Isospin mixing in protonium and annihilation dynamics

We have explored the sensitivity of pp¯-nn¯ isospin mixing in L=0,1 atomic states of protonium to changes in the multipion-exchange contribution to the nucleon-antinucleon (NN¯) potential. The resulting annihilation probabilities γIα for isospin I=0,1 and state α=2S+1LJ are combined with the spin-flavor weights for transitions NN¯→M1M2 in the 3P0 model, and confronted with selected measured branching ratios. Some problems with the phenomenology of the 3P0 model are identified. We compare the 3P0 model with a phenomenological ansatz suggested by Klempt, in which branching ratios are written as a product of spin, isospin, and orbital factors, multiplified by γIα