I wish I could understand this comment on Slashdot
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If you assume no Higgs then you end up with a Lagrangian without any mass terms (because if you put those in you break the local gauge symmetries). However when you do the calculation of e.g. e+e- --> W+W- you have to use the fact that the electron has a mass in the Feynman calculation. This non-zero mass causes you you have a "left over" term which does not cancel in the high energy limit and causes you to break unitarity.
The Higgs mechanism gets around this by adding a new diagram e+e- --> H --> W+W- which precisely cancels the electron mass term. The reason the cancellation is perfect is because the electron gets its mass from coupling to the non-zero Higgs vacuum expectation value.
So effectively you are correct in that the reason the model fails at high energy is because you use the electron mass in the cross-section calculation but have no electron mass term in the Lagrangian so you are not being consistent....but you cannot simply stick a mass term in there without adding symmetry breaking interactions which are not observed in nature. Hence you have to add a Higgs field with a non-zero vacuum expectation value which in turn adds more than just the effective mass terms.
Hope that is comprehensible - it is hard to explain in just typed text!
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by Roger W Moore
I think I need to recap some of my physics learnings books for that.....
