I have tried contacting you thru email. I tried twice to post questions about NoNonsense QFT at your nononsense website. Never heard back so posting here
I am a senior citizen self teaching myself QFT. I may also have emailed to another email address that may or may not be yours.
Page 383 - equation 9.14 assumes the integral over the free hamiltonian commutes with the integral over the interaction hamiltonian. Does that hold for the interactions your books discusses ? If they dont commute the derivations that follow are suspect.
However, if we define the interaction Hamiltonian to only use the solution from the free lagrangian, then I think 9.14 is OK, and that is what your book seems to be doing based on say (9.52) , (9.53), (9.54)
If you look at "QFT for the Gifted Amateur" his discussion is not clear. Consider his (18.15) and page 168 where he defines "H sub I". It appears his formula 18.15 differs from yours since his includes products with exponentials of "H sub naught". Yet he uses his 18.15 exactly like you eventually use your modified (9.19) !!!!
Consider your (5.15) that solves the free KG equation (5.4). Would (5.15) solve (6.26) ? If not , something seems fishy using (5.15) the way your book and "QFT for the Gifted Amateur" does.
Something does not seem quite right to me, even after spending days trying to figure this out.
Do you know of a book that maybe explains the Interaction picture in more detail ? Tong's QFT, QFT for the Gifted Amateur, web searchs did not help me out. I dont have Klauber - does he explain it in detail ?
Any thoughts will be greatly appreciated.
I need to complement your heroic effort with your books. Excellent job.
Mighty social forces, not in the least in science itself, block progress. Egotistical goals are the cause.
Thanks for pointing it out with convincing data. 💯
I have tried contacting you thru email. I tried twice to post questions about NoNonsense QFT at your nononsense website. Never heard back so posting here
I am a senior citizen self teaching myself QFT. I may also have emailed to another email address that may or may not be yours.
Page 383 - equation 9.14 assumes the integral over the free hamiltonian commutes with the integral over the interaction hamiltonian. Does that hold for the interactions your books discusses ? If they dont commute the derivations that follow are suspect.
However, if we define the interaction Hamiltonian to only use the solution from the free lagrangian, then I think 9.14 is OK, and that is what your book seems to be doing based on say (9.52) , (9.53), (9.54)
If you look at "QFT for the Gifted Amateur" his discussion is not clear. Consider his (18.15) and page 168 where he defines "H sub I". It appears his formula 18.15 differs from yours since his includes products with exponentials of "H sub naught". Yet he uses his 18.15 exactly like you eventually use your modified (9.19) !!!!
Consider your (5.15) that solves the free KG equation (5.4). Would (5.15) solve (6.26) ? If not , something seems fishy using (5.15) the way your book and "QFT for the Gifted Amateur" does.
Something does not seem quite right to me, even after spending days trying to figure this out.
Do you know of a book that maybe explains the Interaction picture in more detail ? Tong's QFT, QFT for the Gifted Amateur, web searchs did not help me out. I dont have Klauber - does he explain it in detail ?
Any thoughts will be greatly appreciated.
I need to complement your heroic effort with your books. Excellent job.
Best Wishs and Success