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First measurement of quarkonium polarization in nuclear collisions at the LHC

Acharya, S. ; Adolfsson, J. LU ; Christiansen, P. LU ; Matonoha, O. LU ; Nassirpour, A.F. LU orcid ; Ohlson, A. LU ; Oskarsson, A. LU ; Richert, T. LU ; Rueda, O.V. LU and Silvermyr, D. LU orcid , et al. (2021) In Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 815.
Abstract
The polarization of inclusive J/ψ and ϒ(1S) produced in Pb–Pb collisions at sNN=5.02 TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region 2.5<y<4 and measuring the polar and azimuthal angular distributions of the muons. The polarization parameters λθ, λϕ and λθϕ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval 2<pT<10 GeV/c and pT<15 GeV/c for the J/ψ and ϒ(1S), respectively. The polarization parameters for the J/ψ are found to be compatible with zero, within a maximum of about two standard deviations at low pT, for both reference frames and over the whole pT... (More)
The polarization of inclusive J/ψ and ϒ(1S) produced in Pb–Pb collisions at sNN=5.02 TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region 2.5<y<4 and measuring the polar and azimuthal angular distributions of the muons. The polarization parameters λθ, λϕ and λθϕ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval 2<pT<10 GeV/c and pT<15 GeV/c for the J/ψ and ϒ(1S), respectively. The polarization parameters for the J/ψ are found to be compatible with zero, within a maximum of about two standard deviations at low pT, for both reference frames and over the whole pT range. The values are compared with the corresponding results obtained for pp collisions at s=7 and 8 TeV in a similar kinematic region by the ALICE and LHCb experiments. Although with much larger uncertainties, the polarization parameters for ϒ(1S) production in Pb–Pb collisions are also consistent with zero. © 2021 The Author(s) (Less)
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type
Contribution to journal
publication status
published
subject
in
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
volume
815
article number
136146
publisher
Elsevier
external identifiers
  • scopus:85101795363
ISSN
0370-2693
DOI
10.1016/j.physletb.2021.136146
language
English
LU publication?
yes
id
be166e6a-8d90-472d-ae63-0bc40b840c34
date added to LUP
2022-09-05 09:46:41
date last changed
2023-05-10 15:27:24
@article{be166e6a-8d90-472d-ae63-0bc40b840c34,
  abstract     = {{The polarization of inclusive J/ψ and ϒ(1S) produced in Pb–Pb collisions at sNN=5.02 TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region 2.5&lt;y&lt;4 and measuring the polar and azimuthal angular distributions of the muons. The polarization parameters λθ, λϕ and λθϕ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval 2&lt;pT&lt;10 GeV/c and pT&lt;15 GeV/c for the J/ψ and ϒ(1S), respectively. The polarization parameters for the J/ψ are found to be compatible with zero, within a maximum of about two standard deviations at low pT, for both reference frames and over the whole pT range. The values are compared with the corresponding results obtained for pp collisions at s=7 and 8 TeV in a similar kinematic region by the ALICE and LHCb experiments. Although with much larger uncertainties, the polarization parameters for ϒ(1S) production in Pb–Pb collisions are also consistent with zero. © 2021 The Author(s)}},
  author       = {{Acharya, S. and Adolfsson, J. and Christiansen, P. and Matonoha, O. and Nassirpour, A.F. and Ohlson, A. and Oskarsson, A. and Richert, T. and Rueda, O.V. and Silvermyr, D. and Stenlund, E. and Zurlo, N.}},
  issn         = {{0370-2693}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics}},
  title        = {{First measurement of quarkonium polarization in nuclear collisions at the LHC}},
  url          = {{http://dx.doi.org/10.1016/j.physletb.2021.136146}},
  doi          = {{10.1016/j.physletb.2021.136146}},
  volume       = {{815}},
  year         = {{2021}},
}