Cosmic Rays from Cosmic Strings with Condensates
  We re-visit the production of cosmic rays by cusps on cosmic strings. If a
scalar field (``Higgs'') has a linear interaction with the string world-sheet,
such as would occur if there is a bosonic condensate on the string, cusps on
string loops emit narrow beams of very high energy Higgses which then decay to
give a flux of ultra high energy cosmic rays. The ultra-high energy flux and
the gamma to proton ratio agree with observations if the string scale is $\sim
10^{13}$ GeV. The diffuse gamma ray and proton fluxes are well below current
bounds. Strings that are {\it lighter} and have linear interactions with
scalars produce an excess of direct and diffuse cosmic rays and are ruled out
by observations, while heavier strings ($\sim 10^{15}$ GeV) are constrained by
their gravitational signatures. This leaves a narrow window of parameter space
for the existence of cosmic strings with bosonic condensates.
