Three-Prong Distribution of Massive Narrow QCD Jets
  We study the planar-flow distributions of narrow, highly boosted, massive QCD jets. Using the factorization properties of QCD in the collinear limit, we compute the planar-flow jet function from the one-to-three splitting function at tree-level. We derive the leading-log behavior of the jet function analytically. We also compare our semi-analytic jet function with parton-shower predictions using various generators. 
Matan Field, Guy Gur-Ari, David A. Kosower, Lorenzo Mannelli and Gilad   Perez
hep-ph