July 5, 2012

Higgs boson discovered?

The elusive subatomic particle, dubbed "the God particle", or at least something that looks a lot like it, has been finally found, according to an announcement by the European Organization for Nuclear Research (CERN), whose particle accelerator, the Large Hadron Collider (LHC), spans many kilometers underground the French-Swiss border near Geneva.

"We observe in our data clear signs of a new particle, at the level of 5 sigma, in the mass region around 126 GeV. The outstanding performance of the LHC and ATLAS and the huge efforts of many people have brought us to this exciting stage", said ATLAS experiment spokesperson Fabiola Gianotti, "but a little more time is needed to prepare these results for publication".

"The results are preliminary but the 5 sigma signal at around 125 GeV we’re seeing is dramatic. This is indeed a new particle. We know it must be a boson and it’s the heaviest boson ever found", said CMS experiment spokesperson Joe Incandela. "The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks".

While the implications of this discovery are yet to be refined there is almost no doubt that it will strongly affect our understanding of nature confirming the theoretical set of the so-called Standard Model of particle physics.

The unification theory or Theory of Everything (ToE), which would fuse particle physics and space-time (and gravity) physics described in Einstein's General Relativity is still out of our immediate reach, however consolidating the Standard Model should provide more solid basis for such efforts.

The Higgs Boson is involved in the Higgs mechanism: the why behind particle mass.

4 comments:

  1. "the why behind particle mass."

    Just FYI, while that is the way it is commonly described, a more true statement would be that it is "the why behind FUNDAMENTAL particle mass" (i.e. quarks, various iterations of electrons, weak force carrier particles). Almost all of the mass in an ordinary matter's atoms comes from protons and neutrons (electrons are extremely light relative to protons and neutrons and nuclear binding energy between protons and neutrons is fairly modest relative to the mass of the protons and neutrons themselves) and the vast majority of mass in a proton or neutron comes not from their constituent up and down quarks (which is created via the Higgs boson), but from the mass generated by the exchange of gluons between the three quarks that make up each proton and each neutron, even though, in isolation a gluon has a rest mass of zero. Most of the ordinary mass in the universe consists of binding energy that holds protons and neutrons together, not the fundamental particles that obtain their mass via the Higgs mechanism itself. (Dark matter and dark energy are stories for another day.)

    The Higgs boson is also very important because it has a mathematical role in giving rise to something called vacuum stability, which, if it were absent, would cause big bang class explosions to occur on a regular basis in empty space out of nothing - which wouldn't be good for life on Earth.

    The new results are ruling out far more potential theories of everything than they are validating, however. Now, we only need one, so we don't need to be terribly worried about this fact, but many of the leading contenders for theories of everything (or grand unified theories that explain everything but gravity) are looking less impressive than they did ten or twenty years ago, as a result of these discoveries.

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    1. I understand that strings theory is more or less so "perfect" that can't be really challenged, right? For some this is a virtue, for others a defect. But unusual in any case. So I presume it withstands but probably other theories were reliant on lack of Higgs or certain quite specific values for Higgs, right?

      As for mass, that's what I understood more or less: since being a child, I was puzzled by how could it be that protons/neutrons were MUCH heavier than their component quarks (teachers would avoid explaining when asked), so when I read that Higgs was involved in mass, I immediately thought of quarks and quark triplet particles and the like.

      However I always think all fundamental being expansions of Plank space and photons (not sure how but must be that almost necessarily - my stubborn intuition), and photons are massless, so probably (my wild guess) Higgs' mechanism is somehow involved in the mass of every particle except the hypothetically fundamental massless photons.

      How that can be conciliated. Unsure but I hope Superstrings Theory can one way or another. I don't care about a zillion dimensions (IMO there should be infinite) but I care about how matter (mass) is produced from raw space and energy, what seems in need of a good explanation.

      Particle physics tend to take fundamental particles for granted. I do not: there are too many of them: photons should be enough.

      Hopefully we'll something after this finding, it should force physicists to focus and not drift away too much.

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    2. String theory is seeing a lot of defection from its heyday, in part because the theoretical folks have a hard time deciding what it predicts, and in part because those things it does predict aren't showing up in experiment yet.

      Essentially every version of string theory has embedded within it a theory of all of the forces except gravity called "supersymmetry" (SUSY for short), in some version of SUSY or another. But, there is as of yet no real direct positive experimental evidence for SUSY which does have all sorts of testable predictions. One after another of those versions of SUSY are being ruled out by experiment, although the entire concept isn't dead yet.

      We are at a point where both the Standard Model of Particle Physics (which includes the Higgs boson) is very nearly complete with no definitive gaps, and where there are lose ends (like dark matter) whose solution currently seems to be overconstrained by the evidence with no viable theories that fit it all. Deep theoretical inconsistencies between general relativity and the Standard Model remain unresolved despite decades of efforts to reconcile the two in which experimental evidence at the points of intersection where they could be inconsistent is not possible to obtain yet. There are also a number of oddball experimental results out there that could turn out to be flukes or could mean something.

      We aren't at "the end of physics" yet, but the field is in many respects more adrift than it has been in a long time despite a wealth of new experimental evidence, because all of the beyond the Standard Model, "new physics" darlings of theoretists keep getting killed off by the data.

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    3. I'm not following the matter with such a great interest anymore but I understand that in 2009-10 there were several experimental landmarks that appeared to confirm String Theory quite strongly:

      http://leherensuge.blogspot.com.es/search/label/String%20Theory

      The category includes two predictions confirmed (re. superconductors) and another one made (re. qubits).

      "We are at a point where both the Standard Model of Particle Physics (which includes the Higgs boson) is very nearly complete"...

      But that's from where we come, not where we go to. The Standard Model is not a ToE, just part of whatever the actual ToE is. I consider the Standard Model confirmations rather "trivial" because it is one of the two pillars of any ToE. Einstein's theory did not come from debunking Newton's but from going beyond it. Same for any possible ToE, unless we have really missed something truly important, what I doubt.

      Obviously we need something more than just the Standard Model, which does not explain Everything.

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