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)
ρ(e) PARAMETER
(V −A) theory predicts ρ =0.75.
VALUE EVTS DOCUMENT ID TECN COMMENT
0.747±0.010 OUR FIT
0.744±0.010 OUR AVERAGE
0.747±0.019±0.014 44k HEISTER 01E ALEP 1991–1995 LEP runs
0.744±0.036±0.037 17k ABREU 00L DLPH 1992–1995 runs
0.779±0.047±0.029 25k ACKERSTAFF 99D OPAL 1990–1995 LEP runs
0.68 ±0.04 ±0.07 1 ALBRECHT 98 ARG E ee
cm =9.5–10.6 GeV
0.71 ±0.14 ±0.05 ABE 97O SLD 1993–1995 SLC runs
0.747±0.012±0.004 34k ALEXANDER 97F CLEO E ee cm =10.6 GeV
0.735±0.036±0.020 4.7k 2 ALBRECHT 95 ARG E ee
cm =9.5–10.6 GeV
0.79 ±0.08 ±0.06 3230 3 ALBRECHT 93G ARG E ee
cm =9.4–10.6 GeV
0.64 ±0.06 ±0.07 2753 JANSSEN 89 CBAL E ee cm =9.4–10.6 GeV
0.62 ±0.17 ±0.14 1823 FORD 87B MAC E ee cm =29GeV
0.60 ±0.13 699 BEHRENDS 85 CLEO e + e − near Υ(4S)
0.72 ±0.10 ±0.11 594 BACINO 79B DLCO E ee cm = 3.5–7.4 GeV
•••We do not use the following data for averages, fits, limits, etc. •••
0.732±0.014±0.009 19k AMMAR 97B CLEO Repl. by ALEXAN-
DER 97F
0.793±0.050±0.025 BUSKULIC 95D ALEP Repl. by HEISTER 01E
0.747±0.045±0.028 5106 ALBRECHT 90E ARG Repl. by ALBRECHT 95
1 ALBRECHT 98 use tau pair events of the type τ − τ + → (l − νl ν τ )(π + π 0 ν τ ), and
their charged conjugates.
2 ALBRECHT 95 use tau pair events of the type τ − τ + → (l − νl ν τ )
(h + h − h + (π 0 )ν τ ) and their charged conjugates.
3 ALBRECHT 93G use tau pair events of the type τ − τ + → (μ − νμ ν τ )(e + ν e ν τ )and
their charged conjugates.
ρ(μ) PARAMETER
(V −A) theory predicts ρ =0.75.
VALUE EVTS DOCUMENT ID TECN COMMENT
0.763±0.020 OUR FIT
0.770±0.022 OUR AVERAGE
0.776±0.045±0.019 46k HEISTER 01E ALEP 1991–1995 LEP runs
0.999±0.098±0.045 22k ABREU 00L DLPH 1992–1995 runs
0.777±0.044±0.016 27k ACKERSTAFF 99D OPAL 1990–1995 LEP runs
0.69 ±0.06 ±0.06 1 ALBRECHT 98 ARG E ee
cm =9.5–10.6 GeV
0.54 ±0.28 ±0.14 ABE 97O SLD 1993–1995 SLC runs
0.750±0.017±0.045 22k ALEXANDER 97F CLEO E ee cm =10.6 GeV
0.76 ±0.07 ±0.08 3230 ALBRECHT 93G ARG E ee cm =9.4–10.6 GeV
0.734±0.055±0.027 3041 ALBRECHT 90E ARG E ee cm =9.4–10.6 GeV
0.89 ±0.14 ±0.08 1909 FORD 87B MAC E ee cm =29GeV
0.81 ±0.13 727 BEHRENDS 85 CLEO e + e − near Υ(4S)
•••We do not use the following data for averages, fits, limits, etc. •••
0.747±0.048±0.044 13k AMMAR 97B CLEO Repl. by ALEXAN-
DER 97F
0.693±0.057±0.028 BUSKULIC 95D ALEP Repl. by HEISTER 01E
1 ALBRECHT 98 use tau pair events of the type τ − τ + → (l − νl ν τ )(π + π 0 ν τ ), and
their charged conjugates.
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