Jet Radius and Momentum Splitting Fraction with Dynamical Grooming in Heavy-Ion Collisions

Abstract

We investigate the medium modifications of momentum splitting fraction and groomed jet radius with both dynamical grooming and soft drop algorithms in heavy-ion collisions. In the calculation, the partonic spectrum of initial hard scattering in p+p collisions is provided by the event generator PYTHIA8, and the energy loss of fast parton traversing in a hot/dense quantum-chromodynamic medium is simulated with the linear Boltzmann transport model. We predict the normalized distributions of the groomed jet radius θ g and momentum splitting fraction z g with the dynamical grooming algorithm in Pb+Pb collisions at s NN = 5.02 TeV, then compare these quantities in dynamical grooming at a = 0.1, with that in soft drop at z cut = 0.1 and β = 0. It is found that the normalized distribution ratios Pb+Pb/p+p with respect to z g in z cut = 0.1, β = 0 soft drop case are close to unity, those in a = 0.1 dynamical grooming case show enhancement at small z g, and Pb+Pb/p+p with respect to θ g in the dynamical grooming case demonstrate weaker modification than those in the soft drop counterparts. We further calculate the groomed jet number averaged momentum splitting fraction 〈z g〉jets and averaged groomed jet radius 〈θ g〉jets in p+p and A+A for both grooming cases in three p T ch jet intervals, and find that the originally generated well balanced groomed jets will become more momentum imbalanced and jet size less narrowed due to jet quenching, and weaker medium modification of z g and θ g in the a = 0.1 dynamical grooming case than in the soft drop counterparts.