Timeline for Why does non-relativistic QFT necessarily conserve particle number?
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 18, 2021 at 4:11 | comment | added | anna v | @Quantumwhisp I think that the OP means "particle physics QFT" in the title. | |
| Dec 17, 2021 at 10:52 | comment | added | Quantumwhisp | @Codename47 I misread the section on quasiparticles in the initial question. But in general for a qft, there isn't a distinction between quasiparticles and particles, no? | |
| Dec 16, 2021 at 23:18 | comment | added | Codename 47 | @Quantumwhisp Phonons are quasiparticles, not fundamental particles. | |
| Dec 16, 2021 at 15:10 | comment | added | Quantumwhisp | What about the "creation" of phonons? | |
| Dec 16, 2021 at 15:02 | comment | added | Alex Gower | Yeah you're answer makes perfect sense. I think I assumed he meant that if you don't include an $mc^2$ term in the Lagrangian, somehow particle nunber must be conserved in the framework. But I think he really meant that, for physical Lagrangians, you obviously need sufficient energy to create new particles | |
| Dec 16, 2021 at 15:01 | vote | accept | Alex Gower | ||
| Dec 16, 2021 at 15:01 | comment | added | Codename 47 | I would say so. As you say, you can always write up terms which are non-conserving, but they just don't describe anything physical. I might suggest asking your lecturer for clarification on what exactly they meant, if that is possible. | |
| Dec 16, 2021 at 14:59 | comment | added | Alex Gower | Okay so its not something intrinsic (somehow) in the framework of a non-relativistic QFT. Its just that when you use the correct (physical) Lagrangian and take the non-relativistic limit, the energies are (by definition of non-relativistic) too small to create new particles? | |
| Dec 16, 2021 at 14:57 | history | answered | Codename 47 | CC BY-SA 4.0 |