Big Bang Nucleosynthesis constraints on varying electron mass solution to the Hubble tension

Understand

A cosmological model with a time-varying mass of electrons seems a promising solution for the so-called Hubble tension.

• We examine the big bang nucleosynthesis (BBN) constraints on the time-varying electron mass model, because a larger electron mass gives rise to the smaller neutron decay rate which could affect the light element abundance.
• Additionally, different inferred cosmological parameters, primarily baryon asymmetry, to keep the cosmic background power spectrum unchanged could affect the abundance of light element.
• We find that the predicted helium fraction becomes larger and the deuterium abundance becomes smaller as the electron mass at the BBN time becomes larger.