Search

We explore possible signatures for charged lepton flavour violation (LFV), sparticle discovery at the LHC and dark matter (DM) searches in grand unified theories (GUTs) based on SU(5), flipped SU(5) (FSU(5)) and SU(4)c×SU(2)L×SU(2)R (4-2-2). We assume that soft supersymmetry-breaking terms preserve the group symmetry at some high input scale, and focus on the non-universal effects on different matter representations generated by gauge interactions at lower scales, as well as the charged LFV induced in Type-1 see-saw models of neutrino masses. We identify the different mechanisms that control the relic DM density in the various GUT models, and contrast their LFV and LHC signatures. The SU(5) and 4-2-2 models offer good detection prospects both at the LHC and in LFV searches, though with different LSP compositions, and the SU(5) and FSU(5) models offer LFV within the current reach. The 4-2-2 model allows chargino and gluino coannihilations with neutralinos, and the former offer good detection prospects for both the LHC and LFV, while gluino coannihilations lead to lower LFV rates. Our results indicate that LFV is a powerful tool that complements LHC and DM searches, providing significant insights into the sparticle spectra and neutrino mass parameters in different models. [ABSTRACT FROM AUTHOR]

The various symmetry breaking patterns that are possible with a 24-plet and a 5-plet of Higgs fields in SU(5) are classified. Spontaneous breakdown of SU(5) to SU(3)× U(1) can be achieved (excluding the gauge hierarchy problem) without imposing unnatural constraints on the parameters of the Higgs potential. [ABSTRACT FROM AUTHOR]

Discrete symmetries typically arise when the ten-dimensional heterotic E8×E8 superstring theory is compactified on Calabi–Yau (CY) manifolds and they are expected to play an essential role in phenomenological applications. Yau has shown how a CY manifold that leads to three generation models can be constructed. The discrete symmetries associated with several of these models are found. In particular, the models that have the largest (maximal) discrete symmetries are identified. [ABSTRACT FROM AUTHOR]

We explore the sparticle mass spectra including LSP dark matter within the framework of supersymmetric SU(4)c × SU(2)L × SU(2)R (422) models, taking into account the constraints from extensive LHC and cold dark matter searches. The soft supersymmetry-breaking parameters at MGUT can be non-universal, but consistent with the 422 symmetry. We identify a variety of coannihilation scenarios compatible with LSP dark matter, and study the implications for future supersymmetry searches and the ongoing muon g-2 experiment. [ABSTRACT FROM AUTHOR]

We discuss gauge models based on a superstring motivated rank six subgroup of E. Lepton number is an accidental unbroken symmetry of the models which leads to an essentially stable proton. One of the neutral gauge bosons couples to B- L and may have mass below a TeV. [ABSTRACT FROM AUTHOR]