Electromagnetic fundamental physical constant \(\mu _{\rm{N}}=\frac{m_{\rm{e}}}{m_{\rm{p}}}\ \mu _{\rm{B}}=5.050\ 7866(17)\times 10^{-27}\ \rm{J T}^{-1}\), where \(m_{\rm{e}}\) is the electron rest mass, \(m_{\rm{p}}\) the proton rest mass and \(\mu _{\rm{B}}\) the Bohr magneton.