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Measurement of the impact-parameter dependent azimuthal anisotropy in coherent ρ0 photoproduction in Pb–Pb collisions at sNN=5.02 TeV

Acharya, S. ; Basu, S. LU orcid ; Christiansen, P. LU ; Hansen, J. LU orcid ; Iversen, K.E. LU orcid ; Matonoha, O. LU ; Nepeivoda, R. LU orcid ; Ohlson, A. LU ; Silvermyr, D. LU orcid and Staa, J. LU , et al. (2024) In Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 858.
Abstract
This Letter presents the first measurement of the impact-parameter dependent angular anisotropy in the decay of coherently photoproduced ρ0 mesons. The ρ0 mesons are reconstructed through their decay into pion pairs. The measured anisotropy corresponds to the amplitude of the cos⁡(2ϕ) modulation, where ϕ is the angle between the two vectors formed by the sum and the difference of the transverse momenta of the pions, respectively. The measurement was performed by the ALICE Collaboration at the LHC using data from ultraperipheral Pb–Pb collisions at a center-of-mass energy of sNN=5.02 TeV per nucleon pair. Different impact-parameter regions are selected by classifying the events in nuclear-breakup classes. The amplitude of the cos⁡(2ϕ)... (More)
This Letter presents the first measurement of the impact-parameter dependent angular anisotropy in the decay of coherently photoproduced ρ0 mesons. The ρ0 mesons are reconstructed through their decay into pion pairs. The measured anisotropy corresponds to the amplitude of the cos⁡(2ϕ) modulation, where ϕ is the angle between the two vectors formed by the sum and the difference of the transverse momenta of the pions, respectively. The measurement was performed by the ALICE Collaboration at the LHC using data from ultraperipheral Pb–Pb collisions at a center-of-mass energy of sNN=5.02 TeV per nucleon pair. Different impact-parameter regions are selected by classifying the events in nuclear-breakup classes. The amplitude of the cos⁡(2ϕ) modulation is found to increase by about one order of magnitude from large to small impact parameters. Theoretical calculations describe the measured cos⁡(2ϕ) anisotropy and its impact-parameter dependence as the result of a quantum interference effect at the femtometer scale, arising from the ambiguity regarding which of the nuclei is the photon source in the interaction. © 2024 CERN for the benefit of the ALICE Collaboration (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
858
article number
139017
publisher
Elsevier
external identifiers
  • scopus:85204389624
ISSN
0370-2693
DOI
10.1016/j.physletb.2024.139017
language
English
LU publication?
yes
id
8a18d03e-483a-4056-a3da-59235dd2feb5
date added to LUP
2024-10-14 08:47:39
date last changed
2025-04-04 15:25:58
@article{8a18d03e-483a-4056-a3da-59235dd2feb5,
  abstract     = {{This Letter presents the first measurement of the impact-parameter dependent angular anisotropy in the decay of coherently photoproduced ρ0 mesons. The ρ0 mesons are reconstructed through their decay into pion pairs. The measured anisotropy corresponds to the amplitude of the cos⁡(2ϕ) modulation, where ϕ is the angle between the two vectors formed by the sum and the difference of the transverse momenta of the pions, respectively. The measurement was performed by the ALICE Collaboration at the LHC using data from ultraperipheral Pb–Pb collisions at a center-of-mass energy of sNN=5.02 TeV per nucleon pair. Different impact-parameter regions are selected by classifying the events in nuclear-breakup classes. The amplitude of the cos⁡(2ϕ) modulation is found to increase by about one order of magnitude from large to small impact parameters. Theoretical calculations describe the measured cos⁡(2ϕ) anisotropy and its impact-parameter dependence as the result of a quantum interference effect at the femtometer scale, arising from the ambiguity regarding which of the nuclei is the photon source in the interaction. © 2024 CERN for the benefit of the ALICE Collaboration}},
  author       = {{Acharya, S. and Basu, S. and Christiansen, P. and Hansen, J. and Iversen, K.E. and Matonoha, O. and Nepeivoda, R. and Ohlson, A. and Silvermyr, D. and Staa, J. and Vislavicius, V. and Zurlo, N.}},
  issn         = {{0370-2693}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics}},
  title        = {{Measurement of the impact-parameter dependent azimuthal anisotropy in coherent ρ0 photoproduction in Pb–Pb collisions at sNN=5.02 TeV}},
  url          = {{http://dx.doi.org/10.1016/j.physletb.2024.139017}},
  doi          = {{10.1016/j.physletb.2024.139017}},
  volume       = {{858}},
  year         = {{2024}},
}