Abstract
Processes leading to a final state with at least two high transverse momentum leptons (electrons or muons) are studied using the full e±p data sample collected by the H1 experiment at HERA. The data correspond to an integrated luminosity of 463 pb−1. Di-lepton and tri-lepton event classes are investigated. Cross sections of the production of e+e− and μ+μ− pairs are derived in a restricted phase space dominated by photon–photon collisions. In general, good agreement is found with Standard Model predictions. Events are observed with a total scalar sum of lepton transverse momenta above 100 GeV where the Standard Model expectation is low. In this region, combining di-lepton and tri-lepton classes, five events are observed in e+p collisions, compared to a Standard Model expectation of 0.96±0.12, while no such event is observed in e−p data for 0.64±0.09 expected.
Highlights
Within the Standard Model (SM) the production of multi-lepton events in electron22–proton collisions proceeds mainly via photon–photon interactions, γ γ → + −, where photons are radiated from the incident beam particles [1]
Neutral current (NC) deep-inelastic scattering (DIS) events in which hadrons or radiated photons are wrongly identified as electrons constitute the dominant background contribution
Background to the eμ final state may arise from NC DIS events if hadrons are misidentified as muons
Summary
Events are observed with a total scalar sum of lepton transverse momenta above 100 GeV where the Standard Model expectation is low In this region, combining di-lepton and tri-lepton classes, five events are observed in e+ p collisions, compared to a Standard Model expectation of 0.96 ± 0.12, while no such event is observed in e− p data for 0.64 ± 0.09 expected.
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