The two-prong structure related to the leading subjets inside a reconstructed jet opens new avenues toward
precision constraints on the in-medium modification of parton showers.
In this talk, we present the first resummed calculation of the soft-dropped groomed momentum sharing distribution,
or the jet splitting function, in heavy-ion collisions for both light jets and heavy flavor tagged jets.
Existing light jet splitting function data from the STAR experiment at RHIC and the CMS experiment at LHC
can be understood in the unified framework of soft-collinear effective theory with Glauber gluon interactions.
For heavy flavor jets, very interestingly, the momentum sharing distribution of b-tagged jets is more strongly
modified in comparison to the one for light jets, which provides a novel handle on mass corrections to in-medium parton showers that are at present difficult to constraint using inclusive heavy meson production.