[Paper Review] Spontaneous CPT asymmetry of the Universe

A. A. Andrianov, Paola Giacconi+1 more|arXiv (Cornell University)|Nov 17, 2001

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper investigates spontaneous CPT and Lorentz symmetry breaking in an extended, renormalizable quantum electrodynamics (QED) model via CPT-odd Chern-Simons and axial-vector interactions. It shows that such symmetry breaking leads to observable effects like photon birefringence, electron helicity mass splitting, and high-energy electron decay, with stringent experimental bounds constraining the induced vectors to extremely small values, suggesting a physically consistent but experimentally elusive framework.

ABSTRACT

The extended QED with renormalizable interactions breaking the Lorentz and CPT symmetry is considered and the phenomenological consequences of such a symmetry breaking are illuminated in view of recent discussion of large scale anisotropy of the Universe. Other physical effects in QED with CPT violation are examined, in particular, mass splitting between electrons of different helicities and decay of very high energetic electrons into lower energy electrons and positrons.

Motivation & Objective

• To explore the phenomenological consequences of spontaneous CPT and Lorentz symmetry breaking in quantum field theory.
• To examine the consistency of a modified QED model with renormalizability, gauge invariance, and microcausality.
• To assess the viability of CPT-odd and axial-vector interactions in explaining large-scale cosmic anisotropies.
• To derive bounds on the induced Chern-Simons and axial-vector fields from experimental data on photon birefringence and fermion mass splitting.
• To investigate the dynamical origin of symmetry breaking via axion condensation or background torsion fields.

Proposed method

• Formulates an extended QED Lagrangian with CPT-odd Chern-Simons (CS) coupling via a constant vector ημ and axial-vector coupling bμ to fermions.
• Analyzes dispersion relations for photons and fermions in the presence of ημ and bμ, showing modified energy-momentum spectra.
• Applies canonical quantization to fermions in a constant axial background, deriving energy spectra with helicity-dependent mass splitting.
• Calculates radiatively induced CS vector Δημ via one-loop fermion contributions, showing independence from renormalization scheme.
• Evaluates consistency conditions: space-like ημ for photon quantization and time-like bμ for fermion quantization, requiring precise cancellation in the full dressed vector.
• Uses experimental bounds from radio-wave birefringence, hydrogen masers, and torsion pendulums to constrain ημ and bμ components.

Experimental results

Research questions

• RQ1 Can spontaneous CPT and Lorentz symmetry breaking in QED lead to observable effects such as photon birefringence and electron mass splitting?
• RQ2 What are the implications of a CPT-odd Chern-Simons term and axial-vector coupling for the dispersion relations of photons and fermions?
• RQ3 How do radiative corrections generate an effective CS vector, and is it consistent with microcausality and experimental bounds?
• RQ4 Can the dynamical origin of ημ and bμ be linked to axion condensation or cosmological torsion fields?
• RQ5 What are the energy-scale thresholds for new physical processes like high-energy electron decay due to CPT violation?

Key findings

• The photon dispersion relation in CPT-odd QED exhibits birefringence, with two massless and two massive modes depending on polarization, leading to polarization rotation during propagation.
• The upper bound on the spatial component of the CS vector is |η| ≤ 10−32 eV, derived from radio-wave observations of distant galaxies.
• Electron helicity mass splitting occurs due to a time-like axial vector bμ, with a bound |b₀| < 10−2 eV from electron mass measurements.
• At energies above M ≈ m²/(2|b₀|) ≈ 10² TeV, high-energy electrons may decay into lower-energy electrons and e⁺e⁻ pairs, imposing a physical momentum cutoff.
• The radiatively induced CS vector Δημ = (2α/π)∑bᵃμ is uniquely determined and independent of renormalization scheme, with |Δη| < 10−19 eV estimated from experimental bounds.
• Consistent quantization of both photons and fermions requires precise cancellation between ημ and Δημ components, especially in the time direction, to satisfy microcausality and experimental constraints.