Fast and rigorous constraints on chiral three-nucleon forces from few-body observables*

We explore the constraints on the three-nucleon force (3NF) of chiral effective field theory (ChiEFT) that are  provided by bound-state observables in the A=3 and A=4 sectors. Our statistically rigorous analysis incorporates experimental error, computational method uncertainty, and the uncertainty due to truncation of the ChiEFT expansion at next-to-next-to-leading order. A consistent solution for the 3H binding energy, the 4He binding energy and radius, and the 3H beta-decay rate can only be obtained if ChiEFT truncation errors are included in the analysis. All of these except the beta-decay rate give essentially degenerate constraints on the 3NF low-energy constants, so this observable is crucial for estimating these parameters. We use eigenvector continuation for fast and accurate emulation of No-Core Shell Model calculations of the few-nucleon observables. This facilitates sampling of the posterior probability distribution, allowing us to also determine the distributions of the parameters that quantify the truncation error. We find a ChiEFT expansion parameter of Q=0.33 +/- 0.06 for these observables.