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.

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

Alocco, G.;Boi, S.;De Falco, A.;Fionda, F. M.;Mulliri, A.;Sarritzu, V.;Usai, G. L.;
2023-01-01

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.
2023
MAGNETIC-FIELD; HEAVY; SUPPRESSION; QUARKONIUM
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/383936
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