Testing Fundamental Physics in Antihydrogen Experiments

Abstract

The recent advent of high precision antihydrogen spectroscopy opens the way to stringent experimental tests of the fundamental principles underlying particle physics and general relativity (GR), such as Lorentz and CPT invariance and the Einstein Equivalence Principle (EEP), on pure antimatter systems. In this paper, the nature and implications of these tests is investigated, with special reference to the ALPHA antihydrogen programme at CERN. This is underpinned by a theoretical review of the role of antiparticles, causality and fundamental symmetries in relativistic quantum field theory (QFT) and the theory of time measurement in GR. Low-energy effective theories which break Lorentz and CPT symmetry, or the Strong Equivalence Principle (SEP), are then introduced, together with a review of several `fifth force' scenarios involving new long-range forces which would effectively violate the universality of free-fall, or Weak Equivalence Principle (WEPff). The possible role of CPT violation in determining the matter-antimatter asymmetry of the Universe is discussed. Explicit calculations are given for the dependence on possible Lorentz and CPT violating couplings of the transition frequencies amongst the 1S, 2S and 2P hyperfine states measured in the magnetic field of the ALPHA trap and the resulting bounds are compared with existing limits. An analysis of the implications for the EEP of current free-fall and spectroscopic measurements with antihydrogen is presented and existing and potential bounds on WEPff and the universality of clocks (WEPc) are derived, together with constraints on fifth forces. Future prospects for high-precision antihydrogen spectroscopy, free-fall and gravitational redshift experiments, and anti-atom matter-wave interferometry are described and experimental possibilities involving other antimatter species are briefly outlined.

arXiv comment113 pages, 4 figures. This version contains additional material on non-local QFTs (sect 2.3) and the formalism to analyse annual variations in antihydrogen spectroscopy (sect 3.2.2). An omitted term is included in eq.(3.39). Minor improvements and updates

References in corpus (27)

• Observation of Gravitational Waves from a Binary Black Hole Merger
• Data Tables for Lorentz and CPT Violation
• The Confrontation between General Relativity and Experiment
• Improved Measurement of the Hydrogen 1S - 2S Transition Frequency
• The MICROSCOPE mission: first results of a space test of the Equivalence Principle
• Matter-gravity couplings and Lorentz violation
• Fermions with Lorentz-violating operators of arbitrary dimension
• Phenomenology of the minimal B-L extension of the Standard model: Z' and neutrinos
• Unbroken B-L Symmetry
• Equivalence Principle and Gravitational Redshift
• Lorentz and CPT tests with hydrogen, antihydrogen, and related systems
• Lorentz-violating spinor electrodynamics and Penning traps
• The Refractive Index of Curved Spacetime: the Fate of Causality in QED
• Force-Free Gravitational Redshift: Proposed Gravitational Aharonov-Bohm experiment
• The Causal Structure of QED in Curved Spacetime: Analyticity and the Refractive Index
• Antimatter interferometry for gravity measurements
• Lorentz and CPT Tests with Clock-Comparison Experiments
• Lab-based limits on the Carroll-Field-Jackiw Lorentz-violating electrodynamics
• Higher order corrections to the hydrogen spectrum from the Standard-Model Extension
• Testing Electron Boost Invariance with 2S-1S Hydrogen Spectroscopy
• Quantum Field Theory in a Multi-Metric Background
• Gravitational leptogenesis, C, CP and strong equivalence
• Experimental constraints on the free fall acceleration of antimatter
• Leptogenesis and gravity: baryon asymmetry without decays
• Post-Newtonian particle physics in curved spacetime
• Bimetric QED
• Spontaneous CPT Violation and Quantum Anomalies in a Model for Matter-Antimatter Asymmetry in the Cosmos