Evidence for light-by-light scattering in ultraperipheral PbPb collisions at root S-NN=5.02 TeV

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F19%3A10406346" target="_blank" >RIV/00216208:11320/19:10406346 - isvavai.cz</a>
Result on the web
<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=GJ~~eGjOaE" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=GJ~~eGjOaE</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.nuclphysa.2018.10.018" target="_blank" >10.1016/j.nuclphysa.2018.10.018</a>

Result language
angličtina
Original language name
Evidence for light-by-light scattering in ultraperipheral PbPb collisions at root S-NN=5.02 TeV
Original language description
Evidence for light-by-light (LbL) scattering, gamma gamma -> gamma gamma, in ultraperipheral PbPb collisions at a nucleon-nucleon center of-mass energy of 5.02 TeV is reported. LbL scattering processes are selected in events with just two photons produced, with transverse energy E-T(gamma) > 2 GeV, pseudorapidity vertical bar eta(gamma)vertical bar < 2.4; and diphoton invariant mass m(gamma gamma) > 5 GeV, transverse momentum p(T)(gamma gamma) < 1 GeV, and acoplanarity (1 - Delta phi(gamma gamma)/pi) < 0.01. After all selection criteria, 14 events are observed, compared to 11.1 +/- 1.1 (theo) and 3.8 +/- 1.3 (stat) events expected for signal and background processes respectively. The significance of the signal excess over the background-only hypothesis is 4.10 sigma. The measured fiducial LbL scattering cross section, sigma(fid)(gamma gamma -> gamma gamma) = 122 +/- 46 (stat) +/- 29 (syst) +/- 4 (theo) nb is consistent with the standard model prediction.
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
—
OECD FORD branch
10303 - Particles and field physics

Project
<a href="/en/project/LM2015058" target="_blank" >LM2015058: Research Infrastructure for Experiments at CERN</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year
2019
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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