We study the single production of the fourth family quarks through the process pp--> QjX at the Large Hadron Collider (LHC). We have calculated the decay widths and branching ratios of the fourth family quarks (b and t) in the mass range 300-800 GeV.
The cross sections of signal and background processes have been calculated in a Monte Carlo framework. It is shown that the LHC can discover single t and b quarks if the CKM matrix elements |V_{tq}|,|V_{qb}|>=0.01.
We investigate the effects of unparticles on Compton scattering, e gamma -> e gamma based on a future e^+e^- linear collider such as the CLIC. For different polarization configurations, we calculate the lower limits of the unparticle energy scale Lam
bda_U for a discovery reach at the center of mass energies sqrt(s)=0.5 TeV- 3 TeV. It is shown that, especially, for smaller values of the mass dimension d, (1 <d <1.3), and for high energies and luminosities of the collider these bounds are very significant. As a stringent limit, we find Lambda_U>80 TeV for d<1.3 at sqrt(s)=3 TeV, and 1 ab^(-1) integrated luminosity per year, which is comparable with the limits calculated from other low and high energy physics implications.
We study the process e+e- -->nu nubar gamma to search for its sensitivity to the extra gauge bosons Z_2, Z_3 and W_2 which are suggested by the little Higgs models. We find that the ILC with sqrt(s)=0.5 TeV and CLIC with sqrt(s)=3 TeV cover different
regions of the LHM parameters. We show that this channel can provide accurate determination of the parameters, complementary to measurements of the extra gauge bosons at the coming LHC experiments.
