Thread: CERN set to report probable Higgs Boson sighting this week (Reuters)

Can anybody provide a basic explanation of how the Higgs was predicted?

Wasn't it done out of symmetry considerations; I get the impression that the current model points towards a simple mathematical structure of which the Higgs is an unseen part?

It'd be very philosophically interesting that this approach works.

Pretty sure there's a massive equation, where they basically had a few unknowns.

Originally Posted by DuB

At the risk of further increasing the pedantry level, I have some comments on the "certainty" issue.

I was confused by the 1/400 figure (what the hell does it mean to be "1/400 certain"?) so I poked around a bit to see where that figure comes from. Apparently theory holds that the presence of a Higgs should manifest itself as an excess of energy in the "gamma-gamma channel" (whatever that is), and the event that is causing all this fuss was the observation of an excess of energy in the expected channel of about 3 or 3.5 standard errors above what is normally expected in that channel. In other words, if you think about the range of energy levels that one would expect to observe in that channel--when nothing is actually going on!--as a normal distribution or "bell-shaped curve" of energy levels, then this excess was about 3 standard deviations (or sigma, which the authors of the article in the OP amusing spell "sygma") above the mean of that sampling distribution, which is starting to get pretty far out into the positive tail. The area under the curve (or probability density) of an event greater than 3 sigma or less than 3 sigma is about .00269, or about 1/369. As far as I can tell, this is where the 1/400 figure comes from.

Let's be careful about how we interpret this 1/369 figure. Assuming that what I wrote above is indeed where the figure comes from, then this figure is basically a "p-value," as cmind noted. That is, it is the probability of the observed data, conditional on the hypothesis being false. In other words, if it is in fact the case that there was no Higgs at all, then the odds of seeing an excess of energy of the magnitude that we did are about 369 to 1 against. What is very important to realize is what this figure is not. It is not--and this is important--the probability of the hypothesis being true (or false), conditional on the observed data (that is, the probability that we actually observed a Higgs). We would call such a probability a posterior probability. Arguably this probability is what we really want to know most. Unfortunately, in general P(D|H) does not equal P(H|D). Arriving at this latter probability requires additional information, namely, a distribution of prior probabilities. Although closer, it is also not a type 1 error rate (that is, the probability that we have incorrectly concluded that we observed a Higgs). Such a probability is called an alpha level, and is in fact specified a priori by the data analyst--we know that the probability of a type 1 error will be equal to the chosen alpha level before we ever collect any data.

None of this is to denigrate the present findings. But let's be clear about what exactly is meant when we talk about things like 1/400 certainty.

Heh, well it's been a couple of years since I took stats in university

Being woefully uneducated in everything considered physics, Phil Plait helped me wrap my head around this stuff: Mass effect: Maybe Higgs, maybe not | Bad Astronomy | Discover Magazine

Originally Posted by DuB

At the risk of further increasing the pedantry level, I have some comments on the "certainty" issue.

I was confused by the 1/400 figure (what the hell does it mean to be "1/400 certain"?) so I poked around a bit to see where that figure comes from. Apparently theory holds that the presence of a Higgs should manifest itself as an excess of energy in the "gamma-gamma channel" (whatever that is), and the event that is causing all this fuss was the observation of an excess of energy in the expected channel of about 3 or 3.5 standard errors above what is normally expected in that channel. In other words, if you think about the range of energy levels that one would expect to observe in that channel--when nothing is actually going on!--as a normal distribution or "bell-shaped curve" of energy levels, then this excess was about 3 standard deviations (or sigma, which the authors of the article in the OP amusing spell "sygma") above the mean of that sampling distribution, which is starting to get pretty far out into the positive tail. The area under the curve (or probability density) of an event greater than 3 sigma or less than 3 sigma is about .00269, or about 1/369. As far as I can tell, this is where the 1/400 figure comes from.

Let's be careful about how we interpret this 1/369 figure. Assuming that what I wrote above is indeed where the figure comes from, then this figure is basically a "p-value," as cmind noted. That is, it is the probability of the observed data, conditional on the hypothesis being false. In other words, if it is in fact the case that there was no Higgs at all, then the odds of seeing an excess of energy of the magnitude that we did are about 369 to 1 against. What is very important to realize is what this figure is not. It is not--and this is important--the probability of the hypothesis being true (or false), conditional on the observed data (that is, the probability that we actually observed a Higgs). We would call such a probability a posterior probability. Arguably this probability is what we really want to know most. Unfortunately, in general P(D|H) does not equal P(H|D). Arriving at this latter probability requires additional information, namely, a distribution of prior probabilities. Although closer, it is also not a type 1 error rate (that is, the probability that we have incorrectly concluded that we observed a Higgs). Such a probability is called an alpha level, and is in fact specified a priori by the data analyst--we know that the probability of a type 1 error will be equal to the chosen alpha level before we ever collect any data.

None of this is to denigrate the present findings. But let's be clear about what exactly is meant when we talk about things like 1/400 certainty.

Perfect explanation mate. Thanks for that.

From Marvo's link:
"The Higgs Boson is a particle that Peter "P-Higgy" Higgs came up with to solve a bit of a puzzle in our understanding of particle physics. He did this way back in the sixties, and we've been trying to hunt the fucker ever since. It sometimes gets called the God particle, which is retarded. Please don't."

Originally Posted by Xei

Can anybody provide a basic explanation of how the Higgs was predicted?

I'll take a stab your question. If we look at certain fundamental forces, particularly the electromagnetic and weak nuclear force we notice that they are fairly different in appearance, whereas the electromagnetic force extends over great distances, [actually it appears to have an infinite range] and the weak nuclear force has an extremely short range confined to the nuclei. The electromagnetic force is mediated by a zero mass photon particle and the weak nuclear force is mediated by 3 very massive bosons.

What becomes interesting is that we can unify or bring into a common umbrella, the electromagnetic and weak nuclear reactions and what actually confirms this is the discovery of the +/- W and Z bosons back sometime in the 80's which further supports that this was a very good way to look at things in physics. However, this being the case then this begs the question as to why is it that these two interactions (electromagnetic and weak nuclear interactions) are within a common umbrella, why then is the particle mediator for one force extremely massive while the other has zero mass today? If we go back to the early part of the Universe, we can see that the temperature was hot enough that these two forces were virtually indistinguishable from one another.

Originally Posted by Xei

Wasn't it done out of symmetry considerations; I get the impression that the current model points towards a simple mathematical structure of which the Higgs is an unseen part?

You're absolutely correct in your thinking. Once the Universe cooled down, the symmetry between the two forces were apparently broken. If we go back before this symmetry was broken we will discover that the particles that mediates all of the forces has zero mass. The photon still appears the same today but the W and Z bosons have apparently put on some significant weight..lol. So the question remains, how?

If there is a Higgs-field that all of these particles interact with, then this could explain the differences in masses pertaining to these particles because they would apparently be different from interactions with the Higgs-field. If the Higgs-field exist this will not only explain why the W and Z bosons are so massive it will also add to the completion of the Mendeleev periodic table, not to mention this will also predict that there is a Higgs-boson and give it a kind of range of energies that would pretty much reaffirm all the stuff that we knew before. So The Higgs is the final undiscovered piece out of the standard model. We've found the top quark, I think about 5 or 6 years ago, I can’t remember exactly, but that left the Higgs boson as the one remaining standard model of particle physics particle that we haven’t discovered.

I'm pretty optimistic on the future discovery for this particle. I wonder if it's a super-symmetry boson or standard. The LHC will more than likely be shut down over the winter months and things will resume sometime March or April but they will probably reach a Sigma 5 late fall 2012 or early spring 2013.