There's no event horizon? News to me. Is there not a distance from the center (or singularity, if they exist) of the black hole at which the escape velocity becomes greater than the speed of light? If there's no event horizon can there be Hawking radiation?
Hawking radiation is essentially the idea that just outside where you'd expect an event horizon on general relativity physics, you get a quantum field theory effect not predicted by GR. Which is basically pair production from breakdown of the vaccum itself. As pairs (electron positron to keep it simple - it generalizes to others) of virtual particles pop into existence in a boundary layer near the hole, one of them has a world line that leads into the BH and another has one that leads out (some cross section has this characteristic etc). Thus you get particles that seem to come out of the hole, while their virtual "twins" fall into it. Thus the surface of the E.H. in GR terms is not "black", but emits radiation as a spectrum of "created" particles out of the vaccum. Meanwhile the BH loses mass-energy as net antimatter goes into the hole (effectively). BH entropy is as high as possible - completely disordered, no info about prior state preserved. So the stuff coming out is completely entropic aka black body. If the mass of the BH is high, this "unblackness" of the hole aka QFT driven "leakage" of mass-energy out of the hole, is very small. If that mass is small, the leakage rate may be high compared to the mass of the hole. Otherwise put, massive holes have huge "evaporation lifetimes" - well over the age of the universe - but small ones have modest ones and are appreciably "non-black". The idea here is that particle production seen in an accelerator event might have reflected a tiny mass hole that evaporated rapidly. But they are probably guessing and other ways of accounting for whatever event they are referring to, may well be possible.
FWIW.