5-11 February 2017
Hyatt Regency Chicago
America/Chicago timezone

Investigating the role of coherence effects on jet quenching in Pb-Pb collisions at $\sqrt{s_{NN}} =2.76$ TeV using the Nsubjettiness jet shape by ALICE

8 Feb 2017, 11:20
Regency D

Regency D


Nima Zardoshti (University of Birmingham (GB))


We report measurements of two jet shapes, the ratio of 2-Subjettiness to 1-Subjettiness ($\tau_2/\tau_1$) and the opening angle between the two axes of the 2-Subjettiness jet shape which correspond to the axes of the hardest splitting in the jet. Comparison of these two jet shapes in Pb-Pb and pp collisions highlights the role of coherence effects on jet quenching, in the presence of the QGP medium, by separating two-pronged jets from the rest of the jet population. Coherence effects relate to the ability of the medium to resolve a jet's substructure, which has an impact on the energy loss magnitude and mechanism of the traversing jet. In both collision systems charged jets are found with the anti-$k_t$ algorithm, a resolution parameter of R = 0.4 and a constituent cut off of 0.15 GeV. The reclustering algorithm used to obtain the hardest splitting is the exclusive-$k_t$ algorithm. This analysis uses hadron-jet coincidence techniques in Pb-Pb collisions to reject the combinatorial background and further corrects for background effects by employing various jet shape subtraction techniques and unfolding. Measurements of the Nsubjettiness for jet momenta of $20 - 60$ GeV/c in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV and pp collisions at $\sqrt{s}$ = 7.00 TeV will be presented and compared to PYTHIA simulations.

Collaboration ALICE
Preferred Track Jets and High pT Hadrons

Primary author

Nima Zardoshti (University of Birmingham (GB))

Presentation materials