Elements of the phenomenology of color-octet scalars (sgluons), as predicted in the hybrid N=1/N=2 supersymmetric model, are discussed in the light of forthcoming experiments at the CERN Large Hadron Collider.
The color gauge hyper-multiplet in N=2 supersymmetry consists of the usual N=1 gauge vector/gaugino super-multiplet, joined with a novel gaugino/scalar super-multiplet. Large cross sections are predicted for the production of pairs of the color-octet
scalars $sigma$ [sgluons] at the LHC: $gg, qbar{q} to sigmasigma^{ast}$. Single $sigma$ production is possible at one-loop level, but the $g gto sigma$ amplitude vanishes in the limit of degenerate $L$ and $R$ squarks. When kinematically allowed, $sigma$ decays predominantly into two gluinos, whose cascade decays give rise to a burst of eight or more jets together with four LSPs as signature for $sigma$ pair events at the LHC. $sigma$ can also decay into a squark-antisquark pair at tree level. At one-loop level $sigma$ decays into gluons or a $t bar t$ pair are predicted, generating exciting resonance signatures in the final states. The corresponding partial widths are very roughly comparable to that for three body final states mediated by one virtual squark at tree level.
Gluinos and neutralinos, supersymmetric partners of gluons and neutral electroweak gauge and Higgs bosons, are Majorana particles in the Minimal Supersymmetric Standard Model [MSSM]. Decays of such self-conjugate particles generate charge symmetric e
nsembles of final states. Moreover, production channels of supersymmetric particles at colliders are characteristically affected by the Majorana nature of particles exchanged in the production processes. The sensitivity to the Majorana character of the particles can be quantified by comparing the predictions with Dirac exchange mechanisms. A consistent framework for introducing gluino and neutralino Dirac fields can be designed by extending the N=1 supersymmetry of the MSSM to N=2 in the gauge sector. We examine to which extent like-sign dilepton production in the processes q q -> ~q ~q and e- e- -> ~e- ~e- is affected by the exchange of either Majorana or Dirac gluinos and neutralinos, respectively, at the Large Hadron Collider (LHC) and in the prospective e- e- mode of a lepton linear collider.
We discuss constrained and semi--constrain
