The mass spectrum of the 𝑃-wave mesons is considered in a non-relativistic constituent quark model. The full Hamiltonian used in the investigation includes the kinetic energy, the confinement potential, the one-gluon-exchange potential (OGEP) and the instanton-induced quark-antiquark interaction (III). A good description of the mass spectrum is obtained. The respective role of III and OGEP in the P-wave meson spectrum is discussed.

We review the recent progress of the theoretical understanding of spin polarizabilities of the hyperon in the framework of $SU$(3) heavy baryon chiral perturbation theory (HBChPT). We present the results of a systematic leading-order calculation of hyperon Compton scattering and extract the forward spin polarizability (𝛾0) of hyperons. The results obtained for $\gamma_0$ in the case of nucleons agree with the known results of $SU$(2) HBChPT when kaon loops are not considered.