[問題] Perturbative approach in QFT
這學期修了condensed matter field theory,參考書是Altland & Simons那本(3rd editi
on)。
前面的path integral, field integral都還算能理解,但跟到第四章perturbation theory
就開始不知道在幹嘛了,有人能解釋最基本的架構嗎?
還有,假設phi^4 theory中的coupling constant是g。當我們說"expand the path integra
l for partition function up to second order in g" 是什麼意思呢?
圖中(4.16)是用Wick's theorem得到的,但我也看不太懂怎麼出來的.....
還請各位指點迷津,
https://i.imgur.com/51jES0G.png
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