Amplitude analysis and branching fraction measurement of D⁺→ π⁺π⁰π⁰

We present the first amplitude analysis of the hadronic decay D⁺ → π⁺π⁰π⁰, using e⁺e⁻ collision data collected with the BESIII detector at a center-of-mass energy of 3.773 GeV, corresponding to an integrated luminosity of 20.3 fb⁻¹. The fit fractions of the intermediate processes are measured, in which the D⁺ → ρ(770)⁺π⁰ component is found to be dominant with a branching fraction of (3.08 ± 0.10_stat. ± 0.07_syst.) × 10⁻³. Based on the amplitude analysis, the branching fraction of D⁺ → π⁺π⁰π⁰ is measured to be (4.84 ± 0.05_stat. ± 0.05_syst.) × 10⁻³. In addition, the CP asymmetries, both for specific amplitudes and integrated over the entire phase space, are measured.