1. Measurement of angular and momentum distributions of charged particles within and around jets in Pb plus Pb and pp collisions at root s(NN)=5.02 TeV with the ATLAS detector
- Author
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Álvarez Piqueras, D., Aparisi Pozo, J.A., Bailey, A.J., Barranco, Laura, Cabrera, Susana, Castillo, F.L., Castillo Mª Victoria, Cerda Alberich, L., Costa, María José, Escobar, Carlos, Estrada, Oscar, Ferrer, Antonio, Fiorini, L., Fullana, Esteban, Fuster, Juan, García García, Carmen, García Navarro, José Enrique, González de la Hoz, Santiago, Guerrero Rojas, J.G.R., Gonzalvo Rodríguez, Galo Rafael, Higón, Emilio, Jimenez Pena, Javier, Lacasta Llácer, Carlos, Lozano Bahilo, José J., Madaffari, Daniele, Mamuzic, Judita, Martí García, Salvador, Melini, Davide, Miñano Moya, M., Mitsou, Vasiliki A., Rodriguez Bosca, S., Rodriguez Rodriguez, D., Ruiz Martínez, Arantxa, Salt, José, Santra, A., Sánchez Martínez, Javier, Soldevila, Urmila, Valero, Alberto, Valls Ferrer, Juan Antonio, Vos, Marcel, ATLAS Collaboration, Ministerio de Economía y Competitividad (España), and Ministerio de Ciencia, Innovación y Universidades (España)
- Subjects
Astrophysics::High Energy Astrophysical Phenomena ,High Energy Physics::Experiment ,Nuclear Experiment - Abstract
Studies of the fragmentation of jets into charged particles in heavy-ion collisions can provide information about the mechanism of jet quenching by the hot and dense QCD matter created in such collisions, the quark-gluon plasma. This paper presents a measurement of the angular distribution of charged particles around the jet axis in root s(NN) = 5.02 TeV Pb + Pb and pp collisions, using the ATLAS detector at the LHC. The Pb + Pb and pp data sets have integrated luminosities of 0.49 nb(-1) and 25 pb(-1), respectively. The measurement is performed for jets reconstructed with the anti-k(t) algorithm with radius parameter R = 0.4 and is extended to an angular distance of r = 0.8 from the jet axis. Results are presented as a function of Pb + Pb collision centrality and distance from the jet axis for charged particles with transverse momenta in the 1- to 63-GeV range, matched to jets with transverse momenta in the 126- to 316-GeV range and an absolute value of jet rapidity of less than 1.7. Modifications to the measured distributions are quantified by taking a ratio to the measurements in pp collisions. Yields of charged particles with transverse momenta below 4 GeV are observed to be increasingly enhanced as a function of angular distance from the jet axis, reaching a maximum at r = 0.6. Charged particles with transverse momenta above 4 GeV have an enhanced yield in Pb + Pb collisions in the jet core for angular distances up to r = 0.05 from the jet axis, with a suppression at larger distances.
- Published
- 2019