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Evidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at √sNN = 5.02 TeV
dc.contributor.author | Sirunyan, A.M. | |
dc.contributor.author | Sanders, Stephen J. | |
dc.contributor.author | The CMS Collaboration | |
dc.date.accessioned | 2021-01-26T19:39:32Z | |
dc.date.available | 2021-01-26T19:39:32Z | |
dc.date.issued | 2019-10-10 | |
dc.identifier.citation | A.M. Sirunyan et al., "Evidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at sNN=5.02TeV", Physics Letters B, Volume 797, 2019, 134826, ISSN 0370-2693, https://doi.org/10.1016/j.physletb.2019.134826. (http://www.sciencedirect.com/science/article/pii/S0370269319305404) | en_US |
dc.identifier.uri | http://hdl.handle.net/1808/31254 | |
dc.description | This work is licensed under a Creative Commons Attribution 4.0 International License. | en_US |
dc.description.abstract | Evidence for the light-by-light scattering process, γγ → γγ , 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 μb−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 Eγ T > 2 GeV, pseudorapidity |ηγ | < 2.4, diphoton invariant mass mγγ > 5 GeV, diphoton transverse momentum pγγ T < 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, σfid(γγ → γγ ) = 120±46 (stat)±28 (syst)±12 (theo) nb, is consistent with the standard model prediction. The mγγ distribution is used to set new exclusion limits on the production of pseudoscalar axion-like particles, via the γγ → a → γγ process, in the mass range ma = 5–90 GeV. | en_US |
dc.publisher | Elsevier | en_US |
dc.rights | © 2019 The Author(s). Published by Elsevier B.V. | en_US |
dc.rights.uri | http://creativecommons.org/licenses/by/4.0/ | en_US |
dc.subject | Light-by-light | en_US |
dc.subject | CMS | en_US |
dc.subject | UPC | en_US |
dc.subject | Photoproduction | en_US |
dc.subject | PbPb | en_US |
dc.title | Evidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at √sNN = 5.02 TeV | en_US |
dc.type | Article | en_US |
kusw.kuauthor | Sanders, Stephen J. | |
kusw.kudepartment | Physics and Astronomy | en_US |
dc.identifier.doi | 10.1016/j.physletb.2019.134826 | en_US |
kusw.oaversion | Scholarly/refereed, publisher version | en_US |
kusw.oapolicy | This item meets KU Open Access policy criteria. | en_US |
dc.rights.accessrights | openAccess | en_US |