Color-octet scalars and potentially large CP violation at the LHC

TL;DR

This paper explores CP violation effects in a model with color-octet scalars at the LHC, showing large potential asymmetries in top-antitop production that depend on scalar resonance detection amid background noise.

Contribution

It introduces a model with two neutral color-octet scalars and analyzes their CP violation effects in top-quark pair production at the LHC, highlighting large observable asymmetries.

Findings

Large raw CP asymmetries up to 12% in scalar resonance production

CP violation effects depend on scalar resonance extraction from background

Potential for observing CP violation in top-quark pair channels at the LHC

Abstract

We consider the phenomenology of CP violation in a color-octet extended scalar sector for t\bar{t} production and decay at the LHC. In particular we study the effect of the two neutral color-octet scalars S_I and S_R that occur in the model. There are two new sources of CP violation: a phase in the couplings of S_{I,R} to top-quarks; and two phases in the quartic couplings of the scalar potential. In resonant production of a single S_{I,R} followed by its decay into t\bar{t} pairs through the parton level process gg to S_{I,R} to t\bar{t}, we find large raw CP asymmetries which can reach 12%. These raw asymmetries are, of course, diluted by standard model (SM) t\bar{t} pairs making observation of CP violation contingent on whether the resonance itself can be extracted from the SM background.