There are four main production channels for SM Higgs: ggF, VBF, Higgstrahlung and associated top.
In multiple occasion I've seen experimental bounds referring to say $\sigma(gg \to H \to \tau^+\tau^-)$.
How can experimental people know which events come from ggF instead of say VBF? I though that when people calculate cross section of say $\sigma(pp\to H \to \tau^+\tau^-)$ they take all the events corresponding to $\tau^+\tau^-$ final state which has the invariant mass of ~125 GeV and then subtract the background.
You don't actually know how the Higgs was produced, you only see the decay products, so how experimentallists put bounds on something like $\sigma(gg \to H \to \tau^+\tau^-)$ specifically.