A "second type of neutron" whether it is ultra low momentum or not, would be
largely indistinguishable in characteristics from ultra dense hydrogen UDH but
with a variation in lifetime. It would not be the UDH of Holmlid which he
thinks is long-lived, but there are many theories which are similar, such that
it seems like a more accurate picture will emerge soon.
It would be coincidental if the lifetimes of the two were enough to explain the
discrepancy mentioned previously, which is usually ignored. Wiki sez the free
neutron has a mean lifetime of 15 minutes (881.5±1.5 s) but that is not
accurate. The variation can be 10 seconds or more depending on containment and
other factors. If there are two types then it seems improbable that they would
be that close. The antineutrino would not be present in UDH decay but plenty of
observers feel that it is little more than a kludge anyway.
