Multi-Leptons with High Transverse Momentum at HERA (H1+ZEUS combination)

Events with at least two high transverse momentum leptons (electrons or muons) are 
studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 
$0.94$~fb$^{-1}$. The observed numbers of events are in general agreement with the 
Standard Model predictions. Seven di- and tri-lepton events are observed in $e^+p$ 
collision data with a scalar sum of the lepton transverse momenta above $100$~GeV, while 
\mbox{$1.94 \pm 0.17$} events are expected. Such events are not observed in $e^-p$ 
collisions for which $1.19 \pm 0.12$ are predicted. Total visible and differential 
di-electron and di-muon photoproduction cross sections are extracted in a restricted 
phase space dominated by photon-photon collisions.