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

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