High PT multi-lepton production at HERA

TL;DR

This paper reports on measurements of multi-electron and multi-muon production at high transverse momentum in electron-proton collisions at HERA, extending previous analyses with new data and exploring rare high-$P_T$ events.

Contribution

It presents the first investigation of high-$P_T$ electrons and muons in multi-lepton events at HERA, combining HERA I and II data for comprehensive analysis.

Findings

Good overall agreement with the Standard Model

Observation of high-$P_T$ leptons in low-prediction regions

Enhanced dataset enabling rare event analysis

Abstract

Multi-electron and multi-muon production at high transverse momentum is measured in $ep$ scattering at HERA. Previous published analyses are extended, combining new HERA II data taken in 2003-2004 with previous HERA I data sample. In addition events with high $P_T$ electrons and muons are investigated here for the first time. Yields of di-lepton and tri-lepton events are measured and a general good agreement is found with the Standard Model prediction, dominated by photon-photon interactions. Events are observed with leptons of high transverse momenta in a domain where the Standard Model prediction is low.