What does the author mean here when he says How does a massive particle have a specific chirality? I learned that the only massive single chiral fields are the ones with Majorana mass. Dirac fields are a mix of left-chiral and right chiral fields, they do not have a specific chirality. Is the author thus alluding to Majorana spinors here? Or, which massive fields do have specific chirality? And what do people mean when they say chirality is a Lorentz invariant concept, though it mixes in the Dirac spinors? thanks EDIT: And yes, both Dirac and Majorana spinors break chiral symmetry! Again, how can you say that massive spinors have specific chirality?