Recent spectroscopy studies at Belle

The analyses of states with double $cs$ content and the search for exotics have recently gained much attention. The Belle experiment collected roughly 1 ab⁻¹ integrated luminosity data. While Belle II data-taking is in progress, we have performed a new search for exotic states and cross-section measurements with the full Belle data sets. Here we review the recent analysis of: (a) e⁺e⁻→ Dₛ(*)++DsJ⁻ + $c.c$. from both Υ(2S) decays and continuum production at 10.52 GeV, using the Belle detector at KEKB; (b) the analysis of e⁺e⁻ → ηc J/ψ + $c.c.$ and search for double charmonium states; (c) the study of e⁺e⁻ → Dₛ⁺Dₛ₀(2317)⁻ + $c.c.$ and e⁺e⁻ → Dₛ⁺Dₛ₁(2460)⁻ + $c.c.$ + anything else, in the continuum. Born cross-sections are evaluated, and a possible confirmation of the states seen in the invariant mass system of J/ψφ by LHCb in B decays has been investigated.