The dispersion relation of electrons in, for example, graphene exhibits Dirac cones. The dispersion relation of a Dirac point at $\mathbf{k}=\mathbf{K}$ is linear in the momentum magnitude: $$E=\pm v_F |{\bf k-K}|$$ where $v_F$ the Fermi velocity.
The Fermi velocity can be measured directly by ARPES, or by any momentum-resolved spectroscopy. Are there measurable properties of the system which directly depends on the Fermi velocity in graphene, or in other systems where Dirac cones are present?
Addendum: To exemplify my question imagine that you could change in a gedanken experiment the velocity $v_F$ in the equation above, without changing the Fermi level or any other property of the system. Which physical quantities would be affected?
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