  Quantum trajectory simulations of a cavity QED system comprising an atomic
beam traversing a standing-wave cavity are carried out. The delayed photon
coincident rate for forwards scattering is computed and compared with the
measurements of Rempe et al. [Phys. Rev. Lett. 67, 1727 (1991)] and Foster et
al. [Phys. Rev. A 61, 053821 (2000)]. It is shown that a moderate atomic beam
misalignment can account for the degradation of the predicted correlation. Fits
to the experimental data are made in the weak-field limit with a single
adjustable parameter--the atomic beam tilt from perpendicular to the cavity
axis. Departures of the measurement conditions from the weak-field limit are
discussed.
