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¹	ADACHI 2023C, 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.

²	Previously also reported LEVICHEV 2014. Superseedes ANASHIN 2007.

³	ABLIKIM 2014D fit ${\mathit \sigma (}{{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \tau}^{+}}{{\mathit \tau}^{-}}{)}$ at different energies near threshold.

⁴

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.

⁵	BAI 1996 fit $\sigma\mathrm {({{\mathit e}^{+}} {{\mathit e}^{-}} \rightarrow {{\mathit \tau}^{+}} {{\mathit \tau}^{-}})}$ at different energies near threshold.

⁶	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.

⁷	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.

⁸

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).

⁹	BAI 1992 fit $\sigma\mathrm {({{\mathit e}^{+}} {{\mathit e}^{-}} \rightarrow {{\mathit \tau}^{+}} {{\mathit \tau}^{-}})}$ near threshold using ${{\mathit e}}{{\mathit \mu}}$ events.

References

Except where otherwise noted, content of the 2025 Review of Particle Physics is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) license. The publication of the Review of Particle Physics is supported by US DOE, MEXT (Japan), INFN (Italy) and CERN. Individual collaborators receive support for their PDG activities from their respective institutes or funding agencies. © 2025. See LBNL disclaimers.

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