  A network of observable, macroscopic cosmic (super-)strings may have formed
in the early universe. If so, the cusps that generically develop on
cosmic-string loops emit bursts of gravitational radiation that could be
detectable by both ground- and space-based gravitational-wave interferometers.
Here we report on two versions of a LISA-oriented string-burst search pipeline
that we have developed and tested within the context of the Mock LISA Data
Challenges. The two versions rely on the publicly available MultiNest and PyMC
software packages, respectively. To reduce the effective dimensionality of the
search space, our implementations use the F-statistic to analytically maximize
over the signal's amplitude and polarization, A and psi, and use the FFT to
search quickly over burst arrival times t_C. The standard F-statistic is
essentially a frequentist statistic that maximizes the likelihood; we also
demonstrate an approximate, Bayesian version of the F-statistic that
incorporates realistic priors on A and psi. We calculate how accurately LISA
can expect to measure the physical parameters of string-burst sources. To
understand LISA's angular resolution for string-burst sources, we draw maps of
the waveform fitting factor [maximized over (A psi, t_C)] as a function of sky
position; these maps dramatically illustrate why (for LISA) inferring the
correct sky location of the emitting string loop will often be practically
impossible. We also identify and elucidate several symmetries that are imbedded
in this search problem, and we derive the distribution of cut-off frequencies
f_max for observable bursts.
