We perform a comprehensive study of partonic energy loss reflected in the nuclear modification factors of charged particles and jets measured in PbPb collisions at √(s_ NN) = 2.76 and 5.02 TeV in wide transverse momentum (p_ T) and centrality range. The p_ T distributions in pp collisions are fitted with a modified power law and the nuclear modification factor in PbPb collisions can be obtained using effective shift (Δ p_ T) in the spectrum measured at different centralities. Driven by physics

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... onsideration, the functional form of energy loss given by Δ p_ T can be assumed as power law with different power indices in three different p_ T regions. The power indices and the boundaries of three p_ T regions are obtained by fitting the measured nuclear modification factor as a function of p_ T in all collision centralities simultaneously. The energy loss in different collisions centralities are described in terms of fractional power of number of participants. It is demanded that the power law functions in three p_T regions and their derivatives are continuous at the p_ T boundaries. The Δ p_ T for light charged particles is found to increase linearly with p_ T in low p_ T region below ∼ 5-6 GeV/c and approaches a constant value in high p_ T region above ∼ 22-29 GeV/c with an intermediate power law connecting the two regions. The method is also used for jets and it is found that for jets, the Δ p_ T increases approximately linearly even at very high p_ T.