Precision Tests of Discrete Symmetries at Low Energies

Klaus Jungmann,Elwin A Dijck,Nivedya Valappol,Thomas Meijknecht,Amita Mohanty,Bastian Yip,Lorenz Willmann,J Olivier Grasdijk

doi:10.7566/jpscp.18.011017

Abstract

Low energy precision measurements provide for precise testing of the Standard Model, e.g., in searches for violations of the discrete symmetries charge conjugation (C), parity (P), and time reversal (T) as well as their combinations CP and CPT. We focus here on new experiments concerning atomic parity violation (APV) and searches for a permanent electric dipole moment (EDM) in atoms. In particular, we address precision APV experiments on Ba+ and Ra+ single ions that will enable the extraction of the Weinberg angle at lowest presently accessible momentum transfer. They are expected to contribute towards searches for new particles such as dark Z-bosons. We also review experimental programmes in which an EDM is searched for and we compare them in a common framework. We describe latest EDM searches in heavy effective two-electron atoms such as Xe and Hg. We also indicate possible future prospects of searches for a permanent EDM of the electron using molecules with large enhancement factors.

Highlights

The Standard Model can be considered the best theory in modern in physics
We focus here on new experiments concerning atomic parity violation (APV) and searches for a permanent electric dipole moment (EDM) in atoms
We review experimental programmes in which an EDM is searched for and we compare them in a common framework

Summary

Introduction

The Standard Model can be considered the best theory in modern in physics. It describes all confirmed observations up to date. For important conservation laws such as lepton or baryon numbers we do not know the associated symmetry In this context precision experiments with antiprotons [2], muons [3] or neutrons [4] are very advanced examples of accelerator or reactor based experiments at low energies, which aim to provide data and new observations towards resolving the open puzzles. Every measurement of APV, which is conducted in order to determine a precise value of the electroweak mixing angle (i.e. sin ΘW ), establishes a search for hints of new fundamental particles beyond the Standard Model; searches for time reversal violation as it could be signaled through permanent electric dipole moments (EDMs) on fundamental systems could provide for an ansatz to explain, e.g., the matter-antimatter puzzle.

Atomic Parity Violation

Conclusion