W to Z mass ratio
Atomic & nuclearMeasured
= 0.881 45(13)
- Value
- 0.881 45
- Standard uncertainty
- 1.3 × 10−4
- Relative uncertainty
- 1.5 × 10−4 (147 parts per million)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
Plain
LaTeX
Python
# W to Z mass ratio, CODATA 2022 (NIST)
w_to_z_mass_ratio = 8.8145e-1 # standard uncertainty 0.00013
# SciPy: scipy.constants.physical_constants['W to Z mass ratio']What it is
The ratio of the masses of the W and Z bosons, which carry the weak force. It defines the on-shell weak mixing angle.
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 | 0.881 45(13) | 1.5 × 10−4 | −0.5 σ of 2018 |
| 2018 | 0.881 53(17) | 1.9 × 10−4 |
“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).