On the Theory of Continuous-Spin Particles: Helicity Correspondence in Radiation and Forces

Understand

We have recently shown that continuous-spin particles (CSPs) have covariant single-emission amplitudes with the requisite properties to mediate long-range forces.

• CSPs, the most general massless particle type consistent with Lorentz symmetry, are characterized by a scale \rho.
• Here, we demonstrate a helicity correspondence at CSP energies larger than \rho, in which these amplitudes are well approximated by the familiar ones for particles of helicity 0, 1, or 2.
• These properties follow from Lorentz invariance.