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Higgs Boson Detected?
Travis McGee writes "A scientist says one of the most sought after particles in physics - the Higgs boson - may have been found, but the evidence is still relatively weak. The Higgs boson explains why all other particles have mass and is fundamental to a complete understanding of matter. The report was published in Nature magazine and the BBC has an article." The last time the elusive particle was in the news was 2001.
- less than 3 sigma deviation from background: ignored
- 3-5 sigma deviation: evidence for
- 5+ sigma deviation: discovery
At 9% chance he's wrong, it sounds like he's at around 2 sigma. Which is pretty much ignored by the scientific community. Which is why the LEP was shut down to make way for the LHC.The funny thing is this article in the "related links" section: 'God particle may not exist'
In that December 2001 article, we have statements like this: "Their conclusion is that there was nothing in the data at all to suggest the Higgs is out there - certainly not at energy masses of up to 115 Gigaelectronvolts (GeV), way past the level of 80 GeV where the boson was expected to show itself."
Contrast with March 2004: "Dr Renton cites indirect evidence taken from observations of the behaviour of other particles in colliders that agrees with the figure of 115 gigaelectronvolts for the mass of the Higgs boson."
The great thing, though, is how science done right is self-correcting. As soon as this boson was declared unlikely, researchers apparently began to attempt to prove that it did exist. Now that there's a theory that it exists, more researchers will begin trying to prove them wrong. Eventually, with all the facts out in the open, science will discover something approaching the ideal theory, which will likely be something unexpected.
It's like Microsoft vs. open source... find a bug in Windows, and it takes 9 months to patch it. Find a bug in Linux, and someone will patch it the same day...
(Obligatory disclaimer: I'm no physicist, and talk of "energy masses" and "gigaelectronvolts" makes my head spin. May as well be talking about Vitamegavegamin.)
Stressed? Me? Of course not. Stress is what a rubber band feels before it breaks, silly.
According to this March 10 story at the Above Top Secret News Network, it is not actually news:
Posted by: Throwaway
On: Wed March, 10 2004 @ 20:33 GMT
This is old news, folks. Just signed up to tell you that BBC is recycling news stories to fill column-inches. I'm sitting on site a few hundred yards from the beamline. LEP shut down a couple of years ago, and there's been no real news since then.
My group works exclusively on Higgs searches and more or less leads the effort here on experimental analysis in that direction. Sorry.
9% is nowhere near close enough. And the BBC story is wrong - Higgs doesn't really explain where the mass of all particles comes from. And "the God particle" is a stupid marketing ploy for funding agencies. There's a lot more to go. Higgs has been the fundamental theory hole, not pivot. If we get one, it'll round things off nicely.
Stay tuned for 2007-2008 (9?)
In 1930 or so, Wolfgang Pauli noticed that in all interactions, this strange combination of variables (what we now call spin) stayed constant through those interactions. But he couldn't fully explain beta-decay, or when the nucleus of an atom spits out an electron ... this 'spin' wasn't conserved.
So, Pauli invents an incredible particle: it has little or no mass, hardly ever interacts with anything, but carries spin. It helped his equations balance.
Naturally, most of the scientific world scoffed at his idea at the time: it implied that hundreds of trillions of these things would be flying through space every second. AND they were undetectable?!? Quite a stretch.
But history bore him out, and neutrinos exist. You can see a history of the neutrino here, for more info, including current discrepancies with our understanding of neutrinos.
Quantum mechanics kinda developed the same way ... crazy math with weird conclusions went AHEAD of experiments, and those experiments bore out the math 5 or 10 years later. I believe the same approach is being taken for the matter in the universe (WMAP predicitons), as well as the higgs boson.
Just my 0.02 euro.
"Diplomacy is something you do until you find a rock." --Richard Pound
So, the standard model defines 16 particles. But if there are only those 16, then none of them have mass, so there must be another one, that magically provides mass for the others. Weird. You can't make this stuff up, folks... err... oh, wait.
Nice try. Apart from the fact that the article's description of the role of the Higgs in generating masses isn't quite correct, there's your implication that this is some what frivolous. Well, if you evaluate scientific theories by the accuracy of their predictions, an argument can be made that the standard model of elementary particle physics is the most successful scientific theory of all time -- ranging from making correct predictions of electrodynamic phenomena out to absolutely absurdly large numbers of significant digits, to making predictions about the numbers of certain types of particles that will exist ("there will be one more light neutrino species, but no more after that") -- subsequently confirmed.
There are a lot of things you can fairly criticize particle physicists about; but suggesting that the standard model is removed from reality isn't one of them.
Reminds me of the "dark energy" idea: "Well, we can only find 1/3 of the matter that we know should exist, so the rest is.. well, it's just the dark energy that we can't detect!"
Like many people, you've got "dark matter" and "dark energy" confused (I personally hate the "dark energy" term, and wish Michael Turner (I think it was him) hadn't coined it; but we're stuck with it now). And while either of them may someday turn out to have been a wrong turn in the history of cosmology, neither is an unfounded concept.
The Higgs boson explains why all other particles have mass
More correctly, the existence of the Higgs boson validates an assumption in a theory and theory is what claims to explain why all other particles have mass. The important thing to remember is that these are theories that are explaining things; real world particles explain nothing.
First of all, "dark energy" has nothing to do with the missing mass problem. You meant to say "dark matter." Dark energy is another term for the cosmological constant, a parameter tied to the observed acceleration of the universe. There are completely independent measurements that require this parameter, including supernova acceleration studies and incredibly precise cosmic microwave background measurements.
