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Most limits on the fourth generation heavy top quark (the t) are based on the assumed dominance of t -> Wb, which is expected to be case in the minimal fourth generation framework with a single Higgs (the so called SM4). Here we show, within a variant of a Two Higgs Doublet Model with four generations of fermions, that, in general, a different t detection strategy is required if the physics that underlies the new heavy fermionic degrees of freedom goes beyond the naive SM4. We find that the recent CMS lower bounds: m_{t}< 450 GeV in the semi-leptonic channel pp -> tt -> l u qqbb and m_{t}< 557 GeV in the dilepton channel pp -> tt ->ll u u bb, that were obtained using the customary (SM4-driven) detection strategies, do not apply. In particular, we demonstrate that if the decay t -> ht dominates, then applying the standard CMS search tools leads to a considerably relaxed lower bound: m_{t} >~350 GeV. We, therefore, suggest an alternative search strategy that is more sensitive to beyond SM4 dynamics of the fourth generation fermions.
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.
We show that simultaneous precision measurement of the CP-violating phase in time-dependent Bs --> J/psi phi study and the Bs --> mu+ mu- rate, together with measuring m_t by direct search at the LHC, would determine V_{ts}^*V_{tb} and therefore the
We consider an extension of the Standard Model involving a singlet Higgs and down type vector-like quarks in the light of the current LHC Higgs data. For a good range of the parameters of the Higgs potential, and a mass range for the heavy vector-lik
Natural SUSY suggests the existence of light stop quarks, accessible at the LHC, which are the focus of a dedicated CMS search program. I present two inclusive CMS searches that look for TeV scale colored sparticles in final states with jets, b-tagge
We study the effect of squark-generation mixing on gluino decays in the Minimal Supersymmetric Standard Model (MSSM). We show that due to the effect the quark-flavor violating (QFV) gluino decay branching ratio B(gluino -> c bar{t} (t bar{c}) + neutr