We study the polarization of inclusive J/ψ produced in Pb-Pb collisions at sNN=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<4, for three transverse momentum intervals (2<4, 4<6, 6<10 GeV/c) and as a function of the centrality of the collision for 2<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/ψ 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 3.9σ 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/ψ polarization with respect to the event plane in Pb-Pb collisions at the LHC / Acharya, S., Adamova, D., Adler, A., Aglieri Rinella, G., Agnello, M., Agrawal, N., Ahammed, Z., Ahmad, S., Ahn, S.U., Ahuja, I., Akindinov, A., Al-Turany, M., Aleksandrov, D., Alessandro, B., Alfanda, H.M., Alfaro Molina, R., Ali, B., Ali, Y., Alici, A., Alizadehvandchali, N., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 131:4(2023). [10.1103/PhysRevLett.131.042303]

Measurement of the J/ψ polarization with respect to the event plane in Pb-Pb collisions at the LHC

Cunqueiro L.;Toppi M.;
2023

Abstract

We study the polarization of inclusive J/ψ produced in Pb-Pb collisions at sNN=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<4, for three transverse momentum intervals (2<4, 4<6, 6<10 GeV/c) and as a function of the centrality of the collision for 2<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/ψ 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 3.9σ 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
quark gluon plasma
01 Pubblicazione su rivista::01a Articolo in rivista
Measurement of the J/ψ polarization with respect to the event plane in Pb-Pb collisions at the LHC / Acharya, S., Adamova, D., Adler, A., Aglieri Rinella, G., Agnello, M., Agrawal, N., Ahammed, Z., Ahmad, S., Ahn, S.U., Ahuja, I., Akindinov, A., Al-Turany, M., Aleksandrov, D., Alessandro, B., Alfanda, H.M., Alfaro Molina, R., Ali, B., Ali, Y., Alici, A., Alizadehvandchali, N., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 131:4(2023). [10.1103/PhysRevLett.131.042303]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1723390
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