Unparticle constraints from supernova 1987A

The existence of an unparticle sector, weakly coupled to the standard model, would have a profound impact on supernova (SN) physics. Emission of energy into the unparticle sector from the core of SN 1987A would have significantly shortened the observed neutrino burst. The unparticle interaction with nucleons, neutrinos, electrons and muons is constrained to be so weak that it is unlikely to provide any missing-energy signature at colliders. One important exception are models where scale invariance in the hidden sector is broken by the Higgs vacuum expectation value. In this case the SN emission is suppressed by threshold effects.

Figure 1

Constraints on vector unparticle operators from SN bremsstrahlung emission, assuming $d_{\mathrm{UV}}=3$, for $d=1$, $3/2$, and 2 as indicated. The regions below the contours are excluded.