Recent content by anklimekruk

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    Deriving equation 3.34 in Lancaster's QFT for the gifted amateur

    Maybe ##E_p## is the Energie in the momentum which replaces ##\hbar w_k## in 2.41.There is no more explanation in the book for as much as I can see. In my eyes it must be the notation for the integral version of the discrete case of eq 2.41.I must of course convince myself that it is...
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    Deriving equation 3.34 in Lancaster's QFT for the gifted amateur

    I wrote the question so that there is no need for the book
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    Deriving equation 3.34 in Lancaster's QFT for the gifted amateur

    I would like to know why my question is left without an answer nor a comment
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    Deriving equation 3.34 in Lancaster's QFT for the gifted amateur

    How to derive the relevant equation ? By comparing it to eq 2.41 in the book: ##\hat H = \sum_{k=1}^N\hbar\omega_k (\hat a\dagger_k\hat a_k + 1/2)## I think 3.34 is the integral version of 2.41
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    Deriving equation 3.34 in Lancaster's QFT for the gifted amateur

    Homework Statement How to derive eq.3.34 in Lancaster's book QFT for the gifted amateur Homework Equations ##\hat H= \int d^3 p E_p\hat a\dagger_p\hat a_p## The Attempt at a Solution Comparing
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    Graduate Uncoupled excitations in frequency space for atomic chains

    I thank you for guiding me further to "homework PF" By the way i am p 35.Thanks to your legitimate critics i made an extra effort and understood by my self the mathematics of the previous pages. I found it relatively easy.So i am surely not as you say "going to keep on like this." I hope to...
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    Graduate Uncoupled excitations in frequency space for atomic chains

    I am just a fascinated selfstudent. I understand your time is precious and I fully respect it! It's also a chalenge to understand things by myself. These are two excellent reasons to do my very best to understand before asking a question. Anyhow i am gratefull to you for all your answers.They...
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    Graduate Uncoupled excitations in frequency space for atomic chains

    I am really doing my best to understand before I ask a question! May I ask if it is necessary to mention each time "QFT for the gifted amateur" Thanks again for helping!
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    Graduate Uncoupled excitations in frequency space for atomic chains

    Thanks! thanks!
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    Graduate Uncoupled excitations in frequency space for atomic chains

    In eq's 3.17 and 3.18 p 33 QFT for the gifted amateur Are the constants of proportionality ##\sqrt (n_i+1) and \sqrt n_i## explained somewhere in the book?
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    Graduate Uncoupled excitations in frequency space for atomic chains

    I want to say that i suppose i am wrong because you don't agree and would very much like to understand why?
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    Graduate Uncoupled excitations in frequency space for atomic chains

    Indeed I see I can trivialy plug in.But then I have a product of ##\rm{p_k}## with ##\rm{p_k}## . Thats why I said "I square 2.63 and plug it in 2.59".And the same for 2.62. In my humble opinion this yields the same result. As for the fact that it is going to get much harder,I don't intend to...
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    Graduate Uncoupled excitations in frequency space for atomic chains

    In QFT for the gifted amateur p 26 I square 2.62 and 2.63 then i plug these values into 2.59 to get 2.64 Is it correct?
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    Graduate Uncoupled excitations in frequency space for atomic chains

    Thanks a lot
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    Graduate Uncoupled excitations in frequency space for atomic chains

    I want to ask if i understand it well: In the first equality the - sign becomes + because it is ##p\tilde\dagger##. In the second equality ##p\dagger## becomes ##p## because ##p## is hermitian and the third equality is definition again. Is it correct?
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