Timeline for What prevents this third-order QED scattering from having a non-zero amplitude?
Current License: CC BY-SA 3.0
15 events
| when toggle format | what | by | license | comment | |
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| May 2, 2020 at 9:43 | comment | added | Alex Zeffertt | It was a mistake. I've just checked and he issued an errata doc! | |
| May 2, 2020 at 9:38 | comment | added | Alex Zeffertt | Hi Bass. Are you reading Student Friendly Quantum Field Theory by Klauber? On page 256 he says the Dyson term " $S^{(3)}$ plays no role in QED and can be ignored". I couldn't see why either and was confused. Having read the answers to your question I wonder if this is just a mistake in the book. | |
| S Jan 3, 2018 at 0:10 | history | bounty ended | knzhou | ||
| S Jan 3, 2018 at 0:10 | history | notice removed | knzhou | ||
| Jan 2, 2018 at 23:04 | answer | added | Cosmas Zachos | timeline score: 6 | |
| S Dec 29, 2017 at 1:08 | history | bounty started | knzhou | ||
| S Dec 29, 2017 at 1:08 | history | notice added | knzhou | Draw attention | |
| Sep 15, 2017 at 22:30 | history | tweeted | twitter.com/StackPhysics/status/908820463551483904 | ||
| Sep 15, 2017 at 16:07 | comment | added | user154997 | Your s-channel diagram and all the others where the photon is emitted from another leg, as well as all the t-channel diagrams definitively have a non-zero contribution. $e^+e^-\to e^+e^-\gamma$ was quite important to know at LEP (including a $Z^0$ exchange as well a photon), and a great deal of work has been poured into computing the cross-sections. The classic reference is Anthony C. Hearn, P. K. Kuo, and D. R. Yennie. Radiative corrections to an electron-positron scattering experiment. Phys. Rev., 187:1950–1963, Nov 1969. | |
| Jan 18, 2016 at 14:44 | comment | added | Bass | @ACuriousMind In the lecture notes I'm reading, the professor explained that third-order terms vanish (most likely in the sense of "vanish as a sum because of interference"), and he went on to describe some examples of third-order terms that vanish because of off-shell real particles. Let's wait and see, maybe someone knows it for certain. Thanks. | |
| Jan 18, 2016 at 14:32 | comment | added | OON | @ACuriousMind Yeah, that's true. I would still look at its sum with a similar diagram for the same process with not electron but positron radiating. | |
| Jan 18, 2016 at 14:16 | comment | added | ACuriousMind♦ | Bass, why do you think this diagram should vanish? It just looks like an $e^+ +e ^-\to e^+ + e^-$ concatenated with a bremsstrahlung diagram, and neither of those vanish. That the third-order contributions in total vanish doesn't mean the individual diagrams vanish - it might just destructively interfere with another third-order diagram. | |
| Jan 18, 2016 at 14:14 | comment | added | ACuriousMind♦ | @OON: Furry's theorem is usually stated as "diagrams with a fermion loop and an odd number of external photon legs vanish". It's not immediate to see how to apply it to this diagram. | |
| Jan 18, 2016 at 13:59 | comment | added | OON | Do you remember Furry theorem? Note that it works only for the sum of the diagrams not for individual ones. | |
| Jan 18, 2016 at 13:45 | history | asked | Bass | CC BY-SA 3.0 |