# What is collinear photons?

1. Jan 27, 2012

### ndung200790

What is collinear photon (emission)?I do not understand why call ''collinear'' photon.
Thank you very much for your kind helping.

2. Jan 28, 2012

### mathman

I am not sure of the the context of your question. If you are asking about stimulated emission (lasers), then the stimulated photon goes in the same direction (reinforces) the stimulating photon, so they are collinear.

3. Jan 29, 2012

### ndung200790

In this case,the photons related with the p$^{+}$,
p$^{-}$ and p$_{\bot}$ .

4. Jan 29, 2012

### mathman

Could you define these symbols?

5. Jan 30, 2012

### ndung200790

Thank you very much for your kind heart.Now I have realized the singularities because ''collinear'' photon meaning scattered angle of photon equal pi in QED at very high energy.