Kinematical analogy for marginal dyon decay

Abstract

We describe a kinematical analogy for the marginal decay of ¼-BPS dyons in four-dimensional N = 4 string compactifications. In this analogy, the electric and magnetic charges play the role of spatial momenta, the BPS mass plays the role of energy, and ½BPS dyons correspond to massless particles. Using SO(12, 1) "Lorentz" invariance and standard kinematical formulas in particle physics, we provide simple derivations of the curves of marginal stability. We also show how these curves map into the momentum ellipsoid, and propose some applications of this analogy.