Dynamical suppression of the spin–orbit interaction in hadrons

Spin–dependent interaction in hadrons is considered in the approach of the QCD string. The string moment of inertia, which ensures the correct (inverse) Regge slope $2\pi\sigma$, is found to suppress the spin–orbit interaction. For light quarks and moderate angular momenta the suppression constitutes around 25% whereas for large angular momenta the spin–orbit interaction is suppressed by the factor $L^{-2/5}$. For heavy quarks the effect manifests itself as a string correction for the spin-dependent potential.