Related papers: On the fine-tuning problem in minimal SO(10) SUSY-…
We present an updated assessment of the viability of t-b-tau Yukawa coupling unification in supersymmetric models. For the superpotential Higgs mass parameter mu>0, we find unification to less than 1% is possible, but only for GUT scale…
The unification of gauge and Yukawa couplings within the minimal supersymmetric standard model is studied at the two loop level. We derive an expression for the effective scale, $T_{SUSY}$, which characterizes the supersymmetric particle…
The status of top-bottom-tau Yukawa coupling unification in supersymmetric SO(10) models is reviewed with a particular emphasis on the implications of the Higgs boson mass in the vicinity of 125 GeV, as suggested by the LHC Higgs data. In…
The supersymmetric $SU(6)$ model accompanied by the flavour-blind discrete symmetry $Z_3$ can succesfully deal with such key problems of SUSY GUTs, as are the gauge hierarchy/doublet-triplet splitting, $\mu$-problem and flavour problem. The…
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…
In F-theory GUT constructions Yukawa couplings necessarily take place at the intersection of three matter curves. For generic geometric configurations this gives rise to problematic Yukawa couplings unable to reproduce the observed…
We scan the complete parameter space of the supersymmetric standard model extended by a gauge singlet, which is compatible with the following constraints: universal soft supersymmetry breaking terms at the GUT scale, finite running Yukawa…
Simple supersymmetric grand unified models based on the gauge group SO(10) require --in addition to gauge and matter unification-- the unification of t-b-\tau Yukawa couplings. Yukawa unification, however, only occurs for very special…
I discuss a renormalisable model based on $\Delta(27)$ family symmetry with an $SO(10)$ grand unified theory (GUT) with spontaneous geometrical $CP$ violation. The symmetries are broken close to the GUT breaking scale, yielding the minimal…
We study the so-called new minimal supersymmetric SO(10) GUT(NMSGUT) where explicit spontaneous symmetry breaking allows determination of superheavy spectrum and thus threshold corrections to the effective MSSM couplings. This provides a…
Recent renormalization group calculations of the sparticle mass spectrum in the Minimal Supersymmetric Standard Model (MSSM) show that t-b-\tau Yukawa coupling unification at M_{\rm GUT} is possible when the mass spectra follow the pattern…
We consider a supersymmetric Grand Unified Theory (GUT) based on the gauge group SO(10) suggested by Aulakh et al., which features two--step intermediate symmetry breaking, $SO(10) \to SU(4)_C \times SU(2)_L \times SU(2)_R \to SU(3)_C…
Proton decay is one of the most important predictions of the grand unified theory (GUT). In the supersymmetric (SUSY) GUT, proton decays via the dimension-five operators need to be suppressed. In the $SO(10)$ model where ${\bf…
Group theoretical factors from GUT symmetry breaking can lead to predictions for the ratios of quark and lepton masses at the unification scale. Due to supersymmetric (SUSY) threshold corrections the viability of such predictions can depend…
We discuss the possibility of unifying in a simple and economical manner the Yukawa couplings of third generation fermions in a non-supersymmetric SO(10) model with an intermediate symmetry breaking, focusing on two possible patterns with…
The t-b-tau unification with positive Higgs mass parameter \mu\ in the minimal supersymmetric standard model prefers "just so" Higgs splitting and a light gluino < 500 GeV which appears to be ruled out by the recent LHC searches. We…
Supersymmetric $SO(10)$ models with Yukawa coupling matrices involving only a $10_H$ and a $\overline{126}_H$ of Higgs fields can lead to a predictive and consistent scenario for fermion masses and mixings, including the neutrino sector.…
In Grand Unified Theories (GUTs), the Standard Model (SM) gauge couplings need not be unified at the GUT scale due to the high-dimensional operators. Considering gravity mediated supersymmetry breaking, we study for the first time the…
Grand unification of gauge couplings and fermionic representations remains an appealing proposal to explain the seemingly coincidental structure of the Standard Model. However, to realise the Standard Model at low energies, the unified…
The Supersymmetric SO(10) GUT based on the ${\bf{210\oplus 10\oplus 120\oplus 126\oplus {\bar{126}}}}$ Higgs system has 40 real superpotential parameters of which 2 can be fixed by the Light Higgs doublet fine tuning and one by the…