1. K+  p+ + “nothing” in E949 (1) K+  p+nn (above Kp2)
Published in PRL, (2004)
Charged track momentum from various K decay modes
(2) p0 nn (on Kp2 peak)
This report.
Need tighter photon rejection.
(3) K+  p+nn (below Kp2)
Analysis ongoing.
Require more sophisticated treatment in p+ multiple scatterings.

2. Bifurcation Analysis Bifurcation Analysis Ex.) Km2(g) rejection
Cut1 : Range deviation
Uncorrelated Cut-1 and Cut-2
Rcut-1 = (C+D)/C
Signal Region
A/B = C/D
A = BC/D
= B / (Rcut-1 -1)
Cut2 : Neural Net output

3. Kp2 triggered events

4. Pion decay sequence

5. Pion Decay Sequence

6. Background Mechanism

7. Background Mechanism

8. Pion Decay Sequence : Neural Network

9. Range Stack dE/dx cut

10. Range Stack dE/dx cut

11. Single-beam background rejection