# Why do we need to build photon colliders? Since electron-position colliders are very “clean”

What's the advantage of gamma-gamma colliders? What new physics can be done with it?

• Details, please. The article would seem to answer your questions. Why doesn't it? Include this explanation in your question. – WhatRoughBeast Mar 30 '16 at 2:02
• The academic papers may be too hard to understand, and only focus on a specific area. So I want to learn more. I hope someone can give a more general and easier to understand answer. – Ballistics Mar 30 '16 at 3:04

The strongest physics quest for a $\gamma\gamma$ collider is the production of Higgs bosons as the only particle in the final state, from a very well known initial state.
If the diphoton signal at $750~$GeV observed in the 2015 run of the LHC is confirmed, it would be a very strong push, although reaching that energy with a $\gamma\gamma$ collider is... let's say expensive!
• How can be the production of Higgs bosons in $\gamma\gamma$ colliders direct, if photons don't couple with the Higgs? – Bosoneando Jul 19 '16 at 23:54
• @DarioP exactly my point. The Feynman diagram for gluon fusion (which is the dominant mode at LHC) is exactly the same as the Feynman diagram for the photon fusion that you propose. By the way, in a $e^+e⁻$ collider, Higgs bosons are produced in simpler processes with no loops. See for example fig 2.6 in arxiv.org/abs/1306.6352v1 – Bosoneando Jul 20 '16 at 7:42