Weak mixing angle
Atomic & nuclearMeasured
= 0.223 05(23)
- Value
- 0.223 05
- Standard uncertainty
- 2.3 × 10−4
- Relative uncertainty
- 1.0 × 10−3 (1031 parts per million)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
Plain
LaTeX
Python
# weak mixing angle, CODATA 2022 (NIST)
weak_mixing_angle = 2.2305e-1 # standard uncertainty 0.00023
# SciPy: scipy.constants.physical_constants['weak mixing angle']What it is
A parameter of the electroweak theory that describes how the photon and the Z boson arise as mixtures of two underlying fields. CODATA gives the on-shell value, defined from the W and Z boson masses.
Equations
- on-shell definition
How the value changed, 1998–2022
Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart).
Relative uncertainty
| CODATA | Value (uncertainty) | Relative uncertainty | Change from previous |
|---|---|---|---|
| 2022 | 0.223 05(23) | 1.0 × 10−3 | +0.5 σ of 2018 |
| 2018 | 0.222 90(30) | 1.3 × 10−3 | +0.3 σ of 2014 |
| 2014 | 0.2223(21) | 9.4 × 10−3 | +0.0 σ of 2010 |
| 2010 | 0.2223(21) | 9.4 × 10−3 | −0.4 σ of 2006 |
| 2006 | 0.222 55(56) | 2.5 × 10−3 | +0.5 σ of 2002 |
| 2002 | 0.222 15(76) | 3.4 × 10−3 | −0.1 σ of 1998 |
| 1998 | 0.2224(19) | 8.5 × 10−3 |
“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).