The E949 experiment at Brookhaven National Laboratory has obtained a new result on the rare decay K⁺—>p⁺nn.

The experimental collaboration is now composed of 70 scientists from Canada, Japan, Russia (INR RAS and IHEP, Protvino) and the United States. A third event has been seen and the new branching ratio remains almost twice the SM level (although still consistent with it): BR = (1.47 + 1.30 - 0.89) x 10^-10. This result comes from the phase space region above the K⁺—>p⁺p⁰(K_p2 ) peak. Additional data below the K_p2 peak is under analysis and may contribute comparable sensitivity.

See for details:
Preprint hep-ex/0403036
http://www.bnl.gov/world/
http://www.phy.bnl.gov/e949/