Rare kaon decays: Brookhaven E871

Journal Article · Wed Feb 17 04:00:00 EST 1999 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.57758· OSTI ID:21202571

Ambrose, David A ^[1]

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1. Department of Physics, University of Texas, Austin, Texas 78712 (United States)

This paper describes recent results from the rare kaon decay Experiment 871 at the Brookhaven AGS, which searched for the lepton flavor violating decay K{sub L}{sup 0}{yields}{mu}{sup {+-}}e{sup {+-}}, and measured branching ratios for the GIM and helicity suppressed modes K{sub L}{sup 0}{yields}{mu}{sup +}{mu}{sup -} and K{sub L}{sup 0}{yields}e{sup +}e{sup -}. Observing no candidate {mu}e events, E871 established a new upper limit (90%CL) on the branching fraction of B(K{sub L}{sup 0}{yields}{mu}{sup {+-}}e{sup {+-}})<4.8x10{sup -12}, representing the most sensitive search to date for this decay mode. E871 measured over 6200 {mu}{mu} candidates, a factor of six improvement on all previous measurements combined, giving a preliminary branching fraction of B(K{sub L}{sup 0}{yields}{mu}{sup +}{mu}{sup -})=(7.23{+-}0.22)x10{sup -9}, which should reduce the uncertainty in this decay mode by a factor of three. Lastly, E871 recorded four candidate ee events, the first observation of this rare decay, leading to a branching fraction of B(K{sub L}{sup 0}{yields}e{sup +}e{sup -})=8.7{sub -4.1}{sup +5.7}x10{sup -12}, which equals the smallest branching fraction ever measured in particle physics.

• OSTI ID: 21202571
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 459; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BRANCHING RATIO
BROOKHAVEN AGS
ELECTRONS
FLAVOR MODEL
HELICITY
KAONS NEUTRAL LONG-LIVED
LEPTONIC DECAY
MULTIPARTICLE SPECTROMETERS
MUONS MINUS
MUONS PLUS
PARTICLE IDENTIFICATION
POSITRONS
STANDARD MODEL
SYMMETRY BREAKING