Using a 3.19 fb-1 data sample collected at the s=4.178 GeV with the BESIII detector, we search for the rare decay Ds+→ppe+νe. No significant signal is observed, and an upper limit of B(Ds+→ppe+νe)<2.0×10-4 is set at the 90% confidence level. This measurement is useful input in understanding the baryonic transition of Ds+ mesons.
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The BESIII detector is a magnetic spectrometer located at the Beijing Electron Position Collider (BEPCII) . The cylindrical core of the BESIII detector consists of a helium-based multilayer drift chamber (MDC), a plastic scintillator time-of-flight system (TOF), and a CsI (Tl) electromagnetic calorimeter (EMC), which are all enclosed in a superconducting solenoidal magnet providing a 1.0 T magnetic field. The solenoid is supported by an octagonal flux-return yoke with resistive-plate counter muon-identifier modules interleaved with steel. The acceptance of charged particles and photons is 93% over the solid angle. The charged-particle momentum resolution at is 0.5%, and the resolution is 6% for the electrons from Bhabha scattering. 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. The end-cap TOF system was upgraded in 2015 with multigap resistive plate chamber technology, providing a time resolution of 60 ps .
© 2019 authors. Published by the American Physical Society.