Supernova bounds on Weinberg’s Goldstone bosons

Recently, Weinberg proposed a scenario where Goldstone bosons may be masquerading as fractional cosmic neutrinos. We calculate the energy loss rates through the emission of these Goldstone bosons in a postcollapse supernova core. Invoking the well-established emissivity bound from the Supernova 1987A observations and simulations, we find that nuclear bremsstrahlung processes can notably impose a bound on the Goldstone boson coupling to the Standard Model Higgs, g, dependent on the mass of the associated radial field, mr. We apply the supernova emissivity bound at typical core conditions: a density of ρ ¼ 3 × 1014 g=cm3 and a temperature T ¼ 30 MeV. Even in the conservative limit where mr is large enough compared with the Goldstone boson energies attainable at this temperature, our bound jgj ≲ 0.011ðmr=500 MeVÞ2 is very competitive to those derived from current and projected sensitivities of collider experiments.