Search for New Color-Octet Vector Particle Decaying to ttbar in ppbar Collisions at $\sqrt{s}=1.96$ TeV

TL;DR

This paper reports a search for a hypothetical massive gluon decaying into top quark pairs in proton-antiproton collisions at 1.96 TeV, using data from the Tevatron, and sets limits on its properties.

Contribution

First search to set experimental limits on a color-octet vector particle decaying to top pairs at Tevatron energies.

Findings

No evidence for the massive gluon was observed.

Limits were set on the gluon's coupling strength for masses 400-800 GeV/c^2.

Coupling strength is consistent with zero within the explored parameter space.

Abstract

We present the result of a search for a massive color-octet vector particle, (e.g. a massive gluon) decaying to a pair of top quarks in proton-antiproton collisions with a center-of-mass energy of 1.96 TeV. This search is based on 1.9 fb$^{-1}$ of data collected using the CDF detector during Run II of the Tevatron at Fermilab. We study $t\bar{t}$ events in the lepton+jets channel with at least one $b$-tagged jet. A massive gluon is characterized by its mass, decay width, and the strength of its coupling to quarks. These parameters are determined according to the observed invariant mass distribution of top quark pairs. We set limits on the massive gluon coupling strength for masses between 400 and 800 GeV$/c^2$ and width-to-mass ratios between 0.05 and 0.50. The coupling strength of the hypothetical massive gluon to quarks is consistent with zero within the explored parameter space.