Quarks, Baryons And Chiral Symmetry -

The vacuum of QCD is not empty but is filled with a "condensate" of quark-antiquark pairs (

). While the Higgs mechanism gives quarks their current mass, this accounts for only about of a baryon's total mass. The remaining

), the QCD Lagrangian exhibits . This means that "left-handed" and "right-handed" quarks (defined by their helicity) do not interact with one another and can be rotated independently. If this symmetry were preserved in the vacuum, we would expect to see "parity doubles"—pairs of particles with the same mass but opposite parity. However, observations of the particle spectrum, specifically the lack of such doubles for baryons like the proton, indicate that chiral symmetry is spontaneously broken . Spontaneous Symmetry Breaking and Mass Quarks, Baryons and Chiral Symmetry

each. For a baryon, the three constituent quarks together account for the approximately mass of a proton or neutron.

Chiral symmetry explains why the world around us is massive. The transition from near-massless current quarks to the heavy baryons that make up atomic nuclei is a direct consequence of the strong force's ability to break its own fundamental symmetries. The vacuum of QCD is not empty but

). This condensate acts as a medium that resists the motion of quarks, effectively giving them a "constituent mass" of roughly

is generated dynamically through the energy of the strong interaction and the spontaneous breaking of chiral symmetry. Licensed by Google Understanding Chiral Symmetry In the limit where quark masses are negligible ( Spontaneous Symmetry Breaking and Mass each

The interplay between , baryons , and chiral symmetry forms the foundation of Quantum Chromodynamics (QCD), explaining how the visible mass of the universe arises from the strong interaction. The Role of Quarks and Baryons