Dark Matter-Motivated Searches for Exotic 4th Generation Quarks in Tevatron and Early LHC Data

TL;DR

This paper explores the potential to detect dark matter via exotic 4th generation quarks decaying into top quarks and dark matter particles at the Tevatron and early LHC, highlighting promising discovery prospects.

Contribution

It introduces a novel search channel for dark matter involving exotic 4th generation quarks decaying to top quarks and dark matter, applicable to various models with invisible particles.

Findings

Tevatron can discover T' up to 400 GeV with 20 fb^-1

LHC at 10 TeV can discover T' up to 490 GeV with 300 pb^-1

Dark matter models consistent with DAMA, CDMS, CoGeNT can be tested with existing data.

Abstract

We determine the prospects for finding dark matter at the Tevatron and LHC through the production of exotic 4th generation quarks T' that decay through T' \to t X, where X is dark matter. The resulting signal of t \bar{t} + \met has not previously been considered in searches for 4th generation quarks, but there are both general and specific dark matter motivations for this signal, and with slight modifications, this analysis applies to any scenario where invisible particles are produced in association with top quarks. Current direct and indirect bounds on such exotic quarks restrict their masses to be between 300 and 600 GeV, and the dark matter's mass may be anywhere below m_T'. We simulate the signal and main backgrounds with MadGraph/MadEvent-Pythia-PGS4. For the Tevatron, we find that an integrated luminosity of 20 fb^-1 will allow 3\sigma discovery up to m_T' = 400 GeV and 95% exclusion up to m_T' = 455 GeV. For the 10 TeV LHC with 300 pb^-1, the discovery and exclusion sensitivities rise to 490 GeV and 600 GeV. These scenarios are therefore among the most promising for dark matter at colliders. Perhaps most interestingly, we find that dark matter models that can explain results from the DAMA, CDMS and CoGeNT Collaborations can be tested with high statistical significance using data already collected at the Tevatron and have extraordinarily promising implications for early runs of the LHC.