Search for Stable and Long-Lived Massive Charged Particles in e+e- Collisions at sqrt(s) = 183-209 GeV

TL;DR

This paper reports a search for stable or long-lived massive charged particles with various charges in electron-positron collisions at energies up to 209 GeV, setting new mass and cross-section limits and excluding certain supersymmetric particles.

Contribution

It provides the first comprehensive search for a range of charged massive particles at LEP energies, establishing new exclusion limits within the CMSSM framework.

Findings

No evidence for the production of these particles was observed.

Mass limits of 98-102 GeV were set for various long-lived supersymmetric particles.

Cross-section upper limits between 0.005 and 0.028 pb were established.

Abstract

A search for stable and long-lived massive particles of electric charge |Q/e|=1 or fractional charges of 2/3, 4/3, and 5/3 is reported using data collected by the OPAL detector at LEP, at centre-of-mass energies from 130 to 209 GeV. These particles are assumed to be pair-produced in e+e- collisions and not to interact strongly. No evidence for the production of these particles was observed. Model-independent upper limits on the production cross-section between 0.005 and 0.028 pb have been derived for scalar and spin-1/2 particles with charge +-1. Within the framework of the Constrained Minimal Supersymmetric Standard Model (CMSSM), this implies a lower limit of 98.0 (98.5) GeV on the mass of long-lived right (left)- handed scalar muons and scalar taus. Long-lived charged heavy leptons and charginos are excluded for masses below 102.0 GeV. For particles with fractional charge +-2/3, +-4/3, and +-5/3, the upper limit on the production cross-section varies between 0.005 and 0.020 pb. All mass and cross-section limits are derived at the 95% confidence level and are valid for particles with lifetimes longer than 10-6s.