Observation of D+ ? KS0 a0 (980)+ in the Amplitude Analysis of D+ ? KS0 ?+?

We perform for the first time an amplitude analysis of the decay D+?KS0?+? and report the observation of the decay D+?KS0a0(980)+ using 2.93 fb-1 of e+e- collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector. As the only W-annihilation-free decay among D to a0(980) pseudoscalar, D+?KS0a0(980)+ is the ideal decay in extracting the contributions of the W-emission amplitudes involving a0(980) and to study the final-state interactions. The absolute branching fraction of D+?KS0?+? is measured to be (1.27±0.04stat±0.03syst)%. The branching fractions of intermediate processes D+?KS0a0(980)+ with a0(980)+??+? and D+??+K?0?(1430)0 with K?0?(1430)0?KS0? are measured to be (1.33±0.05stat±0.04syst)% and (0.14±0.03stat±0.01syst)%, respectively. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.