tau - Particle Data Group

Citation: K. Nakamura et al. (Particle Data Group), JP G 37, 075021 (2010) and 2011 partial update for the 2012 edition (URL: http://pdg.lbl.gov)
τ − BRANCHING RATIOS
Γ ( particle − ≥ 0neutrals ≥ 0K 0 ν τ (“1-prong”) ) /Γ total Γ 1 /Γ
Γ 1 /Γ = (Γ 3 +Γ 5 +Γ 9 +Γ 10 +Γ 14 +Γ 16 +Γ 20 +Γ 23 +Γ 27 +Γ 28 +Γ 30 +Γ 35 +Γ 37 +Γ 40 +
Γ 42 +2Γ 47 +Γ 48 +0.708Γ 126 +0.715Γ 128 +0.09Γ 150 +0.09Γ 152 )/Γ
The charged particle here can be e, μ, or hadron. In many analyses, the sum of the
topological branching fractions (1, 3, and 5 prongs) is constrained to be unity. Since
the 5-prong fraction is very small, the measured 1-prong and 3-prong fractions are
highly correlated and cannot be treated as independent quantities in our overall fit.
We arbitrarily choose to use the 3-prong fraction in our fit, and leave the 1-prong
fraction out. We do, however, use these 1-prong measurements in our average below.
Themeasurementsusedonlyfortheaveragearemarked“avg,”whereas“f&a”marks
aresultusedforthefitandtheaverage.
VALUE (%) EVTS DOCUMENT ID TECN COMMENT
85.36 ±0.07 OUR FIT Error includes scale factor of 1.3.
85.26 ±0.13 OUR AVERAGE Error includes scale factor of 1.6. See the ideogram
below.
•••We use the following data for averages but not for fits. •••
85.316±0.093±0.049 avg 78k 1 ABREU 01M DLPH 1992–1995 LEP runs
85.274±0.105±0.073 avg 2 ACHARD 01D L3 1992–1995 LEP runs
84.48 ±0.27 ±0.23 avg ACTON 92H OPAL 1990–1991 LEP runs
•••We do not use the following data for averages, fits, limits, etc. •••
85.45
−0.73 +0.69 ±0.65 DECAMP 92C ALEP Repl. by SCHAEL 05C
1 The correlation coefficients between this measurement and the ABREU 01M measurements
of B(τ → 3-prong) and B(τ → 5-prong) are −0.98 and −0.08 respectively.
2 The correlation coefficients between this measurement and the ACHARD 01D measurements
of B(τ → “3-prong”) and B(τ → “5-prong”) are −0.978 and −0.082 respectively.
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