Speaker
Description
"We report on a search for millicharged particles (mCPs) produced in cosmic ray proton atmospheric interactions using data collected during the first science run of the LUX-ZEPLIN experiment.
The mCPs produced by two processes---meson decay and proton bremsstrahlung---are considered in this study. This search is sensitive to mCPs with masses in the range between 90 MeV/c$^2$ -- 1100 MeV/c$^2$, and with fractional charges greater than $10^{-3}$ that of the electron charge (\textit{e}).
With an exposure of 60 live days and a 5.5~tonne fiducial mass, we observed no significant excess over background. This is the first experimental search for atmospheric mCPs and the first search for mCPs using an underground liquid xenon experiment.
An upper limit of $2\times10^{-3}$~\textit{e} on the charge has been placed on mCPs with a mass of 100 MeV/c$^2$ at $90\%$ confidence level. Within the 100 to 600 MeV/c$^2$ mass range, this result is competitive with published experimental constraints from beam experiments. "
