Atom in a Decayed / Non-Decayed State

[vanhees71]

Other very nice treatments are

P. Danielewicz, Quantum Theory of Nonequilibrium Processes I, Ann. Phys. 152, 239 (1984),
https://doi.org/10.1016/0003-4916(84)90092-7.

P. Danielewicz, Quantum Theory of Nonequilibrium Processes
II. Application to Nuclear Collisions, Ann. Phys. 152, 305
(1984), https://doi.org/10.1016/0003-4916(84)90093-9.

and for the relativistic case

N. P. Landsmann and C. G. van Weert, Real- and
Imaginary-time Field Theory at Finite Temperature and
Density, Physics Reports 145, 141 (1987),
https://doi.org/10.1016/0370-1573(87)90121-9.

Last but not least there's also a nice treatment in Landau&Lifshitz vol. X.

 

[WernerQH]

Last but not least there's also a nice treatment in Landau&Lifshitz vol. X.

Thanks! I was unaware of the sections in vol. X.

I was somewhat biased against Landau&Lifshitz, because I just hate their discussions of "measurement" in vol. III. :-)
One should really teach quantum theory starting with QFT.

 

[Demystifier]

One should really teach quantum theory starting with QFT.

Or why not teaching whole physics by starting with QFT? In fact, there is a textbook doing exactly that:
https://www.amazon.com/dp/9814579394/?tag=pfamazon01-20