A clean signal for a top-like isosinglet fermion at the Large Hadron Collider

Abstract

We predict a clean signal at the Large Hadron Collider ( √ s=14TeV) for a scenario where there is a top-like, charge + 2 3 vectorlike isosinglet fermion. Such a quark, via mixing with the standard model top, can undergo decays via both flavour-changing Z-boson coupling and flavour-changing Yukawa interactions. We concentrate on the latter channel, and study the situation where, following its pair-production, the heavy quark pair gives rise to two tops and two Higgs boson. We show that the case where each Higgs decays in the bb channel, there can be a rather distinct and background-free signal that can unveil the existence of the vectorlike isosinglet quark of this kind.

Reconstruction of vectorlike top partner from fully hadronic final states

“…This will lead to a wrong assumption on the untagged particle's mass when determining the t-h combination from Eqs. (11) and (12). On the other hand, due to the loose mass constraints employed in the Higgs boson tagging algorithm, misidentification of Z as h leads to a broadened mass peak for the vectorlike top.…”

LHC signatures of warped-space vectorlike quarks

“…We assume a b-tagging efficiency ǫ b tag = 0.5, and demand only four of the six b-jets to be b-tagged (ref. [82] also follows a similar approach) to get a better signal rate. We require the two top-quarks to be reconstructed from two b-tagged jets and four J (where J stands for either a light-jet or an untagged b-jet) and then the two h to be reconstructed from the remaining two b-tagged jets and two J.…”

Distinguishing signatures of top- and bottom-type heavy vectorlike quarks at the LHC

“…The collider phenomenology of these vectorlike isosinglets has been considered extensively in the literature (for the most recent studies, see Refs. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]). We consider the possibility of vectorlike isosinglet quarks in both sectors, taking one at a time in addition to the three generations of SM chiral fermions.…”