The need for new search strategies for fourth generation quarks at the LHC

Michael Geller*, Shaouly Bar-Shalom, Gad Eilam

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


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 the 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: mt'>450 GeV in the semileptonic channel pp→t't'→ℓνbqqb and mt'>557 GeV in the dilepton channel pp→t't'→ℓ+ℓ-ννbb, 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: mt'350 GeV. We, therefore, suggest an alternative search strategy that is more sensitive to beyond SM4 dynamics of the fourth generation fermions.

Original languageEnglish
Pages (from-to)121-128
Number of pages8
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number1-3
StatePublished - 29 Aug 2012
Externally publishedYes


FundersFunder number
Technion-Israel Institute of Technology


    Dive into the research topics of 'The need for new search strategies for fourth generation quarks at the LHC'. Together they form a unique fingerprint.

    Cite this