Search for New $T^\prime$ Particles in Final States with Large Jet Multiplicities and Missing Transverse Energy in ppbar Collisions at sqrt(s) = 1.96 TeV

TL;DR

This paper reports a search for hypothetical fourth-generation quarks T' decaying to top quarks and dark matter candidates, using collider data, and sets mass exclusion limits based on the absence of observed excess events.

Contribution

First search for T' quarks decaying to top quarks and dark matter in hadronic final states at Fermilab, establishing mass exclusion limits up to 400 GeV/c2.

Findings

No excess observed over standard model predictions.

Excluded T' masses up to 400 GeV/c2 for certain dark matter masses.

Set 95% confidence level limits on T' production.

Abstract

We present a search for a new particle T' decaying to a top quark via T' -> t + X, where X goes undetected. We use a data sample corresponding to 5.7 fb-1 of integrated luminosity of ppbar collisions with sqrt{s} = 1.96 TeV, collected at Fermilab by the CDF II detector. Our search for pair production of T' is focused on the hadronic decay channel, ppbar -> T'T' -> tt +XX -> bbqqqq + XX. We interpret our results in terms of a model where T' is an exotic fourth generation quark and X is a dark matter candidate. The data are consistent with standard model expectations. We set a limit on the generic production of T'T'->tt+XX, excluding the fourth generation exotic quarks T' at 95% confidence level up to m_T' = 400 GeV/c2 for m_X < 70 GeV/c2.