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

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21340%2F24%3A00380166" target="_blank" >RIV/68407700:21340/24:00380166 - isvavai.cz</a>
Result on the web
<a href="https://doi.org/10.1016/j.physletb.2024.139017" target="_blank" >https://doi.org/10.1016/j.physletb.2024.139017</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.physletb.2024.139017" target="_blank" >10.1016/j.physletb.2024.139017</a>

Result language
angličtina
Original language name
Measurement of the impact-parameter dependent azimuthal anisotropy in coherent ρ0 photoproduction in Pb-Pb collisions at root sNN=5.02 TeV
Original language description
This Letter presents the first measurement of the impact-parameter dependent angular anisotropy in the decay of coherently photoproduced rho(0) mesons. The rho(0) mesons are reconstructed through their decay into pion pairs. The measured anisotropy corresponds to the amplitude of the cos(2 phi) modulation, where phi 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 root 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(2 phi) modulation is found to increase by about one order of magnitude from large to small impact parameters. Theoretical calculations describe the measured cos(2 phi) 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.
Czech name
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Czech description
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Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10303 - Particles and field physics

Project
<a href="/en/project/LM2023040" target="_blank" >LM2023040: Research infrastructure for experiments at CERN</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year
2024
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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