Magnetic Susceptibility of Down Quarks

We can find analytic solutions for some parameters in terms of electron, muon and proton characteristics such as the mass $m$ and the magnetic moment $\mu$. This is done by writing out $\mu$ in terms of magnetic susceptibilities $\chi_{\it{m}}$ and then solving the resulting equations to obtain

\begin{align} \chi_{\it{m}}(\sf{d}) = \chi_{\it{m}}(\sf{b}) - \chi_{\it{m}}(\sf{t}) + \left( \frac{\mathrm{2} \pi \, \mu_{\sf{N}} }{\it{ h e}} \right) \, \mu(\sf{p^{+}}) \, \it{m}(\sf{p^{+}}) \end{align}

where $\mu_{\sf{N}}$ is the and $\pi$, $h$ and $e$ are constants.