Diquark resonance and single top production at the Large Hadron Collider

TL;DR

This paper investigates the potential for detecting a color sextet vector diquark at the LHC through its decay to top and bottom quarks, highlighting its distinctive signals and estimating the discovery reach at different luminosities.

Contribution

It provides a detailed analysis of the resonance production and decay of a specific diquark model, exploring its detectability via single top production signatures at the LHC.

Findings

Diquark resonance can dominate single top production for certain mass ranges.

The diquark decay produces a hard b-jet and large missing energy, aiding detection.

LHC can probe diquark masses up to 3.3 TeV at 7 TeV with 1 fb^{-1}.

Abstract

New physics at the TeV scale is highly anticipated at the LHC. New particles with color, if within the LHC energy reach, will be copiously produced. One such particle is a diquark, having the quantum numbers of two quarks, and can be a scalar or a vector. It will decay to two light quarks, or two top quarks, or a top and a light quark, (up or down type depending on the quantum number of the produced diquark). If singly produced, it can be looked for as a dijet resonance, or as giving extra contribution to the single top production or tt production. In this work, we consider a color sextet vector diquark having the quantum number of (ud) type, its resonance production, and the subsequent decay to tb, giving rise to excess contribution to the single top production. Even though the diquark mass is large, its strong resonance production dominate the weak production of tb for a wide range of the diquark mass. Also its subsequent decay to tb produce a very hard b-jet compared to the usual electroweak production. In addition, the missing energy in the final state event is much larger from the massive diquark decays. Thus, with suitable cuts, the final state with b, bar{b} and a charged lepton together with large missing energy stands out compared to the Standard Model background. We make a detailed study of both the signal and the background. We find that such a diquark is accessible at the 7 TeV LHC upto a mass of about 3.3 TeV with the luminosity 1 fb^{-1}, while the reach goes up to about 4.3 TeV with a luminosity of 10 fb^{-1}.