# ${{\boldsymbol \tau}}$ MASS INSPIRE search

VALUE (MeV) EVTS DOCUMENT ID TECN  COMMENT
$\bf{ 1776.86 \pm0.12}$ OUR AVERAGE
$1776.91$ $\pm0.12$ ${}^{+0.10}_{-0.13}$ 1171 1
 2014 D
BES3 23.3 pb${}^{-1}$, ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $3.54 - 3.60$ GeV
$1776.68$ $\pm0.12$ $\pm0.41$ 682k 2
 2009 AK
BABR 423 fb${}^{-1}$, ${\it{}E}^{\it{}ee}_{\rm{}cm}$=10.6 GeV
$1776.81$ ${}^{+0.25}_{-0.23}$ $\pm0.15$ 81
 2007
KEDR 6.7 pb${}^{-1}$, ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $3.54 - 3.78~$GeV
$1776.61$ $\pm0.13$ $\pm0.35$ 2
 2007
BELL 414 fb${}^{-1}{\it{}E}^{\it{}ee}_{\rm{}cm}$=10.6 GeV
$1775.1$ $\pm1.6$ $\pm1.0$ 13.3k 3
 2000 A
OPAL $1990 - 1995$ LEP runs
$1778.2$ $\pm0.8$ $\pm1.2$
 1997
CLEO ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $10.6$ GeV
$1776.96$ ${}^{+0.18}_{-0.21}$ ${}^{+0.25}_{-0.17}$ 65 4
 1996
BES ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $3.54 - 3.57$ GeV
$1776.3$ $\pm2.4$ $\pm1.4$ 11k 5
 1992 M
ARG ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $9.4 - 10.6$ GeV
$1783$ ${}^{+3}_{-4}$ 692 6
 1978 B
DLCO ${\it{}E}^{\it{}ee}_{\rm{}cm}$= 3.1$-$7.4 GeV
• • • We do not use the following data for averages, fits, limits, etc. • • •
$1777.8$ $\pm0.7$ $\pm1.7$ 35k 7
 1993
CLEO Repl. by ANASTASSOV 1997
$1776.9$ ${}^{+0.4}_{-0.5}$ $\pm0.2$ 14 8
 1992
BES Repl. by BAI 1996
1  ABLIKIM 2014D fit ${\mathit \sigma (}$ ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \tau}^{+}}{{\mathit \tau}^{-}}{)}$ at different energies near threshold.
2  AUBERT 2009AK and BELOUS 2007 fit $\tau$ pseudomass spectrum in ${{\mathit \tau}}$ $\rightarrow$ ${{\mathit \pi}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \nu}_{{\tau}}}$ decays. Result assumes ${\mathit m}_{{{\mathit \nu}_{{\tau}}}}$ = 0.
3  ABBIENDI 2000A fit ${{\mathit \tau}}$ pseudomass spectrum in ${{\mathit \tau}}$ $\rightarrow$ ${{\mathit \pi}^{\pm}}{}\leq{}2{{\mathit \pi}^{0}}{{\mathit \nu}_{{\tau}}}$ and ${{\mathit \tau}}$ $\rightarrow$ ${{\mathit \pi}^{\pm}}$ ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{}\leq{}1{{\mathit \pi}^{0}}{{\mathit \nu}_{{\tau}}}$ decays. Result assumes ${\mathit m}_{{{\mathit \nu}_{{\tau}}}}$=0.
4  BAI 1996 fit $\sigma\mathrm {( {{\mathit e}^{+}} {{\mathit e}^{-}} \rightarrow {{\mathit \tau}^{+}} {{\mathit \tau}^{-}} )}$ at different energies near threshold.
5  ALBRECHT 1992M fit ${{\mathit \tau}}$ pseudomass spectrum in ${{\mathit \tau}^{-}}$ $\rightarrow$ 2 ${{\mathit \pi}^{-}}{{\mathit \pi}^{+}}{{\mathit \nu}_{{\tau}}}$ decays. Result assumes ${\mathit m}_{{{\mathit \nu}_{{\tau}}}}$=0.
6  BACINO 1978B value comes from ${{\mathit e}^{\pm}}{{\mathit X}^{\mp}}$ threshold. Published mass 1782 MeV increased by 1 MeV using the high precision ${{\mathit \psi}{(2S)}}$ mass measurement of ZHOLENTZ 1980 to eliminate the absolute SPEAR energy calibration uncertainty.
7  BALEST 1993 fit spectra of minimum kinematically allowed ${{\mathit \tau}}$ mass in events of the type ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \tau}^{+}}{{\mathit \tau}^{-}}$ $\rightarrow$ (${{\mathit \pi}^{+}}{{\mathit n}}{{\mathit \pi}^{0}}{{\mathit \nu}_{{\tau}}}$ )(${{\mathit \pi}^{-}}{{\mathit m}}{{\mathit \pi}^{0}}{{\mathit \nu}_{{\tau}}}$ ) $\mathit n{}\leq{}$2, $\mathit m{}\leq{}$2, 1${}\leq{}\mathit n+\mathit m{}\leq{}$3. If ${\mathit m}_{{{\mathit \nu}_{{\tau}}}}{}\not=$0, result increases by (${{\mathit m}^{2}}_{{{\mathit \nu}_{{\tau}}}}$/1100 MeV).
8  BAI 1992 fit $\sigma\mathrm {( {{\mathit e}^{+}} {{\mathit e}^{-}} \rightarrow {{\mathit \tau}^{+}} {{\mathit \tau}^{-}} )}$ near threshold using ${{\mathit e}}{{\mathit \mu}}$ events.
References:
 ABLIKIM 2014D
PR D90 012001 Precision Measurement of the Mass of the ${{\mathit \tau}}$ Lepton
 AUBERT 2009AK
PR D80 092005 Measurements of the ${{\mathit \tau}}$ Mass and the Mass Difference of the ${{\mathit \tau}^{+}}$ and ${{\mathit \tau}^{-}}$ at BABAR
 ANASHIN 2007
JETPL 85 347 New Precise Determination of the ${{\mathit \tau}}$ Lepton Mass at KEDR Detector
 BELOUS 2007
PRL 99 011801 Measurement of the ${{\mathit \tau}}$ Lepton Mass and an Upper Limit on the Mass Difference between ${{\mathit \tau}^{+}}$ and ${{\mathit \tau}^{-}}$
 ABBIENDI 2000A
PL B492 23 A Measurement of the ${{\mathit \tau}}$ Mass and First $\mathit CPT$ Test with ${{\mathit \tau}}$ Leptons
 ANASTASSOV 1997
PR D55 2559 Experimental Test of Lepton Universality in ${{\mathit \tau}}$ Decay
 BAI 1996
PR D53 20 Measurement of the Mass of the ${{\mathit \tau}}$ Lepton
 BALEST 1993
PR D47 3671 A Measurement of the ${{\mathit \tau}}$ Lepton Mass
 ALBRECHT 1992M
PL B292 221 A Measurement of the ${{\mathit \tau}}$ Mass
 BAI 1992
PRL 69 3021 Measurement of the Mass of the ${{\mathit \tau}}$ Lepton
 BACINO 1978B
PRL 41 13 Measurement of the Threshold Behaviour of ${{\mathit \tau}^{+}}{{\mathit \tau}^{-}}$ Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation