Measurement of the <i>J/?</i> Polarization with Respect to the Event Plane in Pb-Pb Collisions at the LHC


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Acharya S., Adamová D., Adler A., Aglieri Rinella G., Agnello M., Agrawal N., ...More

PHYSICAL REVIEW LETTERS, vol.131, no.4, 2023 (SCI-Expanded, Scopus) identifier identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 131 Issue: 4
  • Publication Date: 2023
  • Doi Number: 10.1103/physrevlett.131.042303
  • Journal Name: PHYSICAL REVIEW LETTERS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Chemical Abstracts Core, Compendex, INSPEC, zbMATH, DIALNET, Nature Index
  • Open Archive Collection: AVESIS Open Access Collection
  • Yıldız Technical University Affiliated: Yes

Abstract

We study the polarization of inclusive J=. produced in Pb-Pb collisions at ffisffiffiNffiffiNffiffiffip 1/4 5.02 TeV at the LHC in the dimuon channel, via the measurement of the angular distribution of its decay products. We perform the study in the rapidity region 2.5 < y < 4, for three transverse momentum intervals (2 < pT < 4, 4 < pT < 6, 6 < pT < 10 GeV=c) and as a function of the centrality of the collision for 2 < pT < 6 GeV=c. For the first time, the polarization is measured with respect to the event plane of the collision, by considering the angle between the positive-charge decay muon in the J=. rest frame and the axis perpendicular to the event-plane vector in the laboratory system. A small transverse polarization is measured, with a significance reaching 3.9s at low pT and for intermediate centrality values. The polarization could be connected with the behavior of the quark-gluon plasma, formed in Pb-Pb collisions, as a rotating fluid with large vorticity, as well as with the existence of a strong magnetic field in the early stage of its formation.