Higgs Boson or just a new particle?

When I read articles declaring the discovery of the Higgs Boson I come across a note that the research teams are NOT identifying this particle as the Higgs Boson.

“However, the teams, which included hundreds of Britons, stopped short of declaring it the Higgs boson, saying more work is needed to confirm its properties.” Full Article

“They are stopping just short of saying that they have discovered the Higgs boson, which has been postulated to explain why matter has mass and why mass plus gravity equals weight. They are saying only that they have discovered a new subatomic particle that is largely consistent with the predicted Higgs particle.” Full Article

This one at least presents what the scientists are saying; that the “new boson “sings and dances like” the theoretical particle.” Later in the same article “The collider will provide more data later this year, giving scientists a more complete picture of the observed new particle. Researchers will try to determine whether it is a Higgs boson, the particle predicted by the Standard Model.”

So I understand everyone watching the experiment is pretty sure, this is the Higgs Boson!, however, if the scientists doing the work are not declaring this the Higgs Boson quite yet, why is everyone else?

They’re pretty sure it is as well. They’re just being very careful.

I understand that, but why isn’t everyone else following their example and being cautious?

Because a one-in-a-hundred-trillion chance of being wrong is good enough for a regular person to say they’re sure of something, where scientists are only barely starting to get comfortable using cautious optimism with such chances.

Other people have very little to lose if they’re wrong, particularly non-scientists like reporters. They simply run a new story. Oops those guys were wrong when they told us it was almost certainly a Higgs. Furthermore, it’s been some time since a new particle has been found, and people have some idea what “gives the other particles mass” means. If they find an axion, I suspect the general public will start yawning half way through the description of how it helps explain the Strong CP Problem.

Is there really just a “one in a trillion chance” that this boson will have a spin 2? From my limited understanding, we know it is either a spin 0 or a spin 2; but to be the Higgs Boson it must have a spin 0. Ref

Who is everybody else? Every, literally every, article I’ve read includes something about the uncertainty and how it won’t be settled for years. Headlines won’t reflect that, true, but so what? Could you stop linking to articles that get it correct and link to the ones that don’t?

It’s not just headlines. I know you’ve been in on the discussions here about the discovery and you’re familiar that any mention to caution is a footnote, rather than the focus of the discussion. Considering what two prominent scientists are saying;

Prof. Higgs, “It’s very nice to be right sometimes… it has certainly been a long wait.”
Hawking, Britain’s most famous living scientist, said the discovery should earn Higgs the Nobel Prize, but admitted in an interview that it would make him $100 poorer.

It makes no sense to me. Higgs hasn’t been proven right – not yet. Hawking hasn’t lost the bet – not yet.

I don’t know what the actual level of certainty is, and I don’t even understand what the scientists are looking for. I do know that scientists in general tend to be much more cautious about their certainty than the rest of us, which is all I was trying to say.

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.

There is about a 1-in-3 million chance that the detected new particle is not actually a detected new particle. That’s the solid observation.

The properties of this new particle are much less well known. The most telling features will be the production rate and the decay rates to various other particles. The observed production rate agrees with the Standard Model expectation for a Higgs to within 20%, but that’s the most that can be said about that at the moment. The half-dozen decay modes measured so far also agree in rate with SM Higgs expectations, but the errors here are even larger (100%-ish). Optimistic physicists are salivating over the fact that both CMS and ATLAS see no noticeable rate of the Higgs decaying into two tau leptons, but the statistical errors on that decay channel are plenty large enough to accommodate the Standard Model Higgs expectation still.

In any case, it would be very odd for Nature to put a completely random boson right in the wheelhouse of where the Higgs should be and give it a production rate within 20% of a SM Higgs (why not a factor of 10 higher if it’s some unrelated particle?) and have it decay to various other particles in basically the right proportions for a Higgs, even if we’ve only measured these rates so far to within a factor of 2.

So, I’m ready to put my money on “Higgs” even though we really do need to measure all these rates much better to know that there isn’t something unexpected happening. (If there is, it is much more likely to be a Higgs-related perturbation to the theory rather than an out-of-left-field boson. Also note that this statement is dripping with theoretical bias.)

I figure it’s budget-allocation time. Hence the hedging.

