Angular Correlations and Light Gluinos in Multi-jet Photoproduction at   HERA
  A study of $3+1$ jet event photoproduction at HERA is presented. We define an angular variable which is sensitive to the topology of the final state jets and is therefore able to discriminate between the different contributing subprocesses, and between QCD and an abelian gluon model. We also investigate the contribution from the direct production of light gluinos to the $3+1$ cross section. 
R. Mu\~noz-Tapia and W.J. Stirling