MEASUREMENT OF THE DECAY E--]4-GAMMA AT REST(E)

Authors
VONBUSCH H THIROLF P ENDER C HABS D KOCK F SCHULZE T SCHWALM D
Citation
H. Vonbusch et al., MEASUREMENT OF THE DECAY E--]4-GAMMA AT REST(E), Physics letters. Section B, 325(3-4), 1994, pp. 300-307
Citations number
31
Categorie Soggetti
Physics
Journal title
Physics letters. Section B → ACNP
ISSN journal
03702693
Volume
325
Issue
3-4
Year of publication
1994
Pages
300 - 307
Database
ISI
SICI code
0370-2693(1994)325:3-4<300:MOTDEA>2.0.ZU;2-V
Abstract
The decay of e+e- at rest into four photons has been measured in a 20- day experiment at the Heidelberg-Darmstadt Crystal Ball. From a total of 4.9 x 10(10) annihilations observed. 406 4gamma events with an esti mated background contamination of less than 5% have been isolated. Ene rgy and angular distributions are found to agree excellently with simu lations based on QED. Using a parallel measurement of 3gamma-annihilat ion for a reduction of systematic uncertainties, the branching ratio G AMMA4gamma/GAMMA2gamma is obtained to be (1.50 +/- 0.07(stat.)) +/- 0. 09(syst.)) X 10(-6), in agreement with lowest-order QED.