Search for excited leptons in e+e- collisions at sqrt{s}=189-209 GeV

TL;DR

This study conducted a search for excited leptons in electron-positron collisions at energies between 189 and 209 GeV using DELPHI data, setting mass limits and parameter constraints due to no observed signals.

Contribution

It provides the first comprehensive search for excited leptons at LEP energies, establishing new mass limits and constraints on model parameters.

Findings

No evidence for excited lepton production was observed.

Lower mass limits for pair-produced excited leptons range from 94 to 103 GeV/c^2.

Upper limits on the f/Lambda parameter were set as a function of mass.

Abstract

A search for excited lepton production in e+e- collisions was performed using the data collected by the DELPHI detector at LEP at centre-of-mass energies ranging from 189 GeV to 209 GeV, corresponding to an integrated luminosity of approximately 600 pb^{-1}. No evidence for excited lepton production was found. In searches for pair-produced excited leptons, lower mass limits were established in the range 94 - 103 GeV/c^2, depending on the channel and model assumptions. In searches for singly-produced excited leptons, upper limits on the parameter f/Lambda were established as a function of the mass.