The threshold for kaon pair production in 
-machines is just
below the 
-peak. Therefore, the quite good data already available for
should be considerably improved in Daphne. They
follow, as expected, the 
Breit-Wigner excitation curve, as
schematically shown in Figs.(3) and (4).
Some data for higher 
-values are also
existing above the 
-peak, where 
is found to be larger
than 
(see Figs.(5) and (6)).
Further details can be seen in the compilations
[1] and [2], as well as in their
references to original work.
Figure 3: Exitation curves for the 
resonance decaying into
.
A few determinations of the kaon charge radii are also available. They lead to [10]
and to the difference [6] 
, as qualitatively discussed when dealing with
the physical meaning of these charge-radii.
The vector part of the 
decays gives further information on the
related 
transition form factor. Indeed, from the PDG
compilation one deduces [11]
while Sirlin's theorem [9], which is valid up to
first order in SU(3) breaking, predicts
.
The good agreement with the above values adds some confidence to the
whole set of data and their interpretation.
Figure 5: The 
e.m. form factor as a function of energy.
Figure 6: The 
e.m. form factor as a function of energy.
. 