Supernova constraint on self-interacting dark sector particles

We examine the constraints on sub-GeV dark sector particles set by proto-neutron star cooling associated with core-collapse supernova event SN1987a. Considering explicitly a photon portal model, we compute relevant interaction rates of (${A}^{\ensuremath{'}}$) and fermion ($\ensuremath{\chi}$) Standard Model as well their self-interaction inside sector. find that even small fine structure constant ${\ensuremath{\alpha}}_{D}\ensuremath{\ll}1$, self-interactions can easily lead to own self-trapping. This effect strongly limits energy luminosity carried away from core thus drastically affects parameter space be constrained consider specifically two mass ratios ${m}_{{A}^{\ensuremath{'}}}=3{m}_{\ensuremath{\chi}}$ $3{m}_{{A}^{\ensuremath{'}}}={m}_{\ensuremath{\chi}}$ which represent scenarios where decay ${A}^{\ensuremath{'}}$ $\ensuremath{\chi}\overline{\ensuremath{\chi}}$ is allowed or not. For ${m}_{{A}^{\ensuremath{'}}}=3{m}_{\ensuremath{\chi}}$, show this completely evade bounds widely examined for ${\ensuremath{\alpha}}_{D}\ensuremath{\gtrsim}{10}^{\ensuremath{-}7}$. In particular, range ${m}_{\ensuremath{\chi}}\ensuremath{\lesssim}20\text{ }\text{ }\mathrm{MeV}$, only applied weakly self-interacting ${\ensuremath{\alpha}}_{D}\ensuremath{\lesssim}{10}^{\ensuremath{-}15}$. $3{m}_{{A}^{\ensuremath{'}}}={m}_{\ensuremath{\chi}}$, in regions ${\ensuremath{\alpha}}_{D}\ensuremath{\gtrsim}{10}^{\ensuremath{-}7}$ }\mathrm{MeV}$ evaded similarly. Our findings imply existing light generally eluded similar self-trapping mechanism. also implies nonstandard neutrino not consistent SN1987a observation. Same effects take place other known stellar particles.