II. Outstanding research and other results in 2018

a.) Outstanding research and other results

Hadron physics. — We have measured the short-range two-particle correlation functions of identified hadrons in pp, p-Pb, and peripheral Pb-Pb collisions at LHC energies. The extracted radii of the particle emitting source are in the range 1-5 fm, reaching highest values for very high multiplicity p-Pb and Pb-Pb collisions. The observed dependence of the radii on the multiplicity and pair transverse momentum may point to a common critical hadron density reached in the collisions. We have measured two-particle angular correlations in Pb-Pb and pp collisions at √sNN = 5.02 TeV. The width of the near-side jet peak broadens as a function of centrality towards the most central events at low transverse momentum. This broadening is similar to the one previously found in √sNN = 2.76 TeV Pb-Pb collisions.
We have developed a novel combination of established data analysis techniques for the reconstruction of all primary charged particles created in high energy collisions. Its performance in the case of single or many simultaneous proton-proton collisions, and for single heavy-ion collisions, was studied. We gave predictions for high-momentum multiplicity-dependent light- and heavy-flavor jet structures, and demonstrated that vacuum QCD effects such as multiple parton interactions can modify the jet structures, as well as two-particle angular correlation pictures, in high-multiplicity events. We have also introduced a definition of a characteristic jet size measure that is independent of multiplicity. 

b.) Relationship between science and society

Members of the research group participated in the organisation of the following events: International Particle Physics Masterclasses, Researchers’ Night, CERN25 events at the Academy of Sciences and at the Eötvös University.

V. List of important publications in 2018

CMS Collaboration, “Study of Bose-Einstein correlations in pp, pPb, and PbPb collisions at √sNN = 0.9–7 TeV”, Phys. Rev. C 97 (2018) 064912, IF: 3.304
F. Siklér, “A combination of analysis techniques for efficient track reconstruction of high multiplicity events in silicon detectors”, Eur. Phys. J A 54 (2018) 113, IF: 2.799
M. Varga-Kőfaragó [ALICE collaboration], “The evolution of the near-side peak in two-particle number and transverse momentum correlations in Pb-Pb collisions from ALICE”, accepted for publication at Nucl Phys A, arXiv:1807.04558 IF: 1.992
Gy. Bencédi [ALICE Collaboration], “Event-shape- and multiplicity-dependent identified particle production in pp collisions at 13 TeV with ALICE at the LHC”, accepted for publication at Nucl. Phys. A, arXiv:1807.09508 IF: 1.992