  We study a variation of the trapping reaction, A+B->A, in which both the
traps (A) and the particles (B) undergo diffusion, and the traps upon meeting
react according to A+A->0 or A. This two-species reaction-diffusion system is
known to exhibit a non-trivial decay exponent for the B particles, and recently
renormalization group methods have predicted an anomalous dimension in the BB
correlation function. To test these predictions we develop a computer
simulation method, motivated by the technique of Mehra and Grassberger, that
determines the complete probability distribution of the B particles for a given
realization of the A particle dynamics, thus providing a significant increase
the quality of statistics. Our numerical results indeed reveal the anomalous
dimension predicted by the renormalization group, and compare well
quantitatively to precisely known values in cases where the problem can be
related to a 4-walker problem.
