Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Question about time limits of time-dependent perturbation theory

  1. Aug 10, 2010 #1
    I have been using time-dependent perturbation theory for quite a while. Yet, one thing is still not clear to me. I have seen in many books and papers that when they calculate the transition amplitudes, they integrate from 0 to t. While in many other papers and books, the limit is taken to be - infinity to t. Those two limits give completely different results for transition amplitudes and transition probabilities. So which one to use?
  2. jcsd
  3. Aug 10, 2010 #2
    I would expect only 0 to t for the time that the perturbed field is switched on.

    How can you use a transition amplitude based on an infinite amount of time being exposed to the field?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook