New Color-Octet Vector Boson Revisit

TL;DR

This paper re-examines a proposed color-octet axial-vector boson $Z_c$ as an explanation for recent di-jet and top quark asymmetry measurements, showing it can fit the data with specific couplings.

Contribution

The study demonstrates that the $Z_c$ boson can simultaneously explain the di-jet bump and top quark asymmetry without conflicting with existing differential cross section data.

Findings

The di-jet bump can be induced by $Z_c$ with $g_{Z_c q ar q} =0.2 g_s$.

The top quark forward-backward asymmetry $A_{FB}^t$ can be reproduced with appropriate $Z_c$-top coupling.

Theoretical $A_{FB}^t$ matches experimental data within 1-1.8 sigma.

Abstract

Motivated by CDF recent measurements on di-jet invariant mass spectrum where di-jet is associated production with charged leptons ($e/\mu$) and missing energy, we re-examine the previous proposed massive color-octet axial-vector-like boson $Z_c$. Our simulation showed that the di-jet bump around 120-160 GeV can be induced by $Z_c$ with effective coupling $g_{Z_c q \bar q} =0.2 g_s$ (q represents the quark other than top and $g_s$ is the strong coupling constant). Moreover our numerical investigation indicated that the top quark forward-backward asymmetry $A_{FB}^t$ can be reproduced without distorting shape of differential cross section $d\sigma/d M_{t\bar t}$, provided that the $Z_c$ and top quark coupling is appropriately chosen ($g_{Z_c t \bar t} \simeq 4.5 g_{Z_c q \bar q}$). Our results also showed that the theoretical $A_{FB}^t$ as functions of $\Delta y$ and $M_{t\bar t}$ can be consistent with data within $1\sigma$ and $1.8\sigma$ respectively.