On primordial black holes from rapid turns in two-field models

Abstract We study rapid-turn trajectories in a class of two-field cosmological models, whose scalar manifold is the Poincaré disk. Background solutions multi-field inflation, with field-space exhibiting sharp turns, can seed primordial black hole (PBH) formation. investigate exact hidden symmetry and show that they exhibit kind transient period, needed to induce PBH generation. Furthermore, we relax condition find, certain regime, modified improved behavior Hubble η-parameter, which preserve desired shape turning rate function. Interestingly, describe brief ultra-slow roll phase, followed by long-term slow inflation. It notable occurs near center (not boundary) disk, unlike standard α-attractor case.