Speaker
Description
High multiplicity events of small colliding systems at LHC energies show longe-range correlations and azimutal anisothropy that are similar to those seen in heavy ion collisions with comparable multiplicities. Whether this collective-like behaviour can be attributed to the presence of a deconfined state in small systems is an open question. Recent research hints that vacuum QCD effects such as multiple-parton interactions and color reconnection may also explain such collective effects [1]. While we cannot expect jet quenching in small systems, QCD phenomena at the soft-hard boundary may cause a modification of the jet shapes as well as two-particle correlation pictures. Existing and forecoming data at the experiments of the LHC provide means to access such observables.
Based on extensive studies with event generators, we give predictions for multiplicity-dependent jet structures in p+p collisions at high jet-pT. We show that the presence of MPI modifies the jet shapes in high-multiplicity events beyond trivial selection bias. Such high-pT multiplicity-differential probes provide a sensitive validation opportunity for models involving different MPI, color reconnection schemes or parton distribution functions [2]. Jets from heavy-flavor quarks are expected to undergo different fragmentation than light-flavor jets, due to mass and color charge effects. We show a surprizing pattern of multiplicity-dependent structures in jets originating from different flavors. Preliminary correlation results of heavy and light particles, corroborating our findings, will also be shown [3].
[1] Gy.Bencedi, A.Ortiz, H.Bello, J.Phys. G44 (2017) no.6, 065001.
[2] Z.Varga, R.Vertesi, G.G.Barnafoldi, Adv.High Energy Phys. 2019 (2019) 6731362; MDPI Proc. 10 (2019) no.1, 3; In the Proceedings of Zimanyi19 workshop, submitted to Universe.
[3] E.Frajna, R.Vertesi, arXiv:1903.10566 [hep-ph], in the Proceedings of Zimanyi19 workshop, submitted to Universe.
