Using recent experimental data and lattice calculations of scattering lengths of 𝜋𝜋 scattering and
employing dispersive representation of the amplitude based on Roy equations, we compute the
subthreshold parameters of this process. We use Monte Carlo sampling to numerically model
the probability distribution of the results based on all uncertainties in the inputs. In the second
part of the analysis, employing Bayesian inference, we use the new results for the subthreshold
parameters to obtain preliminary constraints on the leading order low energy constant 𝐵0 in the
context of three-flavour chiral perturbation theory.