  In an entanglement swapping process two initially uncorrelated qubits become
entangled, without any direct interaction. We present a model using local
variables aiming at reproducing this remarkable process, under the realistic
assumption of finite detection efficiencies. The model assumes that the local
variables describing the two qubits are initially completely uncorrelated.
Nevertheless, we show that once conditioned on the Bell measurement result, the
local variables bear enough correlation to simulate quantum measurement results
with correlation very close to the quantum prediction. When only a partial Bell
measurement is simulated, as carried out is all experiments so far, then the
model recovers analytically the quantum prediction.
