Three-Body Hypernuclei in Pionless Effective Field Theory

We calculate the structure of three-body hypernuclei with $S=-1$ using pionless effective field theory at leading order in the isospin $I=0$ and $I=1$ sectors. In both sectors, three-body hypernuclei arise naturally from the Efimov effect and a three-body parameter is required at leading order. We apply our theory to the hypertriton and the hypothetical $\Lambda nn$ bound state and calculate the corresponding scaling factors. Moreover, we discuss constraints on the existence of the $\Lambda nn$ bound state. In particular, we elucidate universal correlations between different observables and provide explicit calculations of wave functions and matter radii.