The New Collider

[Alex K]

Why does the weight of the higgs particle matter?

It basically fixes the last unknown parameter of the so called Standard Model which is the theory which correctly describes most known physics at the fundamental level, with few exceptions such as dark matter. The precise value is very interesting because it provides information about what kind of undiscovered physics can await at higher scales. The measured value of about 125 GeV for example excludes certain so called supersymmetric scenarios (though not all!) and points to new phenomena at very high energy scales. If the standard model is valid up to very high energy scales, the higgs mass can determine whether the universe is stable or might decay catastrophically. The measured value turns out to be exactly at the boundary where the universe is barely stable.

[Surgenator]

How will smashing table tops together prove anything, except that some people have too much time on their hands and others take things far too literally for comic effect?

Some examples of physics that can be done are in Alex's link. For example, Lorentz invariance, more commonly known as relativity, at higher energies. There are theories that predict that really high energy photons (light) travel slower because they interact with gravity more often.

[polar bear]

So what is your theory on the standard model? Will the new CERN provide better information and possibly more particles? If it does, why would the weight of higgs have any bearing on stability?

[Alex K]

So what is your theory on the standard model? Will the new CERN provide better information and possibly more particles? If it does, why would the weight of higgs have any bearing on stability?

By the new cern I suppose you mean the next runs of the LHC with 13...14 TeV energy instead of 8. Noone knows whether there are new particles to discover in that range, and anyone who has a strong opinion one way or the other is fooling themselves. The standard model is holding up nicely so far. It is theoretically pretty much self-consistent and it is not imperative that new realistically observable particles or forces exist. The main reason to think that it nevertheless gets modified at energy scales possibly accessible to our colliders is that the observed hierarchy between the scale of so called electroweak physics (roughly represented by the masses of the W,Z, Higgs of 80, 91, 125 GeV respectively) and the next highest scale of new particles should not be very large because such hierarchies are mathematically extremely unstable. If there were such a thing as supersymmetry or if it turned out that the higgs were a composite of other particles, this would be avoided. However, it could iust be that the standard model higge mass parameter is finely tuned in this way. Another reason to still hope that supersymmetry exists at more or less accessible scales is that the unification of the weak, strong and hypercharge forces works out very nicely.

Finally, dark matter might have a particle explanation which is detectable at the LHC, and there are hints to be hopeful, but it doesn't have to.

If the standard model is superseded by a more elaborate theory at scales intermediate between current colliders and the planck scale, the instability argument is moot, and it is therefore very speculative. It just bothers me that the measured parameters are exactly on this instability boundary. I can't lose the feeling that this means something...

The technical reason why this hypothetical instability arises is a bit hard to explain. Ill say it like this: the effects of virtual particles could lead to a situation where making new particles actually temporarily lowers the energy. In such a situation the usual vacuum without real particles is not the lowest energy state any more - one lives in the equivalent of an overheated steam vessel which only needs a nucleation center to suddenly change phases from water to gas, and suddenly blows up.

The new run will provide important information even if no new particles are discovered..By measuring the properties of the Higgs more precisely, one can hope to find deviations from standard model predictions. This is an equally profound type of discovery. By measuring other parameters like the mass of the top quark more precisely, we can evalutate these instability issues more precisely. Last but not least, one can make precision measurements of other known particles to see whether new unseen particles might hide as virtual particles and leave their traces indirectly. There are for example types of decays which do basically not happen if the standard model is correct, and these are great probes to find new particles without really making them.

[polar bear]

I can't lose the feeling that this means something...

What is your gut feeling?

[Alex K]

I can't lose the feeling that this means something...

What is your gut feeling?

My pessimistic gut feeling is that this means that the physics of the Higgs essentially remains unaltered up to scales where this instability arises, roughly 5 orders of magnitude of energy beyond the LHC or more. And that at this scale all kind of magic happens - neutrinos, dark matter, unification. I've written papers on that so maybe i'm biased. If I were correct, this would not mean that there are absolutely no new particles to be discovered, but it severely limits the possibilities. It would also mean that dark matter can be discovered experimentally, but not likely at the LHC.

But really, this is a (well informed) gut feeling, not more. It is impossible to know anything for certain at this point.

[Tonus]

But really, this is a (well informed) gut feeling, not more. It is impossible to know anything for certain at this point.

Oh. Well in that case, I'll just go with "god" as the explanation.

[Alex K]

But really, this is a (well informed) gut feeling, not more. It is impossible to know anything for certain at this point.

Oh. Well in that case, I'll just go with "god" as the explanation.

Good choice, you can't go wrong with that, and as a bonus you don't go to hell.

[vorlon13]

Someday an accelerator is going to produce a turtle, and I am going to jump up and say: AH HA !!!!!

[polar bear]

Seriously about god. Why dont creationist just say god created everything from particles and be done with it? Is there proof to shut them up on that rebuttal?