8 research outputs found
First observation of K-L ->pi(+/-)e(-/+)nu e(+)e(-)
This Letter is the first report of the K-L ->pi(+/-)e(-/+)nu e(+)e(-) decay. Based on 19 208 +/- 144 events, we determine the branching fraction, B(K-L ->pi(+/-)e(-/+)nu e(+)e(-);M(e)(+)e(-)> 5 MeV/c(2),E(e)(+)e(-*)> 30 MeV)=(1.285 +/- 0.041)x10(-5), and Gamma(K-e3ee;M(e)(+)e(-)> 5 MeV/c(2))/Gamma(K-e3)=[4.57 +/- 0.04(stat)+/- 0.14(syst)]x10(-5). This ratio agrees with a theoretical prediction based on chiral perturbation theory (ChPT) calculated to O(p(4)). The measured kinematical distributions agree with those predicted by just ChPT O(p(4)), but show significant disagreement with ones predicted by leading-order ChPT.99
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Observation of direct CP violation in ks, l→ΠΠdecays
We have compared the decay rates of KL and KS toΠ+ Π- Π0Π0 final states using a subset of the data from the KTeV experiment (E832) at Fermilab. We find that the direct-CP-violation parameter Re (μ’/μ) is equal to [28.0±3.0(stat)±2.8(syst)]×10-4. This result definitively establishes the existence of CP violation in a decay process. © 1999 The American Physical Society