Branching Ratio
Branching Ratio
The decay K
is a particularly
attractive
test of the standard model. This GIM suppressed FCNC decay has negligible
long distance
contributions and small, well understood QCD corrections.
It is mediated by loops containing c and t quarks. The hadronic matrix element
can be related to that of K
decay via isospin, so that there is very
little theoretical uncertainty in predicting the branching ratio in terms of
CKM matrix elements and quark masses. In particular, it affords an extremely
clean way of determining |V
.
The experimental measurement is certainly very challenging. The AGS experiment e787 is expected to observe at most a few events. With increased proton intensity expected from the AGS, it should be possible to collect enough events to make a reasonable measurement of the branching ratio. We want to consider an experiment that will see enough events to make a branching ratio measurement of 25% or better.