  I develop an Effective Field Theory (EFT) framework to compute jet
substructure observables for heavy ion collision experiments. As an
illustration, I consider dijet events that accompany the formation of a weakly
coupled Quark Gluon Plasma(QGP) medium in a heavy ion collision and look at an
observable insensitive to jet selection bias: the simultaneous measurement of
jet mass along with the transverse momentum imbalance between the jets that are
groomed to remove soft radiation. Treating the jet as an open quantum system, I
write down a factorization formula within the SCET(Soft Collinear Effective
Theory) framework in the forward scattering regime. The physics of the medium
is encoded in a universal soft field correlator while the jet-medium
interaction is captured by a medium induced jet function. The factorization
formula leads to a Lindblad type equation for the evolution of the reduced
density matrix of the jet in the Markovian approximation. The solution for this
equation allows a resummation of large logarithms that arise due to the final
state measurements imposed while simultaneously summing over multiple
incoherent interactions of the jet with the medium.
