Medium effects in supernovae constraints on light mediators

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In this article, we reevaluate supernovae (SN) constraints on the diffusion time of neutrinos for a family of extensions of the Standard Model that incorporate new light scalar and vector mediators.

• We compute the neutrino mean free path, taking into account medium effects in the neutrino-nucleon scattering cross-section, and a radial dependence of the density, energy, and temperature inside the proto-neutron star to determine the coupling strengths compatible with SN1987A constraints on the time duration signal of diffusing neutrinos.
• We show that medium effects can induce an order of magnitude enhancement in the neutrino mean free path with respect to the vacuum calculation.
• The increase is more significant when new physics terms dominate over the Standard Model contribution (that is, for small mediator mass and large couplings).