Gravitational wave spectrum from kinks on infinite cosmic superstrings
  with Y-junctions
  We calculate the gravitational wave (GW) background spectra from kink
propagation and kink-kink collisions on infinite cosmic superstrings. We take
into account two characteristics of the cosmic superstring network: a small
reconnection probability and Y-junctions. First, a small reconnection
probability increases the number of infinite strings inside the horizon and
enhances the kink production, which leads a larger amplitude of the GW
background. Second, a kink going through a Y-junction transforms into three
daughter kinks. In this way, the existence of Y-junctions also increases the
number of kinks on cosmic superstrings. However, at the same time, it smooths
out the sharpness of kinks rapidly and reduces the number of sharp kinks, which
are responsible for the emissions of strong GW bursts. We compute the number
distribution of kinks as a function of the sharpness by taking into account the
above two effects, and translate it to the amplitude of the GW background
spectra. We first investigate the case of the string network with equal string
tensions, and find that the effect of Y-junctions to smooth out kink sharpness
dominates that of the enhancement of the kink number by a small reconnection
probability, and the GW amplitude turns out to be smaller than the ordinary
cosmic string case. On the other hand, for non-equal string tensions, we find
that there is a parameter space where the GW amplitude is slightly enhanced by
the effect of a small reconnection probability.
