#### Limit on ${{\mathit W}_{{L}}}-{{\mathit W}_{{R}}}$ Mixing Angle $\zeta$

Lighter mass eigenstate ${{\mathit W}_{{1}}}$ = ${{\mathit W}_{{L}}}$ cos $\zeta −{{\mathit W}_{{R}}}$ sin$\zeta$. Light ${{\mathit \nu}_{{R}}}$ assumed unless noted. Values in brackets are from cosmological and astrophysical considerations.
VALUE CL% DOCUMENT ID TECN  COMMENT
• • We do not use the following data for averages, fits, limits, etc. • •
$-0.020\text{ to }0.017$ 90
 2011
TWST ${{\mathit \mu}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \nu}}{{\overline{\mathit \nu}}}$
$<0.022$ 90
 2008
TWST ${{\mathit \mu}}$ $\rightarrow$ ${{\mathit e}}{{\mathit \nu}}{{\overline{\mathit \nu}}}$
$<0.12$ 95 1
 1999 D
OPAL ${{\mathit \tau}}$ decay
$<0.013$ 90 2
 1999
RVUE Electroweak
$<0.0333$ 3
 1997
RVUE ${{\mathit \mu}}$ decay
$<0.04$ 90 4
 1992
CCFR ${{\mathit \nu}}{{\mathit N}}$ scattering
$-0.0006\text{ to }0.0028$ 90 5
 1991
RVUE
$\text{[none 0.00001 - 0.02]}$ 6
 1989 B
ASTR SN 1987A
$<0.040$ 90 7
 1986
ELEC ${{\mathit \mu}}$ decay
$-0.056\text{ to }0.040$ 90 7
 1986
ELEC ${{\mathit \mu}}$ decay
 1 ACKERSTAFF 1999D limit is from ${{\mathit \tau}}$ decay parameters.
 2 CZAKON 1999 perform a simultaneous fit to charged and neutral sectors.
 3 The quoted limit is from ${{\mathit \mu}}$ decay parameters. BARENBOIM 1997 also evaluate limit from ${{\mathit K}_{{L}}}-{{\mathit K}_{{S}}}$ mass difference.
 4 MISHRA 1992 limit is from the absence of extra large-$\mathit x$, large-$\mathit y$ ${{\overline{\mathit \nu}}_{{\mu}}}$ ${{\mathit N}}$ $\rightarrow$ ${{\overline{\mathit \nu}}_{{\mu}}}$ X events at Tevatron, assuming left-handed ${{\mathit \nu}}$ and right-handed ${{\overline{\mathit \nu}}}$ in the neutrino beam. The result gives $\zeta {}^{2}(1−2{{\mathit m}^{2}}_{{{\mathit W}_{{1}}}}/{{\mathit m}^{2}}_{{{\mathit W}_{{2}}}})<0.0015$. The limit is independent of ${{\mathit \nu}_{{R}}}$ mass.
 5 AQUINO 1991 limits obtained from neutron lifetime and asymmetries together with unitarity of the CKM matrix. Manifest left-right asymmetry is assumed.
 6 BARBIERI 1989B limit holds for ${\mathit m}_{{{\mathit \nu}_{{R}}}}{}\leq{}$10 MeV.
 7 First JODIDIO 1986 result assumes ${\mathit m}_{{{\mathit W}_{{R}}}}=\infty{}$, second is for unconstrained ${\mathit m}_{{{\mathit W}_{{R}}}}$.
References:
 BUENO 2011
PR D84 032005 Precise Measurement of Parity Violation in Polarized Muon Decay
 Also
PR D85 039908 (errat.) Publisher's Note BUENO 2011 : Precise Measurement of Parity Violation in Polarized Muon Decay [Phys. Rev. D 84, 032005 (2011)]
 MACDONALD 2008
PR D78 032010 Precision Measurement of the Muon Decay Parameters ${{\mathit \rho}}$ and ${{\mathit \delta}}$
 ACKERSTAFF 1999D
EPJ C8 3 Measurement of the Michel Parameters in Leptonic ${{\mathit \tau}}$ Decays
 CZAKON 1999
PL B458 355 Low-Energy Physics and Left-Right Symmetry: Bounds on the Model Parameters
 BARENBOIM 1997
PR D55 4213 Constraints on the W$_{R}$ Mass and $\mathit CP$ Violation in Left $−$ Right Models
 MISHRA 1992
PRL 68 3499 Search for Right Handed Coupling in ${{\mathit \nu}}$ ${{\mathit n}}$ Scattering
 AQUINO 1991
PL B261 280 Bounds on Manifest Left-Right Symmetry from Neutron $\beta$ Decay
 BARBIERI 1989B
PR D39 1229 Limits on Righthanded Interactions from SN1987a Observations
 JODIDIO 1986
PR D34 1967 Search for Right Handed Currents in Muon Decay
 Also
PR D37 237 (erratum) Search for Right Handed Currents in Muon Decay