First Search for Quirks at the LHC with FASER

Abstract

We present the first LHC search for quirks, particles with Standard Model and a QCD-like infracolor (IC) interactions. The analysis uses data collected in 2022--2024 by FASER, with a $186~\mathrm{fb}^{-1}$ integrated luminosity of proton-proton collisions at a center-of-mass energy $\sqrt{s}=13.6\,\mathrm{TeV}$. Scintillator charge and timing information are used to search for slow pairs of quirks with no QCD color and electric charge $\pm 1$. No events are seen in this nearly background-free search, resulting in the first exclusion of quirks with masses above the weak scale for IC confinement scales in the broad range of $300 \mathrm{eV}<Λ<100\mathrm{keV}$.