A test of reality using quantum entanglement in J/{psi} to {Λ}bar{Λ}

Quantum mechanics (QM) has been criticized for its violation of locality and reality since it was put forward. A series of hidden variable theories (HVTs) were evolved to ensure reality. In this paper, a new method to distinguish QM and HVTs is proposed. The angle between two decay planes is introduced as the observable and the distribution of it under two conditions is deduced. The feasibility to test it on BESIII experiment is discussed.