How to employ $\bar{B}^0_d \to J/ψ(πη,\bar{K}K)$ decays to extract information on $πη$ scattering

Abstract

We demonstrate that dispersion theory allows one to deduce crucial information on $πη$ scattering from the final-state interactions of the light mesons visible in the spectral distributions of the decays $\bar{B}^0_d \to J/ψ(π^0η,K^+K^-,K^0\bar{K}^0)$. Thus high-quality measurements of these differential observables are highly desired. The corresponding rates are predicted to be of the same order of magnitude as those for $\bar{B}^0_d \to J/ψπ^+π^-$ measured recently at LHCb, letting the corresponding measurement appear feasible.

26 pages, 4 figures; v2: discussion extended, new sec. 3 and app. B, as published in JHEP