Birational boundedness of rationally connected Calabi-Yau 3-folds

We prove that rationally connected Calabi-Yau 3-folds with Kawamata log terminal (klt) singularities form a birationally bounded family, or more generally, rationally connected 3 folds of epsilon-CY type form a birationally bounded family for epsilon > 0. Moreover, we show that the set of epsilon-lc log Calabi-Yau pairs (X, B) with coefficients of B bounded away from zero is log bounded modulo flops. As a consequence, we deduce that rationally connected klt Calabi-Yau 3-folds with mld bounded away from 1 are bounded modulo flops. (c) 2020 Elsevier Inc. All rights reserved.