Parton splitting scales of reclustered large-radius jets in high-energy nuclear collisions

We carry out the first theoretical investigation on yields and the hardest parton splitting of large-radius jets reclustered from small radius (R = 0.2) anti-k(t) jets in Pb + Pb collisions, and confront them with the recent ATLAS measurements. The Linear Boltzmann Transport (LBT) model is employed for jet propagation and jet-induced medium excitation in the hot-dense medium. We demonstrate that, with their complex structures, the medium suppression of the reclustered large radius jets at R = 1 is larger than that of inclusive R = 0.4 jets defined conventionally. The large radius jet constituents are reclustered with the k(t )algorithm to obtain the splitting scale root d(12), which characterizes the transverse momentum scale for the hardest splitting in the jet. The large-radius jet production as a function of the splitting scale root d(12) of the hardest parton splitting is overall suppressed in Pb + Pb relative to p + p collisions due to the reduction of jets yields. A detailed analyses show that the alterations of jet substructures in Pb + Pb also make significant contribution to the splitting scale root d(12) dependence of the nuclear modification factor R-AA. Numerical results for the medium modifications of the jet splitting angle Delta R-12 and the splitting fraction z are also presented.