Shedding light on the $t bar t$ asymmetry: the photon handle

We investigate a charge asymmetry in $t bar t gamma$ production at the LHC that provides complementary information to the measured asymmetries in $t bar t$ production. We estimate the experimental uncertainty in its measurement at the LHC with 8 and 14 TeV. For new physics models that simultaneously reproduce the asymmetry excess in $t bar t$ at the Tevatron and the SM-like asymmetry at the LHC, the measurement in $t bar t gamma$ at the LHC could exhibit significant deviations with respect to the SM prediction.