Muon Compton wavelength

$λ_C,μ$ = 1.173 444 110(26) × 10⁻¹⁴ m

Value: 1.173 444 110 × 10⁻¹⁴ m
Standard uncertainty: 2.6 × 10⁻²² m
Relative uncertainty: 2.2 × 10⁻⁸ (22 parts per billion)
Status: Measured
Symbol: $λ_C,μ$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# muon Compton wavelength, CODATA 2022 (NIST)
muon_compton_wavelength = 1.17344411e-14  # m, standard uncertainty 2.6e-22

# SciPy: scipy.constants.physical_constants['muon Compton wavelength']

What it is

The wavelength of a photon whose energy equals the rest energy of the muon, an unstable heavier cousin of the electron (about 207 times its mass) that lives about 2.2 microseconds: h/(mc).

In other units

Unit	Value
CGS (cm)	1.173 444 11 × 10⁻¹²
pm picometre	0.011 734 4411
fm femtometre	11.734 4411

Converted with ConstantID's unit table; digits are rounded to the precision of the value, and a long exact value is rounded only for display. The relative uncertainty is unchanged by conversion to an exactly defined unit.

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	1.173 444 110(26) × 10⁻¹⁴	2.2 × 10⁻⁸	+0.0 σ of 2018
2018	1.173 444 110(26) × 10⁻¹⁴	2.2 × 10⁻⁸	−0.0 σ of 2014
2014	11.734 441 11(26) × 10⁻¹⁵	2.2 × 10⁻⁸	+0.3 σ of 2010
2010	11.734 441 03(30) × 10⁻¹⁵	2.6 × 10⁻⁸	−0.0 σ of 2006
2006	11.734 441 04(30) × 10⁻¹⁵	2.6 × 10⁻⁸	−0.0 σ of 2002
2002	11.734 441 05(30) × 10⁻¹⁵	2.6 × 10⁻⁸	−2.6 σ of 1998
1998	11.734 441 97(35) × 10⁻¹⁵	3.0 × 10⁻⁸

“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).