Abstract
By using 6.32 fb−1 of data collected with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, we perform an amplitude analysis of the decay {D}_s^{+}to {K}_S^0{pi}^{+}{pi}^0 and determine the relative fractions and phase differences of different intermediate processes, which include {K}_S^0rho (770)+, {K}_S^0rho (1450)+, K*(892)0π+, K*(892)+π0, and K*(1410)0π+. With the detection efficiency based on the amplitude analysis results, the absolute branching fraction is measured to be mathrm{mathcal{B}}left({D}_s^{+}to {K}_S^0{pi}^{+}pi 0right)=left(5.43pm {0.30}_{mathrm{stat}}pm {0.15}_{mathrm{syst}}right)times {10}^{-3} .
Highlights
In order to ensure that all candidates fall within the phase-space boundary, the constraint of the signal Ds+ mass is added to the kinematic fit and the updated four-momenta are used for the amplitude analysis
An amplitude analysis has been performed for the decay Ds+ → KS0 π+π0
The results for the fit fractions (FFs) and phases among the different intermediate processes are listed in table 4
Summary
The BESIII detector is a magnetic spectrometer [10, 11] located at the Beijing Electron Positron Collider (BEPCII) [12]. The EMC measures photon energies with a resolution of 2.5% (5%) at 1 GeV in the barrel (end-cap) region. The time resolution of the TOF barrel part is 68 ps, while that of the end-cap part is 110 ps. The end-cap TOF was upgraded in 2015 with multi-gap resistive plate chamber technology, providing a time resolution of 60 ps [13,14,15]. The simulation includes the beam-energy spread and initial-state radiation (ISR) in e+e− annihilations modeled with the generator kkmc [18]. The generic MC samples consist of the production of DDpairs with consideration of quantum coherence for all neutral D modes, the non-DDdecays of the ψ(3770), the ISR production of the J/ψ and ψ(3686) states, and the continuum processes. Final-state radiation from charged particles is incorporated with the photos [23] package
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