Stars as Laboratories for Fundamental Physics - MPP Theory Group

Miscellaneous Exotica 557
nuclei it would correspond to an abundance of one quarked nucleus
(Q-nucleus) in 6×10 17 normal ones.
A small abundance of Q-nuclei could significantly alter the stellar
thermonuclear reaction chains and among other effects change the
solar neutrino predictions (Boyd et al. 1983). Detailed nuclear reaction
chains involving Q-nuclei were studied by Boyd et al. (1985). For
strangelets (lumps of strange quark matter) trapped in stars the nuclear
networks were investigated by Takahashi and Boyd (1988); the effect of
strangelets is similar to that of Q-nuclei. The Q-nuclear reactions were
implemented in a stellar evolution code by Joseph (1984). Predictions
for the solar neutrino flux were worked out by Sur and Boyd (1985).
With a Q-nuclear abundance of order 10 −15 the modified reaction
chains would compete with the standard ones. In the Sun one could
achieve a reduction of the high-energy solar neutrino flux and thus solve
the “old solar neutrino problem” (missing boron neutrinos). However,
Sur and Boyd (1985) predict an increase of the low-energy flux, corresponding
to a substantially increased counting rate at the gallium solar
neutrino experiments. As this contradicts the findings of SAGE and
GALLEX (Sect. 10.3) one concludes that Q-nuclear burning is not the
answer to the solar neutrino problem. Turning the SAGE/GALLEX
observations around one concludes that in the Sun the abundance of
Q-nuclei is below about 10 −15 .
15.6 Supersymmetric Particles
Supersymmetric extensions of the particle-physics standard model are
very popular, among other reasons because the lightest supersymmetric
particle (LSP) could play the role of the cosmic dark matter. In
these models, there is a fermionic partner to all standard bosons, and
a bosonic partner to all standard fermions. The supersymmetric partners
of the photon, the Z ◦ gauge boson, and the neutral Higgs boson
(photino, Zino and Higgsino) would be Majorana fermions. They
would be very much like Majorana neutrinos except that their interaction
strength is not fixed by the Fermi constant but rather depends on
details of the supersymmetric models.
If these “neutralinos” had low enough masses they would be produced
in the interior of stars by the same processes that create neutrinos,
except that the coupling strength has to be adjusted according
to the particular model that one has in mind. Limits to an anomalous
energy loss of stars yielded early constraints on supersymmetric models