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A search for the rare decay K sup + yields. pi. sup +. nu. nu

Technical Report ·
OSTI ID:5929933
This thesis describes an experimental search for the weak decay K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}} performed at Brookhaven National Laboratory during the Winter of 1989 using the E787 Spectrometer designed expressly for this purpose. The first-order contribution to this decay cancels exactly via the Glashow-Iliopoulos-Maiani (GIM) Mechanism. However, the second-order process is expected to give a branching ratio between .6 {yields} 6 {times} 10{sup {minus}10} in the Standard Model. The predicted rate for this process is theoretically well determined; the uncertainty is due to the experimental input parameters of the Model. We find no candidate events in a sample of 1.12 {times} 10{sup 11} kaon decays and we set an upper limit on the branching ratio of 4.4 {times} 10{sup {minus}9} at the 90% confidence level. Using the same data we also set an upper limit on the process K{sup +} {yields} {pi}{sup +}f of 9.3 {times} 10{sup {minus}10} at the 90% confidence level, where f is any neutral massless weakly-interacting particle.
Research Organization:
Princeton Univ., NJ (USA). Dept. of Physics
Sponsoring Organization:
DOE; USDOE, Washington, DC (USA)
DOE Contract Number:
AC02-76ER03072
OSTI ID:
5929933
Report Number(s):
DOE/ER/03072-64; ON: DE91010354
Country of Publication:
United States
Language:
English