Dalitz plot analysis of B0 → D¯ 0πþπ− decays

Abstract

The resonant substructures of B0 → D¯ 0πþπ− decays are studied with the Dalitz plot technique. In this study a data sample corresponding to an integrated luminosity of 3.0 fb−1 of pp collisions collected by the LHCb detector is used. The branching fraction of the B0 → D¯ 0πþπ− decay in the region mðD¯ 0πÞ > 2.1 GeV=c2 is measured to be ð8.46 0.14 0.29 0.40Þ × 10−4, where the first uncertainty is statistical, the second is systematic and the last arises from the normalization channel B0 → Dð2010Þ−πþ. The πþπ− S-wave components are modeled with the isobar and K-matrix formalisms. Results of the Dalitz plot analyses using both models are presented. A resonant structure at mðD¯ 0π−Þ ≈ 2.8 GeV=c2 is confirmed and its spin-parity is determined for the first time as JP ¼ 3−. The branching fraction, mass and width of this structure are determined together with those of the D 0ð2400Þ− and D 2ð2460Þ− resonances. The branching fractions of other B0 → D¯ 0h0 decay components with h0 → πþπ− are also reported. Many of these branching fraction measurements are the most precise to date. The first observation of the decays B0 → D¯ 0f0ð500Þ, B0 → D¯ 0f0ð980Þ, B0 → D¯ 0ρð1450Þ, B0 → D 3ð2760Þ−πþ and the first evidence of B0 → D¯ 0f0ð2020Þ are presented.