We calculate the CP-violating electric and weak dipole form factors of the top quark and the tau lepton in models with scalar leptoquarks coupling only to the third generation of quarks and leptons. We obtain numerical values of the real and imaginary parts of these form factors at various energies for different values of leptoquark masses and couplings. The existing limits on the tau electric and weak dipole form factors allow us to put a limit on the masses and couplings of such leptoquarks and therefore on the top electric and weak dipole form factors. We also discuss constraints on the form factors coming from indirect limits on leptoquark masses and couplings deduced from LEP results on Z properties.

Among the viable alternatives to the standard Higgs mechanism is the recently proposed Little Higgs model. The advantage here is that the model has an elementary light neutral scalar particle, which arises dynamically as against its ad hoc introduction in the standard model. The model also avoids hierarchy problem. We have investigated the 𝑊 pair production at ILC to study the littlest Higgs model using different observables. Specifically, polarization fraction of 𝑊 boson is expected to be measured very accurately at ILC. We use this to put limit on the scale parameter, 𝑓, in the model.

The effect of an anomalous $\gamma W W$ coupling in the $e^{-} \gamma \rightarrow \nu_{e} W^{-}$ process through the angular and energy spectrum of the secondary leptons is investigated. Within the narrowwidth-approximation (NWA), a semianalytical study of the secondary lepton energy angle double distribution is considered. Different observables constructed using this distribution are expected to be very effective to probe the anomalous coupling at a typical International Linear Collider machine. Further, suitable combinations of these observables could be used to disentangle the effect of contributions from different terms in the effective Lagrangian.