# How to know what production channel Higgs came from?

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.