Temperature-dependent C P T violation: Constraints from big bang nucleosynthesis
Year: 2026
Type: article
Abstract: In this study, we explore temperature-dependent C P T violation during big bang nucleosynthesis (BBN) through electron-positron mass asymmetries parametrized by b 0 ( T ) = α T 2 . The T 2 scaling naturally evades stringent laboratory bounds at zero temperature while allowing for significant C P T violation at MeV scales in the early Universe [S. Navas (Particle Data Group), ]. Using a modified version of the BBN code with dynamically-solved chemical potentials and appropriate finite-mass corrections, we constrain electron-positron mass differences from observed abundances of helium-4, deuterium, and N eff . We find that α must be greater than or approximately equal to 10 − 6 GeV − 1 for keV-scale mass differences at BBN. All three observables show no simultaneous 1 σ overlap, though pairwise combinations allow for constrained regions of parameter space. We present two toy models demonstrating how b 0 ( T ) ∝ T 2 arises from field-theoretic mechanisms, including temperature-driven phase transitions. These results provide the most stringent constraints on early-Universe C P T violation in this regime, probing parameter space inaccessible to laboratory experiments.
DOI: 10.1103/ss12-dw3x
Authors: Gabriela Barenboim, Anne-Katherine Burns
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Awards: G1422035950, G176269601, G1764267590, G2262748287, G2917513873, Hunting Invisibles: Dark sectors, Dark matter and Neutrinos, G3220251042, G3480869486, G3681454997, G3780874795, G4042783231, G4087634877, G425668148, G4294200505, G464105488, G4861624602, G5635532810, G603324873, G633297219, G6417970939, G6466192506, G7052861868, G7084143925, G714608666, G7563990732, G7863371703, G8497050386
OpenAlex ID: W7123977966