881 research outputs found
Possible Implications of Asymmetric Fermionic Dark Matter for Neutron Stars
We consider the implications of fermionic asymmetric dark matter for a "mixed
neutron star" composed of ordinary baryons and dark fermions. We find examples,
where for a certain range of dark fermion mass -- when it is less than that of
ordinary baryons -- such systems can reach higher masses than the maximal
values allowed for ordinary ("pure") neutron stars. This is shown both within a
simplified, heuristic Newtonian analytic framework with non-interacting
particles and via a general relativistic numerical calculation, under certain
assumptions for the dark matter equation of state. Our work applies to various
dark fermion models such as mirror matter models and to other models where the
dark fermions have self interactions.Comment: 20 pages, 6 figure
On the -- lifetime difference and decays
In this paper we discuss some aspects of inclusive decays of charmed mesons
and also decays of the lepton into . We find that phase
space effects are likely to explain the observed lifetime ratio = 1.17. In particular one need not appeal to a large annihilation
contribution in the inclusive decay which, being absent in decays
could also contribute to the enhanced decay rate relative to that of the
. Examining a separate problem, we find that the rate for is almost completely dominated by the tiny phase space for the
final eight particle state. Using an effective chiral Lagrangian to estimate
the matrix element yields a branching ratio into the channel of interest far
smaller than the present upper bound.Comment: No figure
SN1987A - a Testing Ground for the KARMEN Anomaly
We show, that SN1987A can serve as an astrophysical laboratory for testing
the viability of the assertion that a new massive neutral fermion is implied by
the KARMEN data. We show that a wide range of the parameters characterizing the
proposed particle is ruled out by the above constraints making this
interpretation very unlikely.Comment: 12 pages, 1 eps figure embedded, to appear in Phys. Lett.
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