A search for Lorentz and CPT violations in double-β decay with the complete exo-200 dataset

Echevers, Jonathan

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https://hdl.handle.net/2142/120196 Copy

Description

Title

A search for Lorentz and CPT violations in double-β decay with the complete exo-200 dataset

Author(s)

Echevers, Jonathan

Issue Date

2023-01-10

Director of Research (if dissertation) or Advisor (if thesis)

Yang, Liang

Doctoral Committee Chair(s)

Hooberman, Benjamin

Committee Member(s)

• Cooper, Lance
• Kahn , Yonatan

Department of Study

Physics

Discipline

Physics

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Neutrino physics
• EXO-200
• liquid xenon
• neutrinoless double beta decay
• Lorentz and CPT violations
• time projection chamber
• Standard Model Extension (SME)

Abstract

Neutrinoless double beta (0vBB) decay is currently one of the most compelling searches in particle physics. If found, it would imply the existence of Majorana fermions and lepton number violation, both new physics beyond the Standard Model. The EXO-200 experiment consisted of a time projection chamber (TPC) with 200 kg of enriched liquid xenon (LXE) optimized to search for 0vBB of Xe-136. Data acquisition took place from 2011 to the end of 2018, with a total exposure of 234.1kg yr. We found no statistically significant evidence for 0vBB, leading to a lower limit on its half-life of 3.5x10^25 yr at the 90% confidence level. In addition, the ultra-low background necessary for this search provides a unique opportunity to probe other exotic processes, such as Lorentz and CPT violation, predicted by the Standard Model extension (SME). This presents itself in double beta decay as a spectral perturbation due to neutrino coupling with an SME Lorentz-violating tensor field. The first search for this process was published in 2016 using a subset of the EXO-200 dataset. In this work, we will present the analysis and status of an updated search using the full EXO-200 dataset, an optimized analysis region, and novel analysis techniques. We will also present some of the work that has been done for the next generation experiment, nEXO. In particular, we discuss the work done at the University of Illinois for the light-readout system.

Graduation Semester

2023-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Jonathan Echevers

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