Search for heavy, long-lived, charged particles with large ionisation energy loss in $pp$ collisions at $\sqrt{s} = 13~\text{TeV}$ using the ATLAS experiment and the full Run 2 dataset

TL;DR

This paper reports a search for heavy, long-lived charged particles in proton-proton collisions at 13 TeV using the ATLAS detector, setting new mass limits based on ionisation energy loss measurements.

Contribution

It introduces a novel search method utilizing ionisation energy loss in the pixel detector to identify long-lived charged particles over a wide mass range.

Findings

No significant excess observed, setting new mass limits for long-lived particles.

Mass limits extend beyond previous searches for R-hadrons, charginos, and staus.

Sensitivity to particles with lifetimes down to about 1 nanosecond.

Abstract

This paper presents a search for hypothetical massive, charged, long-lived particles with the ATLAS detector at the LHC using an integrated luminosity of 139 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}=13$ TeV. These particles are expected to move significantly slower than the speed of light and should be identifiable by their high transverse momenta and anomalously large specific ionisation losses, ${\mathrm{d}}E/\mathrm{d}x$. Trajectories reconstructed solely by the inner tracking system and a ${\mathrm{d}}E/\mathrm{d}x$ measurement in the pixel detector layers provide sensitivity to particles with lifetimes down to ${\cal O}(1)$ $\text{ns}$ with a mass, measured using the Bethe--Bloch relation, ranging from 100 GeV to 3 TeV. Interpretations for pair-production of $R$-hadrons, charginos and staus in scenarios of supersymmetry compatible with these particles being long-lived are presented, with mass limits extending considerably beyond those from previous searches in broad ranges of lifetime.