  A selective sweep describes the reduction of diversity due to strong positive
selection. If the mutation rate to a selectively beneficial allele is
sufficiently high, Pennings and Hermisson (2006a) have shown, that it becomes
likely, that a selective sweep is caused by several individuals. Such an event
is called a soft sweep and the complementary event of a single origin of the
beneficial allele, the classical case, a hard sweep. We give analytical
expressions for the linkage disequilibrium (LD) between two neutral loci linked
to the selected locus, depending on the recurrent mutation to the beneficial
allele, measured by $D$ and $\hat{\sigma_D^2}$, a quantity introduced by Ohta
and Kimura (1969), and conclude that the LD-pattern of a soft sweep differs
substantially from that of a hard sweep due to haplotype structure. We compare
our results with simulations.
