We examine the rare decays B s ! l þ l À and B ! Kl þ l À in the framework of the topcolor-assisted technicolor (TC2) model. The contributions of the new particles predicted by this model to these rare decay processes are evaluated. We find that the values of their branching ratios are larger than the standard model predictions by one order of magnitude in wide range of the parameter space. The longitudinal polarization asymmetry of leptons in B s ! l þ l À can approach Oð10 À2 Þ. The forward-backward asymmetry of leptons in B ! Kl þ l À is not large enough to be measured in future experiments. We also give some discussions about the branching ratios and the asymmetry observables related to these rare decay processes in the littlest Higgs model with T-parity.

It is well known that finding and measuring the masses of particles in the Minimal Supersymmetric Standard Model (MSSM) at the Large Hadron Collider (LHC) may be possible using invariant mass distributions in exclusive channels containing n j jets and n l leptons. We perform this analysis for the (n j , n l ) = (0, 4) decay of heavy Higgs bosons to neutralinos, pp → H/A → χ 0 i χ 0 j (i, j = 2, 3, 4), which then decay to four leptons and two lightest neutralinos χ 0

The left-right twin $Higgs$ ($LRTH$) model is a concrete realization of the twin $Higgs$ mechanism, which predicts the existence of the top partner $T$. In this paper, we consider production of $T$ associated with the top quark $t$ at the high energy linear $e^{+}e^{-}$ collider ($ILC$) and the $LHC$ experiments, and its single production in future linac-ring type $ep$ collider experiment. To compare our results with those of the littlest $Higgs$ model with $T$-parity, we also estimate production of the $T$-even top partner $T_{+}$ via the corresponding processes in these high energy collider experiments. A simply phenomenological analysis is also given.Comment: 21 pages, 10 figures; to be published in Nucl. Phys.

We consider the rare top decays t → qh and [Formula: see text] (q = u or c) in the context of the smallest Higgs model with T-parity (called the LHT model). We find that the LHT model can significantly enhance the values of the branching ratios Br (t → qh) and [Formula: see text] with respect to those predicted by the standard model (SM).

The topcolor scenario generally predicts the existence of the neutral top-pion π0t and the nonuniversal gauge boson Z′, which have flavor changing couplings to ordinary fermions at tree-level. Taking into account the constraints of the lepton flavor violation (LFV) processes μ → eγ and μ → 3e on the relevant free parameters, we consider production of these new particles via the LFV processes eγ → τπ0t and eγ → τZ′ at the international linear e+e− collider (ILC) experiments. We find that the effective cross section for the LFV process eγ → τπ0t is smaller than 0.2fb. While, the effective cross section of the LFV process eγ → τZ′ can reach 12.2fb with reasonable values of the free parameters.