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

ALICE Collaboration

doi:10.1016/j.physletb.2024.139017

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

ALICE Collaboration

Department of Physics

CERN
Université Clermont Auvergne
Czech Academy of Sciences
Variable Energy Cyclotron Centre
National Institute for Nuclear Physics
Aligarh Muslim University
Korea Institute of Science and Technology Information
Pavol Jozef Šafárik University
Goethe University Frankfurt
GSI Helmholtz Centre for Heavy Ion Research
Central China Normal University
Universidad Nacional Autónoma de México
University of Houston
Sungkyunkwan University
University of Bergen
Technical University of Munich
Benemerita Universidad Autonoma de Puebla
Horia Hulubei National Institute of Physics and Nuclear Engineering
University of Derby
University of Münster
Heidelberg University
Lawrence Berkeley National Laboratory
Nantes Université
Université Grenoble Alpes
Universidade de São Paulo
University of Oslo
Yale University

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

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 s_NN=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.

Original language	English
Article number	139017
Journal	Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume	858
DOIs	https://doi.org/10.1016/j.physletb.2024.139017
State	Published - Nov 2024

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10.1016/j.physletb.2024.139017

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@article{85f7b23272cc4c36a2967d77699ae469,

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

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.",

author = "\{ALICE Collaboration\} and S. Acharya and D. Adamov{\'a} and A. Agarwal and \{Aglieri Rinella\}, G. and L. Aglietta and M. Agnello and N. Agrawal and Z. Ahammed and S. Ahmad and Ahn, \{S. U.\} and I. Ahuja and A. Akindinov and V. Akishina and M. Al-Turany and D. Aleksandrov and B. Alessandro and Alfanda, \{H. M.\} and \{Alfaro Molina\}, R. and B. Ali and A. Alici and N. Alizadehvandchali and A. Alkin and J. Alme and G. Alocco and T. Alt and Altamura, \{A. R.\} and I. Altsybeev and Alvarado, \{J. R.\} and Alvarez, \{C. O.R.\} and Anaam, \{M. N.\} and C. Andrei and N. Andreou and A. Andronic and E. Andronov and V. Anguelov and F. Antinori and P. Antonioli and N. Apadula and L. Aphecetche and H. Appelsh{\"a}user and C. Arata and S. Arcelli and M. Aresti and R. Arnaldi and Arneiro, \{J. G.M.C.A.\} and Arsene, \{I. C.\} and M. Arslandok and A. Augustinus and R. Averbeck and B. Kim",

note = "Publisher Copyright: {\textcopyright} 2024 CERN for the benefit of the ALICE Collaboration",

year = "2024",

month = nov,

doi = "10.1016/j.physletb.2024.139017",

language = "English",

volume = "858",

journal = "Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics",

issn = "0370-2693",

publisher = "Elsevier B.V.",

}

TY - JOUR

T1 - Measurement of the impact-parameter dependent azimuthal anisotropy in coherent ρ0 photoproduction in Pb–Pb collisions at sNN=5.02 TeV

AU - ALICE Collaboration

AU - Acharya, S.

AU - Adamová, D.

AU - Agarwal, A.

AU - Aglieri Rinella, G.

AU - Aglietta, L.

AU - Agnello, M.

AU - Agrawal, N.

AU - Ahammed, Z.

AU - Ahmad, S.

AU - Ahn, S. U.

AU - Ahuja, I.

AU - Akindinov, A.

AU - Akishina, V.

AU - Al-Turany, M.

AU - Aleksandrov, D.

AU - Alessandro, B.

AU - Alfanda, H. M.

AU - Alfaro Molina, R.

AU - Ali, B.

AU - Alici, A.

AU - Alizadehvandchali, N.

AU - Alkin, A.

AU - Alme, J.

AU - Alocco, G.

AU - Alt, T.

AU - Altamura, A. R.

AU - Altsybeev, I.

AU - Alvarado, J. R.

AU - Alvarez, C. O.R.

AU - Anaam, M. N.

AU - Andrei, C.

AU - Andreou, N.

AU - Andronic, A.

AU - Andronov, E.

AU - Anguelov, V.

AU - Antinori, F.

AU - Antonioli, P.

AU - Apadula, N.

AU - Aphecetche, L.

AU - Appelshäuser, H.

AU - Arata, C.

AU - Arcelli, S.

AU - Aresti, M.

AU - Arnaldi, R.

AU - Arneiro, J. G.M.C.A.

AU - Arsene, I. C.

AU - Arslandok, M.

AU - Augustinus, A.

AU - Averbeck, R.

AU - Kim, B.

PY - 2024/11

Y1 - 2024/11

N2 - 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.

AB - 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.

UR - https://www.scopus.com/pages/publications/85204389624

U2 - 10.1016/j.physletb.2024.139017

DO - 10.1016/j.physletb.2024.139017

M3 - Article

AN - SCOPUS:85204389624

SN - 0370-2693

VL - 858

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

M1 - 139017

ER -

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

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