Search for vector-like quark production in the lepton+jets and dilepton+jets final states using 5.4 fb - 1 of Run II data
The Standard Model of particle physics provides an excellent description of particle interactions at energies up to ~1 TeV, but it is expected to fail above that scale. Multiple models developed to describe phenomena above the TeV scale predict the existence of very massive, vector-like quarks. A search for single electroweak production of such particles in p$\bar{p}$ collisions at a center-of-mass energy of 1.96 TeV is performed in the W+jets and Z+jets channels. The data were collected by the DØ detector at the Fermilab Tevatron Collider and correspond to an integrated luminosity of 5.4 fb -1 . Events consistent with a heavy object decaying to a vector boson and a jet are selected. We observe no significant excess in comparison to the background prediction and set 95% confidence level upper limits on production cross sections for vector-like quarks decaying to W+jet and Z+jet. Assuming a vector-like quark -- standard model quark coupling parameter $\tilde{κ}$ qQ of unity, we exclude vector-like quarks with mass below 693 GeV for decays to W+jet and mass below 449 GeV for decays to Z+jet. These represent the most sensitive limits to date.