First polarisation measurement of coherently photoproduced J/ψ in ultra-peripheral Pb-Pb collisions at √sNN=5.02 TeV

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389005%3A_____%2F25%3A00637019" target="_blank" >RIV/61389005:_____/25:00637019 - isvavai.cz</a>
Alternative codes found
RIV/68378271:_____/25:00637019
Result on the web
<a href="https://www.sciencedirect.com/science/article/pii/S0370269325002278" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0370269325002278</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.physletb.2025.139466" target="_blank" >10.1016/j.physletb.2025.139466</a>

Result language
angličtina
Original language name
First polarisation measurement of coherently photoproduced J/ψ in ultra-peripheral Pb-Pb collisions at √sNN=5.02 TeV
Original language description
The first measurement of the polarisation of coherently photoproduced J/psi mesons in ultra-peripheral Pb-Pb collisions, using data at root s(NN) = 5.02 TeV, is presented. The J/psi meson is measured via its dimuon decay channel in the forward rapidity interval -4.0 < y < -2.5 using the ALICE detector at the CERN LHC. An event sample corresponding to an integrated luminosity of 750 mu b(-1) +/- 5% (syst) is analysed. Hadronic activity is highly suppressed since the interaction is mediated by a photon. The polar and azimuthal angle distributions of the decay muons are measured, and the polarisation parameters lambda(theta), lambda(phi), lambda(theta phi) are extracted. The analysis is carried out in the helicity frame. The results are found to be consistent with a transversely polarised J/psi. These values are compared with previous measurements by the H1 and ZEUS experiments. The polarisation parameters of coherent J/psi photoproduction in Pb-Pb collisions are found to be consistent with the s-channel helicity conservation hypothesis.
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
10304 - Nuclear physics

Project
Result was created during the realization of more than one project. More information in the Projects tab.
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year
2025
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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