dc.contributor.author | The CMS Collaboration | |
dc.contributor.author | Sen,S. | |
dc.date.accessioned | 2021-06-03T09:15:02Z | |
dc.date.available | 2021-06-03T09:15:02Z | |
dc.date.issued | 2019 | |
dc.identifier.issn | 0370-2693 | |
dc.identifier.uri | http://dx.doi.org/10.1016/j.physletb.2019.134826 | |
dc.identifier.uri | http://hdl.handle.net/11655/24446 | |
dc.description.abstract | Evidence 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. | |
dc.language.iso | en | |
dc.relation.isversionof | 10.1016/j.physletb.2019.134826 | |
dc.rights | Attribution 4.0 United States | |
dc.rights | info:eu-repo/semantics/openAccess | |
dc.rights.uri | https://creativecommons.org/licenses/by/4.0/ | |
dc.subject | CMS | |
dc.subject | Light-by-light | |
dc.subject | PbPb | |
dc.subject | Photoproduction | |
dc.subject | UPC | |
dc.title | Evidence For Light-By-Light Scattering And Searches For Axion-Like Particles In Ultraperipheral Pbpb Collisions At Root S(Nn)=5.02 Tev | |
dc.type | info:eu-repo/semantics/article | |
dc.type | info:eu-repo/semantics/publishedVersion | |
dc.relation.journal | Physics Letters B | |
dc.contributor.department | Fizik Mühendisliği | |
dc.identifier.volume | 797 | |
dc.description.index | WoS | |