Mechanical structure of the pion and nucleon

Mechanical or gravitational form factors—which can be inferred by hard exclusive 2→3 reactions such as deeply virtual Compton scattering—encode the way that energy, momentum and spin are distributed in a hadron, and how they flow through it. The momentum flux densities in particular are commonly interpreted as characterizing mechanical stresses (such as pressure, tension and shear), and through the Cauchy momentum equation they provide a means of mapping out the force felt by sub-components of a composite system. In this talk, I discuss the basic formalism of mechanical form factors—including their definition and how to convert them into densities through Fourier transforms—and the rationale behind the mechanical stress interpretation of them. I also show how de Broglie-Bohm pilot wave theory can be used to draw a sharper image of how these stresses operate.