A Search for Displaced Leptons in the ATLAS Detector

This thesis presents a search for long-lived particles decaying into displaced electrons and/or muons with large impact parameters, providing unique sensitivity to the production of theoretical lepton-partners, sleptons, which are a feature of supersymmetric theories. The results are consistent with background, improving on the previous best limits from the Large Electron Positron Collider (LEP).

Format: Paperback / softback
Length: 146 pages
Publication date: 09 February 2023
Publisher: Springer Nature Switzerland AG

This thesis presents a comprehensive search for long-lived particles that undergo decay into displaced electrons and/or muons, exhibiting significant impact parameters. This distinctive signature holds remarkable potential in detecting the production of theoretical lepton-partners, known as sleptons. These particles are a fundamental aspect of supersymmetric theories, which aim to address profound questions about the nature of the universe. Identifying the signature sought in this thesis is a challenging task, and it is noteworthy that this is the first time it has been explored at the Large Hadron Collider (LHC). By filling a longstanding coverage gap for potential new physics signatures, this research contributes significantly to our understanding of the cosmos.

The thesis delves into the specialized reconstruction and identification algorithms employed to select leptons with large impact parameters. It provides intricate details regarding the background estimation process, which plays a crucial role in achieving accurate results. The findings presented in this thesis are consistent with the background, leading to the calculation of stringent limits on slepton masses and lifetimes within this model. These limits represent a substantial improvement over the previous best limits obtained from the Large Electron Positron Collider (LEP).

The significance of this thesis lies in its ability to uncover new physics phenomena and expand our knowledge of the universe. By exploring the decay of long-lived particles into displaced electrons and/or muons with large impact parameters, scientists can gain insights into the nature of particles and the underlying forces that govern the cosmos. The discovery of sleptons, if confirmed, would not only validate supersymmetric theories but also open up new avenues for further research and exploration.

In conclusion, this thesis represents a significant milestone in the field of particle physics. Through its comprehensive search for long-lived particles decaying into displaced electrons and/or muons with large impact parameters, it contributes to our understanding of the universe and paves the way for future discoveries. The specialized reconstruction and identification algorithms employed, along with the detailed background estimation, provide robust constraints on slepton masses and lifetimes, enhancing our knowledge of the fundamental building blocks of nature.

Weight: 261g
Dimension: 235 x 155 (mm)
ISBN-13: 9783030916749
Edition number: 1st ed. 2022