CarlB said:
The Connection Between Spin and Statistics
W. Pauli Princeton, New Jersey (Received August 19, 1940)
Amazingly, I now see that Pauli comes up here with the Feynman propagator
for the KG equation (18) in position space, in 1940(!) after first presenting the
causal Klein Gordon propagator (15).
He then goes on to dismiss it with the words:
"Theories which would make use of the D1 function in their quantization
would be very much different from the known theories in their consequences."
This because of the propagation outside the light cone...
Regards, Hans
PS:
D = Klein Gordon Causal propagator in 4d position space
F = Klein Gordon Causal propagator in 2d position space
D1 = Feynman KG propagator in 4d position space
F1 = Feynman KG propagator in 2d position space
PPS: The domains (x0>r) etcetera are mixed up in (18)