I know everyone’s going to jump all over me; but I don’t believe in the Higgs Boson, or “gravitons.” I still say they’re barking up the wrong tree.

(Don’t mess with me! I have an apostrophe, and I know how to use it! Bwa-ha-ha-haaaa!)

Hm. I wonder. Is there a really strong argument for the spatial effects we perceive as mass being dependent on a specific boson’s structure/form/nature/whatever, or is it a quality of even more fundamental particles?

I expect any answer would fly over my head, nay, through it like a neutrino.

I thought the real problem with finding the Higgs at this mass was that there are other particles that the SM also predicts along with the Higgs and at this mass, at least some of them should have been spotted already.

To the best of my knowledge, the plain SM doesn’t predict any more particles besides the Higgs; of course, there are various extensions (most popularly the supersymmetric ones) that do, but so far, there’s no experimental indication that any of those gets it right (or more right than the SM, at any rate).

As for ‘how do we know it’s the Higgs?’, well, it’s simply that all of its properties we have observed so far agree with those we expect for the Higgs, and there’s no expectation for there to be another particle with those particles. In particular, while it’s true that the observed particle might have spin 2 instead of 0, the only spin 2 particle we’d expect is the graviton, which is necessarily massless. So while it’s always possible that something unknown is doing we don’t know what, the safe bet here is the Higgs.

As an analogy, take the identification of any everyday object, such as a car: you know your friends car has a certain model, make, mileage, top speed, hood ornament, etc. So when your friend loans you his car, identification of model, mileage, make etc. will make you reasonably confident that this car is, in fact, your friend’s, even if you haven’t yet seen the hood ornament. Of course, it could be that your friend bought a different one, identical in all the respects you’ve yet observed to the old one, or that through some mishap, this isn’t in fact your friends car, but only a very similar one. But it’s a philosophically sterile position to admit such possibilities a high a priory probability.

According to this Live Science article

And further on

So caution is indeed advisable and I think the issue of additional gauge fields and their bosons will become more of an concern.

The issue isn’t additional gauge fields, the issue is that the Higgs-like particle we found may decay in a way that deviates from the Standard Model prediction. This would be very exciting! It could deviate from the Standard Model prediction even if it is the Standard Model Higgs, if, for example, there are some dark matter particle we aren’t accounting for. Or it could be one of several supersymmetric Higgs bosons. Unfortunately, while the data does show minor “hints” that something strange might be going on, none of my fellow physicists are taking those “hints” seriously yet, because the statistical error is so large that they are most likely the result of a statistical fluctuation.

While of course the physicists are careful in teasing apart the details as time moves forward, at this point I would say there is no reason to be cautious about the excitement. No matter what we found, it is exciting, and almost certainly responsible for electroweak symmetry breaking (the main point of the Higgs)!

If this is indeed the Higgs Boson, isn’t supersymmetry feeling a bit ill about now? I was under the impression that the Higgs Boson had to be lighter to fit nicely with supersymmetry.

Thanks for this info. That helps clarify the spin and helped me to find this recent publication on why they tend to believe this is the Higgs Boson. Here

There are quite a few supersymmetry models. In the simplest, they prefer a lower Higgs mass. At higher masses, more fine-tuning is often required. But at the end of the day 125 GeV fits OK with many models of supersymmetry.

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). But you can always write down SUSY models in which breaking should occur at some higher scale, such that it couldn’t have been seen up to know; the only question is how well-motivated these models really are.

As for the Higgs mass of 126 GeV, you’re right that the simplest supersymmetric extension of the SM (MSSM – minimally supersymmetric standard model) would naturally prefer a lower Higgs mass, constrained to about the value of the Z boson (~90 GeV). However, this prediction is altered by taking into account radiative corrections, and can be pushed to a maximum of about 125 GeV – so the observed Higgs may just be consistent with that. But even if it isn’t, there are other ways to extend the SM (such as the imaginatively named NMSSM, next-to-minimally supersymmetric standard model) in which a 125 GeV Higgs can be accommodated. For example, here’s a list of Higgs mass* predictions: several of those getting it approximately right are supersymmetry based.

*So, who’s up for an annual ‘Higgsmas’ celebration on July 4th every year?