The phenomenological cornucopia of SU(3) exotica

TL;DR

This paper catalogs gauge-invariant interactions involving color sextet fields in the Standard Model, introduces a tensor-product method for identifying invariants, and demonstrates its application through LHC phenomenology of new sextet particles.

Contribution

It develops a systematic approach to classify interactions of color sextet fields and applies it to explore novel collider signatures at the LHC.

Findings

Identified new gauge-invariant operators involving sextet fields.

Computed cross sections for sextet production channels at the LHC.

Discussed experimental constraints on sextet fermions from dijet resonance searches.

Abstract

We introduce an effort to catalog the gauge-invariant interactions of Standard Model (SM) particles and new fields in a variety of representations of the SM color gauge group $\text{SU}(3)_{\text{c}}$. In this first installment, we direct this effort toward fields in the six-dimensional (sextet, $\boldsymbol{6}$) representation. We consider effective operators of mass dimension up to seven (comprehensively up to dimension six), featuring both scalar and fermionic color sextets. We use an iterative tensor-product method to identify the color invariants underpinning such operators, emphasizing structures that have received little attention to date. In order to demonstrate the utility of our approach, we study a simple but novel model of color-sextet fields at the Large Hadron Collider (LHC). We compute cross sections for an array of new production channels enabled by our operators, including single-sextet production and sextet production in association with photons or leptons. We also discuss dijet-resonance constraints on a sextet fermion. This example shows that there remains a wide array of fairly minimal but well motivated and unexplored models with extended strong sectors as we await the high-luminosity LHC.