Measurement of the Groomed Jet Radius and Momentum Splitting Fraction in pp and Pb-Pb Collisions at √s.sub.NN./sub. = 5.02 TeV

0556246 - ÚJF 2023 RIV US eng J - Journal Article
Acharya, S. - Adamová, Dagmar - Adler, A. - Bielčík, J. - Bielčíková, Jana - Broz, M. - Contreras, J. G. - Herman, T. - Horák, D. - Isakov, Artem - Kotliarov, Artem - Křížek, Filip - Křížková Gajdošová, K. - Kushpil, Svetlana - Lavička, R. - Mareš, Jiří A. - Petráček, V. - Šafařík, K. - Šumbera, Michal - Torres, S. R. - Trzeciak, B. A. - Závada, Petr … Total 1018 authors
Measurement of the Groomed Jet Radius and Momentum Splitting Fraction in pp and Pb-Pb Collisions at √s_NN = 5.02 TeV.
Physical Review Letters. Roč. 128, č. 10 (2022), č. článku 102001. ISSN 0031-9007. E-ISSN 1079-7114
R&D Projects: GA MŠMT(CZ) LTT17018
Research Infrastructure: CERN-CZ II - 90104
Institutional support: RVO:68378271 ; RVO:61389005
Keywords : ALICE collaboration * heavy ion experiment
OECD category: Nuclear physics; Particles and field physics (FZU-D)
Impact factor: 8.6, year: 2022
Method of publishing: Open access
https://doi.org/10.1103/PhysRevLett.128.102001

This article presents groomed jet substructure measurements in pp and Pb-Pb collisions at root s(NN )= 5.02 TeV with the ALICE detector. The soft drop grooming algorithm provides access to the hard parton splittings inside a jet by removing soft wide-angle radiation. We report the groomed jet momentum splitting fraction, z(g), and the (scaled) groomed jet radius, theta(g). Charged-particle jets are reconstructed at midrapidity using the anti-k(T) algorithm with resolution parameters R = 0.2 and R = 0.4. In heavy-ion collisions, the large underlying event poses a challenge for the reconstruction of groomed jet observables, since fluctuations in the background can cause groomed parton splittings to be misidentified. By using strong grooming conditions to reduce this background, we report these observables fully corrected for detector effects and background fluctuations for the first time. A narrowing of the theta(g) distribution in Pb-Pb collisions compared to pp collisions is seen, which provides direct evidence of the modification of the angular structure of jets in the quark-gluon plasma. No significant modification of the z(g) distribution in Pb-Pb collisions compared to pp collisions is observed. These results are compared with a variety of theoretical models of jet quenching, and provide constraints on jet energy-loss mechanisms and coherence effects in the quark-gluon plasma.
Permanent Link: http://hdl.handle.net/11104/0330523