Single lepton charge asymmetries in t ¯t and t ¯tγ production at the LHC

Abstract

We discuss lepton charge asymmetries in tt¯ and tt¯γ production at the LHC, which can be measured in the semileptonic decay channel tt¯→W+bW−b¯→ℓ+νbqq¯′b¯ (or the charge conjugate). Considering several variants of a new physics scenario with a light colour octet, it is seen that for tt¯ these asymmetries may have a sensitivity competitive with the dilepton asymmetry already measured. For tt¯γ the new leptonic asymmetries, as well as the tt¯ charge asymmetry, will reach their full potential with the high luminosity LHC upgrade. These asymmetries can pinpoint deviations at the 3σ−4σ level for new physics scenarios where the charge asymmetries already measured in tt¯ production agree within 1σ.