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Title: Measuring the branching ratio of the rare decay π 0→e +e -

Abstract

A precise branching ratio measurement of the rare decay π 0→e +e - has been made. The measurement was made with the rare kaon decay experiment KTeV at Fermilab where the source of π 0s was K L → π 0π 0π 0 decaying in flight. A total of 794 fully reconstructed K L → 3π 0 events consistent with two of the intermediate π 0s decaying into ππ and one into e +e - were collected. An estimated 53.2 ± 11.0 of these events were expected to be background. Normalizing to the π 0 Dalitz decay they found Br(π 0 → e +e -, (m e+e-/m π0) 2 > 0.95) = (6.44 ± 0.25(stat) ± 0.22(syst)) x 10 -8 where internal radiation, π 0 → e +e -(γ), was limited by the requirement (m e+e-/m π0) 2 > 0.95 which separated it from the tree level Dalitz decay, π 0 → e +e -γ.

Authors:
 [1]
  1. Univ. of Colorado, Boulder, CO (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
892361
Report Number(s):
FERMILAB-THESIS-2006-12
TRN: US200711%%68
DOE Contract Number:
AC02-76CH03000
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; BRANCHING RATIO; DECAY; FERMILAB; KAONS; TREES; Experiment-HEP

Citation Formats

Niclasen, Rune. Measuring the branching ratio of the rare decay π0→e+e-. United States: N. p., 2006. Web. doi:10.2172/892361.
Niclasen, Rune. Measuring the branching ratio of the rare decay π0→e+e-. United States. doi:10.2172/892361.
Niclasen, Rune. Wed . "Measuring the branching ratio of the rare decay π0→e+e-". United States. doi:10.2172/892361. https://www.osti.gov/servlets/purl/892361.
@article{osti_892361,
title = {Measuring the branching ratio of the rare decay π0→e+e-},
author = {Niclasen, Rune},
abstractNote = {A precise branching ratio measurement of the rare decay π0→e+e- has been made. The measurement was made with the rare kaon decay experiment KTeV at Fermilab where the source of π0s was KL → π0π0π0 decaying in flight. A total of 794 fully reconstructed KL → 3π0 events consistent with two of the intermediate π0s decaying into ππ and one into e+e- were collected. An estimated 53.2 ± 11.0 of these events were expected to be background. Normalizing to the π0 Dalitz decay they found Br(π0 → e+e-, (me+e-/m π0)2 > 0.95) = (6.44 ± 0.25(stat) ± 0.22(syst)) x 10-8 where internal radiation, π0 → e+e-(γ), was limited by the requirement (me+e-/mπ0)2 > 0.95 which separated it from the tree level Dalitz decay, π0 → e+e-γ.},
doi = {10.2172/892361},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2006},
month = {Wed Feb 01 00:00:00 EST 2006}
}

Thesis/Dissertation:
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  • The authors present a measurement of B(π 0 → e +e -γ)/B(π 0 → γγ) using data taken in 1999 by the E832 KTeV experiment at Fermilab. The π 0s were produced by K L decays in flight that are fully reconstructed. They find 63,693 K L → 3π 0 → γγ γγ e +e -γ decays in KTeV data (an increase of a factor of ~ 20 in event statistics over previous experiments), and normalize to K L → 3π 0 → 6γ, to extract B(π 0 → e +e -γ, m e+e- > 15 MeV/c 20 → γγ)more » = (3.920 ± 0.016 ± 0.036) x 10 -3, where the first error is statistical and the second is systematic. Using the Mikaelian and Smith prediction for the e +e - mass spectrum as implemented in the KTeV Monte Carlo to correct to the full e +e - mass range yields B(π 0 → e +e -γ)/B(π 0 → γγ) = (1.1559 ± 0.0046 ± 0.0107)%. This result is consistent with previous measurements and with theoretical predictions, and the uncertainty is a factor of three smaller than any previous measurement.« less
  • In this thesis the author has described the first measurement performed at a hadron collider of the branching fraction of the Cabibbo-suppressed mode B +more » $$\bar{D}$$ 0 K +. The analysis has been performed with 360 pb -1 of data collected by the CDF II detector.« less
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