Color Sextet Scalars at the CERN Large Hadron Collider

TL;DR

This work investigates the collider phenomenology of a color sextet scalar Φ6 at the LHC, focusing on its QCD production and decay into same-sign top-quark pairs. The authors adopt a purely phenomenological framework with Φ6 as an SU(2)_L singlet and examine the dominant decay Φ6 → tt, while discussing flavor constraints and possible hadronization effects. They propose and test a reconstruction strategy in final states with four top quarks, two same-sign leptons, and multiple jets to identify pp → Φ6 Φ6 → tt tt with masses up to around 1 TeV using 100 fb^-1. They compute parton-level production cross sections, compare with color-triplet and color-octet scalars, and demonstrate discovery potential via a dedicated multijet plus same-sign dilepton search, including a full reconstruction of hadronic W and top decays and a resonance in the six-jet system. The results indicate a viable path to discovering or constraining color sextet scalars at the LHC and illustrate how hadronic reconstruction can enable mass and BR measurements in high-multiplicity top-quark final states.

Abstract

Taking a phenomenological approach, we study a color sextet scalar at the LHC. We focus on the QCD production of a color sextet pair Φ_6\barΦ_{6} through gg fusion and q\bar{q} annihilation. Its unique coupling to \bar{ψ^c}ψallows the color sextet scalar to decay into same-sign diquark states, such as Φ_6\to tt/tt^*. We propose a new reconstruction in the multijet plus same sign dilepton with missing transverse energy samples to search for on-shell tt\bar{t}\bar{t} final states from sextet scalar pair production. Thanks to the large QCD production, the search covers the sextet mass range up to 1 TeV for 100 fb^-1 integrated luminosity.

Figures (7)

• Figure 1: Decay width contour for $\Phi_6$ in the mass and coupling plane.
• Figure 2: Production of $\bar{\Phi}_6 \Phi_6$ at the LHC and Tevatron with $\mu_F= M_{\Phi_6}$, fixed scale $\alpha_S(\mu_R)$ with $\mu_R = m_Z$. The PDF set CTEQ6L has been used in all calculation.
• Figure 3: $\text{max}\{p^J_T\}$ and $\text{next-to-max}\{p^J_T\}$
• Figure 4: Reconstructed Hadronic Top Pair. The black(red) line represents the first(second) reconstructed hadronically decaying anti-top quark.
• Figure 5: Reconstructed Sextet from $m_{6j}$ and $M_T$.