Higgs Boson or just a new particle?

[iamnotbatman]

@Half_Man_Half_Wit

Well, whether or not supersymmetry is sitting well with the current experimental situation depends a little on who you listen to… I think the big problem is that in order for supersymmetry to solve the problems it was originally introduced to solve (most notably, the so-called hierarchy problem) it should really pop up quite soon (some say, it should have been seen already).

It should be noted that it is arguable whether supersymmetry was introduced in order to solve the hierarchy problem. Many people, including myself, think supersymmetry is sufficiently well-motivated even ignoring the fact that it can solve the hierarchy problem. Hence, as HMHW points out, it depends who you listen to…

String theory, incidentally, naturally predicts supersymmetry that doesn’t solve the hierarchy problem.

[Dahu]

@Mosier

More about your source link. Right now they are indeed attempting to confirm the spin of the particle they found, but that doesn’t mean that it’s a 50/50 chance of being 0 or 2. I think an analogy is a pretty good way to explain this.

Imagine your friend is giving you directions to his house. He tells you to take first avenue past the red farmhouse on the right, the power plant on the left, the water slide on the right, and the car dealership on the left, to reach his house. It’s the only house in the area, and you’ll recognize it because it’s two stories, painted green, and has a yellow Ford in the driveway.

Now, when you follow his directions, you take first avenue past the farmouse and the power plant and the water slide and the car dealership, and you see a two story house painted green, but you can’t see the driveway yet. What color do you expect the car in the driveway is? Even though there are thousands of possible colors, you are quite certain the car will be a yellow Ford, right? It would be quite unexpected for it to be a red corvette.

In the same way, it would be quite unexpected for the particle assumed to be the Higgs boson to have a spin of 2.

Like the analogy.

But before these experiments, wasn’t a similar analogy also true - that as most (all?) of the other particles predicted by the SM were found, then it was almost certain that when they went looking for it they would find the Higg’s? What were people estimating the chances of not finding it beforehand?

[Half_Man_Half_Wit]

@iamnotbatman

String theory, incidentally, naturally predicts supersymmetry that doesn’t solve the hierarchy problem.

In what sense? I’m no string theorist, but the way I heard the story, you postulate (worldsheet) SUSY in order to be able to describe fermionic excitations, so how does this prediction come about? (Of course, string theory has extra dimensions, so you don’t need SUSY for the hierarchy problem…)

[iamnotbatman]

@Half_Man_Half_Wit

In what sense? I’m no string theorist, but the way I heard the story, you postulate (worldsheet) SUSY in order to be able to describe fermionic excitations, so how does this prediction come about? (Of course, string theory has extra dimensions, so you don’t need SUSY for the hierarchy problem…)

OK, it depends on how you define “predict.” String theory doesn’t work without supersymmetry, and string theory was the motivating context in which supersymmetry was first invented. Since string theory requires supersymmetry, it could be said to predict supersymmetry. And in string theory landscape, naturalness is of course not a problem; the phase space of supersymmetry models in the context of the landscape tends to suggest SUSY being broken at a higher scale. A good introduction might be the first paper on Split SUSY, here. Split SUSY is an example of supersymmetry “predicted” (ie favored) by string theory which does not solve the hierarchy problem.