Probability distribution of the charged isolation momentum $p_{\rm T}^{\text{iso, ch}}$ (see Eq. 2) in pp collisions at $\sqrt{s}=8$ TeV. The isolation threshold $p_{\rm T}^{\text{iso, ch}}< 1.5$ GeV/c is drawn as a dashed grey line. The $p_{\rm T}^{\text{iso, ch}}$ distribution is shown for data (black) and PYTHIA 8 simulations for a signal ($\gamma$-jet) and background (jet-jet) dominated population.