Title Measurement of the $e^{+}e^{-}\rightarrow\gamma\gamma(\gamma)$ cross-section at LEP energies Author Abreu, P. Adam, W. Adye, T. Verbeure, F. et al. Faculty/Department Faculty of Sciences. Biology Faculty of Sciences. Physics Publication type article Publication 1994 Amsterdam , 1994 Subject Physics Source (journal) Physics letters: B. - Amsterdam, 1967, currens Volume/pages 327(1994) :3-4 , p. 386-396 ISSN 0370-2693 ISI A1994NP23100032 Carrier E Target language English (eng) Full text (Publishers DOI) Affiliation University of Antwerp Abstract The total and the differential cross sections for the reaction e+e- --> gammagamma(gamma) have been measured with the DELPHI detector at LEP using an integrated luminosity of 36.9 pb-1. The results agree with the QED predictions and consequently there is no evidence for non-standard channels with the same experimental signature. The lower limits obtained on the QED cutoff parameters are LAMBDA+ > 143 GeV and LAMBDA- > 120 GeV, and the lower bound on the mass of an excited electron with an effective coupling constant lambda(gamma) = 1 is 132 GeV/c2. Upper limits on the branching ratios for the decays Z0 --> gammagamma, Z0 --> pi0gamma, Z0 --> etagamma and Z0 --> gammagammagamma have been determined to be 5.5 x 10(-5), 5.5 x 10(-5), 8.0 x 10(-5), and 1.7 x 10-5 respectively. All the limits are at the 95% confidence level. E-info https://repository.uantwerpen.be/docman/iruaauth/5c5122/97e4382.pdf http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1994NP23100032&DestLinkType=RelatedRecords&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848 http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1994NP23100032&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848 http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1994NP23100032&DestLinkType=CitingArticles&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848 Handle