推 sunev:peskin ? 10/12 12:27
→ chungweitw:1. Check Representation theory of the Lorentz group 10/12 14:07
→ chungweitw:on wikipedia : The Lorentz group has no unitary 10/12 14:08
→ chungweitw:representation of finite dimension, except for the 10/12 14:08
→ chungweitw:trivial representation (where every group element 10/12 14:08
→ chungweitw: is represented by 1). 10/12 14:08
→ chungweitw:2. We can find a faithful representation of Lorentz 10/12 14:10
→ chungweitw:group which is non-unitary. 10/12 14:10
→ chungweitw:If ψ is a wavefunction, the transformation should 10/12 14:10
→ chungweitw:be unitary as you might have learned in QM. 10/12 14:11
→ chungweitw:However, ψ should be considered as a field here.. 10/12 14:11
→ chungweitw:so it's fine if it's not unitary.. 10/12 14:11
→ chungweitw:I will focus on the word "unitary". 10/12 14:15
→ Lanjaja:非常感謝您的解答 我會有坡函數的問題是因為在相對論量子 10/13 08:13
→ Lanjaja:力學的書本上 討論Lorentz covariance of Dirac equation 10/13 08:14
→ Lanjaja:確實boost的generator是non-unitary 所以才推廣r_0(S+)r_0 10/13 08:17
→ Lanjaja:=S^(-1) 所以才引進Ψ-bar解決QM的守恆量問題 而Ψ(x)始終 10/13 08:21
→ Lanjaja:都是波函數 所以我才會疑惑為何波函數在這裡不行? 在相對 10/13 08:22
→ Lanjaja:論量子力學就沒有這種問題? 10/13 08:22
→ chungweitw:但是 (psi+)psi 無法解釋為 density 啊 ( 非 unitary 10/14 00:13
→ chungweitw:transformation ) 10/14 00:13
→ chungweitw:可知不能再把 psi 視為波函數 10/14 00:14
→ chungweitw:(psi+)psi 對應到的應該是粒子數. 方程式不再是單粒子 10/14 00:17
→ chungweitw:波函數方程式. 而是場方程式 10/14 00:17
→ Lanjaja:嗯 謝謝 我不知道到底應不應該直接跳過相對論量子力學 因 10/14 14:14
→ Lanjaja:為就是相對論量子力學出了一些問題 才有量子場論 10/14 14:14
推 xgcj:場論都會說到的 10/15 05:42