Test of CP Violation in $b\bar{b}$ pairs from top quark decay

Abstract

Top pair events provide a source of $b\bar{b}$ pairs, which can be used to probe CP violation in heavy-flavour mixing and decay. In events where one of the $W$ bosons decays leptonically to an electron or muon, the charge of the $W$ boson can be used to determine unambiguously the charge of the accompanying $b$-quark at the time of its production. In cases where the $b$-quark also decays semileptonically to a muon, this sample allows to probe two charge asymmetries constructed with the charge signs of the $W$ and the soft muon. The first measurement of the charge asymmetries in $b\bar{b}$ from top pair decays is hence presented using the data collected with the ATLAS detector during the 8 TeV run of the LHC.