Speaker
Description
This study explores a "win-win" coupling between a scalar field and the cosmic neutrino background to address the Hubble tension and the cosmic coincidence problem. We propose a model featuring a scalar bosonic field with a scale-free, quartic scalar potential $U(\phi) = \lambda \phi^4$ that interacts with neutrinos to generate an effective potential with temperature-dependent degenerate minima. At high temperatures in the early universe, the field is trapped in a frozen minimum where effective neutrino masses vanish. As the cosmic neutrino background cools, the field adiabatically tracks the evolving minimum toward the origin, allowing the neutrino mass to reach its bare value of approximately 0.1 eV at late times. Numerical integration demonstrates that this mechanism produces a subdominant early dark energy component peaking at approximately 10% of the total energy density near matter-radiation equality at a redshift of approximately 3400. This localized energy injection reduces the sound horizon, alleviating the Hubble tension while remaining consistent with Big Bang Nucleosynthesis and Cosmic Microwave Background constraints. The subsequent rapid decay of the early dark energy component ensures the model's convergence to the standard Lambda Cold Dark Matter framework at low redshifts.