We study the reactions K → ππνν̄ within the minimal standard model. We use isospin symmetry to relate the matrix elements to the form factors measured in Kℓ4. We argue that these modes are short distance dominated and can be used for precise determinations of the CKM parameters ρ and η. Depending on the value of the CKM angles we find branching ratios in the following ranges: B(KL → π+π-νν̄) = [2-5] × 10-13; B(KL → π0π0νν̄) = [1-3] × 10-13; B(K+ → π+π0νν̄) = [1-2] × 10-14. We also discuss a possible CP-odd observable.
|Number of pages||6|
|Journal||Physics Letters B|
|Publication status||Published - 26 Sep 1996|