Quote:
Originally Posted by sjastro
Rob and Craig,
The problem with a low Higgs boson mass is that it can create fine tuning problems.
It's difficult to explain without going into some very deep theory but one of the principles of Quantum field theory (QFT) is to define and sum all the momentum changes as a particle goes from an initial quantum state to a final quantum state. This can lead to divergences (the UV catastrophe) where the summed momentums become infinite.
To avoid such infinities the theory needs to be renormalizable.
Quantum electrodynamics and Quantum chromodynamics are examples of renormalizable theories.
Quantum gravity is not renormalizable which is why no one has been able to unify gravity to the other forces.
A problem with a low Higgs mass is that renormalization can add mass to the Higgs boson. To avoid this the theory needs to be very finely tuned.
If SUSY exists then the problem goes away as the infinite terms are cancelled out.
Unfortunately technical papers describing this issue are very complicated and require a knowledge of the mathematical aspects of QFT.
This is one of the "simpler" explanations (warning high maths content). 
http://www.weizmann.ac.il/particle/n...e/chapter1.pdf
Regards
Steven |
Steven, thanks for the info.
I actually get some of that. Renormalization is used to remove infinities and make the theory conform to reality. A low Higgs mass is more sensitive to renormalization. I don't pretend to know how they derived those equations but I understand how the function can diverge to infinity.
So, are you saying with SUSY that renormalisation isn't needed?
Regards, Rob