  We discuss attacks and infections at propagating fronts of percolation
processes based on the extended general epidemic process. The scaling behavior
of the number of the attacked and infected sites in the long time limit at the
ordinary and tricritical percolation transitions is governed by specific
composite operators of the field-theoretic representation of this process. We
calculate corresponding critical exponents for tricritical percolation in
mean-field theory and for ordinary percolation to 1-loop order. Our results
agree well with the available numerical data.

Statistical Mechanics