of deficiencies. Several of these can be addressed within non-supersymmetric theories of grand unification based on $\mathrm{SO}(10)$.…
Grand Unified Theories (GUT) predict proton decay as well as the formation of cosmic strings which can generate gravitational waves. We determine which non-supersymmetric $SO(10)$ breaking chains provide gauge unification in addition to a…
SO(10) supersymmetric grand unified theories [SUSY GUTs] provide a beautiful framework for physics beyond the standard model. Experimental measurements of the three gauge couplings are consistent with unification at a scale $M_G \sim 3…
$SO(10)$ grand unified models have an intermediate symmetry group in between $SO(10)$ and $SU(3)_{C} \otimes SU(2)_{L} \otimes U(1)_{Y}$. Hence they lead to a prediction for proton lifetime in agreement with the experimental lower limit.…
Two-loop evolutions of the gauge couplings in a class of intermediate scale supersymmetric SO(10) models including the effect of third generation Yukawa couplings are studied. The unification scale, the intermediate scale and the value of…
After a brief review of the motivations for grand unification, I discuss the main challenges facing realistic SUSY GUT model building. Achieving doublet-triplet splitting without fine--tuning is chief among them. Symmetry breaking should…
We consider a non-supersymmetric $E_6$ Grand Unified Theory (GUT) with intermediate trinification symmetry $SU(3)_C \times SU(3)_L \times SU(3)_R \times D$ (D denoted as D-parity for discrete left-right symmetry) and study the effect of…
We present a minimal renormalizable non-supersymmetric SO(10) grand unified model with a symmetry breaking sector consisting of Higgs fields in the 54_H + 126_H + 10_H representations. This model admits a single intermediate scale…
We perform a detailed study of the grand unified theories $SO(10)$ and $E(6)$ with left-right intermediate gauge symmetries of the form $SU(N)_L\otimes SU(N)_R \otimes \mathcal{G}$. Proton decay lifetime constrains the unification scale to…
The nucleon decay is a significant phenomenon to verify grand unified theories (GUTs). For the precise prediction of the nucleon lifetime induced by the gauge bosons associated with the unified gauge group, it is important to include the…
It is often argued that in the class of non-supersymmetric SO(10) grand unified theories there is barely any room for reconciling the lower bound on the position of the GUT scale emerging from the proton decay searches and the lower limit…