Search for Heavy Stable and Long-Lived Particles in e+e- Collisions at sqrt(s)=189 GeV

TL;DR

This paper reports a search for heavy stable or long-lived charged particles in electron-positron collisions at 189 GeV, using detector measurements to identify such particles, but finds no evidence and sets exclusion limits on their masses.

Contribution

It introduces a method combining Cherenkov light detection and ionisation loss measurements to search for heavy stable particles at LEP energies.

Findings

No evidence of heavy stable charged particles was observed.

Exclusion limits set on smuon and stau masses up to approximately 88 GeV/c^2.

Combined analysis with previous data extends exclusion limits significantly.

Abstract

A search for stable and long-lived heavy charged particles was performed using the data taken by the DELPHI experiment at an energy of 189 GeV. The Cherenkov light detected in the Ring Imaging Cherenkov Detector and the ionisation loss measured in the Time Projection Chamber were used to identify heavy particles passing through the detector. No evidence for the production of such particles has been found, therefore exclusion limits at 95% confidence level were derived on the masses of left and right handed smuons and staus. The results were combined with previous DELPHI searches in this channel. Including previous DELPHI results, masses of left (right) handed stable smuons and staus can be excluded between 2 GeV/c^2 and 88 (87.5) GeV/c^2 at 95% CL.