Exploiting B-meson decays for Standard Model tests and beyond requires a precise understanding of the strong final-state interactions that can be provided model-independently by means of dispersion theory. This formalism allows one to deduce the universal pion-pion final-state interactions from the accurately known ππ phase shifts and, in the scalar sector, a coupled-channel treatment with the kaon-antikaon system. In this work an analysis of the decays Bˉd0→J/ψπ+π− and Bˉs0→J/ψπ+π− is presented. We find very good agreement with the data up to 1.05 GeV with a number of parameters reduced significantly compared to a phenomenological analysis. In addition, the phases of the amplitudes are correct by construction, a crucial feature when it comes to studies of CP violation in heavy-meson decays.
@article{arxiv.1508.06841,
title = {A model-independent analysis of final-state interactions in \bar B_{d/s}^0 --> J/psi pi pi},
author = {J. T. Daub and C. Hanhart and B. Kubis},
journal= {arXiv preprint arXiv:1508.06841},
year = {2016}
}