2025/06/06 by BESIII Collaboration, Ablikim, M., Achasov, M. N. +688
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)
paper · doi:10.48550/arxiv.2506.05761
We report a study of the semileptonic decays D+→ KS0π0ℓ+ν_ℓ (ℓ = e, μ) based on 20.3 fb-1 of e+e- collision data collected at the center-of-mass energy of 3.773 GeV with the BESIII detector. The D+→ KS0π0μ+νμ decay is observed for the first time, with a branching fraction of (0.896±0.017\rm stat±0.008\rm syst)%, and the branching fraction of D+→ KS0π0e+νe is determined with the improved precision as (0.943±0.012\rm stat±0.010\rm syst)%. From the analysis of the dynamics, we observe that the dominant K^∗(892)0 component is accompanied by an S-wave contribution, which accounts for (7.10 ± 0.68\rm stat ± 0.41\rm syst)% of the total decay rate of the μ+ channel and (6.39 ± 0.17\rm stat ± 0.14\rm syst)% of the e+ channel. Assuming a single-pole dominance parameterization, the hadronic form factor ratios are extracted to be rV=V(0)/A1(0)=1.42 ± 0.03\rm stat ± 0.02\rm syst and r2=A2(0)/A1(0)=0.75 ± 0.03\rm stat ± 0.01\rm syst. Based on the first comprehensive angular and the decay-rate CP asymmetry analysis, the full set of averaged angular and CP asymmetry observables are measured as a function of the momentum-transfer squared; they are consistent with expectations from the Standard Model. No evidence for violation of μ-e lepton-flavor universality is observed in either the full range or the five chosen bins of momentum-transfer squared.