Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       particles
         [gauge and Higgs bosons] see [unranked] elementary bosons
           ["axions and other very light bosons" [hypothetical]]
             1 ["axions" [hypothetical]]
             2 ["X0 light boson" [hypothetical] - light boson]
             3 ["Goldstone bosons" [hypothetical]]