Abstract
Multi-electron production is studied at high electron transverse momentum in positron- and electron-proton collisions using the H1 detector at HERA. The data correspond to an integrated luminosity of 115 pb(-1). Di-electron and tri-electron event yields are measured. Cross sections are derived in a restricted phase space region dominated by photon-photon collisions. In general good agreement is found with the Standard Model predictions. However, for electron pair invariant masses above 100 GeV, three di-electron events and three tri-electron events are observed, compared to Standard Model expectations of 0.30 +/- 0.04 and 0.23 +/- 0.04, respectively.
Highlights
In this paper we describe the first measurement of multielectron production at high transverse momentum (PT ) in electron1-proton interactions at HERA
The fake electron background in the forward region is described by the simulation at the 20% level. – Detailed studies of photon conversions are performed using a sample enriched with elastic Compton events, selected by requiring one central electron plus a second central electromagnetic cluster and no significant additional energy in the calorimeters
High–PT multi-electron production is measured for the first time in ep scattering at HERA
Summary
In this paper we describe the first measurement of multielectron production at high transverse momentum (PT ) in electron1-proton interactions at HERA. Within the Standard Model (SM), the production of multi-lepton events in ep collisions proceeds mainly through photon-photon interactions; photons radiated from the incident electron and proton interact to produce a pair of leptons, γγ → + − [1]. Multi-lepton production may be sensitive to new phenomena, for instance the production of a doubly charged Higgs boson [2] or processes involving bileptons, generic bosons carrying two units of lepton number [3]. Electrons of 27.6 GeV collided with protons of 82√0 or 920 GeV, corresponding to centre-of-mass energies s of 301 GeV or 319 GeV, respectively. As A related study of muon pair production is presented in [4]
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