Single lepton charge asymmetries in $t\bar{t}$ and $t\bar{t}\gamma$ production at the LHC

Abstract

We discuss lepton charge asymmetries in $t\bar{t}$ and $t\bar{t}\gamma$ production at the LHC, which can be measured in the semileptonic decay channel $t\bar{t}\to W^{+}b{W}^{-}\bar{b}\to {\ell }^{+}\nu bq{\bar{q}}^{\prime }\bar{b}$ (or the charge conjugate). Considering several variants of a new physics scenario with a light colour octet, it is seen that for $t\bar{t}$ these asymmetries may have a sensitivity competitive with the dilepton asymmetry already measured. For $t\bar{t}\gamma$ the new leptonic asymmetries, as well as the $t\bar{t}$ charge asymmetry, will reach their full potential with the high luminosity LHC upgrade. These asymmetries can pinpoint deviations at the $3\sigma -4\sigma$ level for new physics scenarios where the charge asymmetries already measured in $t\bar{t}$ production agree within $1\sigma$.

LATeX 16 pages. Comments added, references changed, journal version

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