Search for millicharged particles in proton-proton collisions at \(\sqrt{s} = 13\) TeV

We report on a search for elementary particles with charges much smaller than the electron charge using a data sample of proton-proton collisions provided by the CERN Large Hadron Collider in 2018, corresponding to an integrated luminosity of 37.5 fb\(^{-1}\) at a center-of-mass energy of 13 TeV. A prototype scintillator-based detector is deployed to conduct the first search at a hadron collider sensitive to particles with charges \({\leq}0.1e\). The existence of new particles with masses between 20 and 4700 MeV is excluded at 95% confidence level for charges between \(0.006e\) and \(0.3e\), depending on their mass. New sensitivity is achieved for masses larger than \(700\) MeV.