Using e+e- → Λ+cΛ-c production from a 567 pb-1 data sample collected by BESIII at 4.6 GeV, a full angular analysis is carried out simultaneously on the four decay modes of Λ+c → pK0S, Λπ+, Σ+π0, and Σ0π+. For the first time, the Λ+c transverse polarization is studied in unpolarized e+e- collisions, where a nonzero effect is observed with a statistical significance of 2.1σ. The decay asymmetry parameters of the Λ+c weak hadronic decays into pK0S, Λπ+, Σ+π0 and Σ0π+ are measured to be 0.18 ± 0.43(stat) ± 0.14(syst), -0.80 ± 0.11(stat) ± 0.02(syst), -0.57 ± 0.10(stat) ± 0.07(syst), and -0.73 ± 0.17(stat) ± 0.07(syst), respectively. In comparison with previous results, the measurements for the Λπ+ and Σ+π0 modes are consistent but with improved precision, while the parameters for the pK0S and Σ0π+ modes are measured for the first time.
Bibliographical noteFunding Information:
The BESIII collaboration thanks the staff of BEPCII and the IHEP computing center for their strong support. This work is supported in part by National Key Basic Research Program of China under Contract No. 2015CB856700; National Natural Science Foundation of China (NSFC) under Contracts No. 11335008, No. 11425524, No. 11625523, No. 11635010, No. 11735014; the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; the CAS Center for Excellence in Particle Physics (CCEPP); Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts No. U1532257, No. U1532258, No. U1732263; CAS Key Research Program of Frontier Sciences under Contracts No. QYZDJ-SSW-SLH003, No. QYZDJ-SSW-SLH040; 100 Talents Program of CAS; INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology; German Research Foundation DFG under Contract No. Collaborative Research Center CRC 1044, FOR 2359; Istituto Nazionale di Fisica Nucleare, Italy; Koninklijke Nederlandse Akademie van Wetenschappen (KNAW) under Contract No. 530-4CDP03; Ministry of Development of Turkey under Contract No. DPT2006K-120470; National Science and Technology fund; The Swedish Research Council; U.S. Department of Energy under Contracts No. DE-FG02-05ER41374, No. DE-SC-0010118, No. DE-SC-0012069; University of Groningen (RuG); Helmholtzzentrum fuer Schwerionenforschung GmbH (GSI), Darmstadt; the Knut and Alice Wallenberg Foundation (Sweden) under Contract No. 2016.0157 and the Royal Society, UK under Contract No. DH160214.
© 2019 authors.