Science Constants - Tau Compton Wavelength Symbol: λC,τ Value: 0.69770(11) × 10-15 m Category: - Tau Particle Constants Description: The Compton Wavelength is the wavelength associated with the mass of any particle, given by λ = h / mc, where h is Planck's Constant, m is the mass of the particle and c is the speed of light. The value quoted above is the Compton Wavelength for a tau particle.