Quantum-mechanical interference over macroscopic distances in the system

We argue that the B0B0 state generated in the decay of Y (4S) is well suited for performing tests of Einstein-Podolsky-Rosen correlations, i.e., quantum-mechanical interference effects over macroscopic distances. Using measurements of the ratio R = (# like-sign dilepton events)(# opposite-sign dilepton events) and of the BH-BL mass difference we show that already presently existing data strongly favour the contribution of the interference term to R, as it is required by the rules of quantum mechanics.