Only decays with an electron positron pair in the final state, decays (2.2) and (2.3), have been observed.
Both have been measured
in the same experiment [21].
The decay 
was measured with a branching
ratio of 
with a lower cut on the
electron positron invariant mass of 
.
The measurement is compatible with our calculation including the
form factor effects for the relevant region of phase space.
This measurement
was then extrapolated [21]
using the result of [20] to the
full phase space. Since we disagree with that calculation,
we also disagree with the extrapolation.
In the same experiment, 4 events of the type
were
observed where both electron positron pair invariant masses were
above 140 MeV. This corresponds to a branching ratio for this
region of phase space of 
.
This result is compatible within errors with our calculation, see
table 2.2.
The matrix element of Ref. [20] was again used for the
extrapolation to full phase space[21].
Apart from our numerical disagreement,
the calculation of Ref. [20] was for the case of
non-identical leptons and cannot be applied here.
For the decay 
an upper limit
of 
exists [22]. This upper limit is
compatible with our theoretical result, Eq. (2.23).
The decay 
has not been looked for so far
and should be within the capabilities of DA
NE given the
branching ratio predicted in the previous subsection.
This decay proceeds
almost entirely through the structure dependent terms and is as such a
good test of our calculation.