Regarding dark matter, you seriously trivialize the situation. It's not a case of astronomers being unable to find the matter, like it's a lost set of keys. We see that galaxies and clusters of galaxies experience more gravitation attraction than they should, based on the visible mass. Hence "dark matter." But it's not just that we can't see it; big bang nucleosynthesis tells us that only a small fraction of the matter in the universe is baryonic. Baryons are the normal particles that "stuff" is made of, like you, me, stars, dust, and gas. That means that the missing mass is not simply something we're not seeing (because it doesn't glow, for example), but is something utterly different.
We're not missing mass because we're not good at finding stars, or dust, or whatever. We're missing it because it's something completely, fundamentally different from all of that stuff.
Hm. Go learn some of the math involved, and come back when you understand that there really are some compelling reasons for Higgs to come into the picture. Or are you aware of something that's been overlooked? You have a good reason that photons are massless and W/Z bosons aren't? Can you tell me why electrons weigh less than taus? Can you tell me how "mass" comes about? That plus the fact that the possibilities include standard model Higgs and SUSY Higgs, light Higgs, heavy Higgs, MSSM doublet Higgs, all in different variations... We didn't ask for all these particles to show up. We're just trying to figure out what we're seeing in nature.
Here's a recent overview article on the status of Higgs in the LEP data (refinement and rehashing of stuff that's not really new anymore). Go to http://arxiv.org/PS_cache/hep-ph/pdf/0402/0402231. pdf
The total LEP experiment sigma comes out as less than two for a 115 GeV SM Higgs. That's not compelling. However, some VERY nice "gold-plated" 4-jet events were seen in the ALEPH detector, and it seems like there's a good chance that 115 GeV will be a good place to look in LHC.
Speaking of LHC, here's a webcam that lets you look at the ATLAS detector being built. :)
http://atlaseye-webpub.web.cern.ch/atlaseye-webpub /web-sites/pages/UX15_webcams.htm
If anyone (like me) needs a refresher on what the Higgs Boson entails from the perspective of physics, there's a nice collection of one-page explanations at http://www.phy.uct.ac.za/courses/phy400w/particle/ higgs.htm.
Again, these are two completely separate concepts. One makes things fly apart, the other helps keep things together.
Since the 1930's, it has been known that stars in galaxies orbit the center of the galaxy more quickly than they should, based on the visible matter. This requires extra "dark matter" to provide enough gravitational force to result in the observed rotational speed.That's not quite fair ... as a low energy effective theory, the SM is spectacularly successful, and is not in demonstrable conflict with any experiment to date. This success is underpinned by a reliance on a Higgs-like mechanism. The SM one-doublet model may be economical and incomplete, but because the rest of the model holds up so well to tests, it is hard to see how the correct model wouldn't necessarily have a SM Higgs-like excitation in the low energy limit. Which isn't to say that it will be exactly like the SM Higgs, just that it won't look too different at low energy, or we already would have seen its impact in precision eletroweak measurements, for instance.
it uses a scalar field ... of which there are no other examples in nature
That isn't quite a fair argument, of course ... we have no experimentally confirmed examples of fundamental tensor fields, either, but most of us think gravitons exist :-)
And there isn't a compelling reason to expect light scalar fields, in fact quite the opposite. You are no doubt aware of the quadratic renormalization of scalar masses, whereby their masses are "pulled up" by any interactions they have. So you probably wouldn't expect massless or even light scalars, unless they don't have any interactions (in which case we wouldn't know about them). In SUSY, for instance, you would generically expect scalars to end up with masses near the SUSY breaking scale, something like a few hundred GeV ... well, except for the lightest Higgs, which has to have a mass somewhere in the neighborhood of 100-200 GeV to stabilize the electroweak symmetry breaking transition.
This would allow much more complicated Higgs interactions...
There are plenty of examples of non-fundamental scalar Higgs mechanisms, and even mechanisms that employ fundamental scalars that must be heavier than we've seen. SUSY, dynamical symmetry breaking, extra-dimensions, deconstruction, etc. But they all have their own challenges, usually conflict with existing data. That, of course, is the cardinal sin in physics. No matter how lovely your theory, Nature is always right, and if you don't agree with Her, you lose. :-)
To nitpick, the "N=3" discovery is only valid in the energy range of interest.
To pick nits with your nitpick (how's that for a turn of phrase?), N=3 is the statement that there are no more SM like light neutrinoes, and hence there are only three generations of SM fermions. The precision Z boson line shapes from the four LEP experiments provide exceedingly severe constraints on weakly interacting fermions, and those line shapes are inconsistent with the presence of fermions that we haven't yet seen which are lighter than half the Z mass. In particular, the invisible line shape is consistent with more than 2.something and fewer than 3.somethingelse neutrinos, and since we already know that there are at least three, we conclude that there are only three.
It would have to have odd mixing angles, sure, but a fourth family isn't out of the question.
It would have to have VERY odd interactions with the SM gauge fields, to the point where it wouldn't look much at all like the rest of the SM families. There just isn't room in the precision electroweak data for much else that looks anything like the known SM fermions. In this sense, you probably wouldn't call this "fourth family" a family at all. Additionally, SM like interactions with heavy neutrinos are probably ruled out by cosmological over-closure arguments and astrophysical stellar models, although those arguments are somewhat more tentative.
There might, of course, be non-standard model like heav