Currently I am attempting to find the source of a bug that causes masses and energies to be reconstructed too low.  The following plots are produced from 50000 single-pion events in which all pions have momentum of 5 GeV.  Figure 1 shows the invariant mass distribution of pion candidates and figure 2 the momentum distribution of pion candidates.  The peaks in both plots are clearly well below where they should be.  My suspicion is that the code is reconstructing one decay photon as two photons in too many cases, thus reducing the momentum and invariant mass of the reconstructed pizeros, but I'm not entirely sure.

Figure 1: Invariant mass distribution of pizero candidates

Figure 2: Momentum distribution of pizero candidates