Register to reply

Furry's theorem and soft bremsstrahlung

by Einj
Tags: bremsstrahlung, furry, soft, theorem
Share this thread:
Mar11-14, 08:40 AM
P: 321
Hi everyone, I have a doubt which was actually raised by a recent discussion on this forum.
We know that Furry's theorem says that diagrams with an odd number of photon vanish. Roughly the reason behind that is the charge conjugation symmetry, since under such operation the photon field behaves like [itex]A_\mu\to -A_\mu[/itex].

However, I have seen many times the "soft bremsstrahlung" diagram, i.e. e+e- scattering with the emission of an additional photon. This diagram is usually used to deal with infrared divergences in QED. Why doesn't it vanish?

Thank you very much.
Phys.Org News Partner Physics news on
Vibrational motion of a single molecule measured in real time
Researchers demonstrate ultra low-field nuclear magnetic resonance using Earth's magnetic field
Bubbling down: Discovery suggests surprising uses for common bubbles
Mar11-14, 09:34 AM
Sci Advisor
Bill_K's Avatar
P: 4,160
As was said in that thread, Furry's Theorem applies only when an odd number of photons is connected to the same internal fermion loop.
Vanadium 50
Mar11-14, 09:52 AM
Vanadium 50's Avatar
P: 16,317
Let's not discuss this in two places.

Register to reply

Related Discussions
Bremsstrahlung X rays Classical Physics 9
Why does bremsstrahlung happen Advanced Physics Homework 7
Bremsstrahlung in scintillators High Energy, Nuclear, Particle Physics 8
Soft start soft stop for motor Electrical Engineering 1
Furry Limb Could Be Yeti's General Discussion 18