Dataset

GSI-2024-00245

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Measurement of the J/$\psi$ polarization with respect to the event plane in Pb-Pb collisions at the LHC

ALICE Collaboration (Corresponding author)

2022

Please use a persistent id in citations: doi:10.17182/HEPDATA.139746

Abstract: The polarization of inclusive J/$\psi$ produced in Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV at the LHC was studied by ALICE in the dimuon channel, via the measurement of the angular distribution of its decay products. The study was performed in the rapidity region $ 2.5 < y< 4 $ for three transverse momentum intervals ( $ 2 < p_T $ $<4.4 <$ $p_T < $ $6.6 $ <$p_T $<10 GeV/$c$) and as a function of the centrality of the collision for $2 < P_T < 6 $ GeV/$c$. For the first time, the polarization was measured with respect to the event plane of the collision, by considering the angle between the positive-charge decay muon in the J/$\psi$ 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 3.9$\sigma$ at low $p_T$ and for intermediate centrality values. The polarization could be connected with the existence of a strong magnetic field in the early stage of quark--gluon plasma formation in Pb--Pb collisions, as well as with its behaviour as a rotating fluid with large vorticity.

Note: Journal Article GSI record: GSI-2024-00244

---

Contributing Institute(s):

1. ALICE (ALI)
2. Detektorlabor (DTL)
3. IT (CIT)
4. ExtreMe Matter Institute, EMMI (EXM)
5. Collaboration CERN: ALICE (ALICE@CERN)

Research Program(s):

1. 612 - Cosmic Matter in the Laboratory (POF4-612) (POF4-612)
2. HGS-HIRe - HGS-HIRe for FAIR (HGS-HIRe) (HGS-HIRe)
3. SUC-GSI-Heidelberg - Strategic university cooperation GSI-U Heidelberg (SUC-GSI-HE) (SUC-GSI-HE)
4. SUC-GSI-Frankfurt - Strategic university cooperation GSI-U Frankfurt/M (SUC-GSI-FR) (SUC-GSI-FR)
5. SUC-GSI-Darmstadt - Strategic university cooperation GSI-TU Darmstadt (SUC-GSI-DA) (SUC-GSI-DA)
6. STRONG-2020 - The strong interaction at the frontier of knowledge: fundamental research and applications (824093) (824093)

Experiment(s):

1. LHC: ALICE

Appears in the scientific report 2023

---

---

Linked articles:

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Journal Article Acharya, S. ; Adamova, D. ; Adler, A. ; et al
Measurement of the J/ψ Polarization with Respect to the Event Plane in Pb-Pb Collisions at the LHC
Physical review letters 131(4), 042303 (2023) [10.1103/PhysRevLett.131.042303]2023   Files  Fulltext by arXiv.org BibTeX | EndNote: XML, Text | RIS

---