Measurement of Υ(1S) Elliptic Flow at Forward Rapidity in Pb-Pb Collisions at √sNN=5.02  TeV

Research output: Contribution to journalArticle


The first measurement of the Υ(1S) elliptic flow coefficient (v2) is performed at forward rapidity (2.5<y<4) in Pb–Pb collisions at √sNN=5.02  TeV with the ALICE detector at the LHC. The results are obtained with the scalar product method and are reported as a function of transverse momentum (pT) up to 15  GeV/c in the 5%–60% centrality interval. The measured Υ(1S)v2 is consistent with 0 and with the small positive values predicted by transport models within uncertainties. The v2 coefficient in 2<pT<15  GeV/c is lower than that of inclusive J/ψ mesons in the same pT interval by 2.6 standard deviations. These results, combined with earlier suppression measurements, are in agreement with a scenario in which the Υ(1S) production in Pb–Pb collisions at LHC energies is dominated by dissociation limited to the early stage of the collision, whereas in the J/ψ case there is substantial experimental evidence of an additional regeneration component.


External organisations
  • University of Copenhagen
  • Variable Energy Cyclotron Centre
  • University of Brescia
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Subatomic Physics


  • Atomic physics, Physics, Experimental evidence, Forward rapidity, Pb-Pb collisions, Positive value, Scalar product, Standard deviation, Transport models, Transverse momenta, Binary alloys
Original languageEnglish
Article number192301
JournalPhysical Review Letters
Issue number19
Publication statusPublished - 2019
Publication categoryResearch