First observation and amplitude analysis of the B-→D+K-π- decay

Abstract

Excited charmed mesons are of great theoretical and experimental interest as they allow detailed studies of QCD in an interesting energy regime. Good progress has been achieved in identifying and measuring the parameters of the orbitally excited states, notably from Dalitz plot (DP) analyses of three-body B decays. Relevant examples include the studies of B− → Dþπ−π− [1,2] and B¯ 0 → D0πþπ− [3] decays, which provide information on excited neutral and charged charmed mesons (collectively referred to as D states), respectively. First results on excited charm-strange mesons have also recently been obtained with the DP analysis technique [4-6]. Studies of prompt charm resonance production in eþe− and pp collisions [7,8] have revealed a number of additional high-mass states. Most of these higher-mass states are not yet confirmed by independent analyses, and their spectroscopic identification is unclear. Analyses of resonances produced directly from eþe− and pp collisions do not allow determination of the quantum numbers of the produced states, but can distinguish whether or not they have natural spin parity (i.e. JP in the series 0þ; 1−; 2þ; ). The current experimental knowledge of the neutral D states is summarized in Table I (here and throughout the paper, natural units with ℏ ¼ c ¼ 1 are used). The D 0ð2400Þ0, D1ð2420Þ0, D0 1ð2430Þ0 and D 2ð2460Þ0 mesons are generally understood to be the four orbitally excited (1P) states. The experimental situation as well as the spectroscopic identification of the heavier states is less clear. The B− → DþK−π− decay can be used to study neutral D states. The DþK−π− final state is expected to exhibit resonant structure only in the Dþπ− channel, and unlike the Cabibbo-favored Dþπ−π− final state does not contain any pair of identical particles. This simplifies the analysis of the contributing excited charm states, since partial-wave analysis can be used to help determine the resonances that contribute