Large bulk matter search for fractional charge particles

TL;DR

This study conducted the largest search to date for stable fractional charge particles in silicone oil using a novel oil drop method with electric field and air flow, setting new upper limits on their abundance.

Contribution

Introduces a new oil drop method with electric field and air flow for detecting fractional charge particles, establishing the first upper limits with this technique.

Findings

No fractional charge particles detected within sensitivity limits.

Set a 95% confidence level upper limit of 1.17×10⁻²² particles per nucleon.

Demonstrated advantages and limitations of the new detection method.

Abstract

We have carried out the largest search for stable particles with fractional electric charge, based on an oil drop method that incorporates a horizontal electric field and upward air flow. No evidence for such particles was found, giving a 95% C.L. upper limit of $1.17\times 10^{-22}$ particles per nucleon on the abundance of fractional charge particles in silicone oil for $0.18 e \le |Q_{residual}| \le 0.82 e$. Since this is the first use of this new method we describe the advantages and limitations of the method.