SCET is an effective theory for highly energetic quarks interacting with collinear and/or soft gluons.
It has been used for calculations of the decays of B mesons (quark-antiquark bound states involving a bottom quark) and the properties of jets (sprays of hadrons that emerge from particle collisions when a quark or gluon is produced).
SCET has also been used to calculate electroweak interactions in Higgs boson production.
[1] The new feature of SCET is its ability to handle more than one soft energy scale.
See the original papers were by Christian Bauer, Sean Fleming, Michael Luke, Dan Pirjol, and Iain Stewart: