Phys. Rev. Lett.
87,
021801
(2001)
[5 pages]
First Observation of the Decay KL→π0e+e-γ
A. Alavi-Harati et al. (The KTeV Collaboration)
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A. Alavi-Harati12, T. Alexopoulos12,*, M. Arenton11, K. Arisaka2, S. Averitte10, A. R. Barker5, L. Bellantoni7, A. Bellavance9, J. Belz10,†, R. Ben-David7, D. R. Bergman10, E. Blucher4, G. J. Bock7, C. Bown4, S. Bright4, E. Cheu1, S. Childress7, R. Coleman7, M. D. Corcoran9, G. Corti11, B. Cox11, M. B. Crisler7, A. R. Erwin12, R. Ford7, A. Glazov4, A. Golossanov11, G. Graham4,‡,§, J. Graham4, K. Hagan11, E. Halkiadakis10, J. Hamm1, K. Hanagaki8,**, S. Hidaka8, Y. B. Hsiung7, V. Jejer11, D. A. Jensen7, R. Kessler4, H. G. E. Kobrak3, J. LaDue5, A. Lath10, A. Ledovskoy11, P. L. McBride7, P. Mikelsons5, E. Monnier4,††, T. Nakaya7,‡‡, K. S. Nelson11, H. Nguyen7, V. O'Dell7, M. Pang7, R. Pordes7, V. Prasad4, B. Quinn4, E. J. Ramberg7, R. E. Ray7, A. Roodman4,a, M. Sadamoto8, S. Schnetzer10, K. Senyo8,b, P. Shanahan7, P. S. Shawhan4,c, J. Shields11, W. Slater2, N. Solomey4, S. V. Somalwar10, R. L. Stone10, I. Suzuki8,d, E. C. Swallow4,6, S. A. Taegar1, R. J. Tesarek10,e, G. B. Thomson10, P. A. Toale5, A. Tripathi2, R. Tschirhart7, S. E. Turner2, T. Uchizawa1, Y. W. Wah4, J. Wang1, H. B. White7, J. Whitmore7, B. Winstein4, R. Winston4, T. Yamanaka8, and E. D. Zimmerman4,f (The KTeV Collaboration)
1University of Arizona, Tucson, Arizona 85721
2University of California at Los Angeles, Los Angeles, California 90095
3University of California at San Diego, La Jolla, California 92093
4The Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637
5University of Colorado, Boulder, Colorado 80309
6Elmhurst College, Elmhurst, Illinois 60126
7Fermi National Accelerator Laboratory, Batavia, Illinois 60510
8Osaka University, Toyonaka, Osaka 560-0043 Japan
9Rice University, Houston, Texas 77005
10Rutgers University, Piscataway, New Jersey 08854
11The Department of Physics and Institute of Nuclear and Particle Physics, University of Virginia, Charlottesville, Virginia 22901
12University of Wisconsin, Madison, Wisconsin 53706
Received 28 November 2000; published 25 June 2001
We report on the first observation of the decay KL→π0e+e-γ by the KTeV E799 experiment at Fermilab. Based upon a sample of 48 events with an estimated background of 3.6±1.1 events, we measure the KL→π0e+e-γ branching ratio to be (2.34±0.35±0.13)×10-8. Our data agree with recent O(p6) calculations in chiral perturbation theory that include contributions from vector meson exchange through the parameter aV. A fit was made to the KL→π0e+e-γ data for aV with the result -0.67±0.21±0.12, which is consistent with previous results from KTeV.
© 2001 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.87.021801
DOI:
10.1103/PhysRevLett.87.021801
PACS:
13.20.Eb, 11.30.Er, 12.39.Fe, 13.40.Gp
*Current address: National Technical University, 175 73, Athens, Greece. †Current address: Montana State University, Bozeman, Montana 59717. ‡Current address: Fermi National Accelerator Laboratory, Batavia, Illinois 60510. §To whom correspondence should be addressed. **Current address: Princeton University, Princeton, New Jersey 08544. ††Current address: C.P.P. Marseille/C.N.R.S., France. ‡‡Current address: Kyoto University, 606-8502 Japan. aCurrent address: Stanford Linear Accelerator Center, Stanford, California 94309. bCurrent address: Nagoya University, Nagoya 464-8602 Japan. cCurrent address: California Institute of Technology, Pasadena, California 91125. d e fCurrent address: Columbia University, New York, New York 10027.
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