DOI: 10.1140/epjc/s2002-01074-5
Multi-photon production in e
+e
- collisions
at
181-209 GeV
The OPAL Collaboration (Received: 22 July 2002 / Published online: 8 November 2002 )
Abstract
The process
is studied using data collected by the OPAL
detector at LEP between the years 1997 and 2000.
The data set corresponds to an integrated luminosity
of 672.3 pb
-1 at centre-of-mass energies lying
between 181 GeV and 209 GeV.
Total and differential cross-sections are determined and found to be in
good agreement with the predictions of QED. Fits to the observed
angular distributions are used to set limits
on parameters from several models of physics beyond the Standard Model
such as cut-off parameters, contact interactions of the type
, gravity in extra spatial dimensions and
excited electrons.
In events with three photons in the final state the mass spectrum
of photon pairs is investigated. No narrow resonance
is
found and limits are placed on the product of the
production cross-section and branching ratio.
© Società Italiana di Fisica, Springer-Verlag 2003
