Amplitude analysis of the B+→π+ π+ π- decay

Abstract

The results of an amplitude analysis of the charmless three-body decay B[superscript +]→π[superscript +]π[superscript +]π[superscript -], in which CP-violation effects are taken into account, are reported. The analysis is based on a data sample corresponding to an integrated luminosity of 3 fb[superscript -1] of pp collisions recorded with the LHCb detector. The most challenging aspect of the analysis is the description of the behavior of the π[superscript +]π[superscript -] S-wave contribution, which is achieved by using three complementary approaches based on the isobar model, the K-matrix formalism, and a quasi-model-independent procedure. Additional resonant contributions for all three methods are described using a common isobar model, and include the ρ(770)[superscript 0], ω(782) and ρ(1450)[superscript 0] resonances in the π[superscript +]π[superscript -] P-wave, the f[subscript 2](1270) resonance in the π[superscript +]π[superscript -] D-wave, and the ρ[subscript 3](1690)[superscript 0] resonance in the π[superscript +]π[superscript -] F-wave. Significant CP-violation effects are observed in both S- and D-waves, as well as in the interference between the S- and P-waves. The results from all three approaches agree and provide new insight into the dynamics and the origin of CP-violation effects in B[superscript +]→π[superscript +]π[superscript +]π[superscript -] decays.