Searches for Long-lived particles with the ATLAS experiment

TL;DR

This paper reports on searches for long-lived particles using the ATLAS detector at the LHC, employing time-of-flight and energy loss measurements to identify slow, penetrating particles and those that come to rest within the detector.

Contribution

It introduces novel search techniques for long-lived particles in ATLAS data, including methods to detect particles that decay out-of-time or stop within the detector.

Findings

No significant excess observed over background expectations.

Established new limits on long-lived particle production cross sections.

Demonstrated the effectiveness of time-of-flight and dE/dx measurements in LLP searches.

Abstract

The discovery of a new type of a heavy long-lived particle (LLP) would be of fundamental significance due to their existence in many beyond the Standard Model scenarios. LLPs are anticipated in a wide range of physics models which extend the Standard Model, such as Supersymmetry and Universal Extra Dimensions. Since LLPs produced in 7 TeV pp collisions at the CERN LHC can be slow (beta << 1) and penetrating, time-of-flight and anomalous dE/dx energy loss measurements are promising ways to search for LLPs. In some cases these heavy objects may lose all of their energy and come to rest within the densest parts of the detector volume, decaying later, potentially out-of-time with collisions from the LHC. We present searches for LLPs using the ATLAS experiment, describing the techniques used and the results achieved to date.