Constraints on cosmic strings from the LIGO-Virgo gravitational-wave
  detectors
  Cosmic strings can give rise to a large variety of interesting astrophysical
phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by
cusps are a promising observational signature. In this Letter we present a
search for GWs from cosmic string cusps in data collected by the LIGO and Virgo
gravitational wave detectors between 2005 and 2010, with over 625 days of live
time. We find no evidence of GW signals from cosmic strings. From this result,
we derive new constraints on cosmic string parameters, which complement and
improve existing limits from previous searches for a stochastic background of
GWs from cosmic microwave background measurements and pulsar timing data. In
particular, if the size of loops is given by the gravitational backreaction
scale, we place upper limits on the string tension $G\mu$ below $10^{-8}$ in
some regions of the cosmic string parameter space.
