Observation of events with an isolated high-energy lepton and missing transverse momentum at HERA

A search for events with an imbalance in transverse momentum and with isolated high energy leptons has been carried out at the positron-proton collider HERA. One event with an e^- and five events with a mu^+- are found together with evidence for undetected particles carrying transverse momentum. Within the Standard Model the dominant origin of events with this kind of topology is the production of W bosons with subsequent leptonic decay. Three of the six events are within measurement errors found in a region of phase space likely to be populated by this process, while the remaining events show kinematic properties which are atypical of all Standard Model processes considered.

Note:

18 pages, 5 figures, 2 tables, submitted to Eur. Phys. J Report-no: DESY 98-063

positron p: colliding beams
transverse momentum: missing-energy
lepton: electroproduction
transverse momentum: high
kinematics: phase space
event shape analysis: planarity
W: electroproduction
W: leptonic decay
electroweak interaction: validity test
H1

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