分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-11-10
摘要: We present an amplitude analysis of the decay D0 → K−π+π+π− based on a data sample of 2.93 fb−1 acquired by the BESIII detector at the ψ(3770) resonance. With a nearly background free sample of about 16000 events, we investigate the substructure of the decay and determine the relative fractions and the phases among the different intermediate processes. Our amplitude model includes the two-body decays D0 → K¯ ∗0ρ0, D0 → K−a+(1260) and D0 → K−(1270)π+, the three-body decays D0 → K¯ ∗0π+π− and D0 → K−π+ρ0, as well as the four-body nonresonant decay D0 → K−π+π+π−. The dominant intermediate process is D0 → K−a+(1260), accounting for a fit fraction of 54.6%.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-11-10
摘要: Using 448.0 × 106 ψ(3686) events collected with the BESIII detector, an amplitude analysis is performed for ψ(3686) →γχc1, γχc1→ηπ+π− decays. The most dominant two-body structure observed is a0(980)±π∓; a0(980)±→ηπ±. The a0(980) line shape is modeled using a dispersion relation, and a significant nonzero a0(980) coupling to the η′π channel is measured. We observe χc1→a2(1700)π production for the first time, with a significance larger than 17σ. The production of mesons with exotic quantum numbers, JPC = 1−+, is investigated, and upper limits for the branching fractions χc1 →π1(1400)±π∓, χc1→π1(1600)±π∓, and χc1→π1(2015)±π∓, with subsequent π1(X)±→ηπ± decay, are determined.
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: Various new physics models predict a light CP-odd Higgs boson (labeled as aaa) and open up new decay modes for Z-boson, such as Z→f?faZ→f?faZ \to \bar{f} f a, Z→aγZ→aγZ\to a\gamma and Z→aaaZ→aaaZ\to aaa, which could be explored at the GigaZ option of the