Evidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at root s(NN)=5.02 TeV

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dc.WoS.categoriesAstronomy & Astrophysics; Physics, Nuclear; Physics, Particles & Fieldsen_US
dc.authorid0000-0002-9007-8260en_US
dc.contributor.authorYetkin, Elif Aslı
dc.date.accessioned2020-05-29T12:13:14Z
dc.date.available2020-05-29T12:13:14Z
dc.date.issued2019-10-10
dc.departmentFakülteler, Mühendislik ve Doğa Bilimleri Fakültesi, Enerji Sistemleri Mühendisliği Bölümüen_US
dc.description.abstractEvidence for the light-by-light scattering process, gamma gamma -> gamma gamma, in ultraperipheral PbPb collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV is reported. The analysis is conducted using a data sample corresponding to an integrated luminosity of 390 mu b(-1) recorded by the CMS experiment at the LHC. Light-by-light scattering processes are selected in events with two photons exclusively produced, each with transverse energy E-T(gamma) > 2 GeV, pseudorapidity vertical bar eta(gamma)vertical bar < 2.4, diphoton invariant mass m(gamma gamma) > 5 GeV, diphoton transverse momentum p(T)(gamma gamma) < 1 GeV, and diphoton acoplanarity below 0.01. After all selection criteria are applied, 14 events are observed, compared to expectations of 9.0 +/- 0.9 (theo) events for the signal and 4.0 +/- 1.2 (stat) for the background processes. The excess observed in data relative to the background-only expectation corresponds to a significance of 3.7 standard deviations, and has properties consistent with those expected for the light-by-light scattering signal. The measured fiducial light-by-light scattering cross section, sigma(fid)(gamma gamma -> gamma gamma) = 120 +/- 46(stat) +/- 28(syst) +/- 12(theo) nb, is consistent with the standard model prediction. The m(gamma gamma) distribution is used to set new exclusion limits on the production of pseudoscalar axion-like particles, via the gamma gamma -> a -> gamma gamma process, in the mass range m(a) = 5-90 GeV. (C) 2019 The Author(s). Published by Elsevier B.V.en_US
dc.fullTextLevelFull Texten_US
dc.identifier.doi10.1016/j.physletb.2019.134826
dc.identifier.issn1873-2445
dc.identifier.issn0370-2693
dc.identifier.urihttps://hdl.handle.net/11411/2106
dc.identifier.urihttps://doi.org/10.1016/j.physletb.2019.134826
dc.identifier.wosWOS:000488071200025en_US
dc.identifier.wosqualityQ2en_US
dc.indekslendigikaynakWeb of Scienceen_US
dc.language.isoenen_US
dc.nationalInternationalen_US
dc.numberofauthors500+en_US
dc.publisherElsevieren_US
dc.relation.ispartofPhysics Letters Ben_US
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanıen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectLight-by-lighten_US
dc.subjectCMSen_US
dc.subjectUPCen_US
dc.subjectPhotoproductionen_US
dc.subjectPbPben_US
dc.titleEvidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at root s(NN)=5.02 TeV
dc.typeArticle
dc.volume797en_US

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