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Measurement of the Branching Ratio of {pi}{sup 0} {r_arrow} e{sup +} e{sup {minus}} Using K{sub L} {r_arrow} 3{pi}{sup 0} Decays in Flight

Journal Article · · Physical Review Letters
OSTI ID:365892
; ;  [1]; ; ; ;  [2]; ;  [3]; ; ; ; ; ; ; ; ; ; ; more »; ; ; ; ; ; ;  [4]; ; ; ; ; ;  [5];  [6]; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;  [7]; ; ; ; ; ;  [8]; ;  [9]; ; ; ; ; ; ; ; ; ; ;  [10]; ; ; ; ; ; ; ; ;  [11]; ; « less
  1. University of Arizona, Tucson, Arizona 85721 (United States)
  2. University of California at Los Angeles, Los Angeles, California 90095 (United States)
  3. University of California at San Diego, La Jolla, California 92093 (United States)
  4. The Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637 (United States)
  5. University of Colorado, Boulder, Colorado 80309 (United States)
  6. Elmhurst College, Elmhurst, Illinois 60126 (United States)
  7. Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)
  8. Osaka University, Toyonaka, Osaka 560 (Japan)
  9. Rice University, Houston, Texas 77005 (United States)
  10. Rutgers University, Piscataway, New Jersey 08855 (United States)
  11. The Department of Physics and Institute of Nuclear and Particle Physics, University of Virginia, Charlottesville, Virginia 22901 (United States)
+ Show Author Affiliations

The branching ratio of the rare decay {pi}{sup 0}{r_arrow}e{sup +}e{sup {minus}} has been measured in E799-II, a rare kaon decay experiment using the KTeV detector at Fermilab. We observed 275 candidate {pi}{sup 0}{r_arrow}e{sup +}e{sup {minus}} events, with an expected background of 21.4{plus_minus}6.2 events which includes the contribution from Dalitz decays. We measured B[{pi}{sup 0}{r_arrow}e{sup +}e{sup {minus}},thinsp (m{sub e{sup +}e{sup {minus}}}/m{sub {pi}{sup 0}}){sup 2}{gt}0.95]=(6.09{plus_minus} 0.40{plus_minus}0.24){times}10{sup {minus}8} , where the first error is statistical and the second systematic. This result is the first significant observation of the excess rate for this decay above the unitarity lower bound. {copyright} {ital 1999} {ital The American Physical Society }

OSTI ID:
365892
Journal Information:
Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 5 Vol. 83; ISSN 0031-9007; ISSN PRLTAO
Country of Publication:
United States
Language:
English

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Related Subjects

66 PHYSICS
BRANCHING RATIO
CHIRAL SYMMETRY
ELECTRONS
LEPTONIC DECAY
PAIR PRODUCTION
PARTICLE DECAY
PERTURBATION THEORY
PIONS NEUTRAL
POSITRONS