Search for pair-production of long-lived heavy charged particles in e+e- annihilation

TL;DR

This paper reports a search for long-lived heavy charged particles in electron-positron collisions at various energies, setting mass limits and cross section constraints without observing any candidates.

Contribution

The study provides the first model-independent cross section limits for long-lived charged particles at these energies and translates them into mass bounds within the MSSM framework.

Findings

No candidate events observed.

Set upper limits on production cross section (0.2-0.4 pb).

Established lower mass limits of 67-86 GeV/c^2 for specific particles.

Abstract

A search for pair-production of long-lived, heavy, singly-charged particles has been performed with data collected by the ALEPH detector at a centre-of-mass energy of 172 GeV. Data at \sqrt{s} = 161, 136, and 130 GeV are also included to improve the sensitivity to lower masses. No candidate is found in the data. A model-independent 95% confidence level upper limit on the production cross section at 172 GeV of 0.2-0.4pb is derived for masses between 45 and 86 GeV/c^2. This cross section limit implies, assuming the MSSM, a lower limit of 67 (69) GeV/c^2 on the mass of right- (left-) handed long-lived scalar taus or scalar muons and of 86 GeV/c^2 on the mass of long-lived charginos.