Polarized $pK^-$ scattering in Unitary Baryon Chiral Perturbation Theory

We study $pK^-$ scattering in the energy range from threshold through the $\Lambda(1520)$ peak in UBChPT, taking into account $\mathcal{O}(q)$ vertices from meson-baryon contact interactions and $s$- and $u$-channel ground-state baryon exchange, $s$- and $u$-channel decuplet- and nonet-baryon exchange and $t$-channel vector-meson exchange, as well as $\mathcal{O}(q^2)$ flavor-breaking vertices. Detailed fits to data are presented, including a substantial body of differential cross-section data with meson momentum $q_\mathrm{lab} > 300$ MeV not considered in previous treatments.