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Sufficiency of Microphysical CP/T Violation to Explain the Cosmic Arrow of Time

Ascertain whether the magnitude of CP violation observed in weak interactions (e.g., in kaon decays) and in the lepton sector suffices to generate a macroscopic time-reversal asymmetry that accounts for the observed arrow of time on cosmological scales.

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Background

The paper discusses the CPT theorem in quantum field theory and notes that CP violation, observed in kaon systems and potentially in the lepton sector via leptogenesis, implies T violation. It then questions whether these microscopic sources of T asymmetry are quantitatively sufficient to explain the macroscopic arrow of time observed in the universe.

This uncertainty bridges microphysical symmetry breaking and cosmological phenomena, highlighting the need to evaluate whether observed CP/T violations can produce a large-scale temporal asymmetry consistent with cosmological observations.

References

However, it is unclear whether this violation is significant enough to account for the arrow of time on cosmic scales (cf. [Vaccaro]). The same comment applies to CP violation in the lepton sector (even if it explains the observed matter-antimatter asymmetry in the universe via leptogenesis; see, e.g., [Davidson] and references therein).

— Demystifying Arrow of Time (2405.15796 - Kakushadze, 9 May 2024) in Section 6 (Concluding Remarks)